pkg/polymer/lib/src/build/script_compactor.dart - sdk - 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.

 /** Transfomer that combines multiple dart script tags into a single one. */
 library polymer.src.build.script_compactor;

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

 import 'package:analyzer/src/generated/ast.dart';
 import 'package:analyzer/src/generated/error.dart';
 import 'package:analyzer/src/generated/parser.dart';
 import 'package:analyzer/src/generated/scanner.dart';
 import 'package:barback/barback.dart';
 import 'package:html5lib/parser.dart' show parseFragment;
 import 'package:path/path.dart' as path;
 import 'package:source_maps/span.dart' show SourceFile;

 import 'code_extractor.dart'; // import just for documentation.
 import 'common.dart';

 /**
  * Combines Dart script tags into a single script tag, and creates a new Dart
  * file that calls the main function of each of the original script tags.
  *
  * This transformer assumes that all script tags point to external files. To
  * support script tags with inlined code, use this transformer after running
  * [InlineCodeExtractor] on an earlier phase.
  *
  * Internally, this transformer will convert each script tag into an import
  * statement to a library, and then uses `initPolymer` (see polymer.dart)  to
  * process `@initMethod` and `@CustomTag` annotations in those libraries.
  */
 class ScriptCompactor extends Transformer with PolymerTransformer {
   final TransformOptions options;

   ScriptCompactor(this.options);

   /** Only run on entry point .html files. */
   Future<bool> isPrimary(Asset input) =>
       new Future.value(options.isHtmlEntryPoint(input.id));

   Future apply(Transform transform) {
     var id = transform.primaryInput.id;
     var secondaryId = id.addExtension('.scriptUrls');
     var logger = transform.logger;
     return readPrimaryAsHtml(transform).then((document) {
       return transform.readInputAsString(secondaryId).then((libraryIds) {
         var libraries = (JSON.decode(libraryIds) as Iterable).map(
           (data) => new AssetId.deserialize(data)).toList();
         var mainLibraryId;
         var mainScriptTag;
         bool changed = false;

         for (var tag in document.queryAll('script')) {
           var src = tag.attributes['src'];
           if (src == 'packages/polymer/boot.js') {
             tag.remove();
             continue;
           }
           if (tag.attributes['type'] != 'application/dart') continue;
           if (src == null) {
             logger.warning('unexpected script without a src url. The '
               'ScriptCompactor transformer should run after running the '
               'InlineCodeExtractor', span: tag.sourceSpan);
             continue;
           }
           if (mainLibraryId != null) {
             logger.warning('unexpected script. Only one Dart script tag '
               'per document is allowed.', span: tag.sourceSpan);
             tag.remove();
             continue;
           }
           mainLibraryId = resolve(id, src, logger, tag.sourceSpan);
           mainScriptTag = tag;
         }

         if (mainScriptTag == null) {
           // We didn't find any main library, nothing to do.
           transform.addOutput(transform.primaryInput);
           return null;
         }

         // Emit the bootstrap .dart file
         var bootstrapId = id.addExtension('_bootstrap.dart');
         mainScriptTag.attributes['src'] =
             path.url.basename(bootstrapId.path);

         libraries.add(mainLibraryId);
         var urls = libraries.map((id) => assetUrlFor(id, bootstrapId, logger))
             .where((url) => url != null).toList();
         var buffer = new StringBuffer()..writeln(MAIN_HEADER);
         int i = 0;
         for (; i < urls.length; i++) {
           buffer.writeln("import '${urls[i]}' as i$i;");
         }

         buffer..write('\n')
             ..writeln('void main() {')
             ..writeln('  configureForDeployment([');

         // Inject @CustomTag and @initMethod initializations for each library
         // that is sourced in a script tag.
         i = 0;
         return Future.forEach(libraries, (lib) {
           return _initializersOf(lib, transform, logger).then((initializers) {
             for (var init in initializers) {
               var code = init.asCode('i$i');
               buffer.write("      $code,\n");
             }
             i++;
           });
         }).then((_) {
           buffer..writeln('    ]);')
               ..writeln('  i${urls.length - 1}.main();')
               ..writeln('}');

           transform.addOutput(new Asset.fromString(
                 bootstrapId, buffer.toString()));
           transform.addOutput(new Asset.fromString(id, document.outerHtml));
         });
       });
     });
   }

