| // Copyright (c) 2016, 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, Queue; |
| |
| import 'package:analyzer/dart/element/element.dart'; |
| import 'package:analyzer/dart/element/type.dart' show InterfaceType; |
| import 'package:analyzer/src/dart/element/element.dart' show FieldElementImpl; |
| |
| import '../compiler/js_names.dart' as JS; |
| import '../js_ast/js_ast.dart' as JS; |
| import 'element_helpers.dart'; |
| import 'extension_types.dart'; |
| |
| /// Dart allows all fields to be overridden. |
| /// |
| /// To prevent a performance/code size penalty for allowing this, we analyze |
| /// private classes within each library that is being compiled to determine |
| /// if those fields should be virtual or not. In effect, we devirtualize fields |
| /// when possible by analyzing the class hierarchy and using knowledge of |
| /// which members are private and thus, could not be overridden outside of the |
| /// current library. |
| class VirtualFieldModel { |
| final _modelForLibrary = HashMap<LibraryElement, _LibraryVirtualFieldModel>(); |
| |
| _LibraryVirtualFieldModel _getModel(LibraryElement library) => |
| _modelForLibrary.putIfAbsent( |
| library, () => _LibraryVirtualFieldModel.build(library)); |
| |
| /// Returns true if a field is virtual. |
| bool isVirtual(FieldElement field) => |
| _getModel(field.library).isVirtual(field); |
| } |
| |
| /// This is a building block of [VirtualFieldModel], used to track information |
| /// about a single library that has been analyzed. |
| class _LibraryVirtualFieldModel { |
| /// Fields that are private (or public fields of a private class) and |
| /// overridden in this library. |
| /// |
| /// This means we must generate them as virtual fields using a property pair |
| /// in JavaScript. |
| final _overriddenPrivateFields = HashSet<FieldElement>(); |
| |
| /// Private classes that can be extended outside of this library. |
| /// |
| /// Normally private classes cannot be accessed outside this library, however, |
| /// this can happen if they are extended by a public class, for example: |
| /// |
| /// class _A { int x = 42; } |
| /// class _B { int x = 42; } |
| /// |
| /// // _A is now effectively public for the purpose of overrides. |
| /// class C extends _A {} |
| /// |
| /// The class _A must treat is "x" as virtual, however _B does not. |
| final _extensiblePrivateClasses = HashSet<ClassElement>(); |
| |
| _LibraryVirtualFieldModel.build(LibraryElement library) { |
| var allTypes = library.units.expand((u) => u.types).toList(); |
| |
| // The set of public types is our initial extensible type set. |
| // From there, visit all immediate private types in this library, and so on |
| // from those private types, marking them as extensible. |
| var typesToVisit = |
| Queue<ClassElement>.from(allTypes.where((t) => t.isPublic)); |
| while (typesToVisit.isNotEmpty) { |
| var extensibleType = typesToVisit.removeFirst(); |
| |
| // For each supertype of a public type in this library, |
| // if we encounter a private class, we mark it as being extended, and |
| // add it to our work set if this is the first time we've visited it. |
| for (var type in getImmediateSuperclasses(extensibleType)) { |
| if (!type.isPublic && type.library == library) { |
| if (_extensiblePrivateClasses.add(type)) typesToVisit.add(type); |
| } |
| } |
| } |
| |
| // ClassElement can only look up inherited members with an O(N) scan through |
| // the class, so we build up a mapping of all fields in the library ahead of |
| // time. |
| Map<String, FieldElement> getInstanceFieldMap(ClassElement c) { |
| var instanceFields = c.fields.where((f) => !f.isStatic); |
| return HashMap.fromIterables( |
| instanceFields.map((f) => f.name), instanceFields); |
| } |
| |
| var allFields = |
| HashMap.fromIterables(allTypes, allTypes.map(getInstanceFieldMap)); |
| |
| for (var type in allTypes) { |
| Set<ClassElement> supertypes = null; |
| |
