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dart / sdk.git / acb673ca26bfc1934b052aeef04ea8d4cdf4a56b / . / pkg / dev_compiler / lib / src / compiler / code_generator.dart
blob: 9f70c8dbed50cac38d5ccbc9d0741328c6d13c0e [file] [log] [blame]
// Copyright (c) 2015, the Dart project authors. Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.
import 'dart:collection' show HashMap, HashSet;
import 'dart:math' show min, max;
import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
import 'package:analyzer/dart/ast/ast.dart';
import 'package:analyzer/dart/ast/standard_ast_factory.dart';
import 'package:analyzer/dart/ast/standard_resolution_map.dart';
import 'package:analyzer/dart/ast/token.dart' show Token, TokenType;
import 'package:analyzer/dart/element/element.dart';
import 'package:analyzer/dart/element/type.dart';
import 'package:analyzer/src/dart/ast/token.dart' show StringToken;
import 'package:analyzer/src/dart/element/element.dart';
import 'package:analyzer/src/dart/element/type.dart';
import 'package:analyzer/src/dart/sdk/sdk.dart';
import 'package:analyzer/src/generated/engine.dart' show AnalysisContext;
import 'package:analyzer/src/generated/resolver.dart'
show TypeProvider, NamespaceBuilder;
import 'package:analyzer/src/generated/type_system.dart'
show StrongTypeSystemImpl;
import 'package:analyzer/src/summary/idl.dart' show UnlinkedUnit;
import 'package:analyzer/src/summary/link.dart' as summary_link;
import 'package:analyzer/src/summary/package_bundle_reader.dart';
import 'package:analyzer/src/summary/summarize_ast.dart'
show serializeAstUnlinked;
import 'package:analyzer/src/summary/summarize_elements.dart'
show PackageBundleAssembler;
import 'package:analyzer/src/summary/summary_sdk.dart';
import 'package:analyzer/src/task/strong/ast_properties.dart';
import 'package:path/path.dart' show isWithin, relative, separator;
import '../closure/closure_annotator.dart' show ClosureAnnotator;
import '../js_ast/js_ast.dart' as JS;
import '../js_ast/js_ast.dart' show js;
import 'ast_builder.dart';
import 'compiler.dart' show BuildUnit, CompilerOptions, JSModuleFile;
import 'element_helpers.dart';
import 'extension_types.dart' show ExtensionTypeSet;
import 'js_interop.dart';
import 'js_metalet.dart' as JS;
import 'js_names.dart' as JS;
import 'js_typeref_codegen.dart' show JsTypeRefCodegen;
import 'js_typerep.dart' show JSTypeRep, JSType;
import 'module_builder.dart' show pathToJSIdentifier;
import 'nullable_type_inference.dart' show NullableTypeInference;
import 'property_model.dart';
import 'reify_coercions.dart' show CoercionReifier;
import 'side_effect_analysis.dart' show ConstFieldVisitor, isStateless;
import 'type_utilities.dart';
/// The code generator for Dart Dev Compiler.
///
/// Takes as input resolved Dart ASTs for every compilation unit in every
/// library in the module. Produces a single JavaScript AST for the module as
// output, along with its source map.
///
/// This class attempts to preserve identifier names and structure of the input
/// Dart code, whenever this is possible to do in the generated code.
///
// TODO(jmesserly): we should use separate visitors for statements and
// expressions. Declarations are handled directly, and many minor component
// AST nodes aren't visited, so the visitor pattern isn't helping except for
// expressions (which result in JS.Expression) and statements
// (which result in (JS.Statement).
class CodeGenerator extends Object
with ClosureAnnotator, JsTypeRefCodegen, NullableTypeInference
implements AstVisitor<JS.Node> {
final AnalysisContext context;
final SummaryDataStore summaryData;
final CompilerOptions options;
final StrongTypeSystemImpl rules;
JSTypeRep typeRep;
/// The set of libraries we are currently compiling, and the temporaries used
/// to refer to them.
///
/// We sometimes special case codegen for a single library, as it simplifies
/// name scoping requirements.
final _libraries = new Map<LibraryElement, JS.Identifier>();
/// Imported libraries, and the temporaries used to refer to them.
final _imports = new Map<LibraryElement, JS.TemporaryId>();
/// The list of dart:_runtime SDK functions; these are assumed by other code
/// in the SDK to be generated before anything else.
final _internalSdkFunctions = <JS.ModuleItem>[];
/// The list of output module items, in the order they need to be emitted in.
final _moduleItems = <JS.ModuleItem>[];
/// Table of named and possibly hoisted types.
TypeTable _typeTable;
/// The global extension type table.
final ExtensionTypeSet _extensionTypes;
/// The variable for the target of the current `..` cascade expression.
///
/// Usually a [SimpleIdentifier], but it can also be other expressions
/// that are safe to evaluate multiple times, such as `this`.
Expression _cascadeTarget;
/// The variable for the current catch clause
SimpleIdentifier _catchParameter;
/// In an async* function, this represents the stream controller parameter.
JS.TemporaryId _asyncStarController;
// TODO(jmesserly): fuse this with notNull check.
final _privateNames =
new HashMap<LibraryElement, HashMap<String, JS.TemporaryId>>();
final _initializingFormalTemps =
new HashMap<ParameterElement, JS.TemporaryId>();
JS.Identifier _extensionSymbolsModule;
final _extensionSymbols = new Map<String, JS.TemporaryId>();
JS.Identifier _runtimeModule;
final namedArgumentTemp = new JS.TemporaryId('opts');
final _hasDeferredSupertype = new HashSet<ClassElement>();
/// The type provider from the current Analysis [context].
final TypeProvider types;
final LibraryElement dartCoreLibrary;
final LibraryElement dartJSLibrary;
/// The dart:async `StreamIterator<>` type.
final InterfaceType _asyncStreamIterator;
/// The dart:core `identical` element.
final FunctionElement _coreIdentical;
/// The dart:_interceptors implementation elements.
final ClassElement _jsArray;
final ClassElement _jsBool;
final ClassElement _jsNumber;
final ClassElement _jsString;
final ClassElement boolClass;
final ClassElement intClass;
final ClassElement doubleClass;
final ClassElement interceptorClass;
final ClassElement nullClass;
final ClassElement numClass;
final ClassElement objectClass;
final ClassElement stringClass;
final ClassElement functionClass;
final ClassElement privateSymbolClass;
ConstFieldVisitor _constants;
/// The current function body being compiled.
FunctionBody _currentFunction;
HashMap<TypeDefiningElement, AstNode> _declarationNodes;
/// The stack of currently emitting elements, if generating top-level code
/// for them. This is not used when inside method bodies, because order does
/// not matter for those.
final _topLevelElements = <TypeDefiningElement>[];
/// The current element being loaded.
/// We can use this to determine if we're loading top-level code or not:
///
/// _currentElements.last == _topLevelElements.last
//
// TODO(jmesserly): ideally we'd only track types here, in other words,
// TypeDefiningElement. However we still rely on this for [currentLibrary] so
// we need something to be pushed always.
final _currentElements = <Element>[];
final _deferredProperties = new HashMap<PropertyAccessorElement, JS.Method>();
BuildUnit _buildUnit;
String _libraryRoot;
bool _superAllowed = true;
final _superHelpers = new Map<String, JS.Method>();
List<TypeParameterType> _typeParamInConst;
/// Whether we are currently generating code for the body of a `JS()` call.
bool _isInForeignJS = false;
/// Information about virtual and overridden fields/getters/setters in the
/// class we're currently compiling, or `null` if we aren't compiling a class.
ClassPropertyModel _classProperties;
/// Information about virtual fields for all libraries in the current build
/// unit.
final virtualFields = new VirtualFieldModel();
final _usedCovariantPrivateMembers = new HashSet<ExecutableElement>();
CodeGenerator(
AnalysisContext c, this.summaryData, this.options, this._extensionTypes)
: context = c,
rules = new StrongTypeSystemImpl(c.typeProvider),
types = c.typeProvider,
_asyncStreamIterator =
_getLibrary(c, 'dart:async').getType('StreamIterator').type,
_coreIdentical =
_getLibrary(c, 'dart:core').publicNamespace.get('identical'),
_jsArray = _getLibrary(c, 'dart:_interceptors').getType('JSArray'),
_jsBool = _getLibrary(c, 'dart:_interceptors').getType('JSBool'),
_jsString = _getLibrary(c, 'dart:_interceptors').getType('JSString'),
_jsNumber = _getLibrary(c, 'dart:_interceptors').getType('JSNumber'),
interceptorClass =
_getLibrary(c, 'dart:_interceptors').getType('Interceptor'),
dartCoreLibrary = _getLibrary(c, 'dart:core'),
boolClass = _getLibrary(c, 'dart:core').getType('bool'),
intClass = _getLibrary(c, 'dart:core').getType('int'),
doubleClass = _getLibrary(c, 'dart:core').getType('double'),
numClass = _getLibrary(c, 'dart:core').getType('num'),
nullClass = _getLibrary(c, 'dart:core').getType('Null'),
objectClass = _getLibrary(c, 'dart:core').getType('Object'),
stringClass = _getLibrary(c, 'dart:core').getType('String'),
functionClass = _getLibrary(c, 'dart:core').getType('Function'),
privateSymbolClass =
_getLibrary(c, 'dart:_internal').getType('PrivateSymbol'),
dartJSLibrary = _getLibrary(c, 'dart:js') {
typeRep = new JSTypeRep(rules, types);
}
Element get currentElement => _currentElements.last;
LibraryElement get currentLibrary => currentElement.library;
/// The main entry point to JavaScript code generation.
///
/// Takes the metadata for the build unit, as well as resolved trees and
/// errors, and computes the output module code and optionally the source map.
JSModuleFile compile(BuildUnit unit, List<CompilationUnit> compilationUnits,
List<String> errors) {
_buildUnit = unit;
_libraryRoot = _buildUnit.libraryRoot;
if (!_libraryRoot.endsWith(separator)) {
_libraryRoot += separator;
}
var module = _emitModule(compilationUnits, unit.name);
var dartApiSummary = _summarizeModule(compilationUnits);
return new JSModuleFile(unit.name, errors, options, module, dartApiSummary);
}
List<int> _summarizeModule(List<CompilationUnit> units) {
if (!options.summarizeApi) return null;
if (!units.any((u) => resolutionMap
.elementDeclaredByCompilationUnit(u)
.librarySource
.isInSystemLibrary)) {
var sdk = context.sourceFactory.dartSdk;
summaryData.addBundle(
null,
sdk is SummaryBasedDartSdk
? sdk.bundle
: (sdk as FolderBasedDartSdk).getSummarySdkBundle(true));
}
var assembler = new PackageBundleAssembler();
var uriToUnit = new Map<String, UnlinkedUnit>.fromIterable(units,
key: (u) => u.element.source.uri.toString(),
value: (unit) {
var unlinked = serializeAstUnlinked(unit);
assembler.addUnlinkedUnit(unit.element.source, unlinked);
return unlinked;
});
summary_link
.link(
uriToUnit.keys.toSet(),
(uri) => summaryData.linkedMap[uri],
(uri) => summaryData.unlinkedMap[uri] ?? uriToUnit[uri],
context.declaredVariables.get,
true)
.forEach(assembler.addLinkedLibrary);
var bundle = assembler.assemble();
// Preserve only API-level information in the summary.
bundle.flushInformative();
return bundle.toBuffer();
}
JS.Program _emitModule(List<CompilationUnit> compilationUnits, String name) {
if (_moduleItems.isNotEmpty) {
throw new StateError('Can only call emitModule once.');
}
for (var unit in compilationUnits) {
_usedCovariantPrivateMembers.addAll(getCovariantPrivateMembers(unit));
}
// Transform the AST to make coercions explicit.
compilationUnits = CoercionReifier.reify(compilationUnits);
if (compilationUnits.any((u) => isSdkInternalRuntime(
resolutionMap.elementDeclaredByCompilationUnit(u).library))) {
// Don't allow these to be renamed when we're building the SDK.
// There is JS code in dart:* that depends on their names.
_runtimeModule = new JS.Identifier('dart');
_extensionSymbolsModule = new JS.Identifier('dartx');
} else {
// Otherwise allow these to be renamed so users can write them.
_runtimeModule = new JS.TemporaryId('dart');
_extensionSymbolsModule = new JS.TemporaryId('dartx');
}
_typeTable = new TypeTable(_runtimeModule);
// Initialize our library variables.
var items = <JS.ModuleItem>[];
var isBuildingSdk = false;
for (var unit in compilationUnits) {
var library =
resolutionMap.elementDeclaredByCompilationUnit(unit).library;
if (unit.element != library.definingCompilationUnit) continue;
var libraryTemp = isSdkInternalRuntime(library)
? _runtimeModule
: new JS.TemporaryId(jsLibraryName(_libraryRoot, library));
_libraries[library] = libraryTemp;
items.add(new JS.ExportDeclaration(
js.call('const # = Object.create(null)', [libraryTemp])));
// dart:_runtime has a magic module that holds extension method symbols.
// TODO(jmesserly): find a cleaner design for this.
if (isSdkInternalRuntime(library)) {
isBuildingSdk = true;
items.add(new JS.ExportDeclaration(js
.call('const # = Object.create(null)', [_extensionSymbolsModule])));
}
}
// Collect all class/type Element -> Node mappings
// in case we need to forward declare any classes.
_declarationNodes = new HashMap<TypeDefiningElement, AstNode>.identity();
for (var unit in compilationUnits) {
for (var declaration in unit.declarations) {
var element = declaration.element;
if (element is TypeDefiningElement) {
_declarationNodes[element] = declaration;
}
}
}
if (compilationUnits.isNotEmpty) {
_constants = new ConstFieldVisitor(context,
dummySource: resolutionMap
.elementDeclaredByCompilationUnit(compilationUnits.first)
.source);
}
// Add implicit dart:core dependency so it is first.
emitLibraryName(dartCoreLibrary);
// Visit each compilation unit and emit its code.
//
// NOTE: declarations are not necessarily emitted in this order.
// Order will be changed as needed so the resulting code can execute.
// This is done by forward declaring items.
compilationUnits.forEach(visitCompilationUnit);
assert(_deferredProperties.isEmpty);
// Visit directives (for exports)
compilationUnits.forEach(_emitExportDirectives);
// Declare imports
_finishImports(items);
// Initialize extension symbols
_extensionSymbols.forEach((name, id) {
var value =
new JS.PropertyAccess(_extensionSymbolsModule, _propertyName(name));
if (isBuildingSdk) {
value = js.call('# = Symbol(#)', [value, js.string("dartx.$name")]);
}
items.add(js.statement('const # = #;', [id, value]));
});
// Discharge the type table cache variables and
// hoisted definitions.
items.addAll(_typeTable.discharge());
items.addAll(_internalSdkFunctions);
// Track the module name for each library in the module.
// This data is only required for debugging.
_moduleItems.add(js.statement(
'#.trackLibraries(#, #, ${JSModuleFile.sourceMapHoleID});',
[_runtimeModule, js.string(name), _librariesDebuggerObject()]));
// Add the module's code (produced by visiting compilation units, above)
_copyAndFlattenBlocks(items, _moduleItems);
// Build the module.
return new JS.Program(items, name: _buildUnit.name);
}
JS.ObjectInitializer _librariesDebuggerObject() {
var properties = <JS.Property>[];
_libraries.forEach((library, value) {
// TODO(jacobr): we could specify a short library name instead of the
// full library uri if we wanted to save space.
properties.add(new JS.Property(
js.string(jsLibraryDebuggerName(_libraryRoot, library)), value));
});
return new JS.ObjectInitializer(properties, multiline: true);
}
/// If [e] is a property accessor element, this returns the
/// (possibly synthetic) field that corresponds to it, otherwise returns [e].
Element _getNonAccessorElement(Element e) =>
e is PropertyAccessorElement ? e.variable : e;
/// Returns the name of [e] but removes trailing `=` from setter names.
// TODO(jmesserly): it would be nice if Analyzer had something like this.
// `Element.displayName` is close, but it also normalizes operator names in
// a way we don't want.
String _getElementName(Element e) => _getNonAccessorElement(e).name;
bool _isExternal(Element e) =>
e is ExecutableElement && e.isExternal ||
e is PropertyInducingElement &&
(e.getter.isExternal || e.setter.isExternal);
bool _isJSElement(Element e) =>
e?.library != null &&
_isJSNative(e.library) &&
(_isExternal(e) || e is ClassElement && _isJSNative(e));
String _getJSNameWithoutGlobal(Element e) {
if (!_isJSElement(e)) return null;
var libraryJSName = getAnnotationName(e.library, isPublicJSAnnotation);
var jsName =
getAnnotationName(e, isPublicJSAnnotation) ?? _getElementName(e);
return libraryJSName != null ? '$libraryJSName.$jsName' : jsName;
}
JS.Expression _emitJSInterop(Element e) {
var jsName = _getJSNameWithoutGlobal(e);
return jsName != null ? _emitJSInteropForGlobal(jsName) : null;
}
JS.Expression _emitJSInteropForGlobal(String name) {
var access = _callHelper('global');
for (var part in name.split('.')) {
access = new JS.PropertyAccess(access, js.escapedString(part, "'"));
}
return access;
}
JS.Expression _emitJSInteropStaticMemberName(Element e) {
if (!_isJSElement(e)) return null;
var name = getAnnotationName(e, isPublicJSAnnotation);
if (name != null) {
if (name.contains('.')) {
throw new UnsupportedError(
'static members do not support "." in their names. '
'See https://github.com/dart-lang/sdk/issues/27926');
}
} else {
name = _getElementName(e);
}
return js.escapedString(name, "'");
}
/// Flattens blocks in [items] to a single list.
///
/// This will not flatten blocks that are marked as being scopes.
void _copyAndFlattenBlocks(
List<JS.ModuleItem> result, Iterable<JS.ModuleItem> items) {
for (var item in items) {
if (item is JS.Block && !item.isScope) {
_copyAndFlattenBlocks(result, item.statements);
} else if (item != null) {
result.add(item);
}
}
}
String _libraryToModule(LibraryElement library) {
assert(!_libraries.containsKey(library));
var source = library.source;
// TODO(jmesserly): we need to split out HTML.
if (source.uri.scheme == 'dart') {
return JS.dartSdkModule;
}
var moduleName = _buildUnit.libraryToModule(source);
if (moduleName == null) {
throw new StateError('Could not find module containing "$library".');
}
return moduleName;
}
void _finishImports(List<JS.ModuleItem> items) {
var modules = new Map<String, List<LibraryElement>>();
for (var import in _imports.keys) {
modules.putIfAbsent(_libraryToModule(import), () => []).add(import);
}
String coreModuleName;
if (!_libraries.containsKey(dartCoreLibrary)) {
coreModuleName = _libraryToModule(dartCoreLibrary);
}
modules.forEach((module, libraries) {
// Generate import directives.
//
// Our import variables are temps and can get renamed. Since our renaming
// is integrated into js_ast, it is aware of this possibility and will
// generate an "as" if needed. For example:
//
// import {foo} from 'foo'; // if no rename needed
// import {foo as foo$} from 'foo'; // if rename was needed
//
var imports =
libraries.map((l) => new JS.NameSpecifier(_imports[l])).toList();
if (module == coreModuleName) {
imports.add(new JS.NameSpecifier(_runtimeModule));
imports.add(new JS.NameSpecifier(_extensionSymbolsModule));
}
items.add(new JS.ImportDeclaration(
namedImports: imports, from: js.string(module, "'")));
});
}
/// Called to emit all top-level declarations.
///
/// During the course of emitting one item, we may emit another. For example
///
/// class D extends B { C m() { ... } }
///
/// Because D depends on B, we'll emit B first if needed. However C is not
/// used by top-level JavaScript code, so we can ignore that dependency.
void _emitTypeDeclaration(TypeDefiningElement e) {
var node = _declarationNodes.remove(e);
if (node == null) return null; // not from this module or already loaded.
_currentElements.add(e);
// TODO(jmesserly): this is not really the right place for this.
// Ideally we do this per function body.
//
// We'll need to be consistent about when we're generating functions, and
// only run this on the outermost function, and not any closures.
inferNullableTypes(node);
_moduleItems.add(_visit(node));
var last = _currentElements.removeLast();
assert(identical(e, last));
}
/// Start generating top-level code for the element [e].
///
/// Subsequent [emitDeclaration] calls will cause those elements to be
/// generated before this one, until [finishTopLevel] is called.
void _startTopLevelCodeForClass(TypeDefiningElement e) {
assert(identical(e, currentElement));
_topLevelElements.add(e);
}
/// Finishes the top-level code for the element [e].
void _finishTopLevelCodeForClass(TypeDefiningElement e) {
var last = _topLevelElements.removeLast();
assert(identical(e, last));
}
/// To emit top-level module items, we sometimes need to reorder them.
///
/// This function takes care of that, and also detects cases where reordering
/// failed, and we need to resort to lazy loading, by marking the element as
/// lazy. All elements need to be aware of this possibility and generate code
/// accordingly.
///
/// If we are not emitting top-level code, this does nothing, because all
/// declarations are assumed to be available before we start execution.
/// See [startTopLevel].
void _declareBeforeUse(TypeDefiningElement e) {
if (e == null) return;
var topLevel = _topLevelElements;
if (topLevel.isNotEmpty && identical(currentElement, topLevel.last)) {
// If the item is from our library, try to emit it now.
_emitTypeDeclaration(e);
}
}
@override
visitCompilationUnit(CompilationUnit unit) {
// NOTE: this method isn't the right place to initialize
// per-compilation-unit state. Declarations can be visited out of order,
// this is only to catch things that haven't been emitted yet.
//
// See _emitTypeDeclaration.
_currentElements.add(unit.element);
var isInternalSdk = isSdkInternalRuntime(currentLibrary);
List<VariableDeclaration> fields;
for (var declaration in unit.declarations) {
if (declaration is TopLevelVariableDeclaration) {
inferNullableTypes(declaration);
if (isInternalSdk &&
(declaration.variables.isFinal || declaration.variables.isConst)) {
_emitInternalSdkFields(declaration.variables.variables);
} else {
(fields ??= []).addAll(declaration.variables.variables);
}
continue;
}
if (fields != null) {
_emitTopLevelFields(fields);
fields = null;
}
var element = declaration.element;
if (element is TypeDefiningElement) {
_emitTypeDeclaration(element);
continue;
}
inferNullableTypes(declaration);
var item = _visit(declaration);
if (isInternalSdk && element is FunctionElement) {
_internalSdkFunctions.add(item);
} else {
_moduleItems.add(item);
}
}
if (fields != null) _emitTopLevelFields(fields);
_currentElements.removeLast();
}
void _emitExportDirectives(CompilationUnit unit) {
for (var directive in unit.directives) {
_currentElements.add(directive.element);
directive.accept(this);
_currentElements.removeLast();
}
}
@override
visitLibraryDirective(LibraryDirective node) => null;
@override
visitImportDirective(ImportDirective node) {
// We don't handle imports here.
//
// Instead, we collect imports whenever we need to generate a reference
// to another library. This has the effect of collecting the actually used
// imports.
//
// TODO(jmesserly): if this is a prefixed import, consider adding the prefix
// as an alias?
return null;
}
@override
visitPartDirective(PartDirective node) => null;
@override
visitPartOfDirective(PartOfDirective node) => null;
@override
visitExportDirective(ExportDirective node) {
ExportElement element = node.element;
var currentLibrary = element.library;
var currentNames = currentLibrary.publicNamespace.definedNames;
var exportedNames =
new NamespaceBuilder().createExportNamespaceForDirective(element);
// We only need to export main as it is the only method part of the
// publicly exposed JS API for a library.
// TODO(jacobr): add a library level annotation indicating that all
// contents of a library need to be exposed to JS.
// https://github.com/dart-lang/sdk/issues/26368
var export = exportedNames.get('main');
if (export is FunctionElement) {
// Don't allow redefining names from this library.
if (currentNames.containsKey(export.name)) return null;
var name = _emitTopLevelName(export);
_moduleItems.add(js.statement(
'#.# = #;', [emitLibraryName(currentLibrary), name.selector, name]));
}
}
@override
visitAsExpression(AsExpression node) {
Expression fromExpr = node.expression;
var from = getStaticType(fromExpr);
var to = node.type.type;
JS.Expression jsFrom = _visit(fromExpr);
// If the check was put here by static analysis to ensure soundness, we
// can't skip it. This happens because of unsound covariant generics:
//
// typedef F<T>(T t);
// class C<T> {
// F<T> f;
// add(T t) {
// // required check `t as T`
// }
// }
// main() {
// C<Object> c = new C<int>()..f = (int x) => x.isEven;
// c.f('hi'); // required check `c.f as F<Object>`
// c.add('hi);
// }
//
// NOTE: due to implementation details, we do not currently reify the the
// `C<T>.add` check in CoercionReifier, so it does not reach this point;
// rather we check for it explicitly when emitting methods and fields.
// However we do reify the `c.f` check, so we must not eliminate it.
var isRequiredForSoundness = CoercionReifier.isRequiredForSoundness(node);
if (!isRequiredForSoundness && rules.isSubtypeOf(from, to)) return jsFrom;
// All Dart number types map to a JS double.
if (typeRep.isNumber(from) && typeRep.isNumber(to)) {
// Make sure to check when converting to int.
if (from != types.intType && to == types.intType) {
// TODO(jmesserly): fuse this with notNull check.