   /**
    * Computes the initializers of [dartLibrary]. That is, a closure that calls
    * Polymer.register for each @CustomTag, and any public top-level methods
    * labeled with @initMethod.
    */
   Future<List<_Initializer>> _initializersOf(
       AssetId dartLibrary, Transform transform, TransformLogger logger) {
     var initializers = [];
     return transform.readInputAsString(dartLibrary).then((code) {
       var file = new SourceFile.text(_simpleUriForSource(dartLibrary), code);
       var unit = _parseCompilationUnit(code);

       return Future.forEach(unit.directives, (directive) {
         // Include anything from parts.
         if (directive is PartDirective) {
           var targetId = resolve(dartLibrary, directive.uri.stringValue,
               logger, _getSpan(file, directive));
           return _initializersOf(targetId, transform, logger)
               .then(initializers.addAll);
         }

         // Similarly, include anything from exports except what's filtered by
         // the show/hide combinators.
         if (directive is ExportDirective) {
           var targetId = resolve(dartLibrary, directive.uri.stringValue,
               logger, _getSpan(file, directive));
           return _initializersOf(targetId, transform, logger)
               .then((r) => _processExportDirective(directive, r, initializers));
         }
       }).then((_) {
         // Scan the code for classes and top-level functions.
         for (var node in unit.declarations) {
           if (node is ClassDeclaration) {
             _processClassDeclaration(node, initializers, file, logger);
           } else if (node is FunctionDeclaration &&
               node.metadata.any(_isInitMethodAnnotation)) {
             _processFunctionDeclaration(node, initializers, file, logger);
           }
         }
         return initializers;
       });
     });
   }

   static String _simpleUriForSource(AssetId source) =>
       source.path.startsWith('lib/')
       ? 'package:${source.package}/${source.path.substring(4)}' : source.path;

   /**
    * Filter [exportedInitializers] according to [directive]'s show/hide
    * combinators and add the result to [initializers].
    */
   // TODO(sigmund): call the analyzer's resolver instead?
   static _processExportDirective(ExportDirective directive,
       List<_Initializer> exportedInitializers,
       List<_Initializer> initializers) {
     for (var combinator in directive.combinators) {
       if (combinator is ShowCombinator) {
         var show = combinator.shownNames.map((n) => n.name).toSet();
         exportedInitializers.retainWhere((e) => show.contains(e.symbolName));
       } else if (combinator is HideCombinator) {
         var hide = combinator.hiddenNames.map((n) => n.name).toSet();
         exportedInitializers.removeWhere((e) => hide.contains(e.symbolName));
       }
     }
     initializers.addAll(exportedInitializers);
   }

   /**
    * Add an initializer to register [node] as a polymer element if it contains
    * an appropriate [CustomTag] annotation.
    */
   static _processClassDeclaration(ClassDeclaration node,
       List<_Initializer> initializers, SourceFile file,
       TransformLogger logger) {
     for (var meta in node.metadata) {
       if (!_isCustomTagAnnotation(meta)) continue;
       var args = meta.arguments.arguments;
       if (args == null || args.length == 0) {
         logger.error('Missing argument in @CustomTag annotation',
             span: _getSpan(file, meta));
         continue;
       }

       var tagName = args[0].stringValue;
       var typeName = node.name.name;
       if (typeName.startsWith('_')) {
         logger.error('@CustomTag is no longer supported on private '
           'classes: $tagName', span: _getSpan(file, node.name));
         continue;
       }
       initializers.add(new _CustomTagInitializer(tagName, typeName));
     }
   }