| // Visit accessors in the current class, and see if they override an |
| // otherwise private field. |
| for (var accessor in type.accessors) { |
| // For getter/setter pairs only process them once. |
| if (accessor.correspondingGetter != null) continue; |
| // Ignore abstract or static accessors. |
| if (accessor.isAbstract || accessor.isStatic) continue; |
| // Ignore public accessors in extensible classes. |
| if (accessor.isPublic && |
| (type.isPublic || _extensiblePrivateClasses.contains(type))) { |
| continue; |
| } |
| |
| if (supertypes == null) { |
| supertypes = Set(); |
| void collectSupertypes(ClassElement cls) { |
| if (!supertypes.add(cls)) return; |
| var s = cls.supertype?.element; |
| if (s != null) collectSupertypes(s); |
| cls.mixins.forEach((m) => collectSupertypes(m.element)); |
| } |
| |
| collectSupertypes(type); |
| supertypes.remove(type); |
| supertypes.removeWhere((c) => c.library != type.library); |
| } |
| |
| // Look in all super classes to see if we're overriding a field in our |
| // library, if so mark that field as overridden. |
| var name = accessor.variable.name; |
| _overriddenPrivateFields.addAll( |
| supertypes.map((c) => allFields[c][name]).where((f) => f != null)); |
| } |
| } |
| } |
| |
| /// Returns true if a field inside this library is virtual. |
| bool isVirtual(FieldElement field) { |
| // If the field was marked non-virtual, we know for sure. |
| if (!field.isVirtual) return false; |
| if (field.isStatic) return false; |
| |
| var type = field.enclosingElement; |
| var uri = type.source.uri; |
| if (uri.scheme == 'dart' && uri.path.startsWith('_')) { |
| // There should be no extensible fields in private SDK libraries. |
| return false; |
| } |
| |
| if (field.isPublic) { |
| // Public fields in public classes (or extensible private classes) |
| // are always virtual. |
| // They could be overridden by someone using our library. |
| if (type.isPublic) return true; |
| if (_extensiblePrivateClasses.contains(type)) return true; |
| } |
| |
| // Otherwise, the field is effectively private and we only need to make it |
| // virtual if it's overridden. |
| return _overriddenPrivateFields.contains(field); |
| } |
| } |
| |
| /// Tracks how fields, getters and setters are represented when emitting JS. |
| /// |
| /// Dart classes have implicit features that must be made explicit: |
| /// |
| /// - virtual fields induce a getter and setter pair. |
| /// - getters and setters are independent. |
| /// - getters and setters can be overridden. |
| /// |
| class ClassPropertyModel { |
| final ExtensionTypeSet extensionTypes; |
| |
| /// Fields that are virtual, that is, they must be generated as a property |
| /// pair in JavaScript. |
| /// |
| /// The value property stores the symbol used for the field's storage slot. |
| final virtualFields = <FieldElement, JS.TemporaryId>{}; |
| |
| /// The set of inherited getters, used because JS getters/setters are paired, |
| /// so if we're generating a setter we may need to emit a getter that calls |
| /// super. |
| final inheritedGetters = HashSet<String>(); |
| |
| /// The set of inherited setters, used because JS getters/setters are paired, |
| /// so if we're generating a getter we may need to emit a setter that calls |
| /// super. |
| final inheritedSetters = HashSet<String>(); |
| |
| final mockMembers = <String, ExecutableElement>{}; |
| |
| final extensionMethods = Set<String>(); |
| |
| final extensionAccessors = Set<String>(); |
| |
| /// Parameters that are covariant due to covariant generics. |
| final Set<Element> covariantParameters; |
| |
| ClassPropertyModel.build( |
| this.extensionTypes, |
| VirtualFieldModel fieldModel, |
| ClassElement classElem, |
| this.covariantParameters, |
| Set<ExecutableElement> covariantPrivateMembers) { |
| // Visit superclasses to collect information about their fields/accessors. |
| // This is expensive so we try to collect everything in one pass. |
