pkg/dev_compiler/lib/src/compiler/compiler.dart - sdk.git - Git at Google

 // 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 HashSet, Queue;
 import 'dart:convert' show BASE64, JSON, UTF8;
 import 'dart:io' show File;
 import 'package:analyzer/dart/element/element.dart' show LibraryElement;
 import 'package:analyzer/analyzer.dart'
     show AnalysisError, CompilationUnit, ErrorSeverity;
 import 'package:analyzer/file_system/file_system.dart' show ResourceProvider;
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisEngine;
 import 'package:analyzer/src/generated/source.dart' show DartUriResolver;
 import 'package:analyzer/src/generated/source_io.dart'
     show Source, SourceKind, UriResolver;
 import 'package:analyzer/src/summary/package_bundle_reader.dart'
     show InSummarySource, InputPackagesResultProvider, SummaryDataStore;
 import 'package:analyzer/src/error/codes.dart' show StaticTypeWarningCode;
 import 'package:args/args.dart' show ArgParser, ArgResults;
 import 'package:args/src/usage_exception.dart' show UsageException;
 import 'package:func/func.dart' show Func1;
 import 'package:path/path.dart' as path;
 import 'package:source_maps/source_maps.dart';

 import '../analyzer/context.dart'
     show
         AnalyzerOptions,
         createAnalysisContext,
         createSdkPathResolver,
         createSourceFactory;
 import '../js_ast/js_ast.dart' as JS;
 import 'code_generator.dart' show CodeGenerator;
 import 'error_helpers.dart' show errorSeverity, formatError, sortErrors;
 import 'extension_types.dart' show ExtensionTypeSet;
 import 'js_names.dart' as JS;
 import 'module_builder.dart' show transformModuleFormat, ModuleFormat;
 import 'source_map_printer.dart' show SourceMapPrintingContext;

 /// Compiles a set of Dart files into a single JavaScript module.
 ///
 /// For a single [BuildUnit] definition, this will produce a [JSModuleFile].
 /// Those objects are record types that record the data consumed and produced
 /// for a single compile.
 ///
 /// This class exists to cache global state associated with a single in-memory
 /// AnalysisContext, such as information about extension types in the Dart SDK.
 /// It can be used once to produce a single module, or reused to save warm-up
 /// time. (Currently there is no warm up, but there may be in the future.)
 ///
 /// The SDK source code is assumed to be immutable for the life of this class.
 ///
 /// For all other files, it is up to the [AnalysisContext] to decide whether or
 /// not any caching is performed. By default an analysis context will assume
 /// sources are immutable for the life of the context, and cache information
 /// about them.
 class ModuleCompiler {
   final AnalysisContext context;
   final SummaryDataStore summaryData;
   final ExtensionTypeSet _extensionTypes;

   ModuleCompiler.withContext(AnalysisContext context, this.summaryData)
       : context = context,
         _extensionTypes = new ExtensionTypeSet(context) {
     if (!context.analysisOptions.strongMode) {
       throw new ArgumentError('AnalysisContext must be strong mode');
     }
     if (!context.sourceFactory.dartSdk.context.analysisOptions.strongMode) {
       throw new ArgumentError('AnalysisContext must have strong mode SDK');
     }
   }

   factory ModuleCompiler(AnalyzerOptions options,
       {DartUriResolver sdkResolver,
       ResourceProvider resourceProvider,
       List<UriResolver> fileResolvers}) {
     AnalysisEngine.instance.processRequiredPlugins();

     sdkResolver ??=
         createSdkPathResolver(options.dartSdkSummaryPath, options.dartSdkPath);

     // Read the summaries.
     var summaryData =
         new SummaryDataStore(options.summaryPaths, recordDependencyInfo: true);

     var srcFactory = createSourceFactory(options,
         sdkResolver: sdkResolver,
         fileResolvers: fileResolvers,
         summaryData: summaryData,
         resourceProvider: resourceProvider);

     var context = createAnalysisContext();
     context.sourceFactory = srcFactory;
     context.typeProvider = sdkResolver.dartSdk.context.typeProvider;
     context.resultProvider =
         new InputPackagesResultProvider(context, summaryData);
     options.declaredVariables.forEach(context.declaredVariables.define);
     context.declaredVariables.define('dart.isVM', 'false');

     return new ModuleCompiler.withContext(context, summaryData);
   }

   bool _isFatalError(AnalysisError e, CompilerOptions options) {
     if (errorSeverity(context, e) != ErrorSeverity.ERROR) return false;

     // These errors are not fatal in the REPL compile mode as we
     // allow access to private members across library boundaries
     // and those accesses will show up as undefined members unless
     // additional analyzer changes are made to support them.
     // TODO(jacobr): consider checking that the identifier name
     // referenced by the error is private.
     return !options.replCompile ||
         (e.errorCode != StaticTypeWarningCode.UNDEFINED_GETTER &&
             e.errorCode != StaticTypeWarningCode.UNDEFINED_SETTER &&
             e.errorCode != StaticTypeWarningCode.UNDEFINED_METHOD);
   }

