sdk/lib/_internal/pub/lib/src/barback/dart2js_transformer.dart - sdk.git - Git at Google

 // Copyright (c) 2013, 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.

 library pub.dart2js_transformer;

 import 'dart:async';
 import 'dart:convert';
 import 'dart:io';

 import 'package:analyzer/analyzer.dart';
 import 'package:barback/barback.dart';
 import 'package:path/path.dart' as path;
 import 'package:stack_trace/stack_trace.dart';

 import '../../../../compiler/compiler.dart' as compiler;
 import '../../../../compiler/implementation/dart2js.dart'
     show AbortLeg;
 import '../../../../compiler/implementation/source_file.dart';
 import '../barback.dart';
 import '../dart.dart' as dart;
 import '../io.dart';
 import '../package.dart';
 import '../package_graph.dart';
 import '../utils.dart';

 /// The set of all valid configuration options for this transformer.
 final _validOptions = new Set<String>.from([
   'commandLineOptions', 'checked', 'minify', 'verbose', 'environment',
   'analyzeAll', 'suppressWarnings', 'suppressHints', 'terse'
 ]);

 /// A [Transformer] that uses dart2js's library API to transform Dart
 /// entrypoints in "web" to JavaScript.
 class Dart2JSTransformer extends Transformer {
   final PackageGraph _graph;
   final BarbackSettings _settings;

   /// The [AssetId]s the transformer has discovered so far. Used by pub build
   /// to determine where to copy the JS bootstrap files.
   // TODO(rnystrom): Do something cleaner for this, or eliminate those files.
   final entrypoints = new Set<AssetId>();

   /// If this is non-null, then the transformer is currently being applied, so
   /// subsequent calls to [apply] will wait for this to finish before
   /// proceeding.
   ///
   /// Dart2js uses lots of memory, so if we try to actually run compiles in
   /// parallel, it takes down the VM. Instead, the transformer will force
   /// all applies to be sequential. The tracking bug to do something better
   /// is here: https://code.google.com/p/dart/issues/detail?id=14730.
   Future _running;

   Dart2JSTransformer.withSettings(this._graph, this._settings) {
     var invalidOptions = _settings.configuration.keys.toSet()
         .difference(_validOptions);
     if (invalidOptions.isEmpty) return;

     throw new FormatException("Unrecognized dart2js "
         "${pluralize('option', invalidOptions.length)} "
         "${toSentence(invalidOptions.map((option) => '"$option"'))}.");
   }

   Dart2JSTransformer(PackageGraph graph, BarbackMode mode)
       : this.withSettings(graph, new BarbackSettings({}, mode));

   /// Only ".dart" files within "web/" are processed.
   Future<bool> isPrimary(Asset asset) {
     return new Future.value(
         asset.id.extension == ".dart" &&
         asset.id.path.startsWith("web/"));
   }

   Future apply(Transform transform) {
     // Wait for any ongoing apply to finish first.
     // TODO(rnystrom): If there are multiple simultaneous compiles, this will
     // resume and pause them repeatedly. It still serializes them correctly,
     // but it might be cleaner to use a real queue.
     // TODO(rnystrom): Add a test that this is functionality is helpful.
     if (_running != null) {
       return _running.then((_) => apply(transform));
     }

     var completer = new Completer();
     _running = completer.future;

     var stopwatch = new Stopwatch();
     stopwatch.start();

     return transform.primaryInput.readAsString().then((code) {
       try {
         var id = transform.primaryInput.id;
         var name = id.path;
         if (id.package != _graph.entrypoint.root.name) {
           name += " in ${id.package}";
         }

         var parsed = parseCompilationUnit(code, name: name);
         if (!dart.isEntrypoint(parsed)) return null;
       } on AnalyzerErrorGroup catch (e) {
         transform.logger.error(e.message);
         return null;
       }

       var provider = new _BarbackCompilerProvider(_graph, transform);

       // Create a "path" to the entrypoint script. The entrypoint may not
       // actually be on disk, but this gives dart2js a root to resolve
       // relative paths against.
       var id = transform.primaryInput.id;

       entrypoints.add(id);

       var entrypoint = path.join(_graph.packages[id.package].dir, id.path);