   /**  a method initializer for [function]. */
   static _processFunctionDeclaration(FunctionDeclaration function,
       List<_Initializer> initializers, SourceFile file,
       TransformLogger logger) {
     var name = function.name.name;
     if (name.startsWith('_')) {
       logger.error('@initMethod is no longer supported on private '
         'functions: $name', span: _getSpan(file, function.name));
       return;
     }
     initializers.add(new _InitMethodInitializer(name));
   }
 }

 /** Parse [code] using analyzer. */
 CompilationUnit _parseCompilationUnit(String code) {
   var errorListener = new _ErrorCollector();
   var reader = new CharSequenceReader(code);
   var scanner = new Scanner(null, reader, errorListener);
   var token = scanner.tokenize();
   var parser = new Parser(null, errorListener);
   return parser.parseCompilationUnit(token);
 }

 class _ErrorCollector extends AnalysisErrorListener {
   final errors = <AnalysisError>[];
   onError(error) => errors.add(error);
 }

 // TODO(sigmund): consider support for importing annotations with prefixes.
 bool _isInitMethodAnnotation(Annotation node) =>
     node.name.name == 'initMethod' && node.constructorName == null &&
     node.arguments == null;
 bool _isCustomTagAnnotation(Annotation node) => node.name.name == 'CustomTag';

 abstract class _Initializer {
   String get symbolName;
   String asCode(String prefix);
 }

 class _InitMethodInitializer implements _Initializer {
   String methodName;
   String get symbolName => methodName;
   _InitMethodInitializer(this.methodName);

   String asCode(String prefix) => "$prefix.$methodName";
 }

 class _CustomTagInitializer implements _Initializer {
   String tagName;
   String typeName;
   String get symbolName => typeName;
   _CustomTagInitializer(this.tagName, this.typeName);

   String asCode(String prefix) =>
       "() => Polymer.register('$tagName', $prefix.$typeName)";
 }

 _getSpan(SourceFile file, ASTNode node) => file.span(node.offset, node.end);

 const MAIN_HEADER = """
 library app_bootstrap;

 import 'package:polymer/polymer.dart';
 """;
	// 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.

	/** Transfomer that combines multiple dart script tags into a single one. */
	library polymer.src.build.script_compactor;

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

	import 'package:analyzer/src/generated/ast.dart';
	import 'package:analyzer/src/generated/error.dart';
	import 'package:analyzer/src/generated/parser.dart';
	import 'package:analyzer/src/generated/scanner.dart';
	import 'package:barback/barback.dart';
	import 'package:html5lib/parser.dart' show parseFragment;
	import 'package:path/path.dart' as path;
	import 'package:source_maps/span.dart' show SourceFile;

	import 'code_extractor.dart'; // import just for documentation.
	import 'common.dart';

	/**
	* Combines Dart script tags into a single script tag, and creates a new Dart
	* file that calls the main function of each of the original script tags.
	*
	* This transformer assumes that all script tags point to external files. To
	* support script tags with inlined code, use this transformer after running
	* [InlineCodeExtractor] on an earlier phase.
	*
	* Internally, this transformer will convert each script tag into an import
	* statement to a library, and then uses `initPolymer` (see polymer.dart) to
	* process `@initMethod` and `@CustomTag` annotations in those libraries.
	*/
	class ScriptCompactor extends Transformer with PolymerTransformer {
	final TransformOptions options;

	ScriptCompactor(this.options);

	/** Only run on entry point .html files. */
	Future<bool> isPrimary(Asset input) =>
	new Future.value(options.isHtmlEntryPoint(input.id));