   /// Compiles a single Dart build unit into a JavaScript module.
   ///
   /// *Warning* - this may require resolving the entire world.
   /// If that is not desired, the analysis context must be pre-configured using
   /// summaries before calling this method.
   JSModuleFile compile(BuildUnit unit, CompilerOptions options) {
     var trees = <CompilationUnit>[];
     var errors = <AnalysisError>[];

     var librariesToCompile = new Queue<LibraryElement>();

     var compilingSdk = false;
     for (var sourcePath in unit.sources) {
       var sourceUri = Uri.parse(sourcePath);
       if (sourceUri.scheme == '') {
         sourceUri = path.toUri(path.absolute(sourcePath));
       } else if (sourceUri.scheme == 'dart') {
         compilingSdk = true;
       }
       Source source = context.sourceFactory.forUri2(sourceUri);

       var fileUsage = 'You need to pass at least one existing .dart file as an'
           ' argument.';
       if (source == null) {
         throw new UsageException(
             'Could not create a source for "$sourcePath". The file name is in'
             ' the wrong format or was not found.',
             fileUsage);
       } else if (!source.exists()) {
         throw new UsageException(
             'Given file "$sourcePath" does not exist.', fileUsage);
       }

       // Ignore parts. They need to be handled in the context of their library.
       if (context.computeKindOf(source) == SourceKind.PART) {
         continue;
       }

       librariesToCompile.add(context.computeLibraryElement(source));
     }

     var libraries = new HashSet<LibraryElement>();
     while (librariesToCompile.isNotEmpty) {
       var library = librariesToCompile.removeFirst();
       if (library.source is InSummarySource) continue;
       if (!compilingSdk && library.source.isInSystemLibrary) continue;
       if (!libraries.add(library)) continue;

       librariesToCompile.addAll(library.importedLibraries);
       librariesToCompile.addAll(library.exportedLibraries);

       var tree = context.resolveCompilationUnit(library.source, library);
       trees.add(tree);
       errors.addAll(context.computeErrors(library.source));

       for (var part in library.parts) {
         trees.add(context.resolveCompilationUnit(part.source, library));
         errors.addAll(context.computeErrors(part.source));
       }
     }

     sortErrors(context, errors);

     var messages = <String>[];
     for (var e in errors) {
       var m = formatError(context, e);
       if (m != null) messages.add(m);
     }

     if (!options.unsafeForceCompile &&
         errors.any((e) => _isFatalError(e, options))) {
       return new JSModuleFile.invalid(unit.name, messages, options);
     }
     var codeGenerator =
         new CodeGenerator(context, summaryData, options, _extensionTypes);
     return codeGenerator.compile(unit, trees, messages);
   }
 }

 class CompilerOptions {
   /// Whether to emit the source mapping file.
   ///
   /// This supports debugging the original source code instead of the generated
   /// code.
   final bool sourceMap;

   /// If [sourceMap] is emitted, this will emit a `sourceMappingUrl` comment
   /// into the output JavaScript module.
   final bool sourceMapComment;

   /// Whether to emit the source mapping file inline as a data url.
   final bool inlineSourceMap;

   /// Whether to emit a summary file containing API signatures.
   ///
   /// This is required for a modular build process.
   final bool summarizeApi;

   /// The file extension for summaries.
   final String summaryExtension;

   /// Whether to preserve metdata only accessible via mirrors
   final bool emitMetadata;

   /// Whether to force compilation of code with static errors.
   final bool unsafeForceCompile;

   /// Whether to compile code in a more permissive REPL mode allowing access
   /// to private members across library boundaries.
   final bool replCompile;

   /// Whether to emit Closure Compiler-friendly code.
   final bool closure;

   /// Hoist the types at instance creation sites
   final bool hoistInstanceCreation;

   /// Hoist types from class signatures
   final bool hoistSignatureTypes;

   /// Name types in type tests
   final bool nameTypeTests;

   /// Hoist types in type tests
   final bool hoistTypeTests;

   final bool useAngular2Whitelist;

   /// Enable ES6 destructuring of named parameters. Off by default.
   ///
   /// Older V8 versions do not accept default values with destructuring in
   /// arrow functions yet (e.g. `({a} = {}) => 1`) but happily accepts them
   /// with regular functions (e.g. `function({a} = {}) { return 1 }`).
   ///
   /// Supporting the syntax:
   /// * Chrome Canary (51)
   /// * Firefox
   ///
   /// Not yet supporting:
   /// * Atom (1.5.4)
   /// * Electron (0.36.3)
   // TODO(ochafik): Simplify this code when our target platforms catch up.
   final bool destructureNamedParams;

   /// Mapping from absolute file paths to bazel short path to substitute in
   /// source maps.
   final Map<String, String> bazelMapping;

   /// If specified, the path to write the summary file.
   /// Used when building the SDK.
   final String summaryOutPath;

   const CompilerOptions(
       {this.sourceMap: true,
       this.sourceMapComment: true,
       this.inlineSourceMap: false,
       this.summarizeApi: true,
       this.summaryExtension: 'sum',
       this.unsafeForceCompile: false,
       this.replCompile: false,
       this.emitMetadata: false,
       this.closure: false,
       this.destructureNamedParams: false,
       this.hoistInstanceCreation: true,
       this.hoistSignatureTypes: false,
       this.nameTypeTests: true,
       this.hoistTypeTests: true,
       this.useAngular2Whitelist: false,
       this.bazelMapping: const {},
       this.summaryOutPath});