       // TODO(rnystrom): Should have more sophisticated error-handling here.
       // Need to report compile errors to the user in an easily visible way.
       // Need to make sure paths in errors are mapped to the original source
       // path so they can understand them.
       return Chain.track(dart.compile(
           entrypoint, provider,
           commandLineOptions: _configCommandLineOptions,
           checked: _configBool('checked'),
           minify: _configBool(
               'minify', defaultsTo: _settings.mode == BarbackMode.RELEASE),
           verbose: _configBool('verbose'),
           environment: _configEnvironment,
           packageRoot: path.join(_graph.entrypoint.root.dir, "packages"),
           analyzeAll: _configBool('analyzeAll'),
           suppressWarnings: _configBool('suppressWarnings'),
           suppressHints: _configBool('suppressHints'),
           terse: _configBool('terse'))).then((_) {
         stopwatch.stop();
         transform.logger.info("Took ${stopwatch.elapsed} to compile $id.");
       });
     }).whenComplete(() {
       completer.complete();
       _running = null;
     });
   }

   /// Parses and returns the "commandLineOptions" configuration option.
   List<String> get _configCommandLineOptions {
     if (!_settings.configuration.containsKey('commandLineOptions')) return null;

     var options = _settings.configuration['commandLineOptions'];
     if (options is List && options.every((option) => option is String)) {
       return options;
     }

     throw new FormatException('Invalid value for '
         '\$dart2js.commandLineOptions: ${JSON.encode(options)} (expected list '
         'of strings).');
   }

   /// Parses and returns the "environment" configuration option.
   Map<String, String> get _configEnvironment {
     if (!_settings.configuration.containsKey('environment')) return null;

     var environment = _settings.configuration['environment'];
     if (environment is Map &&
         environment.keys.every((key) => key is String) &&
         environment.values.every((key) => key is String)) {
       return environment;
     }

     throw new FormatException('Invalid value for \$dart2js.environment: '
         '${JSON.encode(environment)} (expected map from strings to strings).');
   }

   /// Parses and returns a boolean configuration option.
   ///
   /// [defaultsTo] is the default value of the option.
   bool _configBool(String name, {bool defaultsTo: false}) {
     if (!_settings.configuration.containsKey(name)) return defaultsTo;
     var value = _settings.configuration[name];
     if (value is bool) return value;
     throw new FormatException('Invalid value for \$dart2js.$name: '
         '${JSON.encode(value)} (expected true or false).');
   }
 }

 /// Defines an interface for dart2js to communicate with barback and pub.
 ///
 /// Note that most of the implementation of diagnostic handling here was
 /// copied from [FormattingDiagnosticHandler] in dart2js. The primary
 /// difference is that it uses barback's logging code and, more importantly, it
 /// handles missing source files more gracefully.
 class _BarbackCompilerProvider implements dart.CompilerProvider {
   final PackageGraph _graph;
   final Transform _transform;

   /// The map of previously loaded files.
   ///
   /// Used to show where an error occurred in a source file.
   final _sourceFiles = new Map<String, SourceFile>();

   // TODO(rnystrom): Make these configurable.
   /// Whether or not warnings should be logged.
   var _showWarnings = true;

   /// Whether or not hints should be logged.
   var _showHints = true;

   /// Whether or not verbose info messages should be logged.
   var _verbose = false;

   /// Whether an exception should be thrown on an error to stop compilation.
   var _throwOnError = false;

   /// This gets set after a fatal error is reported to quash any subsequent
   /// errors.
   var _isAborting = false;

   compiler.Diagnostic _lastKind = null;

   static final int _FATAL =
       compiler.Diagnostic.CRASH.ordinal |
       compiler.Diagnostic.ERROR.ordinal;
   static final int _INFO =
       compiler.Diagnostic.INFO.ordinal |
       compiler.Diagnostic.VERBOSE_INFO.ordinal;

   _BarbackCompilerProvider(this._graph, this._transform);

   /// A [CompilerInputProvider] for dart2js.
   Future<String> provideInput(Uri resourceUri) {
     // We only expect to get absolute "file:" URLs from dart2js.
     assert(resourceUri.isAbsolute);
     assert(resourceUri.scheme == "file");

     var sourcePath = path.fromUri(resourceUri);
     return _readResource(resourceUri).then((source) {
       _sourceFiles[resourceUri.toString()] =
           new StringSourceFile(path.relative(sourcePath), source);
       return source;
     });
   }