// TODO(jmesserly): this does not correctly distinguish user casts from
// required-for-soundness casts.
return _callHelper('asInt(#)', jsFrom);
}
// A no-op in JavaScript.
return jsFrom;
}
var code = isRequiredForSoundness ? '#._check(#)' : '#.as(#)';
return js.call(code, [_emitType(to), jsFrom]);
}
@override
visitIsExpression(IsExpression node) {
// Generate `is` as `dart.is` or `typeof` depending on the RHS type.
JS.Expression result;
var type = node.type.type;
var lhs = _visit(node.expression);
var typeofName = _jsTypeofName(type);
// Inline primitives other than int (which requires a Math.floor check).
if (typeofName != null && type != types.intType) {
result = js.call('typeof # == #', [lhs, js.string(typeofName, "'")]);
} else {
// Always go through a runtime helper, because implicit interfaces.
var castType = _emitType(type);
result = js.call('#.is(#)', [castType, lhs]);
}
if (node.notOperator != null) {
return js.call('!#', result);
}
return result;
}
String _jsTypeofName(DartType t) {
if (typeRep.isNumber(t)) return 'number';
if (t == types.stringType) return 'string';
if (t == types.boolType) return 'boolean';
return null;
}
@override
visitFunctionTypeAlias(FunctionTypeAlias node) => _emitTypedef(node);
@override
visitGenericTypeAlias(GenericTypeAlias node) => _emitTypedef(node);
JS.Statement _emitTypedef(TypeAlias node) {
var element = node.element as FunctionTypeAliasElement;
FunctionType type;
var typeFormals = element.typeParameters;
if (element is GenericTypeAliasElement) {
type = element.function.type;
} else {
type = element.type;
if (typeFormals.isNotEmpty) {
// Skip past the type formals, we'll add them back below, so these
// type parameter names will end up in scope in the generated JS.
type = type.instantiate(typeFormals.map((f) => f.type).toList());
}
}
JS.Expression body = annotate(
_callHelper('typedef(#, () => #)', [
js.string(element.name, "'"),
_emitType(type, nameType: false, lowerTypedef: true)
]),
node,
element);
if (typeFormals.isNotEmpty) {
return _defineClassTypeArguments(element, typeFormals,
js.statement('const # = #;', [element.name, body]));
} else {
return js.statement('# = #;', [_emitTopLevelName(element), body]);
}
}
@override
JS.Expression visitTypeName(node) => _emitTypeAnnotation(node);
@override
JS.Expression visitGenericFunctionType(node) => _emitTypeAnnotation(node);
JS.Expression _emitTypeAnnotation(TypeAnnotation node) {
var type = node.type;
if (type == null) {
// TODO(jmesserly): if the type fails to resolve, should we generate code
// that throws instead?
assert(options.unsafeForceCompile || options.replCompile);
type = types.dynamicType;
}
return _emitType(type);
}
@override
JS.Statement visitClassTypeAlias(ClassTypeAlias node) {
return _emitClassDeclaration(node, node.element, []);
}
JS.Statement _emitJSType(Element e) {
var jsTypeName = getAnnotationName(e, isJSAnnotation);
if (jsTypeName == null || jsTypeName == e.name) return null;
// We export the JS type as if it was a Dart type. For example this allows
// `dom.InputElement` to actually be HTMLInputElement.
// TODO(jmesserly): if we had the JS name on the Element, we could just
// generate it correctly when we refer to it.
return js.statement('# = #;', [_emitTopLevelName(e), jsTypeName]);
}
@override
JS.Statement visitClassDeclaration(ClassDeclaration node) {
return _emitClassDeclaration(node, node.element, node.members);
}
JS.Statement _emitClassDeclaration(Declaration classNode,
ClassElement classElem, List<ClassMember> members) {
// If this class is annotated with `@JS`, then there is nothing to emit.
if (findAnnotation(classElem, isPublicJSAnnotation) != null) return null;
// If this is a JavaScript type, emit it now and then exit.
var jsTypeDef = _emitJSType(classElem);
if (jsTypeDef != null) return jsTypeDef;
JS.Expression className;
if (classElem.typeParameters.isNotEmpty) {
// Generic classes will be defined inside a function that closes over the
// type parameter. So we can use their local variable name directly.
className = new JS.Identifier(classElem.name);
} else {
className = _emitTopLevelName(classElem);
}
var savedClassProperties = _classProperties;
_classProperties = new ClassPropertyModel.build(
_extensionTypes,
virtualFields,
classElem,
getClassCovariantParameters(classNode),
_usedCovariantPrivateMembers);
var memberMap = new Map<Element, Declaration>();
for (var m in members) {
if (m is FieldDeclaration) {
for (var f in m.fields.variables) {
memberMap[f.element as FieldElement] = f;
}
} else {
memberMap[m.element] = m;
}
}
var jsCtors = _defineConstructors(classElem, className, memberMap);
var jsMethods = _emitClassMethods(classElem, members);
_emitSuperclassCovarianceChecks(classNode, jsMethods);
var classExpr = _emitClassExpression(classElem, jsMethods);
var body = <JS.Statement>[];
_emitSuperHelperSymbols(body);
// Emit the class, e.g. `core.Object = class Object { ... }`
_defineClass(classElem, className, classExpr, body);
body.addAll(jsCtors);
// Emit things that come after the ES6 `class ... { ... }`.
var jsPeerNames = _getJSPeerNames(classElem);
JS.Statement deferredBaseClass =
_setBaseClass(classElem, className, jsPeerNames, body);
var finishGenericTypeTest = _emitClassTypeTests(classElem, className, body);
_emitVirtualFieldSymbols(classElem, body);
_emitClassSignature(classElem, className, memberMap, body);
_initExtensionSymbols(classElem);
_defineExtensionMembers(className, body);
_emitClassMetadata(classNode.metadata, className, body);
JS.Statement classDef = _statement(body);
if (isMixinAlias(classElem)) {
// Given `class C = Object with M [implements I1, I2 ...];`
// The resulting class C should function as a mixin.
// To accomplish this, we need to merge the class expression into the
// mixin. For example:
//
// C = dart.mixin(Object, C.__proto__, C)
var oldClassName = className;
if (oldClassName is JS.Identifier) {
className = new JS.TemporaryId(classElem.name);
}
body.add(js.statement('# = #.mixin(#, #.__proto__, #)', [
className,
_runtimeModule,
_emitType(types.objectType),
oldClassName,
oldClassName
]));
}
var typeFormals = classElem.typeParameters;
if (typeFormals.isNotEmpty) {
classDef = _defineClassTypeArguments(
classElem, typeFormals, classDef, className, deferredBaseClass);
}
body = <JS.Statement>[classDef];
_emitStaticFields(classElem, memberMap, body);
if (finishGenericTypeTest != null) body.add(finishGenericTypeTest);
for (var peer in jsPeerNames) {
_registerExtensionType(classElem, peer, body);
}
_classProperties = savedClassProperties;
return _statement(body);
}
JS.Statement _emitClassTypeTests(ClassElement classElem,
JS.Expression className, List<JS.Statement> body) {
JS.Expression getInterfaceSymbol(ClassElement c) {
var library = c.library;
if (library.isDartCore || library.isDartAsync) {
switch (c.name) {
case 'List':
case 'Map':
case 'Iterable':
case 'Future':
case 'Stream':
case 'StreamSubscription':
return _callHelper('is' + c.name);
}
}
return null;
}
void markSubtypeOf(JS.Expression testSymbol) {
body.add(js.statement('#.prototype[#] = true', [className, testSymbol]));
}
for (var iface in classElem.interfaces) {
var prop = getInterfaceSymbol(iface.element);
if (prop != null) markSubtypeOf(prop);
}
if (classElem.library.isDartCore) {
if (classElem == objectClass) {
// Everything is an Object.
body.add(js.statement(
'#.is = function is_Object(o) { return true; }', [className]));
body.add(js.statement(
'#.as = function as_Object(o) { return o; }', [className]));
body.add(js.statement(
'#._check = function check_Object(o) { return o; }', [className]));
return null;
}
if (classElem == stringClass) {
body.add(js.statement(
'#.is = function is_String(o) { return typeof o == "string"; }',
className));
body.add(js.statement(
'#.as = function as_String(o) {'
' if (typeof o == "string" || o == null) return o;'
' return #.as(o, #, false);'
'}',
[className, _runtimeModule, className]));
body.add(js.statement(
'#._check = function check_String(o) {'
' if (typeof o == "string" || o == null) return o;'
' return #.as(o, #, true);'
'}',
[className, _runtimeModule, className]));
return null;
}
if (classElem == functionClass) {
body.add(js.statement(
'#.is = function is_Function(o) { return typeof o == "function"; }',
className));
body.add(js.statement(
'#.as = function as_Function(o) {'
' if (typeof o == "function" || o == null) return o;'
' return #.as(o, #, false);'
'}',
[className, _runtimeModule, className]));
body.add(js.statement(
'#._check = function check_String(o) {'
' if (typeof o == "function" || o == null) return o;'
' return #.as(o, #, true);'
'}',
[className, _runtimeModule, className]));
return null;
}
if (classElem == intClass) {
body.add(js.statement(
'#.is = function is_int(o) {'
' return typeof o == "number" && Math.floor(o) == o;'
'}',
className));
body.add(js.statement(
'#.as = function as_int(o) {'
' if ((typeof o == "number" && Math.floor(o) == o) || o == null)'
' return o;'
' return #.as(o, #, false);'
'}',
[className, _runtimeModule, className]));
body.add(js.statement(
'#._check = function check_int(o) {'
' if ((typeof o == "number" && Math.floor(o) == o) || o == null)'
' return o;'
' return #.as(o, #, true);'
'}',
[className, _runtimeModule, className]));
return null;
}
if (classElem == nullClass) {
body.add(js.statement(
'#.is = function is_Null(o) { return o == null; }', className));
body.add(js.statement(
'#.as = function as_Null(o) {'
' if (o == null) return o;'
' return #.as(o, #, false);'
'}',
[className, _runtimeModule, className]));
body.add(js.statement(
'#._check = function check_Null(o) {'
' if (o == null) return o;'
' return #.as(o, #, true);'
'}',
[className, _runtimeModule, className]));
return null;
}
if (classElem == numClass || classElem == doubleClass) {
body.add(js.statement(
'#.is = function is_num(o) { return typeof o == "number"; }',
className));
body.add(js.statement(
'#.as = function as_num(o) {'
' if (typeof o == "number" || o == null) return o;'
' return #.as(o, #, false);'
'}',
[className, _runtimeModule, className]));
body.add(js.statement(
'#._check = function check_num(o) {'
' if (typeof o == "number" || o == null) return o;'
' return #.as(o, #, true);'
'}',
[className, _runtimeModule, className]));
return null;
}
if (classElem == boolClass) {
body.add(js.statement(
'#.is = function is_bool(o) { return o === true || o === false; }',
className));
body.add(js.statement(
'#.as = function as_bool(o) {'
' if (o === true || o === false || o == null) return o;'
' return #.as(o, #, false);'
'}',
[className, _runtimeModule, className]));
body.add(js.statement(
'#._check = function check_bool(o) {'
' if (o === true || o === false || o == null) return o;'
' return #.as(o, #, true);'
'}',
[className, _runtimeModule, className]));
return null;
}
}
if (classElem.library.isDartAsync) {
if (classElem == types.futureOrType.element) {
var typeParamT = classElem.typeParameters[0].type;
var typeT = _emitType(typeParamT);
var futureOrT = _emitType(types.futureType.instantiate([typeParamT]));
body.add(js.statement('''
#.is = function is_FutureOr(o) {
return #.is(o) || #.is(o);
}
''', [className, typeT, futureOrT]));
// TODO(jmesserly): remove the fallback to `dart.as`. It's only for the
// _ignoreTypeFailure logic.
body.add(js.statement('''
#.as = function as_FutureOr(o) {
if (o == null || #.is(o) || #.is(o)) return o;
return #.as(o, this, false);
}
''', [className, typeT, futureOrT, _runtimeModule]));
body.add(js.statement('''
#._check = function check_FutureOr(o) {
if (o == null || #.is(o) || #.is(o)) return o;
return #.as(o, this, true);
}
''', [className, typeT, futureOrT, _runtimeModule]));
return null;
}
}
body.add(_callHelperStatement('addTypeTests(#);', [className]));
if (classElem.typeParameters.isEmpty) return null;
// For generics, testing against the default instantiation is common,
// so optimize that.
var isClassSymbol = getInterfaceSymbol(classElem);
if (isClassSymbol == null) {
// TODO(jmesserly): we could export these symbols, if we want to mark
// implemented interfaces for user-defined classes.
var id = new JS.TemporaryId("_is_${classElem.name}_default");
_moduleItems.add(
js.statement('const # = Symbol(#);', [id, js.string(id.name, "'")]));
isClassSymbol = id;
}
// Marking every generic type instantiation as a subtype of its default
// instantiation.
markSubtypeOf(isClassSymbol);
// Define the type tests on the default instantiation to check for that
// marker.
var defaultInst = _emitTopLevelName(classElem);
// Return this `addTypeTests` call so we can emit it outside of the generic
// type parameter scope.
return _callHelperStatement(
'addTypeTests(#, #);', [defaultInst, isClassSymbol]);
}
void _emitSymbols(Iterable<JS.TemporaryId> vars, List<JS.ModuleItem> body) {
for (var id in vars) {
body.add(js.statement('const # = Symbol(#)', [id, js.string(id.name)]));
}
}
void _emitSuperHelperSymbols(List<JS.Statement> body) {
_emitSymbols(
_superHelpers.values.map((m) => m.name as JS.TemporaryId), body);
_superHelpers.clear();
}
void _emitVirtualFieldSymbols(
ClassElement classElement, List<JS.Statement> body) {
_classProperties.virtualFields.forEach((field, virtualField) {
body.add(js.statement('const # = Symbol(#);',
[virtualField, js.string('${classElement.name}.${field.name}')]));
});
}
void _defineClass(ClassElement classElem, JS.Expression className,
JS.ClassExpression classExpr, List<JS.Statement> body) {
if (classElem.typeParameters.isNotEmpty) {
body.add(new JS.ClassDeclaration(classExpr));
} else {
body.add(js.statement('# = #;', [className, classExpr]));
}
}
List<JS.Identifier> _emitTypeFormals(List<TypeParameterElement> typeFormals) {
return typeFormals
.map((t) => new JS.Identifier(t.name))
.toList(growable: false);
}
/// Emits a field declaration for TypeScript & Closure's ES6_TYPED
/// (e.g. `class Foo { i: string; }`)
JS.VariableDeclarationList _emitTypeScriptField(FieldElement field) {
return new JS.VariableDeclarationList(field.isStatic ? 'static' : null, [
new JS.VariableInitialization(
new JS.Identifier(
// TODO(ochafik): use a refactored _emitMemberName instead.
field.name,
type: emitTypeRef(field.type)),
null)
]);
}
@override
JS.Statement visitEnumDeclaration(EnumDeclaration node) {
return _emitClassDeclaration(node, node.element, []);
}
/// Wraps a possibly generic class in its type arguments.
JS.Statement _defineClassTypeArguments(TypeDefiningElement element,
List<TypeParameterElement> formals, JS.Statement body,
[JS.Expression className, JS.Statement deferredBaseClass]) {
assert(formals.isNotEmpty);
var typeConstructor = js.call('(#) => { #; #; return #; }', [
_emitTypeFormals(formals),
_typeTable.discharge(formals),
body,
className ?? new JS.Identifier(element.name)
]);
var genericArgs = [typeConstructor];
if (deferredBaseClass != null) {
genericArgs.add(js.call('(#) => { #; }', [className, deferredBaseClass]));
}
var genericCall = _callHelper('generic(#)', [genericArgs]);
if (element.library.isDartAsync &&
(element.name == "Future" || element.name == "_Future")) {
genericCall = _callHelper('flattenFutures(#)', [genericCall]);
}
var genericDef = js.statement(
'# = #;', [_emitTopLevelName(element, suffix: r'$'), genericCall]);
// TODO(jmesserly): this should be instantiate to bounds
var dynType = fillDynamicTypeArgs(element.type);
var genericInst = _emitType(dynType, lowerGeneric: true);
return js.statement(
'{ #; # = #; }', [genericDef, _emitTopLevelName(element), genericInst]);
}
bool _deferIfNeeded(DartType type, ClassElement current) {
if (type is ParameterizedType) {
var typeArguments = type.typeArguments;
for (var typeArg in typeArguments) {
var typeElement = typeArg.element;
// FIXME(vsm): This does not track mutual recursive dependences.
if (current == typeElement || _deferIfNeeded(typeArg, current)) {
return true;
}
}
}
return false;
}
JS.ClassExpression _emitClassExpression(
ClassElement element, List<JS.Method> methods) {
String name = element.name;
var heritage = _emitClassHeritage(element);
var typeParams = _emitTypeFormals(element.typeParameters);
var jsFields = options.closure
? element.fields.map(_emitTypeScriptField).toList()
: null;
return new JS.ClassExpression(new JS.Identifier(name), heritage, methods,
typeParams: typeParams, fields: jsFields);
}
JS.Expression _emitClassHeritage(ClassElement element) {
var type = element.type;
if (type.isObject) return null;
_startTopLevelCodeForClass(element);
// List of "direct" supertypes (supertype + mixins)
var basetypes = [type.superclass]..addAll(type.mixins);
// If any of these are recursive (via type parameter), defer setting
// the real superclass.
if (basetypes.any((t) => _deferIfNeeded(t, element))) {
// Fall back to raw type
basetypes =
basetypes.map((t) => fillDynamicTypeArgs(t.element.type)).toList();
_hasDeferredSupertype.add(element);
}
// List of "direct" JS superclasses
var baseclasses = basetypes
.map((t) => _emitConstructorAccess(t, nameType: false))
.toList();
assert(baseclasses.isNotEmpty);
var heritage = (baseclasses.length == 1)
? baseclasses.first
: _callHelper('mixin(#)', [baseclasses]);
_finishTopLevelCodeForClass(element);
return heritage;
}
/// Provide Dart getters and setters that forward to the underlying native
/// field. Note that the Dart names are always symbolized to avoid
/// conflicts. They will be installed as extension methods on the underlying
/// native type.
List<JS.Method> _emitNativeFieldAccessors(FieldDeclaration node) {
// TODO(vsm): Can this by meta-programmed?
// E.g., dart.nativeField(symbol, jsName)
// Alternatively, perhaps it could be meta-programmed directly in
// dart.registerExtensions?
var jsMethods = <JS.Method>[];
if (!node.isStatic) {
for (var decl in node.fields.variables) {
var field = decl.element as FieldElement;
var name = getAnnotationName(field, isJsName) ?? field.name;
// Generate getter
var fn = new JS.Fun([], js.statement('{ return this.#; }', [name]));
var method =
new JS.Method(_declareMemberName(field.getter), fn, isGetter: true);
jsMethods.add(method);
// Generate setter
if (!decl.isFinal) {
var value = new JS.TemporaryId('value');
fn = new JS.Fun(
[value], js.statement('{ this.# = #; }', [name, value]));
method = new JS.Method(_declareMemberName(field.setter), fn,
isSetter: true);
jsMethods.add(method);
}
}
}
return jsMethods;
}
List<JS.Method> _emitClassMethods(
ClassElement classElem, List<ClassMember> memberNodes) {
var type = classElem.type;
var virtualFields = _classProperties.virtualFields;
var jsMethods = <JS.Method>[];
bool hasJsPeer = findAnnotation(classElem, isJsPeerInterface) != null;
bool hasIterator = false;
if (type.isObject) {
// Dart does not use ES6 constructors.
// Add an error to catch any invalid usage.
jsMethods.add(
new JS.Method(_propertyName('constructor'), js.call(r'''function() {
throw Error("use `new " + #.typeName(#.getReifiedType(this)) +
".new(...)` to create a Dart object");
}''', [_runtimeModule, _runtimeModule])));
} else if (classElem.isEnum) {
// Generate Enum.toString()
var fields = classElem.fields.where((f) => f.type == type).toList();
var mapMap = new List<JS.Property>(fields.length);
for (var i = 0; i < fields.length; ++i) {
mapMap[i] = new JS.Property(
js.number(i), js.string('${type.name}.${fields[i].name}'));
}
jsMethods.add(new JS.Method(
_declareMemberName(types.objectType.getMethod('toString')),
js.call('function() { return #[this.index]; }',
new JS.ObjectInitializer(mapMap, multiline: true))));
}
for (var m in memberNodes) {
if (m is ConstructorDeclaration) {
if (m.factoryKeyword != null &&
m.externalKeyword == null &&
m.body is! NativeFunctionBody) {
jsMethods.add(_emitFactoryConstructor(m));
}
} else if (m is MethodDeclaration) {
jsMethods.add(_emitMethodDeclaration(type, m));
if (m.element is PropertyAccessorElement) {
jsMethods.add(_emitSuperAccessorWrapper(m, type));
}
if (!hasJsPeer && m.isGetter && m.name.name == 'iterator') {
hasIterator = true;
jsMethods.add(_emitIterable(type));
}
} else if (m is FieldDeclaration) {
if (_extensionTypes.isNativeClass(classElem)) {
jsMethods.addAll(_emitNativeFieldAccessors(m));
continue;
}
if (m.isStatic) continue;
for (VariableDeclaration field in m.fields.variables) {
if (virtualFields.containsKey(field.element)) {
jsMethods.addAll(_emitVirtualFieldAccessor(field));
}
}
}
}
jsMethods.addAll(_classProperties.mockMembers.values
.map((e) => _implementMockMember(e, type)));
// If the type doesn't have an `iterator`, but claims to implement Iterable,
// we inject the adaptor method here, as it's less code size to put the
// helper on a parent class. This pattern is common in the core libraries
// (e.g. IterableMixin<E> and IterableBase<E>).
//
// (We could do this same optimization for any interface with an `iterator`
// method, but that's more expensive to check for, so it doesn't seem worth
// it. The above case for an explicit `iterator` method will catch those.)
if (!hasJsPeer && !hasIterator && _implementsIterable(type)) {
jsMethods.add(_emitIterable(type));
}
// Add all of the super helper methods
jsMethods.addAll(_superHelpers.values);
return jsMethods.where((m) => m != null).toList();
}
void _emitSuperclassCovarianceChecks(
Declaration node, List<JS.Method> methods) {
var covariantParams = getSuperclassCovariantParameters(node);
if (covariantParams == null) return;
for (var member in covariantParams.map((p) => p.enclosingElement).toSet()) {
var name = _declareMemberName(member);
if (member is PropertyAccessorElement) {
var param =
covariantParams.lookup(member.parameters[0]) as ParameterElement;
methods.add(new JS.Method(
name,
js.call('function(x) { return super.#(#._check(x)); }',
[name, _emitType(param.type)]),
isSetter: true));
methods.add(new JS.Method(
name, js.call('function() { return super.#; }', [name]),
isGetter: true));
} else if (member is MethodElement) {
var type = member.type;
var body = <JS.Statement>[];
_emitCovarianceBoundsCheck(type.typeFormals, covariantParams, body);
var typeFormals = _emitTypeFormals(type.typeFormals);
var jsParams = new List<JS.Parameter>.from(typeFormals);
bool foundNamedParams = false;
for (var param in member.parameters) {
param = covariantParams.lookup(param) as ParameterElement;
if (param == null) continue;
JS.Parameter jsParam;
if (param.kind == ParameterKind.NAMED) {
foundNamedParams = true;
var name = _propertyName(param.name);
body.add(js.statement('if (# in #) #._check(#.#);', [
name,
namedArgumentTemp,
_emitType(param.type),
namedArgumentTemp,
name
]));
} else {
jsParam = _emitParameter(param);
jsParams.add(jsParam);
if (param.kind == ParameterKind.POSITIONAL) {
body.add(js.statement('if (# !== void 0) #._check(#);',
[jsParam, _emitType(param.type), jsParam]));
} else {
body.add(js
.statement('#._check(#);', [_emitType(param.type), jsParam]));
}
}
}
if (foundNamedParams) jsParams.add(namedArgumentTemp);
if (typeFormals.isEmpty) {
body.add(js.statement('return super.#(#);', [name, jsParams]));
} else {
body.add(js.statement(
'return super.#(#)(#);', [name, typeFormals, jsParams]));
}
var fn = new JS.Fun(jsParams, new JS.Block(body),
typeParams: typeFormals, returnType: emitTypeRef(type.returnType));
methods.add(new JS.Method(name, fn));
} else {
throw new StateError(
'unable to generate a covariant check for element: `$member` '
'(${member.runtimeType})');
}
}
}
/// Emits a Dart factory constructor to a JS static method.
JS.Method _emitFactoryConstructor(ConstructorDeclaration node) {
var element = node.element;
var returnType = emitTypeRef(element.returnType);
var name = _constructorName(element.name);
JS.Fun fun;
var savedFunction = _currentFunction;
_currentFunction = node.body;
var redirect = node.redirectedConstructor;
if (redirect != null) {
// Wacky factory redirecting constructors: factory Foo.q(x, y) = Bar.baz;
var newKeyword = redirect.staticElement.isFactory ? '' : 'new';
// Pass along all arguments verbatim, and let the callee handle them.