   CompilerOptions.fromArguments(ArgResults args)
       : sourceMap = args['source-map'],
         sourceMapComment = args['source-map-comment'],
         inlineSourceMap = args['inline-source-map'],
         summarizeApi = args['summarize'],
         summaryExtension = args['summary-extension'],
         unsafeForceCompile = args['unsafe-force-compile'],
         replCompile = args['repl-compile'],
         emitMetadata = args['emit-metadata'],
         closure = args['closure-experimental'],
         destructureNamedParams = args['destructure-named-params'],
         hoistInstanceCreation = args['hoist-instance-creation'],
         hoistSignatureTypes = args['hoist-signature-types'],
         nameTypeTests = args['name-type-tests'],
         hoistTypeTests = args['hoist-type-tests'],
         useAngular2Whitelist = args['unsafe-angular2-whitelist'],
         bazelMapping = _parseBazelMappings(args['bazel-mapping']),
         summaryOutPath = args['summary-out'];

   static void addArguments(ArgParser parser) {
     parser
       ..addFlag('summarize', help: 'emit an API summary file', defaultsTo: true)
       ..addOption('summary-extension',
           help: 'file extension for Dart summary files',
           defaultsTo: 'sum',
           hide: true)
       ..addFlag('source-map', help: 'emit source mapping', defaultsTo: true)
       ..addFlag('source-map-comment',
           help: 'adds a sourceMappingURL comment to the end of the JS,\n'
               'disable if using X-SourceMap header',
           defaultsTo: true,
           hide: true)
       ..addFlag('inline-source-map',
           help: 'emit source mapping inline', defaultsTo: false)
       ..addFlag('emit-metadata',
           help: 'emit metadata annotations queriable via mirrors',
           defaultsTo: false)
       ..addFlag('closure-experimental',
           help: 'emit Closure Compiler-friendly code (experimental)',
           defaultsTo: false)
       ..addFlag('destructure-named-params',
           help: 'Destructure named parameters', defaultsTo: false, hide: true)
       ..addFlag('unsafe-force-compile',
           help: 'Compile code even if it has errors. ಠ_ಠ\n'
               'This has undefined behavior!',
           defaultsTo: false,
           hide: true)
       ..addFlag('repl-compile',
           help: 'Compile code more permissively when in REPL mode allowing '
               'access to private members across library boundaries.',
           defaultsTo: false,
           hide: true)
       ..addFlag('hoist-instance-creation',
           help: 'Hoist the class type from generic instance creations',
           defaultsTo: true,
           hide: true)
       ..addFlag('hoist-signature-types',
           help: 'Hoist types from class signatures',
           defaultsTo: false,
           hide: true)
       ..addFlag('name-type-tests',
           help: 'Name types used in type tests', defaultsTo: true, hide: true)
       ..addFlag('hoist-type-tests',
           help: 'Hoist types used in type tests', defaultsTo: true, hide: true)
       ..addFlag('unsafe-angular2-whitelist', defaultsTo: false, hide: true)
       ..addOption('bazel-mapping',
           help:
               '--bazel-mapping=genfiles/to/library.dart,to/library.dart uses \n'
               'to/library.dart as the path for library.dart in source maps.',
           allowMultiple: true,
           splitCommas: false,
           hide: true)
       ..addOption('summary-out',
           help: 'location to write the summary file', hide: true);
   }

   static Map<String, String> _parseBazelMappings(Iterable argument) {
     var mappings = <String, String>{};
     for (var mapping in argument) {
       var splitMapping = mapping.split(',');
       if (splitMapping.length >= 2) {
         mappings[path.absolute(splitMapping[0])] = splitMapping[1];
       }
     }
     return mappings;
   }
 }

 /// A unit of Dart code that can be built into a single JavaScript module.
 class BuildUnit {
   /// The name of this module.
   final String name;

   /// All library names are relative to this path/prefix.
   final String libraryRoot;

   /// The list of sources in this module.
   ///
   /// The set of Dart files can be arbitrarily large, but it must contain
   /// complete libraries including all of their parts, as well as all libraries
   /// that are part of a library cycle.
   final List<String> sources;

   /// Given an imported library URI, this will determine to what Dart/JS module
   /// it belongs to.
   // TODO(jmesserly): we should replace this with another way of tracking
   // build units.
   final Func1<Source, String> libraryToModule;

   BuildUnit(this.name, this.libraryRoot, this.sources, this.libraryToModule);
 }

 /// The output of Dart->JS compilation.
 ///
 /// This contains the file contents of the JS module, as well as a list of
 /// Dart libraries that are contained in this module.
 class JSModuleFile {
   /// The name of this module.
   final String name;

   /// The list of messages (errors and warnings)
   final List<String> errors;

   /// The AST that will be used to generate the [code] and [sourceMap] for this
   /// module.
   final JS.Program moduleTree;

   /// The compiler options used to generate this module.
   final CompilerOptions options;

   /// The binary contents of the API summary file, including APIs from each of
   /// the libraries in this module.
   final List<int> summaryBytes;

   JSModuleFile(
       this.name, this.errors, this.options, this.moduleTree, this.summaryBytes);