   /// A [CompilerOutputProvider] for dart2js.
   EventSink<String> provideOutput(String name, String extension) {
     // Dart2js uses an empty string for the name of the entrypoint library.
     // We only expect to get output files associated with that right now. For
     // other files, we'd need some logic to determine the right relative path
     // for it.
     assert(name == "");

     var primaryId = _transform.primaryInput.id;
     var id = new AssetId(primaryId.package, "${primaryId.path}.$extension");

     // Make a sink that dart2js can write to.
     var sink = new StreamController<String>();

     // dart2js gives us strings, but stream assets expect byte lists.
     var stream = UTF8.encoder.bind(sink.stream);

     // And give it to barback as a stream it can read from.
     _transform.addOutput(new Asset.fromStream(id, stream));

     return sink;
   }

   /// A [DiagnosticHandler] for dart2js, loosely based on
   /// [FormattingDiagnosticHandler].
   void handleDiagnostic(Uri uri, int begin, int end,
                         String message, compiler.Diagnostic kind) {
     // TODO(ahe): Remove this when source map is handled differently.
     if (kind.name == "source map") return;

     if (_isAborting) return;
     _isAborting = (kind == compiler.Diagnostic.CRASH);

     var isInfo = (kind.ordinal & _INFO) != 0;
     if (isInfo && uri == null && kind != compiler.Diagnostic.INFO) {
       if (!_verbose && kind == compiler.Diagnostic.VERBOSE_INFO) return;
       _transform.logger.info(message);
       return;
     }

     // [_lastKind] records the previous non-INFO kind we saw.
     // This is used to suppress info about a warning when warnings are
     // suppressed, and similar for hints.
     if (kind != compiler.Diagnostic.INFO) _lastKind = kind;

     var logFn;
     if (kind == compiler.Diagnostic.ERROR) {
       logFn = _transform.logger.error;
     } else if (kind == compiler.Diagnostic.WARNING) {
       if (!_showWarnings) return;
       logFn = _transform.logger.warning;
     } else if (kind == compiler.Diagnostic.HINT) {
       if (!_showHints) return;
       logFn = _transform.logger.warning;
     } else if (kind == compiler.Diagnostic.CRASH) {
       logFn = _transform.logger.error;
     } else if (kind == compiler.Diagnostic.INFO) {
       if (_lastKind == compiler.Diagnostic.WARNING && !_showWarnings) return;
       if (_lastKind == compiler.Diagnostic.HINT && !_showHints) return;
       logFn = _transform.logger.info;
     } else {
       throw new Exception('Unknown kind: $kind (${kind.ordinal})');
     }

     var fatal = (kind.ordinal & _FATAL) != 0;
     if (uri == null) {
       assert(fatal);
       logFn(message);
     } else {
       SourceFile file = _sourceFiles[uri.toString()];
       if (file == null) {
         // We got a message before loading the file, so just report the message
         // itself.
         logFn('$uri: $message');
       } else {
         logFn(file.getLocationMessage(message, begin, end, true, (i) => i));
       }
     }

     if (fatal && _throwOnError) {
       _isAborting = true;
       throw new AbortLeg(message);
     }
   }

   Future<String> _readResource(Uri url) {
     // See if the path is within a package. If so, use Barback so we can use
     // generated Dart assets.

     var id = _sourceUrlToId(url);
     if (id != null) return _transform.readInputAsString(id);

     // If we get here, the path doesn't appear to be in a package, so we'll
     // skip Barback and just hit the file system. This will occur at the very
     // least for dart2js's implementations of the core libraries.
     var sourcePath = path.fromUri(url);
     return Chain.track(new File(sourcePath).readAsString());
   }

   AssetId _sourceUrlToId(Uri url) {
     // See if it's a special path with "packages" or "assets" in it.
     var id = specialUrlToId(url);
     if (id != null) return id;

     // See if it's a path to a "public" asset within the root package. All
     // other files in the root package are not visible to transformers, so
     // should be loaded directly from disk.
     var rootDir = _graph.entrypoint.root.dir;
     var sourcePath = path.fromUri(url);
     if (isBeneath(sourcePath, path.join(rootDir, "lib")) ||
         isBeneath(sourcePath, path.join(rootDir, "asset")) ||
         isBeneath(sourcePath, path.join(rootDir, "web"))) {
       var relative = path.relative(sourcePath, from: rootDir);

       return new AssetId(_graph.entrypoint.root.name, relative);
     }

     return null;
   }
 }
	// Copyright (c) 2013, 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.