// TODO(jmesserly): we'll need something different once we have
// rest/spread support, but this should work for now.
var params =
_emitFormalParameterList(node.parameters, destructure: false);
fun = new JS.Fun(
params,
js.statement(
'{ return $newKeyword #(#); }', [_visit(redirect), params]),
returnType: returnType);
} else {
// Normal factory constructor
var body = <JS.Statement>[];
var init = _emitArgumentInitializers(element, node.parameters);
if (init != null) body.add(init);
body.add(_visit(node.body));
var params = _emitFormalParameterList(node.parameters);
fun = new JS.Fun(params, new JS.Block(body), returnType: returnType);
}
_currentFunction = savedFunction;
return annotate(new JS.Method(name, fun, isStatic: true), node, element);
}
/// Given a class C that implements method M from interface I, but does not
/// declare M, this will generate an implementation that forwards to
/// noSuchMethod.
///
/// For example:
///
/// class Cat {
/// bool eatFood(String food) => true;
/// }
/// class MockCat implements Cat {
/// noSuchMethod(Invocation invocation) => 3;
/// }
///
/// It will generate an `eatFood` that looks like:
///
/// eatFood(...args) {
/// return core.bool.as(this.noSuchMethod(
/// new dart.InvocationImpl.new('eatFood', args)));
/// }
JS.Method _implementMockMember(ExecutableElement method, InterfaceType type) {
var invocationProps = <JS.Property>[];
addProperty(String name, JS.Expression value) {
invocationProps.add(new JS.Property(js.string(name), value));
}
var args = new JS.TemporaryId('args');
var typeParams = _emitTypeFormals(method.type.typeFormals);
var fnArgs = new List<JS.Parameter>.from(typeParams);
JS.Expression positionalArgs;
if (method.type.namedParameterTypes.isNotEmpty) {
addProperty('namedArguments', _callHelper('extractNamedArgs(#)', [args]));
}
if (method is MethodElement) {
addProperty('isMethod', js.boolean(true));
fnArgs.add(new JS.RestParameter(args));
positionalArgs = args;
} else {
var property = method as PropertyAccessorElement;
if (property.isGetter) {
addProperty('isGetter', js.boolean(true));
positionalArgs = new JS.ArrayInitializer([]);
} else if (property.isSetter) {
addProperty('isSetter', js.boolean(true));
fnArgs.add(args);
positionalArgs = new JS.ArrayInitializer([args]);
}
}
if (typeParams.isNotEmpty) {
addProperty('typeArguments', new JS.ArrayInitializer(typeParams));
}
var fnBody =
js.call('this.noSuchMethod(new #.InvocationImpl.new(#, #, #))', [
_runtimeModule,
_declareMemberName(method),
positionalArgs,
new JS.ObjectInitializer(invocationProps)
]);
if (!method.returnType.isDynamic) {
fnBody = js.call('#._check(#)', [_emitType(method.returnType), fnBody]);
}
var fn = new JS.Fun(fnArgs, js.statement('{ return #; }', [fnBody]),
typeParams: typeParams);
return new JS.Method(
_declareMemberName(method,
useExtension: _extensionTypes.isNativeClass(type.element)),
fn,
isGetter: method is PropertyAccessorElement && method.isGetter,
isSetter: method is PropertyAccessorElement && method.isSetter,
isStatic: false);
}
/// This is called whenever a derived class needs to introduce a new field,
/// shadowing a field or getter/setter pair on its parent.
///
/// This is important because otherwise, trying to read or write the field
/// would end up calling the getter or setter, and one of those might not even
/// exist, resulting in a runtime error. Even if they did exist, that's the
/// wrong behavior if a new field was declared.
List<JS.Method> _emitVirtualFieldAccessor(VariableDeclaration field) {
var element = field.element as FieldElement;
var virtualField = _classProperties.virtualFields[element];
var result = <JS.Method>[];
var name = _declareMemberName(element.getter);
var mocks = _classProperties.mockMembers;
if (!mocks.containsKey(element.name)) {
var getter = js.call('function() { return this[#]; }', [virtualField]);
result.add(new JS.Method(name, getter, isGetter: true));
}
if (!mocks.containsKey(element.name + '=')) {
var args = field.isFinal
? [new JS.Super(), name]
: [new JS.This(), virtualField];
String jsCode;
var setter = element.setter;
var covariantParams = _classProperties.covariantParameters;
if (setter != null &&
covariantParams != null &&
covariantParams.contains(setter.parameters[0])) {
args.add(_emitType(setter.parameters[0].type));
jsCode = 'function(value) { #[#] = #._check(value); }';
} else {
jsCode = 'function(value) { #[#] = value; }';
}
result.add(new JS.Method(name, js.call(jsCode, args), isSetter: true));
}
return result;
}
/// Emit a getter or setter that simply forwards to the superclass getter or
/// setter. This is needed because in ES6, if you only override a getter
/// (alternatively, a setter), then there is an implicit override of the
/// setter (alternatively, the getter) that does nothing.
JS.Method _emitSuperAccessorWrapper(
MethodDeclaration method, InterfaceType type) {
var methodElement = method.element as PropertyAccessorElement;
var field = methodElement.variable;
if (!field.isSynthetic) return null;
// Generate a corresponding virtual getter / setter.
var name = _declareMemberName(methodElement);
if (method.isGetter) {
var setter = field.setter;
if ((setter == null || setter.isAbstract) &&
_classProperties.inheritedSetters.contains(field.name)) {
// Generate a setter that forwards to super.
var fn = js.call('function(value) { super[#] = value; }', [name]);
return new JS.Method(name, fn, isSetter: true);
}
} else {
var getter = field.getter;
if ((getter == null || getter.isAbstract) &&
_classProperties.inheritedGetters.contains(field.name)) {
// Generate a getter that forwards to super.
var fn = js.call('function() { return super[#]; }', [name]);
return new JS.Method(name, fn, isGetter: true);
}
}
return null;
}
bool _implementsIterable(InterfaceType t) =>
t.interfaces.any((i) => i.element.type == types.iterableType);
/// Support for adapting dart:core Iterable to ES6 versions.
///
/// This lets them use for-of loops transparently:
/// <https://github.com/lukehoban/es6features#iterators--forof>
///
/// This will return `null` if the adapter was already added on a super type,
/// otherwise it returns the adapter code.
// TODO(jmesserly): should we adapt `Iterator` too?
JS.Method _emitIterable(InterfaceType t) {
// If a parent had an `iterator` (concrete or abstract) or implements
// Iterable, we know the adapter is already there, so we can skip it as a
// simple code size optimization.
var parent = t.lookUpGetterInSuperclass('iterator', t.element.library);
if (parent != null) return null;
var parentType = findSupertype(t, _implementsIterable);
if (parentType != null) return null;
if (t.element.source.isInSystemLibrary &&
t.methods.any((m) => getJSExportName(m) == 'Symbol.iterator')) {
return null;
}
// Otherwise, emit the adapter method, which wraps the Dart iterator in
// an ES6 iterator.
return new JS.Method(
js.call('Symbol.iterator'),
js.call('function() { return new #.JsIterator(this.#); }',
[_runtimeModule, _emitMemberName('iterator', type: t)]) as JS.Fun);
}
JS.Expression _instantiateAnnotation(Annotation node) {
var element = node.element;
if (element is ConstructorElement) {
return _emitInstanceCreationExpression(element, element.returnType,
node.constructorName, node.arguments, true);
} else {
return _visit(node.name);
}
}
/// Gets the JS peer for this Dart type if any, otherwise null.
///
/// For example for dart:_interceptors `JSArray` this will return "Array",
/// referring to the JavaScript built-in `Array` type.
List<String> _getJSPeerNames(ClassElement classElem) {
var jsPeerNames = getAnnotationName(
classElem,
(a) =>
isJsPeerInterface(a) ||
isNativeAnnotation(a) && _extensionTypes.isNativeClass(classElem));
if (classElem.type.isObject) return ['Object'];
if (jsPeerNames == null) return [];
// Omit the special name "!nonleaf" and any future hacks starting with "!"
var result =
jsPeerNames.split(',').where((peer) => !peer.startsWith("!")).toList();
return result;
}
void _registerExtensionType(
ClassElement classElem, String jsPeerName, List<JS.Statement> body) {
var className = _emitTopLevelName(classElem);
if (isPrimitiveType(classElem.type)) {
body.add(_callHelperStatement(
'definePrimitiveHashCode(#.prototype)', className));
}
body.add(_callHelperStatement(
'registerExtension(#, #);', [js.string(jsPeerName), className]));
}
JS.Statement _setBaseClass(ClassElement classElem, JS.Expression className,
List<String> jsPeerNames, List<JS.Statement> body) {
var typeFormals = classElem.typeParameters;
if (jsPeerNames.length == 1 && typeFormals.isNotEmpty) {
var newBaseClass = _callHelper('global.#', jsPeerNames[0]);
body.add(_callHelperStatement(
'setExtensionBaseClass(#, #);', [className, newBaseClass]));
} else if (_hasDeferredSupertype.contains(classElem)) {
// TODO(vsm): consider just threading the deferred supertype through
// instead of recording classElem in a set on the class and recomputing
var newBaseClass = _emitType(classElem.type.superclass,
nameType: false, subClass: classElem, className: className);
if (classElem.type.mixins.isNotEmpty) {
var mixins = classElem.type.mixins
.map((t) => _emitType(t, nameType: false))
.toList();
mixins.insert(0, newBaseClass);
newBaseClass = _callHelper('mixin(#)', [mixins]);
}
var deferredBaseClass = _callHelperStatement(
'setBaseClass(#, #);', [className, newBaseClass]);
if (typeFormals.isNotEmpty) return deferredBaseClass;
body.add(deferredBaseClass);
}
return null;
}
/// Defines all constructors for this class as ES5 constructors.
List<JS.Statement> _defineConstructors(ClassElement classElem,
JS.Expression className, Map<Element, Declaration> memberMap) {
// See if we have a "call" with a statically known function type:
//
// - if it's a method, then it does because all methods do,
// - if it's a getter, check the return type.
//
// Other cases like a getter returning dynamic/Object/Function will be
// handled at runtime by the dynamic call mechanism. So we only
// concern ourselves with statically known function types.
//
// We can ignore `noSuchMethod` because:
// * `dynamic d; d();` without a declared `call` method is handled by dcall.
// * for `class C implements Callable { noSuchMethod(i) { ... } }` we find
// the `call` method on the `Callable` interface.
var callMethod = classElem.type.lookUpInheritedGetterOrMethod('call');
bool isCallable = callMethod is PropertyAccessorElement
? callMethod.returnType is FunctionType
: callMethod != null;
var body = <JS.Statement>[];
if (isCallable) {
// Our class instances will have JS `typeof this == "function"`,
// so make sure to attach the runtime type information the same way
// we would do it for function types.
body.add(js.statement('#.prototype[#] = #;',
[className, _callHelper('_runtimeType'), className]));
}
void addConstructor(String name, JS.Expression jsCtor) {
var ctorName = _constructorName(name);
if (JS.invalidStaticFieldName(name)) {
jsCtor =
_callHelper('defineValue(#, #, #)', [className, ctorName, jsCtor]);
} else {
jsCtor = js.call('#.# = #', [className, ctorName, jsCtor]);
}
body.add(js.statement('#.prototype = #.prototype;', [jsCtor, className]));
}
if (classElem.isMixinApplication) {
var supertype = classElem.supertype;
for (var ctor in classElem.constructors) {
List<JS.Identifier> jsParams = _emitParametersForElement(ctor);
var superCtor = supertype.lookUpConstructor(ctor.name, ctor.library);
var superCall =
_superConstructorCall(classElem, className, superCtor, jsParams);
addConstructor(
ctor.name,
_finishConstructorFunction(
jsParams,
new JS.Block(superCall != null ? [superCall] : []),
isCallable));
}
return body;
}
if (classElem.isEnum) {
assert(!isCallable, 'enums should not be callable');
addConstructor('', js.call('function(x) { this.index = x; }'));
return body;
}
var fields = new List<VariableDeclaration>.from(memberMap.values.where(
(m) =>
m is VariableDeclaration && !(m.element as FieldElement).isStatic));
// Iff no constructor is specified for a class C, it implicitly has a
// default constructor `C() : super() {}`, unless C is class Object.
var defaultCtor = classElem.unnamedConstructor;
if (defaultCtor != null && defaultCtor.isSynthetic) {
assert(classElem.constructors.length == 1,
'default constructor only if no other constructors');
var superCall = _superConstructorCall(classElem, className);
var ctorBody = <JS.Statement>[_initializeFields(fields)];
if (superCall != null) ctorBody.add(superCall);
addConstructor('',
_finishConstructorFunction([], new JS.Block(ctorBody), isCallable));
return body;
}
bool foundConstructor = false;
for (var element in classElem.constructors) {
if (element.isSynthetic || element.isFactory || element.isExternal) {
continue;
}
var ctor = memberMap[element] as ConstructorDeclaration;
if (ctor.body is NativeFunctionBody) continue;
addConstructor(
element.name, _emitConstructor(ctor, fields, isCallable, className));
foundConstructor = true;
}
// If classElement has only factory constructors, and it can be mixed in,
// then we need to emit a special hidden default constructor for use by
// mixins.
if (!foundConstructor && classElem.supertype.isObject) {
body.add(
js.statement('(#[#] = function() { # }).prototype = #.prototype;', [
className,
_callHelper('mixinNew'),
[_initializeFields(fields)],
className
]));
}
return body;
}
/// Emits static fields for a class, and initialize them eagerly if possible,
/// otherwise define them as lazy properties.
void _emitStaticFields(ClassElement classElem,
Map<Element, Declaration> members, List<JS.Statement> body) {
if (classElem.isEnum) {
// Emit enum static fields
var type = classElem.type;
void addField(FieldElement e, JS.Expression value) {
var args = [
_emitStaticAccess(type),
_declareMemberName(e.getter),
value
];
// TODO(jmesserly): should this be the job of `declareMemberName`?
if (JS.invalidStaticFieldName(e.name)) {
body.add(_callHelperStatement('defineValue(#, #, #)', args));
} else {
body.add(js.statement('#.# = #', args));
}
}
int index = 0;
var values = <JS.Expression>[];
for (var f in classElem.fields) {
if (f.type != type) continue;
// static const E id_i = const E(i);
values.add(new JS.PropertyAccess(
_emitStaticAccess(type), _declareMemberName(f.getter)));
var enumValue = _callHelper('const(new (#.#)(#))', [
_emitConstructorAccess(type),
_constructorName(''),
js.number(index++)
]);
addField(f, enumValue);
}
// static const List<E> values = const <E>[id_0 . . . id_n−1];
addField(classElem.getField('values'), _emitConstList(type, values));
return;
}
var lazyStatics = classElem.fields
.where((f) => f.isStatic && !f.isSynthetic)
.map((f) => members[f] as VariableDeclaration)
.toList();
if (lazyStatics.isNotEmpty) {
body.add(_emitLazyFields(classElem, lazyStatics));
}
}
void _emitClassMetadata(List<Annotation> metadata, JS.Expression className,
List<JS.Statement> body) {
// Metadata
if (options.emitMetadata && metadata.isNotEmpty) {
body.add(js.statement('#[#.metadata] = () => #;', [
className,
_runtimeModule,
new JS.ArrayInitializer(
new List<JS.Expression>.from(metadata.map(_instantiateAnnotation)))
]));
}
}
/// Ensure `dartx.` symbols we will use are present.
void _initExtensionSymbols(ClassElement classElem) {
if (_extensionTypes.hasNativeSubtype(classElem.type) ||
classElem.type.isObject) {
for (var members in [classElem.methods, classElem.accessors]) {
for (var m in members) {
if (!m.isAbstract && !m.isStatic && m.isPublic) {
_declareMemberName(m, useExtension: true);
}
}
}
}
}
/// If a concrete class implements one of our extensions, we might need to
/// add forwarders.
void _defineExtensionMembers(
JS.Expression className, List<JS.Statement> body) {
void emitExtensions(
JS.Expression target, Iterable<ExecutableElement> extensions) {
if (extensions.isEmpty) return;
var names = extensions
.map((e) => _declareMemberName(e, useExtension: false))
.toList();
body.add(_callHelperStatement('defineExtensionMembers(#, #);', [
target,
new JS.ArrayInitializer(names, multiline: names.length > 4)
]));
}
// Define mixin members (if any) on the mixin class.
var mixinClass = js.call('#.__proto__', [className]);
emitExtensions(mixinClass, _classProperties.mixinExtensionMembers);
emitExtensions(className, _classProperties.extensionMembers);
}
void _buildSignatureField(
List<JS.Property> sigFields, String name, List<JS.Property> elements) {
if (elements.isEmpty) return;
var o = new JS.ObjectInitializer(elements, multiline: elements.length > 1);
// TODO(vsm): Remove
var e = js.call('() => #', o);
sigFields.add(new JS.Property(_propertyName(name), e));
}
/// Emit the signature on the class recording the runtime type information
void _emitClassSignature(ClassElement classElem, JS.Expression className,
Map<Element, Declaration> annotatedMembers, List<JS.Statement> body) {
if (classElem.interfaces.isNotEmpty) {
body.add(js.statement('#[#.implements] = () => #;', [
className,
_runtimeModule,
new JS.ArrayInitializer(classElem.interfaces.map(_emitType).toList())
]));
}
var staticMethods = <JS.Property>[];
var instanceMethods = <JS.Property>[];
var staticNames = <JS.Expression>[];
for (var method in classElem.methods) {
// TODO(vsm): Clean up all the nasty duplication.
if (method.isAbstract) {
continue;
}
var name = method.name;
DartType reifiedType = _getMemberRuntimeType(method);
// Don't add redundant signatures for inherited methods whose signature
// did not change. If we are not overriding, or if the thing we are
// overriding has a different reified type from ourselves, we must
// emit a signature on this class. Otherwise we will inherit the
// signature from the superclass.
var needsSignature =
classElem.lookUpInheritedConcreteMethod(name, currentLibrary) ==
null ||
_getMemberRuntimeType(classElem.type.lookUpInheritedMethod(name,
library: currentLibrary, thisType: false)) !=
reifiedType;
var annotationNode = annotatedMembers[method] as MethodDeclaration;
var type = _emitAnnotatedFunctionType(
reifiedType, annotationNode?.metadata,
parameters: annotationNode?.parameters?.parameters,
nameType: false,
definite: true);
if (needsSignature) {
var memberName = _declareMemberName(method);
var property = new JS.Property(memberName, type);
// We record the names of static methods separately so we can
// attach metadata to them individually.
// TODO(leafp): Revisit this.
if (method.isStatic) {
staticNames.add(memberName);
staticMethods.add(property);
} else {
instanceMethods.add(property);
}
}
}
var staticGetters = <JS.Property>[];
var instanceGetters = <JS.Property>[];
var staticSetters = <JS.Property>[];
var instanceSetters = <JS.Property>[];
for (var accessor in classElem.accessors) {
if (accessor.isAbstract || accessor.isSynthetic) {
continue;
}
// Static getters/setters cannot be called with dynamic dispatch, nor
// can they be torn off.
// TODO(jmesserly): can we attach static method type info at the tearoff
// point, and avoid saving the information otherwise? Same trick would
// work for top-level functions.
var isStatic = accessor.isStatic;
if (!options.emitMetadata && accessor.isStatic) {
continue;
}
var name = accessor.name;
var isGetter = accessor.isGetter;
var getOverride = isGetter
? classElem.lookUpInheritedConcreteGetter
: classElem.lookUpInheritedConcreteSetter;
var lookup = isGetter
? classElem.type.lookUpInheritedGetter
: classElem.type.lookUpInheritedSetter;
var reifiedType = accessor.type;
// Don't add redundant signatures for inherited methods whose signature
// did not change. If we are not overriding, or if the thing we are
// overriding has a different reified type from ourselves, we must
// emit a signature on this class. Otherwise we will inherit the
// signature from the superclass.
var needsSignature = getOverride(name, currentLibrary) == null ||
lookup(name, library: currentLibrary, thisType: false).type !=
reifiedType;
// TODO(jmesserly): we could reduce work by not saving a full function
// type for getters/setters. These only need 1 type to be saved.
var annotationNode = annotatedMembers[accessor] as MethodDeclaration;
var type = _emitAnnotatedFunctionType(
reifiedType, annotationNode?.metadata,
parameters: annotationNode?.parameters?.parameters,
nameType: false,
definite: true);
if (needsSignature) {
var memberName = _declareMemberName(accessor);
var property = new JS.Property(memberName, type);
(isGetter
? (isStatic ? staticGetters : instanceGetters)
: (isStatic ? staticSetters : instanceSetters))
.add(property);
}
}
var instanceFields = <JS.Property>[];
var staticFields = <JS.Property>[];
for (var field in classElem.fields) {
if (field.isSynthetic && !classElem.isEnum) continue;
// Only instance fields need to be saved for dynamic dispatch.
var isStatic = field.isStatic;
if (!options.emitMetadata && isStatic) {
continue;
}
var fieldNode = annotatedMembers[field] as VariableDeclaration;
var metadata = fieldNode != null
? (fieldNode.parent.parent as FieldDeclaration).metadata
: null;
assert(field.getter != null, '$field in $classElem has no getter???');
var memberName = _declareMemberName(field.getter);
var fieldSig = _emitFieldSignature(field.type,
metadata: metadata, isFinal: field.isFinal);
(isStatic ? staticFields : instanceFields)
.add(new JS.Property(memberName, fieldSig));
}
var constructors = <JS.Property>[];
if (options.emitMetadata) {
for (var ctor in classElem.constructors) {
var annotationNode = annotatedMembers[ctor] as ConstructorDeclaration;
var memberName = _constructorName(ctor.name);
var type = _emitAnnotatedFunctionType(
ctor.type, annotationNode?.metadata,
parameters: annotationNode?.parameters?.parameters,
nameType: false,
definite: true);
constructors.add(new JS.Property(memberName, type));
}
}
var sigFields = <JS.Property>[];
_buildSignatureField(sigFields, 'constructors', constructors);
_buildSignatureField(sigFields, 'fields', instanceFields);
_buildSignatureField(sigFields, 'getters', instanceGetters);
_buildSignatureField(sigFields, 'setters', instanceSetters);
_buildSignatureField(sigFields, 'methods', instanceMethods);
_buildSignatureField(sigFields, 'sfields', staticFields);
_buildSignatureField(sigFields, 'sgetters', staticGetters);
_buildSignatureField(sigFields, 'ssetters', staticSetters);
_buildSignatureField(sigFields, 'statics', staticMethods);
if (!staticMethods.isEmpty) {
assert(!staticNames.isEmpty);
// Emit names so that we can lazily attach metadata to statics
// TODO(leafp): revisit this strategy
sigFields.add(new JS.Property(
_propertyName('names'), new JS.ArrayInitializer(staticNames)));
}
// We set signature here, even if empty, to simplify the work of
// defineExtensionMembers at runtime. See _defineExtensionMembers.
if (!sigFields.isEmpty ||
_classProperties.extensionMembers.isNotEmpty ||
_classProperties.mixinExtensionMembers.isNotEmpty) {
var sig = new JS.ObjectInitializer(sigFields);
body.add(_callHelperStatement('setSignature(#, #);', [className, sig]));
}
// Add static property dart._runtimeType to Object.
// All other Dart classes will (statically) inherit this property.
if (classElem == objectClass) {
body.add(_callHelperStatement('tagComputed(#, () => #.#);',
[className, emitLibraryName(dartCoreLibrary), 'Type']));
}
}
JS.Expression _emitConstructor(
ConstructorDeclaration node,
List<VariableDeclaration> fields,
bool isCallable,
JS.Expression className) {
var params = _emitFormalParameterList(node.parameters);
var savedFunction = _currentFunction;
_currentFunction = node.body;
var savedSuperAllowed = _superAllowed;
_superAllowed = false;
var body = _emitConstructorBody(node, fields, className);
_superAllowed = savedSuperAllowed;
_currentFunction = savedFunction;
return _finishConstructorFunction(params, body, isCallable);
}
JS.Expression _finishConstructorFunction(
List<JS.Parameter> params, JS.Block body, isCallable) {
// We consider a class callable if it inherits from anything with a `call`
// method. As a result, we can know the callable JS function was created
// at the first constructor that was hit.
if (!isCallable) return new JS.Fun(params, body);
return js.call(r'''function callableClass(#) {
if (typeof this !== "function") {
function self(...args) {
return self.call.apply(self, args);
}
self.__proto__ = this.__proto__;
callableClass.call(self, #);
return self;
}
#
}''', [params, params, body]);
}
FunctionType _getMemberRuntimeType(ExecutableElement element) {
// Check whether we have any covariant parameters.
// Usually we don't, so we can use the same type.
if (!element.parameters.any(_isCovariant)) return element.type;
var parameters = element.parameters
.map((p) => new ParameterElementImpl.synthetic(p.name,
_isCovariant(p) ? objectClass.type : p.type, p.parameterKind))
.toList();
var function = new FunctionElementImpl("", -1)
..isSynthetic = true
..returnType = element.returnType
// TODO(jmesserly): do covariant type parameter bounds also need to be
// reified as `Object`?
..shareTypeParameters(element.typeParameters)
..parameters = parameters;
return function.type = new FunctionTypeImpl(function);
}
JS.Expression _constructorName(String name) {
if (name == '') {
// Default constructors (factory or not) use `new` as their name.
return _propertyName('new');
}
return _emitMemberName(name, isStatic: true);
}
JS.Block _emitConstructorBody(ConstructorDeclaration node,
List<VariableDeclaration> fields, JS.Expression className) {
var body = <JS.Statement>[];
ClassDeclaration cls = node.parent;
// Generate optional/named argument value assignment. These can not have
// side effects, and may be used by the constructor's initializers, so it's
// nice to do them first.