   JSModuleFile.invalid(this.name, this.errors, this.options)
       : moduleTree = null,
         summaryBytes = null;

   /// True if this library was successfully compiled.
   bool get isValid => moduleTree != null;

   /// Gets the source code and source map for this JS module, given the
   /// locations where the JS file and map file will be served from.
   ///
   /// Relative URLs will be used to point from the .js file to the .map file
   //
   // TODO(jmesserly): this should match our old logic, but I'm not sure we are
   // correctly handling the pointer from the .js file to the .map file.
   JSModuleCode getCode(ModuleFormat format, String jsUrl, String mapUrl,
       {bool singleOutFile: false}) {
     var opts = new JS.JavaScriptPrintingOptions(
         emitTypes: options.closure,
         allowKeywordsInProperties: true,
         allowSingleLineIfStatements: true);
     JS.SimpleJavaScriptPrintingContext printer;
     SourceMapBuilder sourceMap;
     if (options.sourceMap) {
       var sourceMapContext = new SourceMapPrintingContext();
       sourceMap = sourceMapContext.sourceMap;
       printer = sourceMapContext;
     } else {
       printer = new JS.SimpleJavaScriptPrintingContext();
     }

     var tree =
         transformModuleFormat(format, moduleTree, singleOutFile: singleOutFile);
     tree.accept(
         new JS.Printer(opts, printer, localNamer: new JS.TemporaryNamer(tree)));

     Map builtMap;
     if (options.sourceMap && sourceMap != null) {
       builtMap =
           placeSourceMap(sourceMap.build(jsUrl), mapUrl, options.bazelMapping);

       if (options.sourceMapComment) {
         var relativeMapUrl = path
             .toUri(
                 path.relative(path.fromUri(mapUrl), from: path.dirname(jsUrl)))
             .toString();
         assert(path.dirname(jsUrl) == path.dirname(mapUrl));
         printer.emit('\n//# sourceMappingURL=');
         if (options.inlineSourceMap) {
           var bytes = UTF8.encode(JSON.encode(builtMap));
           var base64 = BASE64.encode(bytes);
           printer..emit('data:application/json;base64,')..emit(base64);
         } else {
           printer.emit(relativeMapUrl);
         }
         printer.emit('\n');
       }
     }

     return new JSModuleCode(printer.getText(), builtMap);
   }

   /// Similar to [getCode] but immediately writes the resulting files.
   ///
   /// If [mapPath] is not supplied but [options.sourceMap] is set, mapPath
   /// will default to [jsPath].map.
   void writeCodeSync(ModuleFormat format, String jsPath,
       {bool singleOutFile: false}) {
     String mapPath = jsPath + '.map';
     var code = getCode(format, jsPath, mapPath, singleOutFile: singleOutFile);
     var c = code.code;
     if (singleOutFile) {
       // In singleOutFile mode we wrap each module in an eval statement to
       // leverage sourceURL to improve the debugging experience when source maps
       // are not enabled.
       //
       // Note: We replace all `/` with `.` so that we don't break relative urls
       // to sources in the original sourcemap. The name of this file is bogus
       // anyways, so it has very little effect on things.
       c += '\n//# sourceURL=${name.replaceAll("/", ".")}.js\n';
       c = 'eval(${JSON.encode(c)});\n';
     }

     var file = new File(jsPath);
     if (!file.parent.existsSync()) file.parent.createSync(recursive: true);
     file.writeAsStringSync(c);

     // TODO(jacobr): it is a bit strange we are writing the source map to a file
     // even when options.inlineSourceMap is true. To be consistent perhaps we
     // should also write a copy of the source file without a sourcemap even when
     // inlineSourceMap is true.
     if (code.sourceMap != null) {
       file = new File(mapPath);
       if (!file.parent.existsSync()) file.parent.createSync(recursive: true);
       file.writeAsStringSync(JSON.encode(code.sourceMap));
     }
   }
 }

 /// The output of compiling a JavaScript module in a particular format.
 class JSModuleCode {
   /// The JavaScript code for this module.
   ///
   /// If a [sourceMap] is available, this will include the `sourceMappingURL`
   /// comment at end of the file.
   final String code;

   /// The JSON of the source map, if generated, otherwise `null`.
   ///
   /// The source paths will initially be absolute paths. They can be adjusted
   /// using [placeSourceMap].
   final Map sourceMap;

   JSModuleCode(this.code, this.sourceMap);
 }

 /// Adjusts the source paths in [sourceMap] to be relative to [sourceMapPath],
 /// and returns the new map.
 // TODO(jmesserly): find a new home for this.
 Map placeSourceMap(
     Map sourceMap, String sourceMapPath, Map<String, String> bazelMappings) {
   var dir = path.dirname(sourceMapPath);
   var map = new Map.from(sourceMap);
   var list = new List.from(map['sources']);
   map['sources'] = list;
   String transformUri(String uri) {
     var match = bazelMappings[path.absolute(uri)];
     if (match != null) return match;

