pkg/observe/lib/transform.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.

 /**
  * Code transform for @observable. The core transformation is relatively
  * straightforward, and essentially like an editor refactoring.
  */
 library observe.transform;

 import 'dart:async';
 import 'package:path/path.dart' as path;
 import 'package:analyzer_experimental/src/generated/ast.dart';
 import 'package:analyzer_experimental/src/generated/error.dart';
 import 'package:analyzer_experimental/src/generated/parser.dart';
 import 'package:analyzer_experimental/src/generated/scanner.dart';
 import 'package:barback/barback.dart';
 import 'package:source_maps/refactor.dart';
 import 'package:source_maps/span.dart' show SourceFile;

 /**
  * A [Transformer] that replaces observables based on dirty-checking with an
  * implementation based on change notifications.
  *
  * The transformation adds hooks for field setters and notifies the observation
  * system of the change.
  */
 class ObservableTransformer extends Transformer {

   Future<bool> isPrimary(Asset input) {
     if (input.id.extension != '.dart') return new Future.value(false);
     // Note: technically we should parse the file to find accurately the
     // observable annotation, but that seems expensive. It would require almost
     // as much work as applying the transform. We rather have some false
     // positives here, and then generate no outputs when we apply this
     // transform.
     return input.readAsString().then((c) => c.contains("@observable"));
   }

   Future apply(Transform transform) {
     return transform.primaryInput
         .then((input) => input.readAsString().then((content) {
       var id = transform.primaryId;
       // TODO(sigmund): improve how we compute this url
       var url = id.path.startsWith('lib/')
             ? 'package:${id.package}/${id.path.substring(4)}' : id.path;
       var sourceFile = new SourceFile.text(url, content);
       var transaction = _transformCompilationUnit(
           content, sourceFile, transform.logger);
       if (!transaction.hasEdits) {
         transform.addOutput(input);
         return;
       }
       var printer = transaction.commit();
       // TODO(sigmund): emit source maps when barback supports it (see
       // dartbug.com/12340)
       printer.build(url);
       transform.addOutput(new Asset.fromString(id, printer.text));
     }));
   }
 }

 TextEditTransaction _transformCompilationUnit(
     String inputCode, SourceFile sourceFile, TransformLogger logger) {
   var unit = _parseCompilationUnit(inputCode);
   return transformObservables(unit, sourceFile, inputCode, logger);
 }

 // TODO(sigmund): make this private. This is currently public so it can be used
 // by the polymer.dart package which is not yet entirely migrated to use
 // pub-serve and pub-deploy.
 TextEditTransaction transformObservables(CompilationUnit unit,
     SourceFile sourceFile, String content, TransformLogger logger) {
   var code = new TextEditTransaction(content, sourceFile);
   for (var directive in unit.directives) {
     if (directive is LibraryDirective && _hasObservable(directive)) {
       logger.warning('@observable on a library no longer has any effect. '
           'It should be placed on individual fields.',
           _getSpan(sourceFile, directive));
       break;
     }
   }

   for (var declaration in unit.declarations) {
     if (declaration is ClassDeclaration) {
       _transformClass(declaration, code, sourceFile, logger);
     } else if (declaration is TopLevelVariableDeclaration) {
       if (_hasObservable(declaration)) {
         logger.warning('Top-level fields can no longer be observable. '
             'Observable fields should be put in an observable objects.',
             _getSpan(sourceFile, declaration));
       }
     }
   }
   return code;
 }

 /** Parse [code] using analyzer_experimental. */
 CompilationUnit _parseCompilationUnit(String code) {
   var errorListener = new _ErrorCollector();
   var scanner = new StringScanner(null, code, 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);
 }

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

 /** True if the node has the `@observable` annotation. */
 bool _hasObservable(AnnotatedNode node) => _hasAnnotation(node, 'observable');

 bool _hasAnnotation(AnnotatedNode node, String name) {
   // TODO(jmesserly): this isn't correct if the annotation has been imported
   // with a prefix, or cases like that. We should technically be resolving, but
   // that is expensive.
   return node.metadata.any((m) => m.name.name == name &&
       m.constructorName == null && m.arguments == null);
 }

 void _transformClass(ClassDeclaration cls, TextEditTransaction code,
     SourceFile file, TransformLogger logger) {

   if (_hasObservable(cls)) {
     logger.warning('@observable on a class no longer has any effect. '
         'It should be placed on individual fields.',
         _getSpan(file, cls));
   }