// Also for const constructors we need to ensure default values are
// available for use by top-level constant initializers.
var init = _emitArgumentInitializers(node.element, node.parameters);
if (init != null) body.add(init);
// Redirecting constructors: these are not allowed to have initializers,
// and the redirecting ctor invocation runs before field initializers.
var redirectCall = node.initializers.firstWhere(
(i) => i is RedirectingConstructorInvocation,
orElse: () => null);
if (redirectCall != null) {
body.add(_emitRedirectingConstructor(redirectCall, className));
return new JS.Block(body);
}
// Generate field initializers.
// These are expanded into each non-redirecting constructor.
// In the future we may want to create an initializer function if we have
// multiple constructors, but it needs to be balanced against readability.
body.add(_initializeFields(fields, node));
var superCall = node.initializers.firstWhere(
(i) => i is SuperConstructorInvocation,
orElse: () => null) as SuperConstructorInvocation;
// If no superinitializer is provided, an implicit superinitializer of the
// form `super()` is added at the end of the initializer list, unless the
// enclosing class is class Object.
var superCallArgs =
superCall != null ? _emitArgumentList(superCall.argumentList) : null;
var jsSuper = _superConstructorCall(
cls.element, className, superCall?.staticElement, superCallArgs);
if (jsSuper != null) body.add(annotate(jsSuper, superCall));
body.add(_visit(node.body));
return new JS.Block(body)..sourceInformation = node;
}
JS.Statement _emitRedirectingConstructor(
RedirectingConstructorInvocation node, JS.Expression className) {
var ctor = node.staticElement;
// We can't dispatch to the constructor with `this.new` as that might hit a
// derived class constructor with the same name.
return js.statement('#.#.call(this, #);', [
className,
_constructorName(ctor.name),
_emitArgumentList(node.argumentList)
]);
}
JS.Statement _superConstructorCall(
ClassElement element, JS.Expression className,
[ConstructorElement superCtor, List<JS.Expression> args]) {
// Get the supertype's unnamed constructor.
superCtor ??= element.supertype?.element?.unnamedConstructor;
if (superCtor == null) {
assert(element.type.isObject || options.unsafeForceCompile);
return null;
}
// We can skip the super call if it's empty. Typically this happens for
// things that extend Object.
if (superCtor.name == '' && !_hasUnnamedSuperConstructor(element)) {
return null;
}
var name = _constructorName(superCtor.name);
return js.statement(
'#.__proto__.#.call(this, #);', [className, name, args ?? []]);
}
bool _hasUnnamedSuperConstructor(ClassElement e) {
var supertype = e.supertype;
if (supertype == null) return false;
if (_hasUnnamedConstructor(supertype.element)) return true;
for (var mixin in e.mixins) {
if (_hasUnnamedConstructor(mixin.element)) return true;
}
return false;
}
bool _hasUnnamedConstructor(ClassElement e) {
if (e.type.isObject) return false;
if (!e.unnamedConstructor.isSynthetic) return true;
if (e.fields.any((f) => !f.isStatic && !f.isSynthetic)) return true;
return _hasUnnamedSuperConstructor(e);
}
/// Initialize fields. They follow the sequence:
///
/// 1. field declaration initializer if non-const,
/// 2. field initializing parameters,
/// 3. constructor field initializers,
/// 4. initialize fields not covered in 1-3
JS.Statement _initializeFields(List<VariableDeclaration> fieldDecls,
[ConstructorDeclaration ctor]) {
// Run field initializers if they can have side-effects.
var fields = new Map<FieldElement, JS.Expression>();
var unsetFields = new Map<FieldElement, VariableDeclaration>();
for (var fieldNode in fieldDecls) {
var element = fieldNode.element as FieldElement;
if (_constants.isFieldInitConstant(fieldNode)) {
unsetFields[element] = fieldNode;
} else {
fields[element] = _visitInitializer(fieldNode);
}
}
// Initialize fields from `this.fieldName` parameters.
if (ctor != null) {
for (var p in ctor.parameters.parameters) {
var element = p.element;
if (element is FieldFormalParameterElement) {
fields[element.field] = _emitSimpleIdentifier(p.identifier);
}
}
// Run constructor field initializers such as `: foo = bar.baz`
for (var init in ctor.initializers) {
if (init is ConstructorFieldInitializer) {
var element = init.fieldName.staticElement as FieldElement;
fields[element] = _visit(init.expression);
} else if (init is AssertInitializer) {
throw new UnimplementedError(
'Assert initializers are not implemented. '
'See https://github.com/dart-lang/sdk/issues/27809');
}
}
}
for (var f in fields.keys) unsetFields.remove(f);
// Initialize all remaining fields
unsetFields.forEach((element, fieldNode) {
JS.Expression value;
if (fieldNode.initializer != null) {
value = _visit(fieldNode.initializer);
} else {
value = new JS.LiteralNull();
}
fields[element] = value;
});
var body = <JS.Statement>[];
fields.forEach((FieldElement e, JS.Expression initialValue) {
JS.Expression access =
_classProperties.virtualFields[e] ?? _declareMemberName(e.getter);
body.add(initialValue
.toAssignExpression(js.call('this.#', [access]))
.toStatement());
});
return _statement(body);
}
FormalParameterList _parametersOf(node) {
// TODO(jmesserly): clean this up. If we can model ES6 spread/rest args, we
// could handle argument initializers more consistently in a separate
// lowering pass.
if (node is ConstructorDeclaration) return node.parameters;
if (node is MethodDeclaration) return node.parameters;
if (node is FunctionDeclaration) node = node.functionExpression;
return (node as FunctionExpression).parameters;
}
/// Emits argument initializers, which handles optional/named args, as well
/// as generic type checks needed due to our covariance.
JS.Statement _emitArgumentInitializers(
ExecutableElement element, FormalParameterList parameters) {
if (parameters == null) return null;
var body = <JS.Statement>[];
_emitCovarianceBoundsCheck(
element.typeParameters, _classProperties?.covariantParameters, body);
for (var param in parameters.parameters) {
var jsParam = _emitSimpleIdentifier(param.identifier);
if (!options.destructureNamedParams &&
param.kind != ParameterKind.REQUIRED) {
if (param.kind == ParameterKind.NAMED) {
// Parameters will be passed using their real names, not the (possibly
// renamed) local variable.
var paramName = js.string(param.identifier.name, "'");
var defaultValue = _defaultParamValue(param);
if (defaultValue != null) {
// TODO(ochafik): Fix `'prop' in obj` to please Closure's renaming.
body.add(js.statement('let # = # && # in # ? #.# : #;', [
jsParam,
namedArgumentTemp,
paramName,
namedArgumentTemp,
namedArgumentTemp,
paramName,
defaultValue,
]));
} else {
body.add(js.statement('let # = # && #.#;', [
jsParam,
namedArgumentTemp,
namedArgumentTemp,
paramName,
]));
}
} else if (param.kind == ParameterKind.POSITIONAL) {
var defaultValue = _defaultParamValue(param);
if (defaultValue != null) {
body.add(js.statement(
'if (# === void 0) # = #;', [jsParam, jsParam, defaultValue]));
}
}
}
var paramElement = resolutionMap.elementDeclaredByFormalParameter(param);
if (_isCovariant(paramElement)) {
var castType = _emitType(paramElement.type);
body.add(js.statement('#._check(#);', [castType, jsParam]));
}
if (_annotatedNullCheck(paramElement)) {
body.add(nullParameterCheck(jsParam));
}
}
return body.isEmpty ? null : _statement(body);
}
bool _isCovariant(ParameterElement p) {
return p.isCovariant ||
(_classProperties?.covariantParameters?.contains(p) ?? false);
}
JS.Expression _defaultParamValue(FormalParameter param) {
if (param is DefaultFormalParameter && param.defaultValue != null) {
var defaultValue = param.defaultValue;
return _isJSUndefined(defaultValue) ? null : _visit(defaultValue);
} else {
return new JS.LiteralNull();
}
}
bool _isJSUndefined(Expression expr) {
expr = expr is AsExpression ? expr.expression : expr;
if (expr is Identifier) {
var element = expr.staticElement;
return isSdkInternalRuntime(element.library) &&
element.name == 'undefined';
}
return false;
}
JS.Fun _emitNativeFunctionBody(MethodDeclaration node) {
String name =
getAnnotationName(node.element, isJSAnnotation) ?? node.name.name;
if (node.isGetter) {
return new JS.Fun([], js.statement('{ return this.#; }', [name]));
} else if (node.isSetter) {
var params =
_emitFormalParameterList(node.parameters, destructure: false);
return new JS.Fun(
params, js.statement('{ this.# = #; }', [name, params.last]));
} else {
return js.call(
'function (...args) { return this.#.apply(this, args); }', name);
}
}
JS.Method _emitMethodDeclaration(InterfaceType type, MethodDeclaration node) {
if (node.isAbstract) {
return null;
}
JS.Fun fn;
if (node.externalKeyword != null || node.body is NativeFunctionBody) {
if (node.isStatic) {
// TODO(vsm): Do we need to handle this case?
return null;
}
fn = _emitNativeFunctionBody(node);
} else {
fn = _emitFunction(node.element, node.parameters, node.body);
}
return annotate(
new JS.Method(_declareMemberName(node.element), fn,
isGetter: node.isGetter,
isSetter: node.isSetter,
isStatic: node.isStatic),
null, // don't annotate as this breaks stepping for one-line functions.
node.element);
}
/// Transform the function so the last parameter is always returned.
///
/// This is useful for indexed set methods, which otherwise would not have
/// the right return value in JS.
JS.Block _alwaysReturnLastParameter(JS.Block body, JS.Parameter lastParam) {
JS.Statement blockBody = body;
if (JS.Return.foundIn(body)) {
// If a return is inside body, transform `(params) { body }` to
// `(params) { (() => { body })(); return value; }`.
// TODO(jmesserly): we could instead generate the return differently,
// and avoid the immediately invoked function.
blockBody = new JS.Call(new JS.ArrowFun([], body), []).toStatement();
}
return new JS.Block([blockBody, new JS.Return(lastParam)]);
}
@override
JS.Statement visitFunctionDeclaration(FunctionDeclaration node) {
assert(node.parent is CompilationUnit);
if (node.externalKeyword != null ||
node.functionExpression.body is NativeFunctionBody) {
return null;
}
if (node.isGetter || node.isSetter) {
PropertyAccessorElement element = node.element;
var pairAccessor = node.isGetter
? element.correspondingSetter
: element.correspondingGetter;
var jsCode = _emitTopLevelProperty(node);
var props = <JS.Method>[jsCode];
if (pairAccessor != null) {
// If we have a getter/setter pair, they need to be defined together.
// If this is the first one, save the generated code for later.
// If this is the second one, get the saved code and emit both.
var pairCode = _deferredProperties.remove(pairAccessor);
if (pairCode == null) {
_deferredProperties[element] = jsCode;
return null;
}
props.add(pairCode);
}
return _callHelperStatement('copyProperties(#, { # });',
[emitLibraryName(currentLibrary), props]);
}
var body = <JS.Statement>[];
var fn = _emitFunctionExpression(node.functionExpression);
if (currentLibrary.source.isInSystemLibrary &&
_isInlineJSFunction(node.functionExpression)) {
fn = _simplifyPassThroughArrowFunCallBody(fn);
}
var element = resolutionMap.elementDeclaredByFunctionDeclaration(node);
var nameExpr = _emitTopLevelName(element);
body.add(annotate(
js.statement('# = #', [nameExpr, fn]),
// Don't annotate as code coverage will consider single line functions
// as covered
null,
element));
if (!isSdkInternalRuntime(element.library)) {
body.add(_emitFunctionTagged(nameExpr, element.type, topLevel: true)
.toStatement());
}
return _statement(body);
}
bool _isInlineJSFunction(FunctionExpression functionExpression) {
var body = functionExpression.body;
if (body is ExpressionFunctionBody) {
return _isJSInvocation(body.expression);
} else if (body is BlockFunctionBody) {
var statements = body.block.statements;
if (statements.length == 1) {
var stat = statements[0];
if (stat is ReturnStatement) {
return _isJSInvocation(stat.expression);
}
}
}
return false;
}
bool _isJSInvocation(Expression expr) =>
expr is MethodInvocation && isInlineJS(expr.methodName.staticElement);
// Simplify `(args) => (() => { ... })()` to `(args) => { ... }`.
// Note: this allows silently passing args through to the body, which only
// works if we don't do weird renamings of Dart params.
JS.Fun _simplifyPassThroughArrowFunCallBody(JS.Fun fn) {
if (fn.body is JS.Block && fn.body.statements.length == 1) {
var stat = fn.body.statements.single;
if (stat is JS.Return && stat.value is JS.Call) {
JS.Call call = stat.value;
if (call.target is JS.ArrowFun && call.arguments.isEmpty) {
JS.ArrowFun innerFun = call.target;
if (innerFun.params.isEmpty) {
return new JS.Fun(fn.params, innerFun.body,
typeParams: fn.typeParams, returnType: fn.returnType);
}
}
}
}
return fn;
}
JS.Method _emitTopLevelProperty(FunctionDeclaration node) {
var name = node.name.name;
return annotate(
new JS.Method(_propertyName(name),
_emitFunctionExpression(node.functionExpression),
isGetter: node.isGetter, isSetter: node.isSetter),
node,
node.element);
}
bool _executesAtTopLevel(AstNode node) {
var ancestor = node.getAncestor((n) =>
n is FunctionBody ||
(n is FieldDeclaration && n.staticKeyword == null) ||
(n is ConstructorDeclaration && n.constKeyword == null));
return ancestor == null;
}
bool _typeIsLoaded(DartType type) {
if (type is FunctionType && (type.name == '' || type.name == null)) {
return (_typeIsLoaded(type.returnType) &&
type.optionalParameterTypes.every(_typeIsLoaded) &&
type.namedParameterTypes.values.every(_typeIsLoaded) &&
type.normalParameterTypes.every(_typeIsLoaded));
}
if (type.isDynamic || type.isVoid || type.isBottom) return true;
if (type is ParameterizedType && !type.typeArguments.every(_typeIsLoaded)) {
return false;
}
return !_declarationNodes.containsKey(type.element);
}
JS.Expression _emitFunctionTagged(JS.Expression fn, DartType type,
{topLevel: false}) {
var lazy = topLevel && !_typeIsLoaded(type);
var typeRep = _emitFunctionType(type, definite: true);
if (lazy) {
return _callHelper('lazyFn(#, () => #)', [fn, typeRep]);
} else {
return _callHelper('fn(#, #)', [fn, typeRep]);
}
}
/// Emits an arrow FunctionExpression node.
///
/// This should be used for all places in Dart's AST where FunctionExpression
/// appears and the function is actually in an Expression context. These
/// correspond to arrow functions in Dart.
///
/// Contrast with [_emitFunctionExpression].
@override
JS.Expression visitFunctionExpression(FunctionExpression node) {
assert(node.parent is! FunctionDeclaration &&
node.parent is! MethodDeclaration);
return _emitFunctionTagged(_emitArrowFunction(node), getStaticType(node),
topLevel: _executesAtTopLevel(node));
}
JS.ArrowFun _emitArrowFunction(FunctionExpression node) {
JS.Fun fn = _emitFunction(node.element, node.parameters, node.body);
return annotate(_toArrowFunction(fn), node);
}
JS.ArrowFun _toArrowFunction(JS.Fun f) {
JS.Node body = f.body;
// Simplify `=> { return e; }` to `=> e`
if (body is JS.Block) {
JS.Block block = body;
if (block.statements.length == 1) {
JS.Statement s = block.statements[0];
if (s is JS.Return && s.value != null) body = s.value;
}
}
// Convert `function(...) { ... }` to `(...) => ...`
// This is for readability, but it also ensures correct `this` binding.
return new JS.ArrowFun(f.params, body,
typeParams: f.typeParams, returnType: f.returnType)
..sourceInformation = f.sourceInformation;
}
/// Emits a non-arrow FunctionExpression node.
///
/// This should be used for all places in Dart's AST where FunctionExpression
/// appears but the function is not actually in an Expression context, such
/// as methods, properties, and top-level functions.
///
/// Contrast with [visitFunctionExpression].
JS.Fun _emitFunctionExpression(FunctionExpression node) {
return annotate(
_emitFunction(node.element, node.parameters, node.body), node);
}
JS.Fun _emitFunction(ExecutableElement element,
FormalParameterList parameters, FunctionBody body) {
FunctionType type = element.type;
// normal function (sync), vs (sync*, async, async*)
var isSync = !(element.isAsynchronous || element.isGenerator);
var formals = _emitFormalParameterList(parameters, destructure: isSync);
var typeFormals = _emitTypeFormals(type.typeFormals);
formals.insertAll(0, typeFormals);
JS.Block code = isSync
? _emitFunctionBody(element, parameters, body)
: new JS.Block(
[_emitGeneratorFunction(element, parameters, body).toReturn()]);
if (element.isOperator && formals.isNotEmpty) {
if (element.name == '[]=') {
// []= methods need to return the value. We could also address this at
// call sites, but it's cleaner to instead transform the operator method.
code = _alwaysReturnLastParameter(code, formals.last);
} else if (element.name == '==' && !element.library.isInSdk) {
// In Dart `operator ==` methods are not called with a null argument.
// This is handled before calling them. For performance reasons, we push
// this check inside the method, to simplify our `equals` helper.
//
// TODO(jmesserly): in most cases this check is not necessary, because
// the Dart code already handles it (typically by an `is` check).
// Eliminate it when possible.
code = new JS.Block([
js.statement('if (# == null) return false;', [formals.first]),
code
]);
}
}
return new JS.Fun(formals, code,
typeParams: typeFormals, returnType: emitTypeRef(type.returnType));
}
JS.Block _emitFunctionBody(ExecutableElement element,
FormalParameterList parameters, FunctionBody body) {
var savedFunction = _currentFunction;
_currentFunction = body;
var initArgs = _emitArgumentInitializers(element, parameters);
var block = _visit<JS.Block>(body);
if (initArgs != null) block = new JS.Block([initArgs, block]);
if (body is BlockFunctionBody) {
var params = element.parameters.map((e) => e.name).toSet();
bool shadowsParam = body.block.statements.any((s) =>
s is VariableDeclarationStatement &&
s.variables.variables.any((v) => params.contains(v.name.name)));
if (shadowsParam) {
block = new JS.Block([
new JS.Block([block], isScope: true)
]);
}
}
_currentFunction = savedFunction;
return block;
}
void _emitCovarianceBoundsCheck(List<TypeParameterElement> typeFormals,
Set<Element> covariantParams, List<JS.Statement> body) {
if (covariantParams == null) return;
for (var t in typeFormals) {
t = covariantParams.lookup(t) as TypeParameterElement;
if (t != null) {
body.add(_callHelperStatement('checkTypeBound(#, #, #)',
[_emitType(t.type), _emitType(t.bound), _propertyName(t.name)]));
}
}
}
JS.Expression _emitGeneratorFunction(ExecutableElement element,
FormalParameterList parameters, FunctionBody body) {
var kind = element.isSynchronous ? 'sync' : 'async';
if (element.isGenerator) kind += 'Star';
// Transforms `sync*` `async` and `async*` function bodies
// using ES6 generators.
//
// `sync*` wraps a generator in a Dart Iterable<T>:
//
// function name(<args>) {
// return dart.syncStar(function* name(<args>) {
// <body>
// }, T, <args>).bind(this);
// }
//
// We need to include <args> in case any are mutated, so each `.iterator`
// gets the same initial values.
//
// TODO(jmesserly): we could omit the args for the common case where args
// are not mutated inside the generator.
//
// In the future, we might be able to simplify this, see:
// https://github.com/dart-lang/sdk/issues/28320
// `async` works the same, but uses the `dart.async` helper.
//
// In the body of a `sync*` and `async`, `yield`/`await` are both generated
// simply as `yield`.
//
// `async*` uses the `dart.asyncStar` helper, and also has an extra `stream`
// argument to the generator, which is used for passing values to the
// _AsyncStarStreamController implementation type.
// `yield` is specially generated inside `async*`, see visitYieldStatement.
// `await` is generated as `yield`.
// runtime/_generators.js has an example of what the code is generated as.
var savedController = _asyncStarController;
var jsParams = _emitFormalParameterList(parameters);
if (kind == 'asyncStar') {
_asyncStarController = new JS.TemporaryId('stream');
jsParams.insert(0, _asyncStarController);
} else {
_asyncStarController = null;
}
var savedSuperAllowed = _superAllowed;
_superAllowed = false;
// Visit the body with our async* controller set.
var jsBody = _emitFunctionBody(element, parameters, body);
_superAllowed = savedSuperAllowed;
_asyncStarController = savedController;
DartType returnType = _getExpectedReturnType(element);
JS.Expression gen = new JS.Fun(jsParams, jsBody,
isGenerator: true, returnType: emitTypeRef(returnType));
// Name the function if possible, to get better stack traces.
var name = element.name;
name = _friendlyOperatorName[name] ?? name;
if (name.isNotEmpty) {
gen = new JS.NamedFunction(new JS.Identifier(name), gen);
}
if (JS.This.foundIn(gen)) {
gen = js.call('#.bind(this)', gen);
}
var T = _emitType(returnType);
return _callHelper('#(#)', [
kind,
[gen, T]..addAll(_emitFormalParameterList(parameters, destructure: false))
]);
}
@override
JS.Statement visitFunctionDeclarationStatement(
FunctionDeclarationStatement node) {
var func = node.functionDeclaration;
if (func.isGetter || func.isSetter) {
return js.comment('Unimplemented function get/set statement: $node');
}
var fn = _emitFunctionExpression(func.functionExpression);
var name = new JS.Identifier(func.name.name);
JS.Statement declareFn;
if (JS.This.foundIn(fn)) {
declareFn = js.statement('const # = #.bind(this);', [name, fn]);
} else {
declareFn = new JS.FunctionDeclaration(name, fn);
}
var element = func.element;
declareFn = annotate(declareFn, node, element);
return new JS.Block(
[declareFn, _emitFunctionTagged(name, element.type).toStatement()]);
}
/// Emits a simple identifier, including handling an inferred generic
/// function instantiation.
@override
JS.Expression visitSimpleIdentifier(SimpleIdentifier node) {
var typeArgs = _getTypeArgs(node.staticElement, node.staticType);
var simpleId = _emitSimpleIdentifier(node);
if (typeArgs == null) {
return simpleId;
}
return _callHelper('gbind(#, #)', [simpleId, typeArgs]);
}
/// Emits a simple identifier, handling implicit `this` as well as
/// going through the qualified library name if necessary, but *not* handling
/// inferred generic function instantiation.
JS.Expression _emitSimpleIdentifier(SimpleIdentifier node) {
var accessor = resolutionMap.staticElementForIdentifier(node);
if (accessor == null) {
return _throwUnsafe('unresolved identifier: ' + (node.name ?? '<null>'));
}
// Get the original declaring element. If we had a property accessor, this
// indirects back to a (possibly synthetic) field.
var element = accessor;
if (accessor is PropertyAccessorElement) element = accessor.variable;
// type literal
if (element is TypeDefiningElement) {
_declareBeforeUse(element);
var typeName = _emitType(fillDynamicTypeArgs(element.type));
// If the type is a type literal expression in Dart code, wrap the raw
// runtime type in a "Type" instance.
if (!_isInForeignJS && _isTypeLiteral(node)) {
typeName = _callHelper('wrapType(#)', typeName);
}
return typeName;
}
// library member
if (element.enclosingElement is CompilationUnitElement) {
return _emitTopLevelName(accessor);
}
var name = element.name;
// Unqualified class member. This could mean implicit-this, or implicit
// call to a static from the same class.
if (element is ClassMemberElement && element is! ConstructorElement) {
bool isStatic = element.isStatic;
var type = element.enclosingElement.type;
var member = _emitMemberName(name,
isStatic: isStatic, type: type, element: accessor);
if (isStatic) {
var dynType = _emitStaticAccess(type);
return new JS.PropertyAccess(dynType, member);
}
// For instance members, we add implicit-this.
// For method tear-offs, we ensure it's a bound method.
if (element is MethodElement &&
!inInvocationContext(node) &&
!_isJSNative(element.enclosingElement)) {
return _callHelper('bind(this, #)', member);
}
return js.call('this.#', member);
}
if (element is ParameterElement) {
return _emitParameter(element);
}
// If this is one of our compiler's temporary variables, return its JS form.
if (element is TemporaryVariableElement) {
return element.jsVariable;
}
return new JS.Identifier(name);
}
/// Returns `true` if the type name referred to by [node] is used in a
/// position where it should evaluate as a type literal -- an object of type
/// Type.
bool _isTypeLiteral(SimpleIdentifier node) {
var parent = node.parent;
// Static member call.
if (parent is MethodInvocation || parent is PropertyAccess) return false;
// An expression like "a.b".
if (parent is PrefixedIdentifier) {
// In "a.b", "b" may be a type literal, but "a", is not.
if (node != parent.identifier) return false;
// If the prefix expression is itself used as an invocation, like
// "a.b.c", then "b" is not a type literal.
var grand = parent.parent;
if (grand is MethodInvocation || grand is PropertyAccess) return false;
return true;
}
// In any other context, it's a type literal.
return true;
}
JS.Identifier _emitParameter(ParameterElement element,
{bool declaration: false}) {
// initializing formal parameter, e.g. `Point(this._x)`
// TODO(jmesserly): type ref is not attached in this case.
if (element.isInitializingFormal && element.isPrivate) {
/// Rename private names so they don't shadow the private field symbol.