| for (var base in getSuperclasses(classElem)) { |
| for (var accessor in base.accessors) { |
| // For getter/setter pairs only process them once. |
| if (accessor.correspondingGetter != null) continue; |
| |
| var field = accessor.variable; |
| // Ignore private names from other libraries. |
| if (field.isPrivate && accessor.library != classElem.library) { |
| continue; |
| } |
| |
| if (field.getter?.isAbstract == false) inheritedGetters.add(field.name); |
| if (field.setter?.isAbstract == false) inheritedSetters.add(field.name); |
| } |
| } |
| |
| _collectMockMembers(classElem.type); |
| _collectExtensionMembers(classElem); |
| |
| var virtualAccessorNames = HashSet<String>() |
| ..addAll(inheritedGetters) |
| ..addAll(inheritedSetters) |
| ..addAll(extensionAccessors) |
| ..addAll(mockMembers.values |
| .map((m) => m is PropertyAccessorElement ? m.variable.name : m.name)); |
| |
| // Visit accessors in the current class, and see if they need to be |
| // generated differently based on the inherited fields/accessors. |
| for (var accessor in classElem.accessors) { |
| // For getter/setter pairs only process them once. |
| if (accessor.correspondingGetter != null) continue; |
| // Also ignore abstract fields. |
| if (accessor.isAbstract || accessor.isStatic) continue; |
| |
| var field = accessor.variable; |
| var name = field.name; |
| // Is it a field? |
| if (!field.isSynthetic && field is FieldElementImpl) { |
| var setter = field.setter; |
| if (virtualAccessorNames.contains(name) || |
| fieldModel.isVirtual(field) || |
| setter != null && |
| covariantParameters != null && |
| covariantParameters.contains(setter.parameters[0]) && |
| covariantPrivateMembers.contains(setter)) { |
| virtualFields[field] = JS.TemporaryId(name); |
| } |
| } |
| } |
| } |
| |
| void _collectMockMembers(InterfaceType type) { |
| // TODO(jmesserly): every type with nSM will generate new stubs for all |
| // abstract members. For example: |
| // |
| // class C { m(); noSuchMethod(...) { ... } } |
| // class D extends C { m(); noSuchMethod(...) { ... } } |
| // |
| // We'll generate D.m even though it is not necessary. |
| // |
| // Doing better is a bit tricky, as our current codegen strategy for the |
| // mock methods encodes information about the number of arguments (and type |
| // arguments) that D expects. |
| var element = type.element; |
| if (!hasNoSuchMethod(element)) return; |
| |
| // Collect all unimplemented members. |
| // |
| // Initially, we track abstract and concrete members separately, then |
| // remove concrete from the abstract set. This is done because abstract |
| // members are allowed to "override" concrete ones in Dart. |
| // (In that case, it will still be treated as a concrete member and can be |
| // called at runtime.) |
| var concreteMembers = HashSet<String>(); |
| |
| void visit(InterfaceType type, bool isAbstract) { |
| if (type == null) return; |
| visit(type.superclass, isAbstract); |
| for (var m in type.mixins) visit(m, isAbstract); |
| for (var i in type.interfaces) visit(i, true); |
| |
| for (var m in [type.methods, type.accessors].expand((m) => m)) { |
| if (m.isStatic) continue; |
| if (isAbstract || m.isAbstract) { |
| mockMembers[m.name] = m; |
| } else { |
| concreteMembers.add(m.name); |
| } |
| } |
| } |
| |
| visit(type, false); |
| |
| concreteMembers.forEach(mockMembers.remove); |
| } |
| |
| void _collectExtensionMembers(ClassElement element) { |
| if (extensionTypes.isNativeClass(element)) return; |
| |
| // Find all generic interfaces that could be used to call into members of |
| // this class. This will help us identify which parameters need checks |
| // for soundness. |
| var allNatives = HashSet<String>(); |
| _collectNativeMembers(element.type, allNatives); |
| if (allNatives.isEmpty) return; |
| |
| // For members on this class, check them against all generic interfaces. |