	Future apply(Transform transform) {
	var id = transform.primaryInput.id;
	var secondaryId = id.addExtension('.scriptUrls');
	var logger = transform.logger;
	return readPrimaryAsHtml(transform).then((document) {
	return transform.readInputAsString(secondaryId).then((libraryIds) {
	var libraries = (JSON.decode(libraryIds) as Iterable).map(
	(data) => new AssetId.deserialize(data)).toList();
	var mainLibraryId;
	var mainScriptTag;
	bool changed = false;

	for (var tag in document.queryAll('script')) {
	var src = tag.attributes['src'];
	if (src == 'packages/polymer/boot.js') {
	tag.remove();
	continue;
	}
	if (tag.attributes['type'] != 'application/dart') continue;
	if (src == null) {
	logger.warning('unexpected script without a src url. The '
	'ScriptCompactor transformer should run after running the '
	'InlineCodeExtractor', span: tag.sourceSpan);
	continue;
	}
	if (mainLibraryId != null) {
	logger.warning('unexpected script. Only one Dart script tag '
	'per document is allowed.', span: tag.sourceSpan);
	tag.remove();
	continue;
	}
	mainLibraryId = resolve(id, src, logger, tag.sourceSpan);
	mainScriptTag = tag;
	}

	if (mainScriptTag == null) {
	// We didn't find any main library, nothing to do.
	transform.addOutput(transform.primaryInput);
	return null;
	}

	// Emit the bootstrap .dart file
	var bootstrapId = id.addExtension('_bootstrap.dart');
	mainScriptTag.attributes['src'] =
	path.url.basename(bootstrapId.path);

	libraries.add(mainLibraryId);
	var urls = libraries.map((id) => assetUrlFor(id, bootstrapId, logger))
	.where((url) => url != null).toList();
	var buffer = new StringBuffer()..writeln(MAIN_HEADER);
	int i = 0;
	for (; i < urls.length; i++) {
	buffer.writeln("import '${urls[i]}' as i$i;");
	}

	buffer..write('\n')
	..writeln('void main() {')
	..writeln(' configureForDeployment([');

	// Inject @CustomTag and @initMethod initializations for each library
	// that is sourced in a script tag.
	i = 0;
	return Future.forEach(libraries, (lib) {
	return _initializersOf(lib, transform, logger).then((initializers) {
	for (var init in initializers) {
	var code = init.asCode('i$i');
	buffer.write(" $code,\n");
	}
	i++;
	});
	}).then((_) {
	buffer..writeln(' ]);')
	..writeln(' i${urls.length - 1}.main();')
	..writeln('}');

	transform.addOutput(new Asset.fromString(
	bootstrapId, buffer.toString()));
	transform.addOutput(new Asset.fromString(id, document.outerHtml));
	});
	});
	});
	}

	/**
	* Computes the initializers of [dartLibrary]. That is, a closure that calls
	* Polymer.register for each @CustomTag, and any public top-level methods
	* labeled with @initMethod.
	*/
	Future<List<_Initializer>> _initializersOf(
	AssetId dartLibrary, Transform transform, TransformLogger logger) {
	var initializers = [];
	return transform.readInputAsString(dartLibrary).then((code) {
	var file = new SourceFile.text(_simpleUriForSource(dartLibrary), code);
	var unit = _parseCompilationUnit(code);

	return Future.forEach(unit.directives, (directive) {
	// Include anything from parts.
	if (directive is PartDirective) {
	var targetId = resolve(dartLibrary, directive.uri.stringValue,
	logger, _getSpan(file, directive));
	return _initializersOf(targetId, transform, logger)
	.then(initializers.addAll);
	}

	// Similarly, include anything from exports except what's filtered by
	// the show/hide combinators.
	if (directive is ExportDirective) {
	var targetId = resolve(dartLibrary, directive.uri.stringValue,
	logger, _getSpan(file, directive));
	return _initializersOf(targetId, transform, logger)
	.then((r) => _processExportDirective(directive, r, initializers));
	}
	}).then((_) {
	// Scan the code for classes and top-level functions.
	for (var node in unit.declarations) {
	if (node is ClassDeclaration) {
	_processClassDeclaration(node, initializers, file, logger);
	} else if (node is FunctionDeclaration &&
	node.metadata.any(_isInitMethodAnnotation)) {
	_processFunctionDeclaration(node, initializers, file, logger);
	}
	}
	return initializers;
	});
	});
	}

	static String _simpleUriForSource(AssetId source) =>
	source.path.startsWith('lib/')
	? 'package:${source.package}/${source.path.substring(4)}' : source.path;