	library pub.dart2js_transformer;

	import 'dart:async';
	import 'dart:convert';
	import 'dart:io';

	import 'package:analyzer/analyzer.dart';
	import 'package:barback/barback.dart';
	import 'package:path/path.dart' as path;
	import 'package:stack_trace/stack_trace.dart';

	import '../../../../compiler/compiler.dart' as compiler;
	import '../../../../compiler/implementation/dart2js.dart'
	show AbortLeg;
	import '../../../../compiler/implementation/source_file.dart';
	import '../barback.dart';
	import '../dart.dart' as dart;
	import '../io.dart';
	import '../package.dart';
	import '../package_graph.dart';
	import '../utils.dart';

	/// The set of all valid configuration options for this transformer.
	final _validOptions = new Set<String>.from([
	'commandLineOptions', 'checked', 'minify', 'verbose', 'environment',
	'analyzeAll', 'suppressWarnings', 'suppressHints', 'terse'
	]);

	/// A [Transformer] that uses dart2js's library API to transform Dart
	/// entrypoints in "web" to JavaScript.
	class Dart2JSTransformer extends Transformer {
	final PackageGraph _graph;
	final BarbackSettings _settings;

	/// The [AssetId]s the transformer has discovered so far. Used by pub build
	/// to determine where to copy the JS bootstrap files.
	// TODO(rnystrom): Do something cleaner for this, or eliminate those files.
	final entrypoints = new Set<AssetId>();

	/// If this is non-null, then the transformer is currently being applied, so
	/// subsequent calls to [apply] will wait for this to finish before
	/// proceeding.
	///
	/// Dart2js uses lots of memory, so if we try to actually run compiles in
	/// parallel, it takes down the VM. Instead, the transformer will force
	/// all applies to be sequential. The tracking bug to do something better
	/// is here: https://code.google.com/p/dart/issues/detail?id=14730.
	Future _running;

	Dart2JSTransformer.withSettings(this._graph, this._settings) {
	var invalidOptions = _settings.configuration.keys.toSet()
	.difference(_validOptions);
	if (invalidOptions.isEmpty) return;

	throw new FormatException("Unrecognized dart2js "
	"${pluralize('option', invalidOptions.length)} "
	"${toSentence(invalidOptions.map((option) => '"$option"'))}.");
	}

	Dart2JSTransformer(PackageGraph graph, BarbackMode mode)
	: this.withSettings(graph, new BarbackSettings({}, mode));

	/// Only ".dart" files within "web/" are processed.
	Future<bool> isPrimary(Asset asset) {
	return new Future.value(
	asset.id.extension == ".dart" &&
	asset.id.path.startsWith("web/"));
	}

	Future apply(Transform transform) {
	// Wait for any ongoing apply to finish first.
	// TODO(rnystrom): If there are multiple simultaneous compiles, this will
	// resume and pause them repeatedly. It still serializes them correctly,
	// but it might be cleaner to use a real queue.
	// TODO(rnystrom): Add a test that this is functionality is helpful.
	if (_running != null) {
	return _running.then((_) => apply(transform));
	}

	var completer = new Completer();
	_running = completer.future;

	var stopwatch = new Stopwatch();
	stopwatch.start();

	return transform.primaryInput.readAsString().then((code) {
	try {
	var id = transform.primaryInput.id;
	var name = id.path;
	if (id.package != _graph.entrypoint.root.name) {
	name += " in ${id.package}";
	}

	var parsed = parseCompilationUnit(code, name: name);
	if (!dart.isEntrypoint(parsed)) return null;
	} on AnalyzerErrorGroup catch (e) {
	transform.logger.error(e.message);
	return null;
	}

	var provider = new _BarbackCompilerProvider(_graph, transform);

	// Create a "path" to the entrypoint script. The entrypoint may not
	// actually be on disk, but this gives dart2js a root to resolve
	// relative paths against.
	var id = transform.primaryInput.id;

	entrypoints.add(id);

	var entrypoint = path.join(_graph.packages[id.package].dir, id.path);