/// The renamer would handle this, but it would prefer to rename the
/// temporary used for the private symbol. Instead rename the parameter.
return _initializingFormalTemps.putIfAbsent(
element, () => new JS.TemporaryId(element.name.substring(1)));
}
var type = declaration ? emitTypeRef(element.type) : null;
return new JS.Identifier(element.name, type: type);
}
List<Annotation> _parameterMetadata(FormalParameter p) =>
(p is NormalFormalParameter)
? p.metadata
: (p as DefaultFormalParameter).parameter.metadata;
// Wrap a result - usually a type - with its metadata. The runtime is
// responsible for unpacking this.
JS.Expression _emitAnnotatedResult(
JS.Expression result, List<Annotation> metadata) {
if (options.emitMetadata && metadata != null && metadata.isNotEmpty) {
result = new JS.ArrayInitializer(
[result]..addAll(metadata.map(_instantiateAnnotation)));
}
return result;
}
JS.Expression _emitAnnotatedType(DartType type, List<Annotation> metadata,
{bool nameType: true}) {
metadata ??= [];
var typeName = _emitType(type, nameType: nameType);
return _emitAnnotatedResult(typeName, metadata);
}
JS.Expression _emitFieldSignature(DartType type,
{List<Annotation> metadata, bool isFinal: true}) {
var args = [_emitType(type)];
if (options.emitMetadata && metadata != null && metadata.isNotEmpty) {
args.add(new JS.ArrayInitializer(
metadata.map(_instantiateAnnotation).toList()));
}
return _callHelper(isFinal ? 'finalFieldType(#)' : 'fieldType(#)', [args]);
}
JS.ArrayInitializer _emitTypeNames(
List<DartType> types, List<FormalParameter> parameters,
{bool nameType: true}) {
var result = <JS.Expression>[];
for (int i = 0; i < types.length; ++i) {
var metadata = parameters != null
? _parameterMetadata(parameters[i])
: <Annotation>[];
result.add(_emitAnnotatedType(types[i], metadata));
}
return new JS.ArrayInitializer(result);
}
JS.ObjectInitializer _emitTypeProperties(Map<String, DartType> types) {
var properties = <JS.Property>[];
types.forEach((name, type) {
var key = _propertyName(name);
var value = _emitType(type);
properties.add(new JS.Property(key, value));
});
return new JS.ObjectInitializer(properties);
}
/// Emit the pieces of a function type, as an array of return type,
/// regular args, and optional/named args.
JS.Expression _emitFunctionType(FunctionType type,
{List<FormalParameter> parameters,
bool lowerTypedef: false,
bool nameType: true,
definite: false}) {
var parameterTypes = type.normalParameterTypes;
var optionalTypes = type.optionalParameterTypes;
var namedTypes = type.namedParameterTypes;
var rt = _emitType(type.returnType, nameType: nameType);
var ra = _emitTypeNames(parameterTypes, parameters, nameType: nameType);
List<JS.Expression> typeParts;
if (namedTypes.isNotEmpty) {
assert(optionalTypes.isEmpty);
// TODO(vsm): Pass in annotations here as well.
var na = _emitTypeProperties(namedTypes);
typeParts = [rt, ra, na];
} else if (optionalTypes.isNotEmpty) {
assert(namedTypes.isEmpty);
var oa = _emitTypeNames(
optionalTypes, parameters?.sublist(parameterTypes.length),
nameType: nameType);
typeParts = [rt, ra, oa];
} else {
typeParts = [rt, ra];
}
JS.Expression fullType;
var typeFormals = type.typeFormals;
String helperCall;
if (typeFormals.isNotEmpty) {
var tf = _emitTypeFormals(typeFormals);
addTypeFormalsAsParameters(List<JS.Expression> elements) {
var names = _typeTable.discharge(typeFormals);
var array = new JS.ArrayInitializer(elements);
return names.isEmpty
? js.call('(#) => #', [tf, array])
: js.call('(#) => {#; return #;}', [tf, names, array]);
}
typeParts = [addTypeFormalsAsParameters(typeParts)];
helperCall = definite ? 'gFnType(#)' : 'gFnTypeFuzzy(#)';
// If any explicit bounds were passed, emit them.
if (typeFormals.any((t) => t.bound != null)) {
var bounds = typeFormals.map((t) => _emitType(t.type.bound)).toList();
typeParts.add(addTypeFormalsAsParameters(bounds));
}
} else {
helperCall = definite ? 'fnType(#)' : 'fnTypeFuzzy(#)';
}
fullType = _callHelper(helperCall, [typeParts]);
if (!nameType) return fullType;
return _typeTable.nameType(type, fullType, definite: definite);
}
JS.Expression _emitAnnotatedFunctionType(
FunctionType type, List<Annotation> metadata,
{List<FormalParameter> parameters,
bool lowerTypedef: false,
bool nameType: true,
bool definite: false}) {
var result = _emitFunctionType(type,
parameters: parameters,
lowerTypedef: lowerTypedef,
nameType: nameType,
definite: definite);
return _emitAnnotatedResult(result, metadata);
}
/// Emits an expression that lets you access statics on a [type] from code.
///
/// If [nameType] is true, then the type will be named. In addition,
/// if [hoistType] is true, then the named type will be hoisted.
JS.Expression _emitConstructorAccess(DartType type, {bool nameType: true}) {
return _emitJSInterop(type.element) ?? _emitType(type, nameType: nameType);
}
/// Emits an expression that lets you access statics on a [type] from code.
JS.Expression _emitStaticAccess(DartType type) {
// Make sure we aren't attempting to emit a static access path to a type
// that does not have a valid static access path.
assert(!type.isVoid &&
!type.isDynamic &&
!type.isBottom &&
type is! TypeParameterType);
// For statics, we add the raw type name, without generics or
// library prefix. We don't need those because static calls can't use
// the generic type.
type = fillDynamicTypeArgs(type);
var element = type.element;
_declareBeforeUse(element);
var interop = _emitJSInterop(element);
if (interop != null) return interop;
assert(type.name != '' && type.name != null);
return _emitTopLevelNameNoInterop(element);
}
/// Emits a Dart [type] into code.
///
/// If [lowerTypedef] is set, a typedef will be expanded as if it were a
/// function type. Similarly if [lowerGeneric] is set, the `List$()` form
/// will be used instead of `List`. These flags are used when generating
/// the definitions for typedefs and generic types, respectively.
///
/// If [subClass] is set, then we are setting the base class for the given
/// class and should emit the given [className], which will already be
/// defined.
///
/// If [nameType] is true, then the type will be named. In addition,
/// if [hoistType] is true, then the named type will be hoisted.
JS.Expression _emitType(DartType type,
{bool lowerTypedef: false,
bool lowerGeneric: false,
bool nameType: true,
ClassElement subClass,
JS.Expression className}) {
// The void and dynamic types are not defined in core.
if (type.isVoid) {
return _callHelper('void');
} else if (type.isDynamic) {
return _callHelper('dynamic');
} else if (type.isBottom) {
return _callHelper('bottom');
}
var element = type.element;
if (element is TypeDefiningElement) {
_declareBeforeUse(element);
}
// Type parameters don't matter as JS interop types cannot be reified.
// We have to use lazy JS types because until we have proper module
// loading for JS libraries bundled with Dart libraries, we will sometimes
// need to load Dart libraries before the corresponding JS libraries are
// actually loaded.
// Given a JS type such as:
// @JS('google.maps.Location')
// class Location { ... }
// We can't emit a reference to MyType because the JS library that defines
// it may be loaded after our code. So for now, we use a special lazy type
// object to represent MyType.
// Anonymous JS types do not have a corresponding concrete JS type so we
// have to use a helper to define them.
if (_isObjectLiteral(element)) {
return _callHelper('anonymousJSType(#)', js.escapedString(element.name));
}
var jsName = _getJSNameWithoutGlobal(element);
if (jsName != null) {
return _callHelper('lazyJSType(() => #, #)',
[_emitJSInteropForGlobal(jsName), js.escapedString(jsName)]);
}
// TODO(jmesserly): like constants, should we hoist function types out of
// methods? Similar issue with generic types. For all of these, we may want
// to canonicalize them too, at least when inside the same library.
var name = type.name;
if (name == '' || name == null || lowerTypedef) {
// TODO(jmesserly): should we change how typedefs work? They currently
// go through use similar logic as generic classes. This makes them
// different from universal function types.
return _emitFunctionType(type as FunctionType,
lowerTypedef: lowerTypedef, nameType: nameType);
}
if (type is TypeParameterType) {
_typeParamInConst?.add(type);
return new JS.Identifier(name);
}
if (type == subClass?.type) return className;
if (type is ParameterizedType) {
var args = type.typeArguments;
Iterable jsArgs = null;
if (args.any((a) => !a.isDynamic)) {
jsArgs = args.map((x) => _emitType(x,
nameType: nameType, subClass: subClass, className: className));
} else if (lowerGeneric || element == subClass) {
jsArgs = [];
}
if (jsArgs != null) {
var genericName = _emitTopLevelNameNoInterop(element, suffix: '\$');
var typeRep = js.call('#(#)', [genericName, jsArgs]);
return nameType ? _typeTable.nameType(type, typeRep) : typeRep;
}
}
return _emitTopLevelNameNoInterop(element);
}
JS.PropertyAccess _emitTopLevelName(Element e, {String suffix: ''}) {
return _emitJSInterop(e) ?? _emitTopLevelNameNoInterop(e, suffix: suffix);
}
JS.PropertyAccess _emitTopLevelNameNoInterop(Element e, {String suffix: ''}) {
var name = getJSExportName(e) ?? _getElementName(e);
return new JS.PropertyAccess(
emitLibraryName(e.library), _propertyName(name + suffix));
}
@override
JS.Expression visitAssignmentExpression(AssignmentExpression node) {
var left = node.leftHandSide;
var right = node.rightHandSide;
if (node.operator.type == TokenType.EQ) return _emitSet(left, right);
var op = node.operator.lexeme;
assert(op.endsWith('='));
op = op.substring(0, op.length - 1); // remove trailing '='
return _emitOpAssign(left, right, op, node.staticElement, context: node);
}
JS.MetaLet _emitOpAssign(
Expression left, Expression right, String op, MethodElement element,
{Expression context}) {
if (op == '??') {
// Desugar `l ??= r` as ((x) => x == null ? l = r : x)(l)
// Note that if `x` contains subexpressions, we need to ensure those
// are also evaluated only once. This is similar to desugaring for
// postfix expressions like `i++`.
// Handle the left hand side, to ensure each of its subexpressions are
// evaluated only once.
var vars = <JS.MetaLetVariable, JS.Expression>{};
var x = _bindLeftHandSide(vars, left, context: left);
// Capture the result of evaluating the left hand side in a temp.
var t = _bindValue(vars, 't', x, context: x);
return new JS.MetaLet(vars, [
js.call('# == null ? # : #', [_visit(t), _emitSet(x, right), _visit(t)])
]);
}
// Desugar `x += y` as `x = x + y`, ensuring that if `x` has subexpressions
// (for example, x is IndexExpression) we evaluate those once.
var vars = <JS.MetaLetVariable, JS.Expression>{};
var lhs = _bindLeftHandSide(vars, left, context: context);
// TODO(leafp): The element for lhs here will be the setter element
// instead of the getter element if lhs is a property access. This
// interferes with nullability analysis.
Expression inc = ast.binaryExpression(lhs, op, right)
..staticElement = element
..staticType = getStaticType(lhs);
var castTo = getImplicitOperationCast(left);
if (castTo != null) inc = CoercionReifier.castExpression(inc, castTo);
return new JS.MetaLet(vars, [_emitSet(lhs, inc)]);
}
JS.Expression _emitSet(Expression left, Expression right) {
if (left is IndexExpression) {
var target = _getTarget(left);
if (_useNativeJsIndexer(target.staticType)) {
return js.call(
'#[#] = #', [_visit(target), _visit(left.index), _visit(right)]);
}
return _emitSend(target, '[]=', [left.index, right]);
}
if (left is SimpleIdentifier) {
return _emitSetSimpleIdentifier(left, right);
}
Expression target = null;
SimpleIdentifier id;
if (left is PropertyAccess) {
if (left.operator.lexeme == '?.') {
return _emitNullSafeSet(left, right);
}
target = _getTarget(left);
id = left.propertyName;
} else if (left is PrefixedIdentifier) {
if (isLibraryPrefix(left.prefix)) {
return _emitSet(left.identifier, right);
}
target = left.prefix;
id = left.identifier;
} else {
assert(false);
}
if (isDynamicInvoke(target)) {
return _callHelper('#(#, #, #)', [
_emitDynamicOperationName('dput'),
_visit(target),
_emitMemberName(id.name),
_visit(right)
]);
}
var accessor = id.staticElement;
if (accessor is PropertyAccessorElement) {
var field = accessor.variable;
if (field is FieldElement) {
return _emitSetField(left, right, field, _visit(target));
}
}
return _badAssignment('Unhandled assignment', left, right);
}
JS.Expression _badAssignment(String problem, Expression lhs, Expression rhs) {
// TODO(sra): We should get here only for compiler bugs or weirdness due to
// --unsafe-force-compile. Once those paths have been addressed, throw at
// compile time.
return _callHelper('throwUnimplementedError((#, #, #))',
[js.string('$lhs ='), _visit(rhs), js.string(problem)]);
}
/// Emits assignment to a simple identifier. Handles all legal simple
/// identifier assignment targets (local, top level library member, implicit
/// `this` or class, etc.)
JS.Expression _emitSetSimpleIdentifier(
SimpleIdentifier node, Expression right) {
JS.Expression unimplemented() {
return _badAssignment("Unimplemented: unknown name '$node'", node, right);
}
var accessor = resolutionMap.staticElementForIdentifier(node);
if (accessor == null) return unimplemented();
// Get the original declaring element. If we had a property accessor, this
// indirects back to a (possibly synthetic) field.
var element = accessor;
if (accessor is PropertyAccessorElement) element = accessor.variable;
if (element is TypeDefiningElement) {
_declareBeforeUse(element);
}
if (element is LocalVariableElement || element is ParameterElement) {
return _emitSetLocal(node, element, right);
}
if (element.enclosingElement is CompilationUnitElement) {
// Top level library member.
return _emitSetTopLevel(node, accessor, right);
}
// Unqualified class member. This could mean implicit `this`, or implicit
// static from the same class.
if (element is FieldElement) {
return _emitSetField(node, right, element, new JS.This());
}
// We should not get here.
return unimplemented();
}
/// Emits assignment to a simple local variable or parameter.
JS.Expression _emitSetLocal(
SimpleIdentifier node, Element element, Expression rhs) {
JS.Expression target;
if (element is TemporaryVariableElement) {
// If this is one of our compiler's temporary variables, use its JS form.
target = element.jsVariable;
} else if (element is ParameterElement) {
target = _emitParameter(element);
} else {
target = new JS.Identifier(element.name);
}
return _visit<JS.Expression>(rhs)
.toAssignExpression(annotate(target, node));
}
/// Emits assignment to library scope element [element].
JS.Expression _emitSetTopLevel(
Expression lhs, PropertyAccessorElement element, Expression rhs) {
return _visit<JS.Expression>(rhs)
.toAssignExpression(annotate(_emitTopLevelName(element), lhs));
}
/// Emits assignment to a static field element or property.
JS.Expression _emitSetField(Expression left, Expression right,
FieldElement field, JS.Expression jsTarget) {
var type = field.enclosingElement.type;
var isStatic = field.isStatic;
var member = _emitMemberName(field.name,
isStatic: isStatic, type: type, element: field.setter);
jsTarget = isStatic
? new JS.PropertyAccess(_emitStaticAccess(type), member)
: _emitTargetAccess(jsTarget, member, field.setter);
return _visit<JS.Expression>(right)
.toAssignExpression(annotate(jsTarget, left));
}
JS.Expression _emitNullSafeSet(PropertyAccess node, Expression right) {
// Emit `obj?.prop = expr` as:
//
// (_ => _ == null ? null : _.prop = expr)(obj).
//
// We could use a helper, e.g.: `nullSafeSet(e1, _ => _.v = e2)`
//
// However with MetaLet, we get clean code in statement or void context,
// or when one of the expressions is stateless, which seems common.
var vars = <JS.MetaLetVariable, JS.Expression>{};
var left = _bindValue(vars, 'l', node.target);
var body = js.call('# == null ? null : #',
[_visit(left), _emitSet(_stripNullAwareOp(node, left), right)]);
return new JS.MetaLet(vars, [body]);
}
@override
JS.Block visitExpressionFunctionBody(ExpressionFunctionBody node) {
var ret = annotate(
_visit<JS.Expression>(node.expression).toReturn(), node.expression);
return new JS.Block([ret]);
}
@override
JS.Block visitEmptyFunctionBody(EmptyFunctionBody node) => new JS.Block([]);
@override
JS.Block visitBlockFunctionBody(BlockFunctionBody node) {
return new JS.Block(_visitList(node.block.statements));
}
@override
JS.Block visitBlock(Block node) =>
new JS.Block(_visitList(node.statements), isScope: true);
@override
visitMethodInvocation(MethodInvocation node) {
if (_isDeferredLoadLibrary(node.target, node.methodName)) {
// We are calling loadLibrary() on a deferred library prefix.
return _callHelper('loadLibrary()');
}
if (node.operator?.lexeme == '?.') {
return _emitNullSafe(node);
}
var e = node.methodName.staticElement;
var result = _emitForeignJS(node, e);
if (result != null) return result;
if (e?.name == 'extensionSymbol' &&
e.library.isInSdk &&
e.library.source.uri.toString() == 'dart:_runtime') {
var args = node.argumentList.arguments;
var firstArg = args.length == 1 ? args[0] : null;
if (firstArg is StringLiteral) {
return _getExtensionSymbolInternal(firstArg.stringValue);
}
}
var target = _getTarget(node);
if (target == null || isLibraryPrefix(target)) {
return _emitFunctionCall(node);
}
if (node.methodName.name == 'call') {
var targetType = resolutionMap.staticTypeForExpression(target);
if (targetType is FunctionType) {
// Call methods on function types should be handled as regular function
// invocations.
return _emitFunctionCall(node, node.target);
}
if (targetType.isDartCoreFunction || targetType.isDynamic) {
// TODO(vsm): Can a call method take generic type parameters?
return _emitDynamicInvoke(
node, _visit(target), _emitArgumentList(node.argumentList));
}
}
return _emitMethodCall(target, node);
}
JS.Expression _emitTarget(Expression target, Element member, bool isStatic) {
if (isStatic) {
if (member is ConstructorElement) {
return _emitConstructorAccess(member.enclosingElement.type);
}
if (member is PropertyAccessorElement) {
var field = member.variable;
if (field is FieldElement) {
return _emitStaticAccess(field.enclosingElement.type);
}
}
if (member is MethodElement) {
return _emitStaticAccess(member.enclosingElement.type);
}
}
return _visit(target);
}
/// Emits the [JS.PropertyAccess] for accessors or method calls to
/// [jsTarget].[jsName], replacing `super` if it is not allowed in scope.
JS.Expression _emitTargetAccess(
JS.Expression jsTarget, JS.Expression jsName, Element member) {
if (!_superAllowed && jsTarget is JS.Super) {
return _getSuperHelper(member, jsName)
..sourceInformation = jsTarget.sourceInformation;
}
return new JS.PropertyAccess(jsTarget, jsName);
}
JS.Expression _getSuperHelper(Element member, JS.Expression jsName) {
var jsMethod = _superHelpers.putIfAbsent(member.name, () {
if (member is PropertyAccessorElement) {
var isSetter = member.isSetter;
var fn = js.call(
isSetter
? 'function(x) { super[#] = x; }'
: 'function() { return super[#]; }',
[jsName]);
return new JS.Method(new JS.TemporaryId(member.variable.name), fn,
isGetter: !isSetter, isSetter: isSetter);
} else {
var method = member as MethodElement;
var name = method.name;
var params = new List<JS.Identifier>.from(
_emitTypeFormals(method.typeParameters));
for (var param in method.parameters) {
if (param.parameterKind == ParameterKind.NAMED) {
params.add(namedArgumentTemp);
break;
}
params.add(new JS.Identifier(param.name));
}
var fn = js.call(
'function(#) { return super[#](#); }', [params, jsName, params]);
return new JS.Method(new JS.TemporaryId(name), fn);
}
});
return new JS.PropertyAccess(new JS.This(), jsMethod.name);
}
JS.Expression _emitMethodCall(Expression target, MethodInvocation node) {
var args = _emitArgumentList(node.argumentList);
var typeArgs = _emitInvokeTypeArguments(node);
var type = getStaticType(target);
var element = node.methodName.staticElement;
bool isStatic = element is ExecutableElement && element.isStatic;
var name = node.methodName.name;
var jsName =
_emitMemberName(name, type: type, isStatic: isStatic, element: element);
JS.Expression jsTarget = _emitTarget(target, element, isStatic);
if (isDynamicInvoke(target) || isDynamicInvoke(node.methodName)) {
if (typeArgs != null) {
return _callHelper('#(#, #, #, #)', [
_emitDynamicOperationName('dgsend'),
jsTarget,
new JS.ArrayInitializer(typeArgs),
jsName,
args
]);
} else {
return _callHelper('#(#, #, #)',
[_emitDynamicOperationName('dsend'), jsTarget, jsName, args]);
}
}
if (_isObjectMemberCall(target, name)) {
assert(typeArgs == null); // Object methods don't take type args.
return _callHelper('#(#, #)', [name, jsTarget, args]);
}
jsTarget = _emitTargetAccess(jsTarget, jsName, element);
var castTo = getImplicitOperationCast(node);
if (castTo != null) {
jsTarget = js.call('#._check(#)', [_emitType(castTo), jsTarget]);
}
if (typeArgs != null) args.insertAll(0, typeArgs);
return new JS.Call(jsTarget, args);
}
JS.Expression _emitDynamicInvoke(
InvocationExpression node, JS.Expression fn, List<JS.Expression> args) {
var typeArgs = _emitInvokeTypeArguments(node);
if (typeArgs != null) {
return _callHelper(
'dgcall(#, #, #)', [fn, new JS.ArrayInitializer(typeArgs), args]);
} else {
return _callHelper('dcall(#, #)', [fn, args]);
}
}
bool _doubleEqIsIdentity(Expression left, Expression right) {
// If we statically know LHS or RHS is null we can use ==.
if (_isNull(left) || _isNull(right)) return true;
// If the representation of the two types will not induce conversion in
// JS then we can use == .
return !typeRep.equalityMayConvert(left.staticType, right.staticType);
}
bool _tripleEqIsIdentity(Expression left, Expression right) {
// If either is non-nullable, then we don't need to worry about
// equating null and undefined, and so we can use triple equals.
return !isNullable(left) || !isNullable(right);
}
bool _isCoreIdentical(Expression node) {
return node is Identifier && node.staticElement == _coreIdentical;
}
JS.Expression _emitJSDoubleEq(List<JS.Expression> args,
{bool negated = false}) {
var op = negated ? '# != #' : '# == #';
return js.call(op, args);
}
JS.Expression _emitJSTripleEq(List<JS.Expression> args,
{bool negated = false}) {
var op = negated ? '# !== #' : '# === #';
return js.call(op, args);
}
JS.Expression _emitCoreIdenticalCall(List<Expression> arguments,
{bool negated = false}) {
if (arguments.length != 2) {
// Shouldn't happen in typechecked code
return _callHelper(
'throw(Error("compile error: calls to `identical` require 2 args")');
}
var left = arguments[0];
var right = arguments[1];
var args = [_visit(left), _visit(right)];
if (_tripleEqIsIdentity(left, right)) {
return _emitJSTripleEq(args, negated: negated);
}
if (_doubleEqIsIdentity(left, right)) {
return _emitJSDoubleEq(args, negated: negated);
}
var code = negated ? '!#' : '#';
return js.call(code, new JS.Call(_emitTopLevelName(_coreIdentical), args));
}
/// Emits a function call, to a top-level function, local function, or
/// an expression.
JS.Expression _emitFunctionCall(InvocationExpression node,
[Expression function]) {
function ??= node.function;
var castTo = getImplicitOperationCast(function);
if (castTo != null) {
function = CoercionReifier.castExpression(function, castTo);
}
if (_isCoreIdentical(function)) {
return _emitCoreIdenticalCall(node.argumentList.arguments);
}
var fn = _visit(function);
var args = _emitArgumentList(node.argumentList);
if (isDynamicInvoke(function)) {
return _emitDynamicInvoke(node, fn, args);
}
var typeArgs = _emitInvokeTypeArguments(node);
if (typeArgs != null) args.insertAll(0, typeArgs);
return new JS.Call(fn, args);
}
List<JS.Expression> _emitInvokeTypeArguments(InvocationExpression node) {
return _emitFunctionTypeArguments(
node.function.staticType, node.staticInvokeType, node.typeArguments);
}
/// If `g` is a generic function type, and `f` is an instantiation of it,
/// then this will return the type arguments to apply, otherwise null.