	/**
	* Filter [exportedInitializers] according to [directive]'s show/hide
	* combinators and add the result to [initializers].
	*/
	// TODO(sigmund): call the analyzer's resolver instead?
	static _processExportDirective(ExportDirective directive,
	List<_Initializer> exportedInitializers,
	List<_Initializer> initializers) {
	for (var combinator in directive.combinators) {
	if (combinator is ShowCombinator) {
	var show = combinator.shownNames.map((n) => n.name).toSet();
	exportedInitializers.retainWhere((e) => show.contains(e.symbolName));
	} else if (combinator is HideCombinator) {
	var hide = combinator.hiddenNames.map((n) => n.name).toSet();
	exportedInitializers.removeWhere((e) => hide.contains(e.symbolName));
	}
	}
	initializers.addAll(exportedInitializers);
	}

	/**
	* Add an initializer to register [node] as a polymer element if it contains
	* an appropriate [CustomTag] annotation.
	*/
	static _processClassDeclaration(ClassDeclaration node,
	List<_Initializer> initializers, SourceFile file,
	TransformLogger logger) {
	for (var meta in node.metadata) {
	if (!_isCustomTagAnnotation(meta)) continue;
	var args = meta.arguments.arguments;
	if (args == null \|\| args.length == 0) {
	logger.error('Missing argument in @CustomTag annotation',
	span: _getSpan(file, meta));
	continue;
	}

	var tagName = args[0].stringValue;
	var typeName = node.name.name;
	if (typeName.startsWith('_')) {
	logger.error('@CustomTag is no longer supported on private '
	'classes: $tagName', span: _getSpan(file, node.name));
	continue;
	}
	initializers.add(new _CustomTagInitializer(tagName, typeName));
	}
	}

	/** a method initializer for [function]. */
	static _processFunctionDeclaration(FunctionDeclaration function,
	List<_Initializer> initializers, SourceFile file,
	TransformLogger logger) {
	var name = function.name.name;
	if (name.startsWith('_')) {
	logger.error('@initMethod is no longer supported on private '
	'functions: $name', span: _getSpan(file, function.name));
	return;
	}
	initializers.add(new _InitMethodInitializer(name));
	}
	}

	/** Parse [code] using analyzer. */
	CompilationUnit _parseCompilationUnit(String code) {
	var errorListener = new _ErrorCollector();
	var reader = new CharSequenceReader(code);
	var scanner = new Scanner(null, reader, errorListener);
	var token = scanner.tokenize();
	var parser = new Parser(null, errorListener);
	return parser.parseCompilationUnit(token);
	}

	class _ErrorCollector extends AnalysisErrorListener {
	final errors = <AnalysisError>[];
	onError(error) => errors.add(error);
	}

	// TODO(sigmund): consider support for importing annotations with prefixes.
	bool _isInitMethodAnnotation(Annotation node) =>
	node.name.name == 'initMethod' && node.constructorName == null &&
	node.arguments == null;
	bool _isCustomTagAnnotation(Annotation node) => node.name.name == 'CustomTag';

	abstract class _Initializer {
	String get symbolName;
	String asCode(String prefix);
	}

	class _InitMethodInitializer implements _Initializer {
	String methodName;
	String get symbolName => methodName;
	_InitMethodInitializer(this.methodName);

	String asCode(String prefix) => "$prefix.$methodName";
	}

	class _CustomTagInitializer implements _Initializer {
	String tagName;
	String typeName;
	String get symbolName => typeName;
	_CustomTagInitializer(this.tagName, this.typeName);

	String asCode(String prefix) =>
	"() => Polymer.register('$tagName', $prefix.$typeName)";
	}

	_getSpan(SourceFile file, ASTNode node) => file.span(node.offset, node.end);

	const MAIN_HEADER = """
	library app_bootstrap;

	import 'package:polymer/polymer.dart';
	""";