| var seenConcreteMembers = HashSet<String>(); |
| _findExtensionMembers(element.type, seenConcreteMembers, allNatives); |
| // Add mock members. These are compiler-generated concrete members that |
| // forward to `noSuchMethod`. |
| for (var m in mockMembers.values) { |
| var name = m is PropertyAccessorElement ? m.variable.name : m.name; |
| if (seenConcreteMembers.add(name) && allNatives.contains(name)) { |
| var extMembers = m is PropertyAccessorElement |
| ? extensionAccessors |
| : extensionMethods; |
| extMembers.add(name); |
| } |
| } |
| |
| // For members of the superclass, we may need to add checks because this |
| // class adds a new unsafe interface. Collect those checks. |
| |
| var visited = HashSet<ClassElement>()..add(element); |
| var existingMembers = HashSet<String>(); |
| |
| void visitImmediateSuper(InterfaceType type) { |
| // For members of mixins/supertypes, check them against new interfaces, |
| // and also record any existing checks they already had. |
| var oldCovariant = HashSet<String>(); |
| _collectNativeMembers(type, oldCovariant); |
| var newCovariant = allNatives.difference(oldCovariant); |
| if (newCovariant.isEmpty) return; |
| |
| existingMembers.addAll(oldCovariant); |
| |
| void visitSuper(InterfaceType type) { |
| var element = type.element; |
| if (visited.add(element)) { |
| _findExtensionMembers(type, seenConcreteMembers, newCovariant); |
| element.mixins.reversed.forEach(visitSuper); |
| var s = element.supertype; |
| if (s != null) visitSuper(s); |
| } |
| } |
| |
| visitSuper(type); |
| } |
| |
| element.mixins.reversed.forEach(visitImmediateSuper); |
| var s = element.supertype; |
| if (s != null) visitImmediateSuper(s); |
| } |
| |
| /// Searches all concrete instance members declared on this type, skipping |
| /// already [seenConcreteMembers], and adds them to [extensionMembers] if |
| /// needed. |
| /// |
| /// By tracking the set of seen members, we can visit superclasses and mixins |
| /// and ultimately collect every most-derived member exposed by a given type. |
| void _findExtensionMembers(InterfaceType type, |
| HashSet<String> seenConcreteMembers, Set<String> allNatives) { |
| // We only visit each most derived concrete member. |
| // To avoid visiting an overridden superclass member, we skip members |
| // we've seen, and visit starting from the class, then mixins in |
| // reverse order, then superclasses. |
| for (var m in type.methods) { |
| var name = m.name; |
| if (!m.isStatic && |
| !m.isAbstract && |
| seenConcreteMembers.add(name) && |
| allNatives.contains(name)) { |
| extensionMethods.add(name); |
| } |
| } |
| for (var m in type.accessors) { |
| var name = m.variable.name; |
| if (!m.isStatic && |
| !m.isAbstract && |
| seenConcreteMembers.add(name) && |
| allNatives.contains(name)) { |
| extensionAccessors.add(name); |
| } |
| } |
| if (type.element.isEnum) { |
| extensionMethods.add('toString'); |
| } |
| } |
| |
| /// Collects all supertypes that may themselves contain native subtypes, |
| /// excluding [Object], for example `List` is implemented by several native |
| /// types. |
| void _collectNativeMembers(InterfaceType type, Set<String> members) { |
| var element = type.element; |
| if (extensionTypes.hasNativeSubtype(type)) { |
| for (var m in type.methods) { |
| if (m.isPublic && !m.isStatic) members.add(m.name); |
| } |
| for (var m in type.accessors) { |
| if (m.isPublic && !m.isStatic) members.add(m.variable.name); |
| } |
| } |
| for (var m in element.mixins.reversed) { |
| _collectNativeMembers(m, members); |
| } |
| for (var i in element.interfaces) { |
| _collectNativeMembers(i, members); |
| } |
| if (!type.isObject) { |
| _collectNativeMembers(element.supertype, members); |
| } |
| if (element.isEnum) { |
| // TODO(jmesserly): analyzer does not create the synthetic element |
| // for the enum's `toString()` method, so we'll use the one on Object. |
| members.add('toString'); |
| } |
| } |
| } |