     // Fall back to a relative path.
     return path.toUri(path.relative(path.fromUri(uri), from: dir)).toString();
   }

   for (int i = 0; i < list.length; i++) {
     list[i] = transformUri(list[i]);
   }
   map['file'] = transformUri(map['file']);
   return map;
 }
	// 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 HashSet, Queue;
	import 'dart:convert' show BASE64, JSON, UTF8;
	import 'dart:io' show File;
	import 'package:analyzer/dart/element/element.dart' show LibraryElement;
	import 'package:analyzer/analyzer.dart'
	show AnalysisError, CompilationUnit, ErrorSeverity;
	import 'package:analyzer/file_system/file_system.dart' show ResourceProvider;
	import 'package:analyzer/src/generated/engine.dart'
	show AnalysisContext, AnalysisEngine;
	import 'package:analyzer/src/generated/source.dart' show DartUriResolver;
	import 'package:analyzer/src/generated/source_io.dart'
	show Source, SourceKind, UriResolver;
	import 'package:analyzer/src/summary/package_bundle_reader.dart'
	show InSummarySource, InputPackagesResultProvider, SummaryDataStore;
	import 'package:analyzer/src/error/codes.dart' show StaticTypeWarningCode;
	import 'package:args/args.dart' show ArgParser, ArgResults;
	import 'package:args/src/usage_exception.dart' show UsageException;
	import 'package:func/func.dart' show Func1;
	import 'package:path/path.dart' as path;
	import 'package:source_maps/source_maps.dart';

	import '../analyzer/context.dart'
	show
	AnalyzerOptions,
	createAnalysisContext,
	createSdkPathResolver,
	createSourceFactory;
	import '../js_ast/js_ast.dart' as JS;
	import 'code_generator.dart' show CodeGenerator;
	import 'error_helpers.dart' show errorSeverity, formatError, sortErrors;
	import 'extension_types.dart' show ExtensionTypeSet;
	import 'js_names.dart' as JS;
	import 'module_builder.dart' show transformModuleFormat, ModuleFormat;
	import 'source_map_printer.dart' show SourceMapPrintingContext;

	/// Compiles a set of Dart files into a single JavaScript module.
	///
	/// For a single [BuildUnit] definition, this will produce a [JSModuleFile].
	/// Those objects are record types that record the data consumed and produced
	/// for a single compile.
	///
	/// This class exists to cache global state associated with a single in-memory
	/// AnalysisContext, such as information about extension types in the Dart SDK.
	/// It can be used once to produce a single module, or reused to save warm-up
	/// time. (Currently there is no warm up, but there may be in the future.)
	///
	/// The SDK source code is assumed to be immutable for the life of this class.
	///
	/// For all other files, it is up to the [AnalysisContext] to decide whether or
	/// not any caching is performed. By default an analysis context will assume
	/// sources are immutable for the life of the context, and cache information
	/// about them.
	class ModuleCompiler {
	final AnalysisContext context;
	final SummaryDataStore summaryData;
	final ExtensionTypeSet _extensionTypes;

	ModuleCompiler.withContext(AnalysisContext context, this.summaryData)
	: context = context,
	_extensionTypes = new ExtensionTypeSet(context) {
	if (!context.analysisOptions.strongMode) {
	throw new ArgumentError('AnalysisContext must be strong mode');
	}
	if (!context.sourceFactory.dartSdk.context.analysisOptions.strongMode) {
	throw new ArgumentError('AnalysisContext must have strong mode SDK');
	}
	}

	factory ModuleCompiler(AnalyzerOptions options,
	{DartUriResolver sdkResolver,
	ResourceProvider resourceProvider,
	List<UriResolver> fileResolvers}) {
	AnalysisEngine.instance.processRequiredPlugins();

	sdkResolver ??=
	createSdkPathResolver(options.dartSdkSummaryPath, options.dartSdkPath);

	// Read the summaries.
	var summaryData =
	new SummaryDataStore(options.summaryPaths, recordDependencyInfo: true);

	var srcFactory = createSourceFactory(options,
	sdkResolver: sdkResolver,
	fileResolvers: fileResolvers,
	summaryData: summaryData,
	resourceProvider: resourceProvider);

	var context = createAnalysisContext();
	context.sourceFactory = srcFactory;
	context.typeProvider = sdkResolver.dartSdk.context.typeProvider;
	context.resultProvider =
	new InputPackagesResultProvider(context, summaryData);
	options.declaredVariables.forEach(context.declaredVariables.define);
	context.declaredVariables.define('dart.isVM', 'false');

	return new ModuleCompiler.withContext(context, summaryData);
	}

	bool _isFatalError(AnalysisError e, CompilerOptions options) {
	if (errorSeverity(context, e) != ErrorSeverity.ERROR) return false;

	// These errors are not fatal in the REPL compile mode as we
	// allow access to private members across library boundaries
	// and those accesses will show up as undefined members unless
	// additional analyzer changes are made to support them.
	// TODO(jacobr): consider checking that the identifier name
	// referenced by the error is private.
	return !options.replCompile \|\|
	(e.errorCode != StaticTypeWarningCode.UNDEFINED_GETTER &&
	e.errorCode != StaticTypeWarningCode.UNDEFINED_SETTER &&
	e.errorCode != StaticTypeWarningCode.UNDEFINED_METHOD);
	}