	// TODO(rnystrom): Should have more sophisticated error-handling here.
	// Need to report compile errors to the user in an easily visible way.
	// Need to make sure paths in errors are mapped to the original source
	// path so they can understand them.
	return Chain.track(dart.compile(
	entrypoint, provider,
	commandLineOptions: _configCommandLineOptions,
	checked: _configBool('checked'),
	minify: _configBool(
	'minify', defaultsTo: _settings.mode == BarbackMode.RELEASE),
	verbose: _configBool('verbose'),
	environment: _configEnvironment,
	packageRoot: path.join(_graph.entrypoint.root.dir, "packages"),
	analyzeAll: _configBool('analyzeAll'),
	suppressWarnings: _configBool('suppressWarnings'),
	suppressHints: _configBool('suppressHints'),
	terse: _configBool('terse'))).then((_) {
	stopwatch.stop();
	transform.logger.info("Took ${stopwatch.elapsed} to compile $id.");
	});
	}).whenComplete(() {
	completer.complete();
	_running = null;
	});
	}

	/// Parses and returns the "commandLineOptions" configuration option.
	List<String> get _configCommandLineOptions {
	if (!_settings.configuration.containsKey('commandLineOptions')) return null;

	var options = _settings.configuration['commandLineOptions'];
	if (options is List && options.every((option) => option is String)) {
	return options;
	}

	throw new FormatException('Invalid value for '
	'\$dart2js.commandLineOptions: ${JSON.encode(options)} (expected list '
	'of strings).');
	}

	/// Parses and returns the "environment" configuration option.
	Map<String, String> get _configEnvironment {
	if (!_settings.configuration.containsKey('environment')) return null;

	var environment = _settings.configuration['environment'];
	if (environment is Map &&
	environment.keys.every((key) => key is String) &&
	environment.values.every((key) => key is String)) {
	return environment;
	}

	throw new FormatException('Invalid value for \$dart2js.environment: '
	'${JSON.encode(environment)} (expected map from strings to strings).');
	}

	/// Parses and returns a boolean configuration option.
	///
	/// [defaultsTo] is the default value of the option.
	bool _configBool(String name, {bool defaultsTo: false}) {
	if (!_settings.configuration.containsKey(name)) return defaultsTo;
	var value = _settings.configuration[name];
	if (value is bool) return value;
	throw new FormatException('Invalid value for \$dart2js.$name: '
	'${JSON.encode(value)} (expected true or false).');
	}
	}

	/// Defines an interface for dart2js to communicate with barback and pub.
	///
	/// Note that most of the implementation of diagnostic handling here was
	/// copied from [FormattingDiagnosticHandler] in dart2js. The primary
	/// difference is that it uses barback's logging code and, more importantly, it
	/// handles missing source files more gracefully.
	class _BarbackCompilerProvider implements dart.CompilerProvider {
	final PackageGraph _graph;
	final Transform _transform;

	/// The map of previously loaded files.
	///
	/// Used to show where an error occurred in a source file.
	final _sourceFiles = new Map<String, SourceFile>();

	// TODO(rnystrom): Make these configurable.
	/// Whether or not warnings should be logged.
	var _showWarnings = true;

	/// Whether or not hints should be logged.
	var _showHints = true;

	/// Whether or not verbose info messages should be logged.
	var _verbose = false;

	/// Whether an exception should be thrown on an error to stop compilation.
	var _throwOnError = false;

	/// This gets set after a fatal error is reported to quash any subsequent
	/// errors.
	var _isAborting = false;

	compiler.Diagnostic _lastKind = null;

	static final int _FATAL =
	compiler.Diagnostic.CRASH.ordinal \|
	compiler.Diagnostic.ERROR.ordinal;
	static final int _INFO =
	compiler.Diagnostic.INFO.ordinal \|
	compiler.Diagnostic.VERBOSE_INFO.ordinal;

	_BarbackCompilerProvider(this._graph, this._transform);

	/// A [CompilerInputProvider] for dart2js.
	Future<String> provideInput(Uri resourceUri) {
	// We only expect to get absolute "file:" URLs from dart2js.
	assert(resourceUri.isAbsolute);
	assert(resourceUri.scheme == "file");

	var sourcePath = path.fromUri(resourceUri);
	return _readResource(resourceUri).then((source) {
	_sourceFiles[resourceUri.toString()] =
	new StringSourceFile(path.relative(sourcePath), source);
	return source;
	});
	}