List<JS.Expression> _emitFunctionTypeArguments(DartType g, DartType f,
[TypeArgumentList typeArgs]) {
if (g is FunctionType &&
g.typeFormals.isNotEmpty &&
f is FunctionType &&
f.typeFormals.isEmpty) {
return _recoverTypeArguments(g, f).map(_emitType).toList(growable: false);
} else if (typeArgs != null) {
// Dynamic calls may have type arguments, even though the function types
// are not known.
return _visitList(typeArgs.arguments);
}
return null;
}
/// Given a generic function type [g] and an instantiated function type [f],
/// find a list of type arguments TArgs such that `g<TArgs> == f`,
/// and return TArgs.
///
/// This function must be called with type [f] that was instantiated from [g].
Iterable<DartType> _recoverTypeArguments(FunctionType g, FunctionType f) {
// TODO(jmesserly): this design is a bit unfortunate. It would be nice if
// resolution could simply create a synthetic type argument list.
assert(identical(g.element, f.element));
assert(g.typeFormals.isNotEmpty && f.typeFormals.isEmpty);
assert(g.typeFormals.length + g.typeArguments.length ==
f.typeArguments.length);
// Instantiation in Analyzer works like this:
// Given:
// {U/T} <S> T -> S
// Where {U/T} represents the typeArguments (U) and typeParameters (T) list,
// and <S> represents the typeFormals.
//
// Now instantiate([V]), and the result should be:
// {U/T, V/S} T -> S.
//
// Therefore, we can recover the typeArguments from our instantiated
// function.
return f.typeArguments.skip(g.typeArguments.length);
}
/// Emits code for the `JS(...)` macro.
_emitForeignJS(MethodInvocation node, Element e) {
if (isInlineJS(e)) {
var args = node.argumentList.arguments;
// arg[0] is static return type, used in `RestrictedStaticTypeAnalyzer`
var code = args[1];
List<Expression> templateArgs;
String source;
if (code is StringInterpolation) {
if (args.length > 2) {
throw new ArgumentError(
"Can't mix template args and string interpolation in JS calls.");
}
templateArgs = <Expression>[];
source = code.elements.map((element) {
if (element is InterpolationExpression) {
templateArgs.add(element.expression);
return '#';
} else {
return (element as InterpolationString).value;
}
}).join();
} else {
templateArgs = args.skip(2).toList();
source = (code as StringLiteral).stringValue;
}
// TODO(vsm): Constructors in dart:html and friends are trying to
// allocate a type defined on window/self, but this often conflicts a
// with the generated extension class in scope. We really should
// qualify explicitly in dart:html itself.
var constructorPattern = new RegExp("new [A-Z][A-Za-z]+\\(");
if (constructorPattern.matchAsPrefix(source) != null) {
var containingClass = node.parent;
while (
containingClass != null && containingClass is! ClassDeclaration) {
containingClass = containingClass.parent;
}
if (containingClass is ClassDeclaration &&
_extensionTypes.isNativeClass(containingClass.element)) {
var constructorName = source.substring(4, source.indexOf('('));
var className = containingClass.name.name;
if (className == constructorName) {
source =
source.replaceFirst('new $className(', 'new self.$className(');
}
}
}
JS.Expression visitTemplateArg(Expression arg) {
if (arg is InvocationExpression) {
var e = arg is MethodInvocation
? arg.methodName.staticElement
: (arg as FunctionExpressionInvocation).staticElement;
if (e?.name == 'getGenericClass' &&
e.library.name == 'dart._runtime' &&
arg.argumentList.arguments.length == 1) {
var typeArg = arg.argumentList.arguments[0];
if (typeArg is SimpleIdentifier) {
var typeElem = typeArg.staticElement;
if (typeElem is TypeDefiningElement &&
typeElem.type is ParameterizedType) {
return _emitTopLevelNameNoInterop(typeElem, suffix: '\$');
}
}
}
}
return _visit(arg);
}
// TODO(rnystrom): The JS() calls are almost never nested, and probably
// really shouldn't be, but there are at least a couple of calls in the
// HTML library where an argument to JS() is itself a JS() call. If those
// go away, this can just assert(!_isInForeignJS).
// Inside JS(), type names evaluate to the raw runtime type, not the
// wrapped Type object.
var wasInForeignJS = _isInForeignJS;
_isInForeignJS = true;
var jsArgs = templateArgs.map(visitTemplateArg).toList();
_isInForeignJS = wasInForeignJS;
var result = js.parseForeignJS(source).instantiate(jsArgs);
// `throw` is emitted as a statement by `parseForeignJS`.
assert(result is JS.Expression || node.parent is ExpressionStatement);
return result;
}
return null;
}
@override
JS.Expression visitFunctionExpressionInvocation(
FunctionExpressionInvocation node) =>
_emitFunctionCall(node);
List<JS.Expression> _emitArgumentList(ArgumentList node) {
var args = <JS.Expression>[];
var named = <JS.Property>[];
for (var arg in node.arguments) {
if (arg is NamedExpression) {
named.add(_visit(arg));
} else if (arg is MethodInvocation && isJsSpreadInvocation(arg)) {
args.add(
new JS.RestParameter(_visit(arg.argumentList.arguments.single)));
} else {
args.add(_visit(arg));
}
}
if (named.isNotEmpty) {
args.add(new JS.ObjectInitializer(named));
}
return args;
}
@override
JS.Property visitNamedExpression(NamedExpression node) {
assert(node.parent is ArgumentList);
return new JS.Property(
_propertyName(node.name.label.name), _visit(node.expression));
}
List<JS.Parameter> _emitParametersForElement(ExecutableElement member) {
var jsParams = <JS.Identifier>[];
for (var p in member.parameters) {
if (p.parameterKind != ParameterKind.NAMED) {
jsParams.add(new JS.Identifier(p.name));
} else {
jsParams.add(new JS.TemporaryId('namedArgs'));
break;
}
}
return jsParams;
}
List<JS.Parameter> _emitFormalParameterList(FormalParameterList node,
{bool destructure: true}) {
if (node == null) return [];
destructure = destructure && options.destructureNamedParams;
var result = <JS.Parameter>[];
var namedVars = <JS.DestructuredVariable>[];
var hasNamedArgsConflictingWithObjectProperties = false;
var needsOpts = false;
for (FormalParameter param in node.parameters) {
if (param.kind == ParameterKind.NAMED) {
if (destructure) {
if (_jsObjectProperties.contains(param.identifier.name)) {
hasNamedArgsConflictingWithObjectProperties = true;
}
JS.Expression name;
JS.SimpleBindingPattern structure = null;
String paramName = param.identifier.name;
if (JS.invalidVariableName(paramName)) {
name = js.string(paramName);
structure = new JS.SimpleBindingPattern(_visit(param.identifier));
} else {
name = _visit(param.identifier);
}
var defaultValue = _defaultParamValue(param);
namedVars.add(new JS.DestructuredVariable(
name: name, structure: structure, defaultValue: defaultValue));
} else {
needsOpts = true;
}
} else {
var jsParam = _visit(param);
var defaultValue = _defaultParamValue(param);
result.add(destructure && defaultValue != null
? new JS.DestructuredVariable(
name: jsParam, defaultValue: defaultValue)
: jsParam);
}
}
if (needsOpts) {
result.add(namedArgumentTemp);
} else if (namedVars.isNotEmpty) {
// Note: `var {valueOf} = {}` extracts `Object.prototype.valueOf`, so
// in case there are conflicting names we create an object without
// any prototype.
var defaultOpts = hasNamedArgsConflictingWithObjectProperties
? js.call('Object.create(null)')
: js.call('{}');
result.add(new JS.DestructuredVariable(
structure: new JS.ObjectBindingPattern(namedVars),
type: emitNamedParamsArgType(node.parameterElements),
defaultValue: defaultOpts));
}
return result;
}
/// See ES6 spec (and `Object.getOwnPropertyNames(Object.prototype)`):
/// http://www.ecma-international.org/ecma-262/6.0/#sec-properties-of-the-object-prototype-object
/// http://www.ecma-international.org/ecma-262/6.0/#sec-additional-properties-of-the-object.prototype-object
static final Set<String> _jsObjectProperties = new Set<String>()
..addAll([
"constructor",
"toString",
"toLocaleString",
"valueOf",
"hasOwnProperty",
"isPrototypeOf",
"propertyIsEnumerable",
"__defineGetter__",
"__lookupGetter__",
"__defineSetter__",
"__lookupSetter__",
"__proto__"
]);
@override
JS.Statement visitExpressionStatement(ExpressionStatement node) =>
_visit(node.expression).toStatement();
@override
JS.EmptyStatement visitEmptyStatement(EmptyStatement node) =>
new JS.EmptyStatement();
@override
JS.Statement visitAssertStatement(AssertStatement node) {
// TODO(jmesserly): only emit in checked mode.
var condition = node.condition;
var conditionType = condition.staticType;
JS.Expression jsCondition = _visit(condition);
if (conditionType is FunctionType &&
conditionType.parameters.isEmpty &&
conditionType.returnType == types.boolType) {
jsCondition = _callHelper('test(#())', jsCondition);
} else if (conditionType != types.boolType) {
jsCondition = _callHelper('dassert(#)', jsCondition);
} else if (isNullable(condition)) {
jsCondition = _callHelper('test(#)', jsCondition);
}
return js.statement(' if (!#) #.assertFailed(#);', [
jsCondition,
_runtimeModule,
node.message != null ? [_visit(node.message)] : []
]);
}
@override
JS.Statement visitReturnStatement(ReturnStatement node) {
var e = node.expression;
if (e == null) return new JS.Return();
return _visit<JS.Expression>(e).toReturn();
}
@override
JS.Statement visitYieldStatement(YieldStatement node) {
JS.Expression jsExpr = _visit(node.expression);
var star = node.star != null;
if (_asyncStarController != null) {
// async* yields are generated differently from sync* yields. `yield e`
// becomes:
//
// if (stream.add(e)) return;
// yield;
//
// `yield* e` becomes:
//
// if (stream.addStream(e)) return;
// yield;
var helperName = star ? 'addStream' : 'add';
return js.statement('{ if(#.#(#)) return; #; }',
[_asyncStarController, helperName, jsExpr, new JS.Yield(null)]);
}
// A normal yield in a sync*
return jsExpr.toYieldStatement(star: star);
}
@override
JS.Expression visitAwaitExpression(AwaitExpression node) {
return new JS.Yield(_visit(node.expression));
}
/// This is not used--we emit top-level fields as we are emitting the
/// compilation unit, see [visitCompilationUnit].
@override
visitTopLevelVariableDeclaration(TopLevelVariableDeclaration node) {
assert(false);
}
/// This is not used--we emit fields as we are emitting the class,
/// see [visitClassDeclaration].
@override
visitFieldDeclaration(FieldDeclaration node) {
assert(false);
}
@override
JS.Statement visitVariableDeclarationStatement(
VariableDeclarationStatement node) {
// Special case a single variable with an initializer.
// This helps emit cleaner code for things like:
// var result = []..add(1)..add(2);
var variables = node.variables.variables;
if (variables.length == 1) {
var variable = variables[0];
var initializer = variable.initializer;
if (initializer != null) {
var name = new JS.Identifier(variable.name.name);
JS.Expression value;
if (_annotatedNullCheck(variable.element)) {
value = notNull(initializer);
} else if (initializer is FunctionExpression) {
// This improve stack traces for the pattern:
//
// var f = (y) => y.doesNotExist();
//
// ... by moving the type tagging after of the variable declaration:
//
// let f = (y) => y.doesNotExist();
// dart.fn(f, typeOfF);
//
value = _emitArrowFunction(initializer);
return new JS.Block([
value.toVariableDeclaration(name),
_emitFunctionTagged(name, getStaticType(initializer),
topLevel: _executesAtTopLevel(node))
.toStatement()
]);
} else {
value = _visit(initializer);
}
return value.toVariableDeclaration(name);
}
}
return _visit<JS.Expression>(node.variables).toStatement();
}
@override
visitVariableDeclarationList(VariableDeclarationList node) {
return new JS.VariableDeclarationList('let', _visitList(node.variables));
}
@override
visitVariableDeclaration(VariableDeclaration node) {
if (node.element is PropertyInducingElement) {
// All fields are handled elsewhere.
assert(false);
return null;
}
var name = new JS.Identifier(node.name.name,
type: emitTypeRef(
resolutionMap.elementDeclaredByVariableDeclaration(node).type));
return new JS.VariableInitialization(name, _visitInitializer(node));
}
/// Emits a list of top-level field.
void _emitTopLevelFields(List<VariableDeclaration> fields) {
_moduleItems.add(_emitLazyFields(currentLibrary, fields));
}
/// Treat dart:_runtime fields as safe to eagerly evaluate.
// TODO(jmesserly): it'd be nice to avoid this special case.
void _emitInternalSdkFields(List<VariableDeclaration> fields) {
for (var field in fields) {
// Skip our magic undefined constant.
var element = field.element as TopLevelVariableElement;
if (element.name == 'undefined') continue;
_moduleItems.add(annotate(
js.statement('# = #;',
[_emitTopLevelName(field.element), _visitInitializer(field)]),
field,
field.element));
}
}
JS.Expression _visitInitializer(VariableDeclaration node) {
var value = _annotatedNullCheck(node.element)
? notNull(node.initializer)
: _visit(node.initializer);
// explicitly initialize to null, to avoid getting `undefined`.
// TODO(jmesserly): do this only for vars that aren't definitely assigned.
return value ?? new JS.LiteralNull();
}
JS.Statement _emitLazyFields(
Element target, List<VariableDeclaration> fields) {
var methods = [];
for (var node in fields) {
var name = node.name.name;
var element = node.element;
assert(element.getAncestor((e) => identical(e, target)) != null,
"target is $target but enclosing element is ${element.enclosingElement}");
var access = _emitMemberName(name, isStatic: true);
methods.add(annotate(
new JS.Method(
access,
js.call('function() { return #; }', _visitInitializer(node))
as JS.Fun,
isGetter: true),
node,
_findAccessor(element, getter: true)));
// TODO(jmesserly): currently uses a dummy setter to indicate writable.
if (!node.isFinal && !node.isConst) {
methods.add(annotate(
new JS.Method(access, js.call('function(_) {}') as JS.Fun,
isSetter: true),
node,
_findAccessor(element, getter: false)));
}
}
var objExpr = target is ClassElement
? _emitTopLevelName(target)
: emitLibraryName(target);
return _callHelperStatement('defineLazy(#, { # });', [objExpr, methods]);
}
PropertyAccessorElement _findAccessor(VariableElement element,
{bool getter}) {
var parent = element.enclosingElement;
if (parent is ClassElement) {
return getter
? parent.getGetter(element.name)
: parent.getSetter(element.name);
}
return null;
}
JS.Expression _emitConstructorName(
ConstructorElement element, DartType type) {
return _emitJSInterop(type.element) ??
new JS.PropertyAccess(
_emitConstructorAccess(type), _constructorName(element.name));
}
@override
visitConstructorName(ConstructorName node) {
return _emitConstructorName(node.staticElement, node.type.type);
}
JS.Expression _emitInstanceCreationExpression(
ConstructorElement element,
DartType type,
SimpleIdentifier name,
ArgumentList argumentList,
bool isConst) {
JS.Expression emitNew() {
JS.Expression ctor;
bool isFactory = false;
bool isNative = false;
if (element == null) {
ctor = _throwUnsafe('unresolved constructor: ${type?.name ?? '<null>'}'
'.${name?.name ?? '<unnamed>'}');
} else {
ctor = _emitConstructorName(element, type);
isFactory = element.isFactory;
var classElem = element.enclosingElement;
isNative = _isJSNative(classElem);
}
var args = _emitArgumentList(argumentList);
// Native factory constructors are JS constructors - use new here.
return isFactory && !isNative
? new JS.Call(ctor, args)
: new JS.New(ctor, args);
}
if (element != null && _isObjectLiteral(element.enclosingElement)) {
return _emitObjectLiteral(argumentList);
}
if (isConst) return _emitConst(emitNew);
return emitNew();
}
bool _isObjectLiteral(Element classElem) {
return _isJSNative(classElem) &&
findAnnotation(classElem, isJSAnonymousAnnotation) != null;
}
bool _isJSNative(Element e) =>
findAnnotation(e, isPublicJSAnnotation) != null;
JS.Expression _emitObjectLiteral(ArgumentList argumentList) {
var args = _emitArgumentList(argumentList);
if (args.isEmpty) {
return js.call('{}');
}
assert(args.single is JS.ObjectInitializer);
return args.single;
}
@override
visitInstanceCreationExpression(InstanceCreationExpression node) {
var element = resolutionMap.staticElementForConstructorReference(node);
var constructor = node.constructorName;
var name = constructor.name;
var type = constructor.type.type;
if (node.isConst &&
element?.name == 'fromEnvironment' &&
element.library.isDartCore) {
var value = node.accept(_constants.constantVisitor);
if (value == null || value.isNull) {
return new JS.LiteralNull();
}
// Handle unknown value: when the declared variable wasn't found, and no
// explicit default value was passed either.
// TODO(jmesserly): ideally Analyzer would simply resolve this to the
// default value that is specified in the SDK. Instead we implement that
// here. `bool.fromEnvironment` defaults to `false`, the others to `null`:
// https://api.dartlang.org/stable/1.20.1/dart-core/bool/bool.fromEnvironment.html
if (value.isUnknown) {
return type == types.boolType
? js.boolean(false)
: new JS.LiteralNull();
}
if (value.type == types.boolType) {
var boolValue = value.toBoolValue();
return boolValue != null ? js.boolean(boolValue) : new JS.LiteralNull();
}
if (value.type == types.intType) {
var intValue = value.toIntValue();
return intValue != null ? js.number(intValue) : new JS.LiteralNull();
}
if (value.type == types.stringType) {
var stringValue = value.toStringValue();
return stringValue != null
? js.escapedString(stringValue)
: new JS.LiteralNull();
}
throw new StateError('failed to evaluate $node');
}
return _emitInstanceCreationExpression(
element, type, name, node.argumentList, node.isConst);
}
bool isPrimitiveType(DartType t) => typeRep.isPrimitive(t);
/// Given a Dart type return the known implementation type, if any.
/// Given `bool`, `String`, or `num`/`int`/`double`,
/// returns the corresponding type in `dart:_interceptors`:
/// `JSBool`, `JSString`, and `JSNumber` respectively, otherwise null.
InterfaceType getImplementationType(DartType t) {
JSType rep = typeRep.typeFor(t);
// Number, String, and Bool are final
if (rep == JSType.jsNumber) return _jsNumber.type;
if (rep == JSType.jsBoolean) return _jsBool.type;
if (rep == JSType.jsString) return _jsString.type;
return null;
}
JS.Statement nullParameterCheck(JS.Expression param) {
var call = _callHelper('argumentError((#))', [param]);
return js.statement('if (# == null) #;', [param, call]);
}
JS.Expression notNull(Expression expr) {
if (expr == null) return null;
var jsExpr = _visit(expr);
if (!isNullable(expr)) return jsExpr;
return _callHelper('notNull(#)', jsExpr);
}
JS.Expression _emitEqualityOperator(BinaryExpression node, Token op) {
var left = node.leftOperand;
var right = node.rightOperand;
var leftType = left.staticType;
var negated = op.type == TokenType.BANG_EQ;
if (left is SuperExpression) {
return _emitSend(left, op.lexeme, [right]);
}
// Conceptually `x == y` in Dart is defined as:
//
// If either x or y is null, then they are equal iff they are both null.
// Otherwise, equality is the result of calling `x.==(y)`.
//
// In practice, `x.==(y)` is equivalent to `identical(x, y)` in many cases:
// - when either side is known to be `null` (literal or Null type)
// - left side is an enum
// - left side is a primitive type
//
// We also compile `operator ==` methods to ensure they check the right side
// for null`. This allows us to skip the check at call sites.
//
// TODO(leafp,jmesserly): we could use class hierarchy analysis to check
// if `operator ==` was overridden, similar to how we devirtualize private
// fields.
var isEnum = leftType is InterfaceType && leftType.element.isEnum;
var usesIdentity = typeRep.isPrimitive(leftType) ||
isEnum ||
_isNull(left) ||
_isNull(right);
// If we know that the left type uses identity for equality, we can
// sometimes emit better code, either `===` or `==`.
if (usesIdentity) {
return _emitCoreIdenticalCall([left, right], negated: negated);
}
// If the left side is nullable, we need to use a runtime helper to check
// for null. We could inline the null check, but it did not seem to have
// a measurable performance effect (possibly the helper is simple enough to
// be inlined).
if (isNullable(left)) {
var code = negated ? '!#.equals(#, #)' : '#.equals(#, #)';
return js.call(code, [_runtimeModule, _visit(left), _visit(right)]);
}
// Otherwise we emit a call to the == method.
var name = _emitMemberName('==', type: leftType);
var code = negated ? '!#[#](#)' : '#[#](#)';
return js.call(code, [_visit(left), name, _visit(right)]);
}
@override
JS.Expression visitBinaryExpression(BinaryExpression node) {
var op = node.operator;
// The operands of logical boolean operators are subject to boolean
// conversion.
if (op.type == TokenType.BAR_BAR ||
op.type == TokenType.AMPERSAND_AMPERSAND) {
return _visitTest(node);
}
if (op.type.isEqualityOperator) return _emitEqualityOperator(node, op);
var left = node.leftOperand;
var right = node.rightOperand;
if (op.type.lexeme == '??') {
// TODO(jmesserly): leave RHS for debugging?
// This should be a hint or warning for dead code.
if (!isNullable(left)) return _visit(left);
var vars = <JS.MetaLetVariable, JS.Expression>{};
// Desugar `l ?? r` as `l != null ? l : r`
var l = _visit(_bindValue(vars, 'l', left, context: left));
return new JS.MetaLet(vars, [
js.call('# != null ? # : #', [l, l, _visit(right)])
]);
}
var leftType = getStaticType(left);
var rightType = getStaticType(right);
if (typeRep.binaryOperationIsPrimitive(leftType, rightType) ||
leftType == types.stringType && op.type == TokenType.PLUS) {
// special cases where we inline the operation
// these values are assumed to be non-null (determined by the checker)
// TODO(jmesserly): it would be nice to just inline the method from core,
// instead of special cases here.
JS.Expression binary(String code) {
return js.call(code, [notNull(left), notNull(right)]);
}
JS.Expression bitwise(String code) {
return _coerceBitOperationResultToUnsigned(node, binary(code));
}
switch (op.type) {
case TokenType.TILDE_SLASH:
// `a ~/ b` is equivalent to `(a / b).truncate()`
var div = ast.binaryExpression(left, '/', right)
..staticType = node.staticType;
return _emitSend(div, 'truncate', []);
case TokenType.PERCENT:
// TODO(sra): We can generate `a % b + 0` if both are non-negative
// (the `+ 0` is to coerce -0.0 to 0).
return _emitSend(left, op.lexeme, [right]);
case TokenType.AMPERSAND:
return bitwise('# & #');
case TokenType.BAR:
return bitwise('# | #');
case TokenType.CARET:
return bitwise('# ^ #');
case TokenType.GT_GT:
int shiftCount = _asIntInRange(right, 0, 31);
if (_is31BitUnsigned(left) && shiftCount != null) {
return binary('# >> #');
}
if (_isDefinitelyNonNegative(left) && shiftCount != null) {
return binary('# >>> #');
}
// If the context selects out only bits that can't be affected by the
// sign position we can use any JavaScript shift, `(x >> 6) & 3`.
if (shiftCount != null &&
_parentMasksToWidth(node, 31 - shiftCount)) {
return binary('# >> #');
}
return _emitSend(left, op.lexeme, [right]);
case TokenType.LT_LT:
if (_is31BitUnsigned(node)) {
// Result is 31 bit unsigned which implies the shift count was small
// enough not to pollute the sign bit.
return binary('# << #');
}
if (_asIntInRange(right, 0, 31) != null) {
return _coerceBitOperationResultToUnsigned(node, binary('# << #'));
}
return _emitSend(left, op.lexeme, [right]);
default:
// TODO(vsm): When do Dart ops not map to JS?
return binary('# $op #');
}
}
return _emitSend(left, op.lexeme, [right]);
}
/// Bit operations are coerced to values on [0, 2^32). The coercion changes
/// the interpretation of the 32-bit value from signed to unsigned. Most
/// JavaScript operations interpret their operands as signed and generate
/// signed results.
JS.Expression _coerceBitOperationResultToUnsigned(
Expression node, JS.Expression uncoerced) {
// Don't coerce if the parent will coerce.