	/// Compiles a single Dart build unit into a JavaScript module.
	///
	/// Warning - this may require resolving the entire world.
	/// If that is not desired, the analysis context must be pre-configured using
	/// summaries before calling this method.
	JSModuleFile compile(BuildUnit unit, CompilerOptions options) {
	var trees = <CompilationUnit>[];
	var errors = <AnalysisError>[];

	var librariesToCompile = new Queue<LibraryElement>();

	var compilingSdk = false;
	for (var sourcePath in unit.sources) {
	var sourceUri = Uri.parse(sourcePath);
	if (sourceUri.scheme == '') {
	sourceUri = path.toUri(path.absolute(sourcePath));
	} else if (sourceUri.scheme == 'dart') {
	compilingSdk = true;
	}
	Source source = context.sourceFactory.forUri2(sourceUri);

	var fileUsage = 'You need to pass at least one existing .dart file as an'
	' argument.';
	if (source == null) {
	throw new UsageException(
	'Could not create a source for "$sourcePath". The file name is in'
	' the wrong format or was not found.',
	fileUsage);
	} else if (!source.exists()) {
	throw new UsageException(
	'Given file "$sourcePath" does not exist.', fileUsage);
	}

	// Ignore parts. They need to be handled in the context of their library.
	if (context.computeKindOf(source) == SourceKind.PART) {
	continue;
	}

	librariesToCompile.add(context.computeLibraryElement(source));
	}

	var libraries = new HashSet<LibraryElement>();
	while (librariesToCompile.isNotEmpty) {
	var library = librariesToCompile.removeFirst();
	if (library.source is InSummarySource) continue;
	if (!compilingSdk && library.source.isInSystemLibrary) continue;
	if (!libraries.add(library)) continue;

	librariesToCompile.addAll(library.importedLibraries);
	librariesToCompile.addAll(library.exportedLibraries);

	var tree = context.resolveCompilationUnit(library.source, library);
	trees.add(tree);
	errors.addAll(context.computeErrors(library.source));

	for (var part in library.parts) {
	trees.add(context.resolveCompilationUnit(part.source, library));
	errors.addAll(context.computeErrors(part.source));
	}
	}

	sortErrors(context, errors);

	var messages = <String>[];
	for (var e in errors) {
	var m = formatError(context, e);
	if (m != null) messages.add(m);
	}

	if (!options.unsafeForceCompile &&
	errors.any((e) => _isFatalError(e, options))) {
	return new JSModuleFile.invalid(unit.name, messages, options);
	}
	var codeGenerator =
	new CodeGenerator(context, summaryData, options, _extensionTypes);
	return codeGenerator.compile(unit, trees, messages);
	}
	}

	class CompilerOptions {
	/// Whether to emit the source mapping file.
	///
	/// This supports debugging the original source code instead of the generated
	/// code.
	final bool sourceMap;

	/// If [sourceMap] is emitted, this will emit a `sourceMappingUrl` comment
	/// into the output JavaScript module.
	final bool sourceMapComment;

	/// Whether to emit the source mapping file inline as a data url.
	final bool inlineSourceMap;

	/// Whether to emit a summary file containing API signatures.
	///
	/// This is required for a modular build process.
	final bool summarizeApi;

	/// The file extension for summaries.
	final String summaryExtension;

	/// Whether to preserve metdata only accessible via mirrors
	final bool emitMetadata;

	/// Whether to force compilation of code with static errors.
	final bool unsafeForceCompile;

	/// Whether to compile code in a more permissive REPL mode allowing access
	/// to private members across library boundaries.
	final bool replCompile;

	/// Whether to emit Closure Compiler-friendly code.
	final bool closure;

	/// Hoist the types at instance creation sites
	final bool hoistInstanceCreation;

	/// Hoist types from class signatures
	final bool hoistSignatureTypes;

	/// Name types in type tests
	final bool nameTypeTests;

	/// Hoist types in type tests
	final bool hoistTypeTests;

	final bool useAngular2Whitelist;

	/// Enable ES6 destructuring of named parameters. Off by default.
	///
	/// Older V8 versions do not accept default values with destructuring in
	/// arrow functions yet (e.g. `({a} = {}) => 1`) but happily accepts them
	/// with regular functions (e.g. `function({a} = {}) { return 1 }`).
	///
	/// Supporting the syntax:
	/// * Chrome Canary (51)
	/// * Firefox
	///
	/// Not yet supporting:
	/// * Atom (1.5.4)
	/// * Electron (0.36.3)
	// TODO(ochafik): Simplify this code when our target platforms catch up.
	final bool destructureNamedParams;

	/// Mapping from absolute file paths to bazel short path to substitute in
	/// source maps.
	final Map<String, String> bazelMapping;

	/// If specified, the path to write the summary file.
	/// Used when building the SDK.
	final String summaryOutPath;

	const CompilerOptions(
	{this.sourceMap: true,
	this.sourceMapComment: true,
	this.inlineSourceMap: false,
	this.summarizeApi: true,
	this.summaryExtension: 'sum',
	this.unsafeForceCompile: false,
	this.replCompile: false,
	this.emitMetadata: false,
	this.closure: false,
	this.destructureNamedParams: false,
	this.hoistInstanceCreation: true,
	this.hoistSignatureTypes: false,
	this.nameTypeTests: true,
	this.hoistTypeTests: true,
	this.useAngular2Whitelist: false,
	this.bazelMapping: const {},
	this.summaryOutPath});