   // We'd like to track whether observable was declared explicitly, otherwise
   // report a warning later below. Because we don't have type analysis (only
   // syntactic understanding of the code), we only report warnings that are
   // known to be true.
   var declaresObservable = false;
   if (cls.extendsClause != null) {
     var id = _getSimpleIdentifier(cls.extendsClause.superclass.name);
     if (id.name == 'ObservableBase') {
       code.edit(id.offset, id.end, 'ChangeNotifierBase');
       declaresObservable = true;
     } else if (id.name == 'ChangeNotifierBase') {
       declaresObservable = true;
     } else if (id.name != 'PolymerElement' && id.name != 'CustomElement'
         && id.name != 'Object') {
       // TODO(sigmund): this is conservative, consider using type-resolution to
       // improve this check.
       declaresObservable = true;
     }
   }

   if (cls.withClause != null) {
     for (var type in cls.withClause.mixinTypes) {
       var id = _getSimpleIdentifier(type.name);
       if (id.name == 'ObservableMixin') {
         code.edit(id.offset, id.end, 'ChangeNotifierMixin');
         declaresObservable = true;
         break;
       } else if (id.name == 'ChangeNotifierMixin') {
         declaresObservable = true;
         break;
       } else {
         // TODO(sigmund): this is conservative, consider using type-resolution
         // to improve this check.
         declaresObservable = true;
       }
     }
   }

   if (!declaresObservable && cls.implementsClause != null) {
     // TODO(sigmund): consider adding type-resolution to give a more precise
     // answer.
     declaresObservable = true;
   }

   // Track fields that were transformed.
   var instanceFields = new Set<String>();
   var getters = new List<String>();
   var setters = new List<String>();

   for (var member in cls.members) {
     if (member is FieldDeclaration) {
       bool isStatic = _hasKeyword(member.keyword, Keyword.STATIC);
       if (isStatic) {
         if (_hasObservable(member)){
           logger.warning('Static fields can no longer be observable. '
               'Observable fields should be put in an observable objects.',
               _getSpan(file, member));
         }
         continue;
       }
       if (_hasObservable(member)) {
         if (!declaresObservable) {
           logger.warning('Observable fields should be put in an observable'
               ' objects. Please declare that this class extends from '
               'ObservableBase, includes ObservableMixin, or implements '
               'Observable.',
               _getSpan(file, member));

         }
         _transformFields(member.fields, code, member.offset, member.end);

         var names = member.fields.variables.map((v) => v.name.name);

         getters.addAll(names);
         if (!_isReadOnly(member.fields)) {
           setters.addAll(names);
           instanceFields.addAll(names);
         }
       }
     }
     // TODO(jmesserly): this is a temporary workaround until we can remove
     // getValueWorkaround and setValueWorkaround.
     if (member is MethodDeclaration) {
       if (_hasKeyword(member.propertyKeyword, Keyword.GET)) {
         getters.add(member.name.name);
       } else if (_hasKeyword(member.propertyKeyword, Keyword.SET)) {
         setters.add(member.name.name);
       }
     }
   }

   // If nothing was @observable, bail.
   if (instanceFields.length == 0) return;

   // Fix initializers, because they aren't allowed to call the setter.
   for (var member in cls.members) {
     if (member is ConstructorDeclaration) {
       _fixConstructor(member, code, instanceFields);
     }
   }
 }

 SimpleIdentifier _getSimpleIdentifier(Identifier id) =>
     id is PrefixedIdentifier ? (id as PrefixedIdentifier).identifier : id;


 bool _hasKeyword(Token token, Keyword keyword) =>
     token is KeywordToken && (token as KeywordToken).keyword == keyword;

 String _getOriginalCode(TextEditTransaction code, ASTNode node) =>
     code.original.substring(node.offset, node.end);

 void _fixConstructor(ConstructorDeclaration ctor, TextEditTransaction code,
     Set<String> changedFields) {

   // Fix normal initializers
   for (var initializer in ctor.initializers) {
     if (initializer is ConstructorFieldInitializer) {
       var field = initializer.fieldName;
       if (changedFields.contains(field.name)) {
         code.edit(field.offset, field.end, '__\$${field.name}');
       }
     }
   }

   // Fix "this." initializer in parameter list. These are tricky:
   // we need to preserve the name and add an initializer.
   // Preserving the name is important for named args, and for dartdoc.
   // BEFORE: Foo(this.bar, this.baz) { ... }
   // AFTER:  Foo(bar, baz) : __$bar = bar, __$baz = baz { ... }

   var thisInit = [];
   for (var param in ctor.parameters.parameters) {
     if (param is DefaultFormalParameter) {
       param = param.parameter;
     }
     if (param is FieldFormalParameter) {
       var name = param.identifier.name;
       if (changedFields.contains(name)) {
         thisInit.add(name);
         // Remove "this." but keep everything else.
         code.edit(param.thisToken.offset, param.period.end, '');
       }
     }
   }

   if (thisInit.length == 0) return;