	/// A [CompilerOutputProvider] for dart2js.
	EventSink<String> provideOutput(String name, String extension) {
	// Dart2js uses an empty string for the name of the entrypoint library.
	// We only expect to get output files associated with that right now. For
	// other files, we'd need some logic to determine the right relative path
	// for it.
	assert(name == "");

	var primaryId = _transform.primaryInput.id;
	var id = new AssetId(primaryId.package, "${primaryId.path}.$extension");

	// Make a sink that dart2js can write to.
	var sink = new StreamController<String>();

	// dart2js gives us strings, but stream assets expect byte lists.
	var stream = UTF8.encoder.bind(sink.stream);

	// And give it to barback as a stream it can read from.
	_transform.addOutput(new Asset.fromStream(id, stream));

	return sink;
	}

	/// A [DiagnosticHandler] for dart2js, loosely based on
	/// [FormattingDiagnosticHandler].
	void handleDiagnostic(Uri uri, int begin, int end,
	String message, compiler.Diagnostic kind) {
	// TODO(ahe): Remove this when source map is handled differently.
	if (kind.name == "source map") return;

	if (_isAborting) return;
	_isAborting = (kind == compiler.Diagnostic.CRASH);

	var isInfo = (kind.ordinal & _INFO) != 0;
	if (isInfo && uri == null && kind != compiler.Diagnostic.INFO) {
	if (!_verbose && kind == compiler.Diagnostic.VERBOSE_INFO) return;
	_transform.logger.info(message);
	return;
	}

	// [_lastKind] records the previous non-INFO kind we saw.
	// This is used to suppress info about a warning when warnings are
	// suppressed, and similar for hints.
	if (kind != compiler.Diagnostic.INFO) _lastKind = kind;

	var logFn;
	if (kind == compiler.Diagnostic.ERROR) {
	logFn = _transform.logger.error;
	} else if (kind == compiler.Diagnostic.WARNING) {
	if (!_showWarnings) return;
	logFn = _transform.logger.warning;
	} else if (kind == compiler.Diagnostic.HINT) {
	if (!_showHints) return;
	logFn = _transform.logger.warning;
	} else if (kind == compiler.Diagnostic.CRASH) {
	logFn = _transform.logger.error;
	} else if (kind == compiler.Diagnostic.INFO) {
	if (_lastKind == compiler.Diagnostic.WARNING && !_showWarnings) return;
	if (_lastKind == compiler.Diagnostic.HINT && !_showHints) return;
	logFn = _transform.logger.info;
	} else {
	throw new Exception('Unknown kind: $kind (${kind.ordinal})');
	}

	var fatal = (kind.ordinal & _FATAL) != 0;
	if (uri == null) {
	assert(fatal);
	logFn(message);
	} else {
	SourceFile file = _sourceFiles[uri.toString()];
	if (file == null) {
	// We got a message before loading the file, so just report the message
	// itself.
	logFn('$uri: $message');
	} else {
	logFn(file.getLocationMessage(message, begin, end, true, (i) => i));
	}
	}

	if (fatal && _throwOnError) {
	_isAborting = true;
	throw new AbortLeg(message);
	}
	}

	Future<String> _readResource(Uri url) {
	// See if the path is within a package. If so, use Barback so we can use
	// generated Dart assets.

	var id = _sourceUrlToId(url);
	if (id != null) return _transform.readInputAsString(id);

	// If we get here, the path doesn't appear to be in a package, so we'll
	// skip Barback and just hit the file system. This will occur at the very
	// least for dart2js's implementations of the core libraries.
	var sourcePath = path.fromUri(url);
	return Chain.track(new File(sourcePath).readAsString());
	}

	AssetId _sourceUrlToId(Uri url) {
	// See if it's a special path with "packages" or "assets" in it.
	var id = specialUrlToId(url);
	if (id != null) return id;

	// See if it's a path to a "public" asset within the root package. All
	// other files in the root package are not visible to transformers, so
	// should be loaded directly from disk.
	var rootDir = _graph.entrypoint.root.dir;
	var sourcePath = path.fromUri(url);
	if (isBeneath(sourcePath, path.join(rootDir, "lib")) \|\|
	isBeneath(sourcePath, path.join(rootDir, "asset")) \|\|
	isBeneath(sourcePath, path.join(rootDir, "web"))) {
	var relative = path.relative(sourcePath, from: rootDir);

	return new AssetId(_graph.entrypoint.root.name, relative);
	}

	return null;
	}
	}