	CompilerOptions.fromArguments(ArgResults args)
	: sourceMap = args['source-map'],
	sourceMapComment = args['source-map-comment'],
	inlineSourceMap = args['inline-source-map'],
	summarizeApi = args['summarize'],
	summaryExtension = args['summary-extension'],
	unsafeForceCompile = args['unsafe-force-compile'],
	replCompile = args['repl-compile'],
	emitMetadata = args['emit-metadata'],
	closure = args['closure-experimental'],
	destructureNamedParams = args['destructure-named-params'],
	hoistInstanceCreation = args['hoist-instance-creation'],
	hoistSignatureTypes = args['hoist-signature-types'],
	nameTypeTests = args['name-type-tests'],
	hoistTypeTests = args['hoist-type-tests'],
	useAngular2Whitelist = args['unsafe-angular2-whitelist'],
	bazelMapping = _parseBazelMappings(args['bazel-mapping']),
	summaryOutPath = args['summary-out'];

	static void addArguments(ArgParser parser) {
	parser
	..addFlag('summarize', help: 'emit an API summary file', defaultsTo: true)
	..addOption('summary-extension',
	help: 'file extension for Dart summary files',
	defaultsTo: 'sum',
	hide: true)
	..addFlag('source-map', help: 'emit source mapping', defaultsTo: true)
	..addFlag('source-map-comment',
	help: 'adds a sourceMappingURL comment to the end of the JS,\n'
	'disable if using X-SourceMap header',
	defaultsTo: true,
	hide: true)
	..addFlag('inline-source-map',
	help: 'emit source mapping inline', defaultsTo: false)
	..addFlag('emit-metadata',
	help: 'emit metadata annotations queriable via mirrors',
	defaultsTo: false)
	..addFlag('closure-experimental',
	help: 'emit Closure Compiler-friendly code (experimental)',
	defaultsTo: false)
	..addFlag('destructure-named-params',
	help: 'Destructure named parameters', defaultsTo: false, hide: true)
	..addFlag('unsafe-force-compile',
	help: 'Compile code even if it has errors. ಠ_ಠ\n'
	'This has undefined behavior!',
	defaultsTo: false,
	hide: true)
	..addFlag('repl-compile',
	help: 'Compile code more permissively when in REPL mode allowing '
	'access to private members across library boundaries.',
	defaultsTo: false,
	hide: true)
	..addFlag('hoist-instance-creation',
	help: 'Hoist the class type from generic instance creations',
	defaultsTo: true,
	hide: true)
	..addFlag('hoist-signature-types',
	help: 'Hoist types from class signatures',
	defaultsTo: false,
	hide: true)
	..addFlag('name-type-tests',
	help: 'Name types used in type tests', defaultsTo: true, hide: true)
	..addFlag('hoist-type-tests',
	help: 'Hoist types used in type tests', defaultsTo: true, hide: true)
	..addFlag('unsafe-angular2-whitelist', defaultsTo: false, hide: true)
	..addOption('bazel-mapping',
	help:
	'--bazel-mapping=genfiles/to/library.dart,to/library.dart uses \n'
	'to/library.dart as the path for library.dart in source maps.',
	allowMultiple: true,
	splitCommas: false,
	hide: true)
	..addOption('summary-out',
	help: 'location to write the summary file', hide: true);
	}

	static Map<String, String> _parseBazelMappings(Iterable argument) {
	var mappings = <String, String>{};
	for (var mapping in argument) {
	var splitMapping = mapping.split(',');
	if (splitMapping.length >= 2) {
	mappings[path.absolute(splitMapping[0])] = splitMapping[1];
	}
	}
	return mappings;
	}
	}

	/// A unit of Dart code that can be built into a single JavaScript module.
	class BuildUnit {
	/// The name of this module.
	final String name;

	/// All library names are relative to this path/prefix.
	final String libraryRoot;

	/// The list of sources in this module.
	///
	/// The set of Dart files can be arbitrarily large, but it must contain
	/// complete libraries including all of their parts, as well as all libraries
	/// that are part of a library cycle.
	final List<String> sources;

	/// Given an imported library URI, this will determine to what Dart/JS module
	/// it belongs to.
	// TODO(jmesserly): we should replace this with another way of tracking
	// build units.
	final Func1<Source, String> libraryToModule;

	BuildUnit(this.name, this.libraryRoot, this.sources, this.libraryToModule);
	}

	/// The output of Dart->JS compilation.
	///
	/// This contains the file contents of the JS module, as well as a list of
	/// Dart libraries that are contained in this module.
	class JSModuleFile {
	/// The name of this module.
	final String name;

	/// The list of messages (errors and warnings)
	final List<String> errors;

	/// The AST that will be used to generate the [code] and [sourceMap] for this
	/// module.
	final JS.Program moduleTree;

	/// The compiler options used to generate this module.
	final CompilerOptions options;

	/// The binary contents of the API summary file, including APIs from each of
	/// the libraries in this module.
	final List<int> summaryBytes;

	JSModuleFile(
	this.name, this.errors, this.options, this.moduleTree, this.summaryBytes);