   // TODO(jmesserly): smarter formatting with indent, etc.
   var inserted = thisInit.map((i) => '__\$$i = $i').join(', ');

   int offset;
   if (ctor.separator != null) {
     offset = ctor.separator.end;
     inserted = ' $inserted,';
   } else {
     offset = ctor.parameters.end;
     inserted = ' : $inserted';
   }

   code.edit(offset, offset, inserted);
 }

 bool _isReadOnly(VariableDeclarationList fields) {
   return _hasKeyword(fields.keyword, Keyword.CONST) ||
       _hasKeyword(fields.keyword, Keyword.FINAL);
 }

 void _transformFields(VariableDeclarationList fields, TextEditTransaction code,
     int begin, int end) {

   if (_isReadOnly(fields)) return;

   var indent = guessIndent(code.original, begin);
   var replace = new StringBuffer();

   // Unfortunately "var" doesn't work in all positions where type annotations
   // are allowed, such as "var get name". So we use "dynamic" instead.
   var type = 'dynamic';
   if (fields.type != null) {
     type = _getOriginalCode(code, fields.type);
   }

   for (var field in fields.variables) {
     var initializer = '';
     if (field.initializer != null) {
       initializer = ' = ${_getOriginalCode(code, field.initializer)}';
     }

     var name = field.name.name;

     // TODO(jmesserly): should we generate this one one line, so source maps
     // don't break?
     if (replace.length > 0) replace.write('\n\n$indent');
     replace.write('''
 $type __\$$name$initializer;
 $type get $name => __\$$name;
 set $name($type value) {
   __\$$name = notifyPropertyChange(const Symbol('$name'), __\$$name, value);
 }
 '''.replaceAll('\n', '\n$indent'));
   }

   code.edit(begin, end, '$replace');
 }
	// 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.

	/**
	* Code transform for @observable. The core transformation is relatively
	* straightforward, and essentially like an editor refactoring.
	*/
	library observe.transform;

	import 'dart:async';
	import 'package:path/path.dart' as path;
	import 'package:analyzer_experimental/src/generated/ast.dart';
	import 'package:analyzer_experimental/src/generated/error.dart';
	import 'package:analyzer_experimental/src/generated/parser.dart';
	import 'package:analyzer_experimental/src/generated/scanner.dart';
	import 'package:barback/barback.dart';
	import 'package:source_maps/refactor.dart';
	import 'package:source_maps/span.dart' show SourceFile;

	/**
	* A [Transformer] that replaces observables based on dirty-checking with an
	* implementation based on change notifications.
	*
	* The transformation adds hooks for field setters and notifies the observation
	* system of the change.
	*/
	class ObservableTransformer extends Transformer {

	Future<bool> isPrimary(Asset input) {
	if (input.id.extension != '.dart') return new Future.value(false);
	// Note: technically we should parse the file to find accurately the
	// observable annotation, but that seems expensive. It would require almost
	// as much work as applying the transform. We rather have some false
	// positives here, and then generate no outputs when we apply this
	// transform.
	return input.readAsString().then((c) => c.contains("@observable"));
	}

	Future apply(Transform transform) {
	return transform.primaryInput
	.then((input) => input.readAsString().then((content) {
	var id = transform.primaryId;
	// TODO(sigmund): improve how we compute this url
	var url = id.path.startsWith('lib/')
	? 'package:${id.package}/${id.path.substring(4)}' : id.path;
	var sourceFile = new SourceFile.text(url, content);
	var transaction = _transformCompilationUnit(
	content, sourceFile, transform.logger);
	if (!transaction.hasEdits) {
	transform.addOutput(input);
	return;
	}
	var printer = transaction.commit();
	// TODO(sigmund): emit source maps when barback supports it (see
	// dartbug.com/12340)
	printer.build(url);
	transform.addOutput(new Asset.fromString(id, printer.text));
	}));
	}
	}

	TextEditTransaction _transformCompilationUnit(
	String inputCode, SourceFile sourceFile, TransformLogger logger) {
	var unit = _parseCompilationUnit(inputCode);
	return transformObservables(unit, sourceFile, inputCode, logger);
	}

	// TODO(sigmund): make this private. This is currently public so it can be used
	// by the polymer.dart package which is not yet entirely migrated to use
	// pub-serve and pub-deploy.
	TextEditTransaction transformObservables(CompilationUnit unit,
	SourceFile sourceFile, String content, TransformLogger logger) {
	var code = new TextEditTransaction(content, sourceFile);
	for (var directive in unit.directives) {
	if (directive is LibraryDirective && _hasObservable(directive)) {
	logger.warning('@observable on a library no longer has any effect. '
	'It should be placed on individual fields.',
	_getSpan(sourceFile, directive));
	break;
	}
	}

	for (var declaration in unit.declarations) {
	if (declaration is ClassDeclaration) {
	_transformClass(declaration, code, sourceFile, logger);
	} else if (declaration is TopLevelVariableDeclaration) {
	if (_hasObservable(declaration)) {
	logger.warning('Top-level fields can no longer be observable. '
	'Observable fields should be put in an observable objects.',
	_getSpan(sourceFile, declaration));
	}
	}
	}
	return code;
	}