AstNode parent = _parentOperation(node);
if (_nodeIsBitwiseOperation(parent)) return uncoerced;
// Don't do a no-op coerce if the most significant bit is zero.
if (_is31BitUnsigned(node)) return uncoerced;
// If the consumer of the expression is '==' or '!=' with a constant that
// fits in 31 bits, adding a coercion does not change the result of the
// comparison, e.g. `a & ~b == 0`.
if (parent is BinaryExpression) {
var tokenType = parent.operator.type;
Expression left = parent.leftOperand;
Expression right = parent.rightOperand;
if (tokenType == TokenType.EQ_EQ || tokenType == TokenType.BANG_EQ) {
const int MAX = 0x7fffffff;
if (_asIntInRange(right, 0, MAX) != null) return uncoerced;
if (_asIntInRange(left, 0, MAX) != null) return uncoerced;
} else if (tokenType == TokenType.GT_GT) {
if (_isDefinitelyNonNegative(left) &&
_asIntInRange(right, 0, 31) != null) {
// Parent will generate `# >>> n`.
return uncoerced;
}
}
}
return js.call('# >>> 0', uncoerced);
}
AstNode _parentOperation(AstNode node) {
node = node.parent;
while (node is ParenthesizedExpression) node = node.parent;
return node;
}
bool _nodeIsBitwiseOperation(AstNode node) {
if (node is BinaryExpression) {
switch (node.operator.type) {
case TokenType.AMPERSAND:
case TokenType.BAR:
case TokenType.CARET:
return true;
}
return false;
}
if (node is PrefixExpression) {
return node.operator.type == TokenType.TILDE;
}
return false;
}
int _asIntInRange(Expression expr, int low, int high) {
expr = expr.unParenthesized;
if (expr is IntegerLiteral) {
if (expr.value >= low && expr.value <= high) return expr.value;
return null;
}
Identifier id;
if (expr is SimpleIdentifier) {
id = expr;
} else if (expr is PrefixedIdentifier && !expr.isDeferred) {
id = expr.identifier;
} else {
return null;
}
var element = id.staticElement;
if (element is PropertyAccessorElement && element.isGetter) {
var variable = element.variable;
int value = variable?.computeConstantValue()?.toIntValue();
if (value != null && value >= low && value <= high) return value;
}
return null;
}
bool _isDefinitelyNonNegative(Expression expr) {
expr = expr.unParenthesized;
if (expr is IntegerLiteral) {
return expr.value >= 0;
}
if (_nodeIsBitwiseOperation(expr)) return true;
// TODO(sra): Lengths of known list types etc.
return false;
}
/// Does the parent of [node] mask the result to [width] bits or fewer?
bool _parentMasksToWidth(AstNode node, int width) {
AstNode parent = _parentOperation(node);
if (parent == null) return false;
if (_nodeIsBitwiseOperation(parent)) {
if (parent is BinaryExpression &&
parent.operator.type == TokenType.AMPERSAND) {
Expression left = parent.leftOperand;
Expression right = parent.rightOperand;
final int MAX = (1 << width) - 1;
if (_asIntInRange(right, 0, MAX) != null) return true;
if (_asIntInRange(left, 0, MAX) != null) return true;
}
return _parentMasksToWidth(parent, width);
}
return false;
}
/// Determines if the result of evaluating [expr] will be an non-negative
/// value that fits in 31 bits.
bool _is31BitUnsigned(Expression expr) {
const int MAX = 32; // Includes larger and negative values.
/// Determines how many bits are required to hold result of evaluation
/// [expr]. [depth] is used to bound exploration of huge expressions.
int bitWidth(Expression expr, int depth) {
if (expr is IntegerLiteral) {
return expr.value >= 0 ? expr.value.bitLength : MAX;
}
if (++depth > 5) return MAX;
if (expr is BinaryExpression) {
var left = expr.leftOperand.unParenthesized;
var right = expr.rightOperand.unParenthesized;
switch (expr.operator.type) {
case TokenType.AMPERSAND:
return min(bitWidth(left, depth), bitWidth(right, depth));
case TokenType.BAR:
case TokenType.CARET:
return max(bitWidth(left, depth), bitWidth(right, depth));
case TokenType.GT_GT:
int shiftValue = _asIntInRange(right, 0, 31);
if (shiftValue != null) {
int leftWidth = bitWidth(left, depth);
return leftWidth == MAX ? MAX : max(0, leftWidth - shiftValue);
}
return MAX;
case TokenType.LT_LT:
int leftWidth = bitWidth(left, depth);
int shiftValue = _asIntInRange(right, 0, 31);
if (shiftValue != null) {
return min(MAX, leftWidth + shiftValue);
}
int rightWidth = bitWidth(right, depth);
if (rightWidth <= 5) {
// e.g. `1 << (x & 7)` has a rightWidth of 3, so shifts by up to
// (1 << 3) - 1 == 7 bits.
return min(MAX, leftWidth + ((1 << rightWidth) - 1));
}
return MAX;
default:
return MAX;
}
}
int value = _asIntInRange(expr, 0, 0x7fffffff);
if (value != null) return value.bitLength;
return MAX;
}
return bitWidth(expr, 0) < 32;
}
bool _isNull(Expression expr) =>
expr is NullLiteral || getStaticType(expr).isDartCoreNull;
SimpleIdentifier _createTemporary(String name, DartType type,
{bool nullable: true, JS.Expression variable, bool dynamicInvoke}) {
// We use an invalid source location to signal that this is a temporary.
// See [_isTemporary].
// TODO(jmesserly): alternatives are
// * (ab)use Element.isSynthetic, which isn't currently used for
// LocalVariableElementImpl, so we could repurpose to mean "temp".
// * add a new property to LocalVariableElementImpl.
// * create a new subtype of LocalVariableElementImpl to mark a temp.
var id = astFactory
.simpleIdentifier(new StringToken(TokenType.IDENTIFIER, name, -1));
variable ??= new JS.TemporaryId(name);
id.staticElement = new TemporaryVariableElement.forNode(id, variable);
id.staticType = type;
setIsDynamicInvoke(id, dynamicInvoke ?? type.isDynamic);
addTemporaryVariable(id.staticElement, nullable: nullable);
return id;
}
JS.Expression _cacheConst(JS.Expression expr()) {
var savedTypeParams = _typeParamInConst;
_typeParamInConst = [];
var jsExpr = expr();
bool usesTypeParams = _typeParamInConst.isNotEmpty;
_typeParamInConst = savedTypeParams;
// TODO(jmesserly): if it uses type params we can still hoist it up as far
// as it will go, e.g. at the level the generic class is defined where type
// params are available.
if (_currentFunction == null || usesTypeParams) return jsExpr;
var temp = new JS.TemporaryId('const');
_moduleItems.add(js.statement('let #;', [temp]));
return js.call('# || (# = #)', [temp, temp, jsExpr]);
}
JS.Expression _emitConst(JS.Expression expr()) =>
_cacheConst(() => _callHelper('const(#)', expr()));
/// Returns a new expression, which can be be used safely *once* on the
/// left hand side, and *once* on the right side of an assignment.
/// For example: `expr1[expr2] += y` can be compiled as
/// `expr1[expr2] = expr1[expr2] + y`.
///
/// The temporary scope will ensure `expr1` and `expr2` are only evaluated
/// once: `((x1, x2) => x1[x2] = x1[x2] + y)(expr1, expr2)`.
///
/// If the expression does not end up using `x1` or `x2` more than once, or
/// if those expressions can be treated as stateless (e.g. they are
/// non-mutated variables), then the resulting code will be simplified
/// automatically.
///
/// [scope] can be mutated to contain any new temporaries that were created,
/// unless [expr] is a SimpleIdentifier, in which case a temporary is not
/// needed.
Expression _bindLeftHandSide(
Map<JS.MetaLetVariable, JS.Expression> scope, Expression expr,
{Expression context}) {
Expression result;
if (expr is IndexExpression) {
IndexExpression index = expr;
result = astFactory.indexExpressionForTarget(
_bindValue(scope, 'o', index.target, context: context),
index.leftBracket,
_bindValue(scope, 'i', index.index, context: context),
index.rightBracket);
} else if (expr is PropertyAccess) {
PropertyAccess prop = expr;
result = astFactory.propertyAccess(
_bindValue(scope, 'o', _getTarget(prop), context: context),
prop.operator,
prop.propertyName);
} else if (expr is PrefixedIdentifier) {
PrefixedIdentifier ident = expr;
if (isLibraryPrefix(ident.prefix)) {
return expr;
}
result = astFactory.prefixedIdentifier(
_bindValue(scope, 'o', ident.prefix, context: context)
as SimpleIdentifier,
ident.period,
ident.identifier);
} else {
return expr as SimpleIdentifier;
}
result.staticType = expr.staticType;
setIsDynamicInvoke(result, isDynamicInvoke(expr));
return result;
}
/// Creates a temporary to contain the value of [expr]. The temporary can be
/// used multiple times in the resulting expression. For example:
/// `expr ** 2` could be compiled as `expr * expr`. The temporary scope will
/// ensure `expr` is only evaluated once: `(x => x * x)(expr)`.
///
/// If the expression does not end up using `x` more than once, or if those
/// expressions can be treated as stateless (e.g. they are non-mutated
/// variables), then the resulting code will be simplified automatically.
///
/// [scope] will be mutated to contain the new temporary's initialization.
Expression _bindValue(Map<JS.MetaLetVariable, JS.Expression> scope,
String name, Expression expr,
{Expression context}) {
// No need to do anything for stateless expressions.
if (isStateless(_currentFunction, expr, context)) return expr;
var variable = new JS.MetaLetVariable(name);
var t = _createTemporary(name, getStaticType(expr),
variable: variable,
dynamicInvoke: isDynamicInvoke(expr),
nullable: isNullable(expr));
scope[variable] = _visit(expr);
return t;
}
/// Desugars postfix increment.
///
/// In the general case [expr] can be one of [IndexExpression],
/// [PrefixExpression] or [PropertyAccess] and we need to
/// ensure sub-expressions are evaluated once.
///
/// We also need to ensure we can return the original value of the expression,
/// and that it is only evaluated once.
///
/// We desugar this using let*.
///
/// For example, `expr1[expr2]++` can be transformed to this:
///
/// // psuedocode mix of Scheme and JS:
/// (let* (x1=expr1, x2=expr2, t=expr1[expr2]) { x1[x2] = t + 1; t })
///
/// The [JS.MetaLet] nodes automatically simplify themselves if they can.
/// For example, if the result value is not used, then `t` goes away.
@override
JS.Expression visitPostfixExpression(PostfixExpression node) {
var op = node.operator;
var expr = node.operand;
var dispatchType = getStaticType(expr);
if (typeRep.unaryOperationIsPrimitive(dispatchType)) {
if (!isNullable(expr)) {
return js.call('#$op', _visit(expr));
}
}
assert(op.lexeme == '++' || op.lexeme == '--');
// Handle the left hand side, to ensure each of its subexpressions are
// evaluated only once.
var vars = <JS.MetaLetVariable, JS.Expression>{};
var left = _bindLeftHandSide(vars, expr, context: expr);
// Desugar `x++` as `(x1 = x0 + 1, x0)` where `x0` is the original value
// and `x1` is the new value for `x`.
var x = _bindValue(vars, 'x', left, context: expr);
var one = ast.integerLiteral(1)..staticType = types.intType;
var increment = ast.binaryExpression(x, op.lexeme[0], one)
..staticElement = node.staticElement
..staticType = getStaticType(expr);
var body = <JS.Expression>[_emitSet(left, increment), _visit(x)];
return new JS.MetaLet(vars, body, statelessResult: true);
}
@override
JS.Expression visitPrefixExpression(PrefixExpression node) {
var op = node.operator;
// Logical negation, `!e`, is a boolean conversion context since it is
// defined as `e ? false : true`.
if (op.lexeme == '!') return _visitTest(node);
var expr = node.operand;
var dispatchType = getStaticType(expr);
if (typeRep.unaryOperationIsPrimitive(dispatchType)) {
if (op.lexeme == '~') {
if (typeRep.isNumber(dispatchType)) {
JS.Expression jsExpr = js.call('~#', notNull(expr));
return _coerceBitOperationResultToUnsigned(node, jsExpr);
}
return _emitSend(expr, op.lexeme[0], []);
}
if (!isNullable(expr)) {
return js.call('$op#', _visit(expr));
}
if (op.lexeme == '++' || op.lexeme == '--') {
// We need a null check, so the increment must be expanded out.
var vars = <JS.MetaLetVariable, JS.Expression>{};
var x = _bindLeftHandSide(vars, expr, context: expr);
var one = ast.integerLiteral(1)..staticType = types.intType;
var increment = ast.binaryExpression(x, op.lexeme[0], one)
..staticElement = node.staticElement
..staticType = getStaticType(expr);
return new JS.MetaLet(vars, [_emitSet(x, increment)]);
}
return js.call('$op#', notNull(expr));
}
if (op.lexeme == '++' || op.lexeme == '--') {
// Increment or decrement requires expansion.
// Desugar `++x` as `x = x + 1`, ensuring that if `x` has subexpressions
// (for example, x is IndexExpression) we evaluate those once.
var one = ast.integerLiteral(1)..staticType = types.intType;
return _emitOpAssign(expr, one, op.lexeme[0], node.staticElement,
context: expr);
}
var operatorName = op.lexeme;
// Use the name from the Dart spec.
if (operatorName == '-') operatorName = 'unary-';
return _emitSend(expr, operatorName, []);
}
// Cascades can contain [IndexExpression], [MethodInvocation] and
// [PropertyAccess]. The code generation for those is handled in their
// respective visit methods.
@override
visitCascadeExpression(CascadeExpression node) {
var savedCascadeTemp = _cascadeTarget;
var vars = <JS.MetaLetVariable, JS.Expression>{};
_cascadeTarget = _bindValue(vars, '_', node.target, context: node);
var sections = _visitList<JS.Expression>(node.cascadeSections);
sections.add(_visit(_cascadeTarget));
var result = new JS.MetaLet(vars, sections, statelessResult: true);
_cascadeTarget = savedCascadeTemp;
return result;
}
@override
visitParenthesizedExpression(ParenthesizedExpression node) =>
// The printer handles precedence so we don't need to.
_visit(node.expression);
@override
visitDefaultFormalParameter(DefaultFormalParameter node) {
return _emitParameter(node.element, declaration: true);
}
JS.Parameter _emitNormalFormalParameter(NormalFormalParameter node) {
var id = _emitParameter(node.element, declaration: true);
var isRestArg = findAnnotation(node.element, isJsRestAnnotation) != null;
return isRestArg ? new JS.RestParameter(id) : id;
}
@override
visitSimpleFormalParameter(SimpleFormalParameter node) =>
_emitNormalFormalParameter(node);
@override
visitFieldFormalParameter(FieldFormalParameter node) =>
_emitNormalFormalParameter(node);
@override
visitFunctionTypedFormalParameter(FunctionTypedFormalParameter node) =>
_emitNormalFormalParameter(node);
@override
JS.This visitThisExpression(ThisExpression node) => new JS.This();
@override
JS.Expression visitSuperExpression(SuperExpression node) => new JS.Super();
@override
visitPrefixedIdentifier(PrefixedIdentifier node) {
if (_isDeferredLoadLibrary(node.prefix, node.identifier)) {
// We are tearing off "loadLibrary" on a library prefix.
return _callHelper('loadLibrary');
}
if (isLibraryPrefix(node.prefix)) {
return _visit(node.identifier);
} else {
return _emitAccess(node.prefix, node.identifier, node.staticType);
}
}
@override
visitPropertyAccess(PropertyAccess node) {
if (node.operator.lexeme == '?.') {
return _emitNullSafe(node);
}
return _emitAccess(_getTarget(node), node.propertyName, node.staticType);
}
JS.Expression _emitNullSafe(Expression node) {
// Desugar `obj?.name` as ((x) => x == null ? null : x.name)(obj)
var target = _getTarget(node);
var vars = <JS.MetaLetVariable, JS.Expression>{};
var t = _bindValue(vars, 't', target, context: target);
return new JS.MetaLet(vars, [
js.call('# == null ? null : #',
[_visit(t), _visit(_stripNullAwareOp(node, t))])
]);
}
// TODO(jmesserly): this is dropping source location.
Expression _stripNullAwareOp(Expression node, Expression newTarget) {
if (node is PropertyAccess) {
return ast.propertyAccess(newTarget, node.propertyName);
} else {
var invoke = node as MethodInvocation;
return ast.methodInvoke(newTarget, invoke.methodName,
invoke.typeArguments, invoke.argumentList.arguments)
..staticInvokeType = invoke.staticInvokeType;
}
}
/// Everything in Dart is an Object and supports the 4 members on Object,
/// so we have to use a runtime helper to handle values such as `null` and
/// native types.
///
/// For example `null.toString()` is legal in Dart, so we need to generate
/// that as `dart.toString(obj)`.
bool _isObjectMemberCall(Expression target, String memberName) {
return isObjectMember(memberName) && isNullable(target);
}
List<JS.Expression> _getTypeArgs(Element member, DartType instantiated) {
DartType type;
if (member is ExecutableElement) {
type = member.type;
} else if (member is VariableElement) {
type = member.type;
}
// TODO(jmesserly): handle explicitly passed type args.
if (type == null) return null;
return _emitFunctionTypeArguments(type, instantiated);
}
/// Shared code for [PrefixedIdentifier] and [PropertyAccess].
JS.Expression _emitAccess(
Expression target, SimpleIdentifier memberId, DartType resultType) {
var accessor = memberId.staticElement;
// If `member` is a getter/setter, get the corresponding
var field = _getNonAccessorElement(accessor);
String memberName = memberId.name;
var typeArgs = _getTypeArgs(accessor, resultType);
bool isStatic = field is ClassMemberElement && field.isStatic;
var jsName = _emitMemberName(memberName,
type: getStaticType(target), isStatic: isStatic, element: accessor);
if (isDynamicInvoke(target)) {
return _callHelper('#(#, #)',
[_emitDynamicOperationName('dload'), _visit(target), jsName]);
}
var jsTarget = _emitTarget(target, accessor, isStatic);
var isSuper = jsTarget is JS.Super;
if (isSuper &&
accessor.isSynthetic &&
field is FieldElementImpl &&
!virtualFields.isVirtual(field)) {
// If super.x is a sealed field, then x is an instance property since
// subclasses cannot override x.
jsTarget = annotate(new JS.This(), target);
}
JS.Expression result;
if (_isObjectMemberCall(target, memberName)) {
if (_isObjectMethod(memberName)) {
result = _callHelper('bind(#, #)', [jsTarget, jsName]);
} else {
result = _callHelper('#(#)', [memberName, jsTarget]);
}
} else if (accessor is MethodElement &&
!isStatic &&
!_isJSNative(accessor.enclosingElement)) {
if (isSuper) {
result = _callHelper('bind(this, #, #)',
[jsName, _emitTargetAccess(jsTarget, jsName, accessor)]);
} else {
result = _callHelper('bind(#, #)', [jsTarget, jsName]);
}
} else {
result = _emitTargetAccess(jsTarget, jsName, accessor);
}
return typeArgs == null
? result
: _callHelper('gbind(#, #)', [result, typeArgs]);
}
JS.LiteralString _emitDynamicOperationName(String name) =>
js.string(options.replCompile ? '${name}Repl' : name);
/// Emits a generic send, like an operator method.
///
/// **Please note** this function does not support method invocation syntax
/// `obj.name(args)` because that could be a getter followed by a call.
/// See [visitMethodInvocation].
JS.Expression _emitSend(
Expression target, String name, List<Expression> args) {
var type = getStaticType(target);
var memberName = _emitMemberName(name, type: type);
if (isDynamicInvoke(target)) {
// dynamic dispatch
var dynamicHelper = const {'[]': 'dindex', '[]=': 'dsetindex'}[name];
if (dynamicHelper != null) {
return _callHelper(
'$dynamicHelper(#, #)', [_visit(target), _visitList(args)]);
} else {
return _callHelper(
'dsend(#, #, #)', [_visit(target), memberName, _visitList(args)]);
}
}
// Generic dispatch to a statically known method.
return js.call('#.#(#)', [_visit(target), memberName, _visitList(args)]);
}
@override
visitIndexExpression(IndexExpression node) {
var target = _getTarget(node);
if (_useNativeJsIndexer(target.staticType)) {
return new JS.PropertyAccess(_visit(target), _visit(node.index));
}
return _emitSend(target, '[]', [node.index]);
}
// TODO(jmesserly): ideally we'd check the method and see if it is marked
// `external`, but that doesn't work because it isn't in the element model.
bool _useNativeJsIndexer(DartType type) =>
findAnnotation(type.element, isJSAnnotation) != null;
/// Gets the target of a [PropertyAccess], [IndexExpression], or
/// [MethodInvocation]. These three nodes can appear in a [CascadeExpression].
Expression _getTarget(node) {
assert(node is IndexExpression ||
node is PropertyAccess ||
node is MethodInvocation);
return node.isCascaded ? _cascadeTarget : node.target;
}
@override
visitConditionalExpression(ConditionalExpression node) {
return js.call('# ? # : #', [
_visitTest(node.condition),
_visit(node.thenExpression),
_visit(node.elseExpression)
]);
}
@override
visitThrowExpression(ThrowExpression node) {
var expr = _visit(node.expression);
if (node.parent is ExpressionStatement) {
return _callHelperStatement('throw(#);', expr);
} else {
return _callHelper('throw(#)', expr);
}
}
@override
visitRethrowExpression(RethrowExpression node) {
if (node.parent is ExpressionStatement) {
return js.statement('throw #;', _visit(_catchParameter));
} else {
return js.call('throw #', _visit(_catchParameter));
}
}
/// Visits a statement, and ensures the resulting AST handles block scope
/// correctly. Essentially, we need to promote a variable declaration
/// statement into a block in some cases, e.g.
///
/// do var x = 5; while (false); // Dart
/// do { let x = 5; } while (false); // JS
JS.Statement _visitScope(Statement stmt) {
var result = _visit(stmt);
if (result is JS.ExpressionStatement &&
result.expression is JS.VariableDeclarationList) {
return new JS.Block([result]);
}
return result;
}
@override
JS.If visitIfStatement(IfStatement node) {
return new JS.If(_visitTest(node.condition),
_visitScope(node.thenStatement), _visitScope(node.elseStatement));
}
@override
JS.For visitForStatement(ForStatement node) {
var init = _visit(node.initialization);
if (init == null) init = _visit(node.variables);
var update = _visitListToBinary(node.updaters, ',');
if (update != null) update = update.toVoidExpression();
var condition = node.condition == null ? null : _visitTest(node.condition);
return new JS.For(init, condition, update, _visitScope(node.body));
}
@override
JS.While visitWhileStatement(WhileStatement node) {
return new JS.While(_visitTest(node.condition), _visitScope(node.body));
}
@override
JS.Do visitDoStatement(DoStatement node) {
return new JS.Do(_visitScope(node.body), _visitTest(node.condition));
}
@override
JS.Statement visitForEachStatement(ForEachStatement node) {
if (node.awaitKeyword != null) {
return _emitAwaitFor(node);
}
var init = _visit(node.identifier);
var iterable = _visit(node.iterable);
var body = _visitScope(node.body);
if (init == null) {
var name = node.loopVariable.identifier.name;
init = js.call('let #', name);
if (_annotatedNullCheck(node.loopVariable.element)) {
body =
new JS.Block([nullParameterCheck(new JS.Identifier(name)), body]);
}
}
return new JS.ForOf(init, iterable, body);
}
JS.Statement _emitAwaitFor(ForEachStatement node) {
// Emits `await for (var value in stream) ...`, which desugars as:
//
// var iter = new StreamIterator(stream);
// try {
// while (await iter.moveNext()) {
// var value = iter.current;
// ...
// }
// } finally {
// await iter.cancel();
// }
//
// Like the Dart VM, we call cancel() always, as it's safe to call if the
// stream has already been cancelled.
//
// TODO(jmesserly): we may want a helper if these become common. For now the
// full desugaring seems okay.
var streamIterator = rules.instantiateToBounds(_asyncStreamIterator);
var createStreamIter = _emitInstanceCreationExpression(
(streamIterator.element as ClassElement).unnamedConstructor,
streamIterator,
null,
ast.argumentList([node.iterable]),
false);
var iter = _visit(_createTemporary('it', streamIterator, nullable: false));
var init = _visit(node.identifier);
if (init == null) {
init = js
.call('let # = #.current', [node.loopVariable.identifier.name, iter]);
} else {
init = js.call('# = #.current', [init, iter]);
}
return js.statement(
'{'
' let # = #;'
' try {'
' while (#) { #; #; }'
' } finally { #; }'
'}',
[
iter,
createStreamIter,
new JS.Yield(js.call('#.moveNext()', iter)),
init,
_visit(node.body),
new JS.Yield(js.call('#.cancel()', iter))
]);
}
@override
visitBreakStatement(BreakStatement node) {
var label = node.label;
return new JS.Break(label?.name);
}
@override
visitContinueStatement(ContinueStatement node) {
var label = node.label;
return new JS.Continue(label?.name);
}
@override
visitTryStatement(TryStatement node) {
var savedSuperAllowed = _superAllowed;
_superAllowed = false;
var finallyBlock = _visit(node.finallyBlock);
_superAllowed = savedSuperAllowed;
return new JS.Try(
_visit(node.body), _visitCatch(node.catchClauses), finallyBlock);
}
_visitCatch(NodeList<CatchClause> clauses) {
if (clauses == null || clauses.isEmpty) return null;
// TODO(jmesserly): need a better way to get a temporary variable.
// This could incorrectly shadow a user's name.
var savedCatch = _catchParameter;
if (clauses.length == 1 && clauses.single.exceptionParameter != null) {
// Special case for a single catch.