	JSModuleFile.invalid(this.name, this.errors, this.options)
	: moduleTree = null,
	summaryBytes = null;

	/// True if this library was successfully compiled.
	bool get isValid => moduleTree != null;

	/// Gets the source code and source map for this JS module, given the
	/// locations where the JS file and map file will be served from.
	///
	/// Relative URLs will be used to point from the .js file to the .map file
	//
	// TODO(jmesserly): this should match our old logic, but I'm not sure we are
	// correctly handling the pointer from the .js file to the .map file.
	JSModuleCode getCode(ModuleFormat format, String jsUrl, String mapUrl,
	{bool singleOutFile: false}) {
	var opts = new JS.JavaScriptPrintingOptions(
	emitTypes: options.closure,
	allowKeywordsInProperties: true,
	allowSingleLineIfStatements: true);
	JS.SimpleJavaScriptPrintingContext printer;
	SourceMapBuilder sourceMap;
	if (options.sourceMap) {
	var sourceMapContext = new SourceMapPrintingContext();
	sourceMap = sourceMapContext.sourceMap;
	printer = sourceMapContext;
	} else {
	printer = new JS.SimpleJavaScriptPrintingContext();
	}

	var tree =
	transformModuleFormat(format, moduleTree, singleOutFile: singleOutFile);
	tree.accept(
	new JS.Printer(opts, printer, localNamer: new JS.TemporaryNamer(tree)));

	Map builtMap;
	if (options.sourceMap && sourceMap != null) {
	builtMap =
	placeSourceMap(sourceMap.build(jsUrl), mapUrl, options.bazelMapping);

	if (options.sourceMapComment) {
	var relativeMapUrl = path
	.toUri(
	path.relative(path.fromUri(mapUrl), from: path.dirname(jsUrl)))
	.toString();
	assert(path.dirname(jsUrl) == path.dirname(mapUrl));
	printer.emit('\n//# sourceMappingURL=');
	if (options.inlineSourceMap) {
	var bytes = UTF8.encode(JSON.encode(builtMap));
	var base64 = BASE64.encode(bytes);
	printer..emit('data:application/json;base64,')..emit(base64);
	} else {
	printer.emit(relativeMapUrl);
	}
	printer.emit('\n');
	}
	}

	return new JSModuleCode(printer.getText(), builtMap);
	}

	/// Similar to [getCode] but immediately writes the resulting files.
	///
	/// If [mapPath] is not supplied but [options.sourceMap] is set, mapPath
	/// will default to [jsPath].map.
	void writeCodeSync(ModuleFormat format, String jsPath,
	{bool singleOutFile: false}) {
	String mapPath = jsPath + '.map';
	var code = getCode(format, jsPath, mapPath, singleOutFile: singleOutFile);
	var c = code.code;
	if (singleOutFile) {
	// In singleOutFile mode we wrap each module in an eval statement to
	// leverage sourceURL to improve the debugging experience when source maps
	// are not enabled.
	//
	// Note: We replace all `/` with `.` so that we don't break relative urls
	// to sources in the original sourcemap. The name of this file is bogus
	// anyways, so it has very little effect on things.
	c += '\n//# sourceURL=${name.replaceAll("/", ".")}.js\n';
	c = 'eval(${JSON.encode(c)});\n';
	}

	var file = new File(jsPath);
	if (!file.parent.existsSync()) file.parent.createSync(recursive: true);
	file.writeAsStringSync(c);

	// TODO(jacobr): it is a bit strange we are writing the source map to a file
	// even when options.inlineSourceMap is true. To be consistent perhaps we
	// should also write a copy of the source file without a sourcemap even when
	// inlineSourceMap is true.
	if (code.sourceMap != null) {
	file = new File(mapPath);
	if (!file.parent.existsSync()) file.parent.createSync(recursive: true);
	file.writeAsStringSync(JSON.encode(code.sourceMap));
	}
	}
	}

	/// The output of compiling a JavaScript module in a particular format.
	class JSModuleCode {
	/// The JavaScript code for this module.
	///
	/// If a [sourceMap] is available, this will include the `sourceMappingURL`
	/// comment at end of the file.
	final String code;

	/// The JSON of the source map, if generated, otherwise `null`.
	///
	/// The source paths will initially be absolute paths. They can be adjusted
	/// using [placeSourceMap].
	final Map sourceMap;

	JSModuleCode(this.code, this.sourceMap);
	}

	/// Adjusts the source paths in [sourceMap] to be relative to [sourceMapPath],
	/// and returns the new map.
	// TODO(jmesserly): find a new home for this.
	Map placeSourceMap(
	Map sourceMap, String sourceMapPath, Map<String, String> bazelMappings) {
	var dir = path.dirname(sourceMapPath);
	var map = new Map.from(sourceMap);
	var list = new List.from(map['sources']);
	map['sources'] = list;
	String transformUri(String uri) {
	var match = bazelMappings[path.absolute(uri)];
	if (match != null) return match;

	// Fall back to a relative path.
	return path.toUri(path.relative(path.fromUri(uri), from: dir)).toString();
	}

	for (int i = 0; i < list.length; i++) {
	list[i] = transformUri(list[i]);
	}
	map['file'] = transformUri(map['file']);
	return map;
	}