_catchParameter = clauses.single.exceptionParameter;
} else {
_catchParameter = _createTemporary('e', types.dynamicType);
}
JS.Statement catchBody = js.statement('throw #;', _visit(_catchParameter));
for (var clause in clauses.reversed) {
catchBody = _catchClauseGuard(clause, catchBody);
}
var catchVarDecl = _visit(_catchParameter);
_catchParameter = savedCatch;
return new JS.Catch(catchVarDecl, new JS.Block([catchBody]));
}
JS.Statement _catchClauseGuard(CatchClause clause, JS.Statement otherwise) {
var then = visitCatchClause(clause);
// Discard following clauses, if any, as they are unreachable.
if (clause.exceptionType == null) return then;
// TODO(jmesserly): this is inconsistent with [visitIsExpression], which
// has special case for typeof.
var castType = _emitType(clause.exceptionType.type);
return new JS.If(js.call('#.is(#)', [castType, _visit(_catchParameter)]),
then, otherwise);
}
JS.Statement _statement(List<JS.Statement> statements) {
// TODO(jmesserly): empty block singleton?
if (statements.length == 0) return new JS.Block([]);
if (statements.length == 1) return statements[0];
return new JS.Block(statements);
}
/// Visits the catch clause body. This skips the exception type guard, if any.
/// That is handled in [_visitCatch].
@override
JS.Statement visitCatchClause(CatchClause node) {
var body = <JS.Statement>[];
var savedCatch = _catchParameter;
if (node.catchKeyword != null) {
var name = node.exceptionParameter;
if (name != null && name != _catchParameter) {
body.add(js
.statement('let # = #;', [_visit(name), _visit(_catchParameter)]));
_catchParameter = name;
}
if (node.stackTraceParameter != null) {
var stackVar = node.stackTraceParameter.name;
body.add(js.statement('let # = #.stackTrace(#);',
[stackVar, _runtimeModule, _visit(name)]));
}
}
body.add(new JS.Block(_visitList(node.body.statements)));
_catchParameter = savedCatch;
return _statement(body);
}
@override
JS.Case visitSwitchCase(SwitchCase node) {
var expr = _visit(node.expression);
var body = _visitList<JS.Statement>(node.statements);
if (node.labels.isNotEmpty) {
body.insert(0, js.comment('Unimplemented case labels: ${node.labels}'));
}
// TODO(jmesserly): make sure we are statically checking fall through
return new JS.Case(expr, new JS.Block(body));
}
@override
JS.Default visitSwitchDefault(SwitchDefault node) {
var body = _visitList<JS.Statement>(node.statements);
if (node.labels.isNotEmpty) {
body.insert(0, js.comment('Unimplemented case labels: ${node.labels}'));
}
// TODO(jmesserly): make sure we are statically checking fall through
return new JS.Default(new JS.Block(body));
}
@override
JS.Switch visitSwitchStatement(SwitchStatement node) =>
new JS.Switch(_visit(node.expression), _visitList(node.members));
@override
JS.Statement visitLabeledStatement(LabeledStatement node) {
var result = _visit(node.statement);
for (var label in node.labels.reversed) {
result = new JS.LabeledStatement(label.label.name, result);
}
return result;
}
@override
visitIntegerLiteral(IntegerLiteral node) => js.number(node.value);
@override
visitDoubleLiteral(DoubleLiteral node) => js.number(node.value);
@override
visitNullLiteral(NullLiteral node) => new JS.LiteralNull();
@override
visitSymbolLiteral(SymbolLiteral node) {
JS.Expression emitSymbol() {
// TODO(vsm): Handle qualified symbols correctly.
var last = node.components.last.toString();
var name = js.string(node.components.join('.'), "'");
if (last.startsWith('_')) {
var nativeSymbol = _emitPrivateNameSymbol(currentLibrary, last);
return js.call('new #.new(#, #)', [
_emitConstructorAccess(privateSymbolClass.type),
name,
nativeSymbol
]);
} else {
return js
.call('#.new(#)', [_emitConstructorAccess(types.symbolType), name]);
}
}
return _emitConst(emitSymbol);
}
@override
JS.Expression visitListLiteral(ListLiteral node) {
var elementType = (node.staticType as InterfaceType).typeArguments[0];
if (node.constKeyword == null) {
return _emitList(elementType, _visitList(node.elements));
}
return _cacheConst(
() => _emitConstList(elementType, _visitList(node.elements)));
}
JS.Expression _emitConstList(
DartType elementType, List<JS.Expression> elements) {
// dart.constList helper internally depends on _interceptors.JSArray.
_declareBeforeUse(_jsArray);
return _callHelper('constList(#, #)',
[new JS.ArrayInitializer(elements), _emitType(elementType)]);
}
JS.Expression _emitList(DartType itemType, List<JS.Expression> items) {
var list = new JS.ArrayInitializer(items);
// TODO(jmesserly): analyzer will usually infer `List<Object>` because
// that is the least upper bound of the element types. So we rarely
// generate a plain `List<dynamic>` anymore.
if (itemType.isDynamic) return list;
// Call `new JSArray<E>.of(list)`
var arrayType = _jsArray.type.instantiate([itemType]);
return js.call('#.of(#)', [_emitType(arrayType), list]);
}
@override
visitMapLiteral(MapLiteral node) {
// TODO(jmesserly): we can likely make these faster.
JS.Expression emitMap() {
var entries = node.entries;
Object mapArguments = null;
var type = node.staticType as InterfaceType;
var typeArgs = type.typeArguments;
var reifyTypeArgs = typeArgs.any((t) => !t.isDynamic);
if (entries.isEmpty && !reifyTypeArgs) {
mapArguments = [];
} else if (entries.every((e) => e.key is StringLiteral)) {
// Use JS object literal notation if possible, otherwise use an array.
// We could do this any time all keys are non-nullable String type.
// For now, support StringLiteral as the common non-nullable String case.
var props = <JS.Property>[];
for (var e in entries) {
props.add(new JS.Property(_visit(e.key), _visit(e.value)));
}
mapArguments = new JS.ObjectInitializer(props);
} else {
var values = <JS.Expression>[];
for (var e in entries) {
values.add(_visit(e.key));
values.add(_visit(e.value));
}
mapArguments = new JS.ArrayInitializer(values);
}
var types = <JS.Expression>[];
if (reifyTypeArgs) {
types.addAll(typeArgs.map((e) => _emitType(e)));
}
return _callHelper('map(#, #)', [mapArguments, types]);
}
if (node.constKeyword != null) return _emitConst(emitMap);
return emitMap();
}
@override
JS.LiteralString visitSimpleStringLiteral(SimpleStringLiteral node) =>
js.escapedString(node.value, node.isSingleQuoted ? "'" : '"');
@override
JS.Expression visitAdjacentStrings(AdjacentStrings node) =>
_visitListToBinary(node.strings, '+');
@override
JS.Expression visitStringInterpolation(StringInterpolation node) {
var strings = <String>[];
var interpolations = <JS.Expression>[];
var expectString = true;
for (var e in node.elements) {
if (e is InterpolationString) {
assert(expectString);
expectString = false;
// Escape the string as necessary for use in the eventual `` quotes.
// TODO(jmesserly): this call adds quotes, and then we strip them off.
var str = js.escapedString(e.value, '`').value;
strings.add(str.substring(1, str.length - 1));
} else {
assert(!expectString);
expectString = true;
interpolations.add(_visit(e));
}
}
return new JS.TaggedTemplate(
_callHelper('str'), new JS.TemplateString(strings, interpolations));
}
@override
visitInterpolationExpression(InterpolationExpression node) =>
_visit(node.expression);
@override
visitBooleanLiteral(BooleanLiteral node) => js.boolean(node.value);
T _visit<T extends JS.Node>(AstNode node) {
if (node == null) return null;
var result = node.accept(this) as T;
return result != null ? annotate(result, node) : null;
}
List<R> _visitList<R extends JS.Node>(Iterable<AstNode> nodes) {
return nodes?.map<R>(_visit)?.toList();
}
/// Visits a list of expressions, creating a comma expression if needed in JS.
JS.Expression _visitListToBinary(List<Expression> nodes, String operator) {
if (nodes == null || nodes.isEmpty) return null;
return new JS.Expression.binary(_visitList(nodes), operator);
}
/// Generates an expression for a boolean conversion context (if, while, &&,
/// etc.), where conversions and null checks are implemented via `dart.test`
/// to give a more helpful message.
// TODO(sra): When nullablility is available earlier, it would be cleaner to
// build an input AST where the boolean conversion is a single AST node.
JS.Expression _visitTest(Expression node) {
JS.Expression finish(JS.Expression result) {
return annotate(result, node);
}
if (node is PrefixExpression && node.operator.lexeme == '!') {
// TODO(leafp): consider a peephole opt for identical
// and == here.
return finish(js.call('!#', _visitTest(node.operand)));
}
if (node is ParenthesizedExpression) {
return finish(_visitTest(node.expression));
}
if (node is BinaryExpression) {
JS.Expression shortCircuit(String code) {
return finish(js.call(code,
[_visitTest(node.leftOperand), _visitTest(node.rightOperand)]));
}
var op = node.operator.type.lexeme;
if (op == '&&') return shortCircuit('# && #');
if (op == '||') return shortCircuit('# || #');
}
if (node is AsExpression && CoercionReifier.isRequiredForSoundness(node)) {
assert(node.staticType == types.boolType);
return _callHelper('dtest(#)', _visit(node.expression));
}
JS.Expression result = _visit(node);
if (isNullable(node)) result = _callHelper('test(#)', result);
return result;
}
/// Like [_emitMemberName], but for declaration sites.
///
/// Unlike call sites, we always have an element available, so we can use it
/// directly rather than computing the relevant options for [_emitMemberName].
JS.Expression _declareMemberName(ExecutableElement e, {bool useExtension}) {
return _emitMemberName(_getElementName(e),
isStatic: e.isStatic,
useExtension:
useExtension ?? _extensionTypes.isNativeClass(e.enclosingElement),
element: e);
}
/// This handles member renaming for private names and operators.
///
/// Private names are generated using ES6 symbols:
///
/// // At the top of the module:
/// let _x = Symbol('_x');
/// let _y = Symbol('_y');
/// ...
///
/// class Point {
/// Point(x, y) {
/// this[_x] = x;
/// this[_y] = y;
/// }
/// get x() { return this[_x]; }
/// get y() { return this[_y]; }
/// }
///
/// For user-defined operators the following names are allowed:
///
/// <, >, <=, >=, ==, -, +, /, ~/, *, %, |, ^, &, <<, >>, []=, [], ~
///
/// They generate code like:
///
/// x['+'](y)
///
/// There are three exceptions: [], []= and unary -.
/// The indexing operators we use `get` and `set` instead:
///
/// x.get('hi')
/// x.set('hi', 123)
///
/// This follows the same pattern as ECMAScript 6 Map:
/// <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map>
///
/// Unary minus looks like: `x._negate()`.
///
/// Equality is a bit special, it is generated via the Dart `equals` runtime
/// helper, that checks for null. The user defined method is called '=='.
///
JS.Expression _emitMemberName(String name,
{DartType type,
bool isStatic: false,
bool useExtension,
Element element}) {
// Static members skip the rename steps and may require JS interop renames.
if (isStatic) {
return _emitJSInteropStaticMemberName(element) ?? _propertyName(name);
}
// We allow some (illegal in Dart) member names to be used in our private
// SDK code. These renames need to be included at every declaration,
// including overrides in subclasses.
if (element != null) {
var runtimeName = getJSExportName(element);
if (runtimeName != null) {
var parts = runtimeName.split('.');
if (parts.length < 2) return _propertyName(runtimeName);
JS.Expression result = new JS.Identifier(parts[0]);
for (int i = 1; i < parts.length; i++) {
result = new JS.PropertyAccess(result, _propertyName(parts[i]));
}
return result;
}
}
if (name.startsWith('_')) {
return _emitPrivateNameSymbol(currentLibrary, name);
}
useExtension ??= _isSymbolizedMember(type, name);
// When generating synthetic names, we use _ as the prefix, since Dart names
// won't have this (eliminated above), nor will static names reach here.
switch (name) {
case '[]':
name = '_get';
break;
case '[]=':
name = '_set';
break;
case 'unary-':
name = '_negate';
break;
case '==':
name = '_equals';
break;
case 'constructor':
case 'prototype':
name = '_$name';
break;
}
if (useExtension) {
return _getExtensionSymbolInternal(name);
}
return _propertyName(name);
}
/// This is an internal method used by [_emitMemberName] and the
/// optimized `dart:_runtime extensionSymbol` builtin to get the symbol
/// for `dartx.<name>`.
///
/// Do not call this directly; you want [_emitMemberName], which knows how to
/// handle the many details involved in naming.
JS.TemporaryId _getExtensionSymbolInternal(String name) {
return _extensionSymbols.putIfAbsent(name,
() => new JS.TemporaryId('\$${_friendlyOperatorName[name] ?? name}'));
}
var _forwardingCache = new HashMap<Element, Map<String, ExecutableElement>>();
Element _lookupForwardedMember(ClassElement element, String name) {
// We only care about public methods.
if (name.startsWith('_')) return null;
var map = _forwardingCache.putIfAbsent(element, () => {});
if (map.containsKey(name)) return map[name];
// Note, for a public member, the library should not matter.
var library = element.library;
var member = element.lookUpMethod(name, library) ??
element.lookUpGetter(name, library) ??
element.lookUpSetter(name, library);
member = (member != null &&
member.isSynthetic &&
member is PropertyAccessorElement)
? member.variable
: member;
map[name] = member;
return member;
}
/// Don't symbolize native members that just forward to the underlying
/// native member. We limit this to non-renamed members as the receiver
/// may be a mock type.
///
/// Note, this is an underlying assumption here that, if another native type
/// subtypes this one, it also forwards this member to its underlying native
/// one without renaming.
bool _isSymbolizedMember(DartType type, String name) {
while (type is TypeParameterType) {
type = (type as TypeParameterType).bound;
}
if (type == null || type.isDynamic || type.isObject) {
return isObjectMember(name);
} else if (type is InterfaceType) {
var element = type.element;
if (_extensionTypes.isNativeClass(element)) {
var member = _lookupForwardedMember(element, name);
// Fields on a native class are implicitly native.
// Methods/getters/setters are marked external/native.
if (member is FieldElement ||
member is ExecutableElement && member.isExternal) {
var jsName = getAnnotationName(member, isJsName);
return jsName != null && jsName != name;
} else {
// Non-external members must be symbolized.
return true;
}
}
// If the receiver *may* be a native type (i.e., an interface allowed to
// be implemented by a native class), conservatively symbolize - we don't
// know whether it'll be implemented via forwarding.
// TODO(vsm): Consider CHA here to be less conservative.
return _extensionTypes.isNativeInterface(element);
} else if (type is FunctionType) {
return true;
}
return false;
}
JS.TemporaryId _emitPrivateNameSymbol(LibraryElement library, String name) {
return _privateNames
.putIfAbsent(library, () => new HashMap())
.putIfAbsent(name, () {
var id = new JS.TemporaryId(name);
_moduleItems.add(
js.statement('const # = Symbol(#);', [id, js.string(id.name, "'")]));
return id;
});
}
FunctionBody _functionBody(node) =>
node is FunctionDeclaration ? node.functionExpression.body : node.body;
/// Returns the canonical name to refer to the Dart library.
JS.Identifier emitLibraryName(LibraryElement library) {
// It's either one of the libraries in this module, or it's an import.
return _libraries[library] ??
_imports.putIfAbsent(library,
() => new JS.TemporaryId(jsLibraryName(_libraryRoot, library)));
}
T annotate<T extends JS.Node>(T node, AstNode original, [Element element]) {
if (options.closure && element != null) {
node.closureAnnotation =
closureAnnotationFor(node, original, element, namedArgumentTemp.name);
}
return node..sourceInformation = original;
}
/// Return true if this is one of the methods/properties on all Dart Objects
/// (toString, hashCode, noSuchMethod, runtimeType).
///
/// Operator == is excluded, as it is handled as part of the equality binary
/// operator.
bool isObjectMember(String name) {
// We could look these up on Object, but we have hard coded runtime helpers
// so it's not really providing any benefit.
switch (name) {
case 'hashCode':
case 'toString':
case 'noSuchMethod':
case 'runtimeType':
case '==':
return true;
}
return false;
}
bool _isObjectMethod(String name) =>
name == 'toString' || name == 'noSuchMethod';
// TODO(leafp): Various analyzer pieces computed similar things.
// Share this logic somewhere?
DartType _getExpectedReturnType(ExecutableElement element) {
FunctionType functionType = element.type;
if (functionType == null) {
return DynamicTypeImpl.instance;
}
var type = functionType.returnType;
InterfaceType expectedType = null;
if (element.isAsynchronous) {
if (element.isGenerator) {
// Stream<T> -> T
expectedType = types.streamType;
} else {
// Future<T> -> T
expectedType = types.futureType;
}
} else {
if (element.isGenerator) {
// Iterable<T> -> T
expectedType = types.iterableType;
} else {
// T -> T
return type;
}
}
if (type.isDynamic) {
return type;
} else if (type is InterfaceType && type.element == expectedType.element) {
return type.typeArguments[0];
} else {
// TODO(leafp): The above only handles the case where the return type
// is exactly Future/Stream/Iterable. Handle the subtype case.
return DynamicTypeImpl.instance;
}
}
JS.Expression _callHelper(String code, [args]) {
if (args is List) {
args.insert(0, _runtimeModule);
} else if (args != null) {
args = [_runtimeModule, args];
} else {
args = _runtimeModule;
}
return js.call('#.$code', args);
}
JS.Statement _callHelperStatement(String code, args) {
if (args is List) {
args.insert(0, _runtimeModule);
} else {
args = [_runtimeModule, args];
}
return js.statement('#.$code', args);
}
JS.Expression _throwUnsafe(String message) => _callHelper(
'throw(Error(#))', js.escapedString("compile error: $message"));
_unreachable(AstNode node) {
throw new UnsupportedError(
'tried to generate an unreachable node: `$node`');
}
/// Unused, see methods for emitting declarations.
@override
visitAnnotation(node) => _unreachable(node);
/// Unused, see [_emitArgumentList].
@override
visitArgumentList(ArgumentList node) => _unreachable(node);
/// Unused, see [_emitFieldInitializers].
@override
visitAssertInitializer(node) => _unreachable(node);
/// Not visited, but maybe they should be?
/// See <https://github.com/dart-lang/sdk/issues/29347>
@override
visitComment(node) => _unreachable(node);
/// Not visited, but maybe they should be?
/// See <https://github.com/dart-lang/sdk/issues/29347>
@override
visitCommentReference(node) => _unreachable(node);
/// Unused, handled by imports/exports.
@override
visitConfiguration(node) => _unreachable(node);
/// Unusued, see [_emitConstructor].
@override
visitConstructorDeclaration(node) => _unreachable(node);
/// Unusued, see [_emitFieldInitializers].
@override
visitConstructorFieldInitializer(node) => _unreachable(node);
/// Unusued, see [_emitRedirectingConstructor].
@override
visitRedirectingConstructorInvocation(node) => _unreachable(node);
/// Unusued. Handled in [visitForEachStatement].
@override
visitDeclaredIdentifier(node) => _unreachable(node);
/// Unused, handled by imports/exports.
@override
visitDottedName(node) => _unreachable(node);
/// Unused, handled by [visitEnumDeclaration].
@override
visitEnumConstantDeclaration(node) => _unreachable(node); // see
/// Unused, see [_emitClassHeritage].
@override
visitExtendsClause(node) => _unreachable(node);
/// Unused, see [_emitFormalParameterList].
@override
visitFormalParameterList(node) => _unreachable(node);
/// Unused, handled by imports/exports.
@override
visitShowCombinator(node) => _unreachable(node);
/// Unused, handled by imports/exports.
@override
visitHideCombinator(node) => _unreachable(node);
/// Unused, see [_emitClassHeritage].
@override
visitImplementsClause(node) => _unreachable(node);
/// Unused, handled by [visitStringInterpolation].
@override
visitInterpolationString(node) => _unreachable(node);
/// Unused, labels are handled by containing statements.
@override
visitLabel(node) => _unreachable(node);
/// Unused, handled by imports/exports.
@override
visitLibraryIdentifier(node) => _unreachable(node);
/// Unused, see [visitMapLiteral].
@override
visitMapLiteralEntry(node) => _unreachable(node);
/// Unused, see [_emitMethodDeclaration].
@override
visitMethodDeclaration(node) => _unreachable(node);
/// Unused, these are not visited.
@override
visitNativeClause(node) => _unreachable(node);
/// Unused, these are not visited.
@override
visitNativeFunctionBody(node) => _unreachable(node);
/// Unused, handled by [_emitConstructor].
@override
visitSuperConstructorInvocation(node) => _unreachable(node);
/// Unused, this can be handled when emitting the module if needed.
@override
visitScriptTag(node) => _unreachable(node);
/// Unused, see [_emitType].
@override
visitTypeArgumentList(node) => _unreachable(node);
/// Unused, see [_emitType].
@override
visitTypeParameter(node) => _unreachable(node);
/// Unused, see [_emitType].
@override
visitTypeParameterList(node) => _unreachable(node);
/// Unused, see [_emitClassHeritage].
@override
visitWithClause(node) => _unreachable(node);
}
/// Choose a canonical name from the [library] element.
///
/// This never uses the library's name (the identifier in the `library`
/// declaration) as it doesn't have any meaningful rules enforced.
String jsLibraryName(String libraryRoot, LibraryElement library) {
var uri = library.source.uri;
if (uri.scheme == 'dart') {
return uri.path;
}
// TODO(vsm): This is not necessarily unique if '__' appears in a file name.
var encodedSeparator = '__';
String qualifiedPath;
if (uri.scheme == 'package') {
// Strip the package name.
// TODO(vsm): This is not unique if an escaped '/'appears in a filename.
// E.g., "foo/bar.dart" and "foo$47bar.dart" would collide.
qualifiedPath = uri.pathSegments.skip(1).join(encodedSeparator);
} else if (isWithin(libraryRoot, uri.toFilePath())) {
qualifiedPath = relative(uri.toFilePath(), from: libraryRoot)
.replaceAll(separator, encodedSeparator);
} else {
// We don't have a unique name.
throw 'Invalid library root. $libraryRoot does not contain ${uri
.toFilePath()}';
}
return pathToJSIdentifier(qualifiedPath);
}
/// Debugger friendly name for a Dart Library.
String jsLibraryDebuggerName(String libraryRoot, LibraryElement library) {
var uri = library.source.uri;
// For package: and dart: uris show the entire
if (uri.scheme == 'dart' || uri.scheme == 'package') return uri.toString();
var filePath = uri.toFilePath();
if (!isWithin(libraryRoot, filePath)) {
throw 'Invalid library root. $libraryRoot does not contain ${uri
.toFilePath()}';
}
// Relative path to the library.
return relative(filePath, from: libraryRoot);
}
/// Shorthand for identifier-like property names.
/// For now, we emit them as strings and the printer restores them to
/// identifiers if it can.
// TODO(jmesserly): avoid the round tripping through quoted form.
JS.LiteralString _propertyName(String name) => js.string(name, "'");
// TODO(jacobr): we would like to do something like the following
// but we don't have summary support yet.
// bool _supportJsExtensionMethod(AnnotatedNode node) =>
// _getAnnotation(node, "SupportJsExtensionMethod") != null;
/// A special kind of element created by the compiler, signifying a temporary
/// variable. These objects use instance equality, and should be shared
/// everywhere in the tree where they are treated as the same variable.
class TemporaryVariableElement extends LocalVariableElementImpl {
final JS.Expression jsVariable;
TemporaryVariableElement.forNode(Identifier name, this.jsVariable)
: super.forNode(name);
int get hashCode => identityHashCode(this);
bool operator ==(Object other) => identical(this, other);
}
bool isLibraryPrefix(Expression node) =>
node is SimpleIdentifier && node.staticElement is PrefixElement;
LibraryElement _getLibrary(AnalysisContext c, String uri) =>
c.computeLibraryElement(c.sourceFactory.forUri(uri));
/// Returns `true` if [target] is a prefix for a deferred library and [name]
/// is "loadLibrary".
///
/// If so, the expression should be compiled to call the runtime's
/// "loadLibrary" helper function.
bool _isDeferredLoadLibrary(Expression target, SimpleIdentifier name) {
if (name.name != "loadLibrary") return false;
if (target is! SimpleIdentifier) return false;
var targetIdentifier = target as SimpleIdentifier;
if (targetIdentifier.staticElement is! PrefixElement) return false;
var prefix = targetIdentifier.staticElement as PrefixElement;
// The library the prefix is referring to must come from a deferred import.
var containingLibrary = resolutionMap
.elementDeclaredByCompilationUnit(target.root as CompilationUnit)
.library;
var imports = containingLibrary.getImportsWithPrefix(prefix);
return imports.length == 1 && imports[0].isDeferred;
}
bool _annotatedNullCheck(Element e) =>
e != null && findAnnotation(e, isNullCheckAnnotation) != null;
final _friendlyOperatorName = {
'<': 'lessThan',
'>': 'greaterThan',
'<=': 'lessOrEquals',
'>=': 'greaterOrEquals',
'-': 'minus',
'+': 'plus',
'/': 'divide',
'~/': 'floorDivide',
'*': 'times',
'%': 'modulo',
'|': 'bitOr',
'^': 'bitXor',
'&': 'bitAnd',
'<<': 'leftShift',
'>>': 'rightShift',
'~': 'bitNot',
// These ones are always renamed, hence the choice of `_` to avoid conflict
// with Dart names. See _emitMemberName.
'==': '_equals',
'[]': '_get',
'[]=': '_set',
'unary-': '_negate',
};