	/** Parse [code] using analyzer_experimental. */
	CompilationUnit _parseCompilationUnit(String code) {
	var errorListener = new _ErrorCollector();
	var scanner = new StringScanner(null, code, 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);
	}

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

	/** True if the node has the `@observable` annotation. */
	bool _hasObservable(AnnotatedNode node) => _hasAnnotation(node, 'observable');

	bool _hasAnnotation(AnnotatedNode node, String name) {
	// TODO(jmesserly): this isn't correct if the annotation has been imported
	// with a prefix, or cases like that. We should technically be resolving, but
	// that is expensive.
	return node.metadata.any((m) => m.name.name == name &&
	m.constructorName == null && m.arguments == null);
	}

	void _transformClass(ClassDeclaration cls, TextEditTransaction code,
	SourceFile file, TransformLogger logger) {

	if (_hasObservable(cls)) {
	logger.warning('@observable on a class no longer has any effect. '
	'It should be placed on individual fields.',
	_getSpan(file, cls));
	}

	// We'd like to track whether observable was declared explicitly, otherwise
	// report a warning later below. Because we don't have type analysis (only
	// syntactic understanding of the code), we only report warnings that are
	// known to be true.
	var declaresObservable = false;
	if (cls.extendsClause != null) {
	var id = _getSimpleIdentifier(cls.extendsClause.superclass.name);
	if (id.name == 'ObservableBase') {
	code.edit(id.offset, id.end, 'ChangeNotifierBase');
	declaresObservable = true;
	} else if (id.name == 'ChangeNotifierBase') {
	declaresObservable = true;
	} else if (id.name != 'PolymerElement' && id.name != 'CustomElement'
	&& id.name != 'Object') {
	// TODO(sigmund): this is conservative, consider using type-resolution to
	// improve this check.
	declaresObservable = true;
	}
	}

	if (cls.withClause != null) {
	for (var type in cls.withClause.mixinTypes) {
	var id = _getSimpleIdentifier(type.name);
	if (id.name == 'ObservableMixin') {
	code.edit(id.offset, id.end, 'ChangeNotifierMixin');
	declaresObservable = true;
	break;
	} else if (id.name == 'ChangeNotifierMixin') {
	declaresObservable = true;
	break;
	} else {
	// TODO(sigmund): this is conservative, consider using type-resolution
	// to improve this check.
	declaresObservable = true;
	}
	}
	}

	if (!declaresObservable && cls.implementsClause != null) {
	// TODO(sigmund): consider adding type-resolution to give a more precise
	// answer.
	declaresObservable = true;
	}

	// Track fields that were transformed.
	var instanceFields = new Set<String>();
	var getters = new List<String>();
	var setters = new List<String>();

	for (var member in cls.members) {
	if (member is FieldDeclaration) {
	bool isStatic = _hasKeyword(member.keyword, Keyword.STATIC);
	if (isStatic) {
	if (_hasObservable(member)){
	logger.warning('Static fields can no longer be observable. '
	'Observable fields should be put in an observable objects.',
	_getSpan(file, member));
	}
	continue;
	}
	if (_hasObservable(member)) {
	if (!declaresObservable) {
	logger.warning('Observable fields should be put in an observable'
	' objects. Please declare that this class extends from '
	'ObservableBase, includes ObservableMixin, or implements '
	'Observable.',
	_getSpan(file, member));

	}
	_transformFields(member.fields, code, member.offset, member.end);

	var names = member.fields.variables.map((v) => v.name.name);

	getters.addAll(names);
	if (!_isReadOnly(member.fields)) {
	setters.addAll(names);
	instanceFields.addAll(names);
	}
	}
	}
	// TODO(jmesserly): this is a temporary workaround until we can remove
	// getValueWorkaround and setValueWorkaround.
	if (member is MethodDeclaration) {
	if (_hasKeyword(member.propertyKeyword, Keyword.GET)) {
	getters.add(member.name.name);
	} else if (_hasKeyword(member.propertyKeyword, Keyword.SET)) {
	setters.add(member.name.name);
	}
	}
	}

	// If nothing was @observable, bail.
	if (instanceFields.length == 0) return;

	// Fix initializers, because they aren't allowed to call the setter.
	for (var member in cls.members) {
	if (member is ConstructorDeclaration) {
	_fixConstructor(member, code, instanceFields);
	}
	}
	}

	SimpleIdentifier _getSimpleIdentifier(Identifier id) =>
	id is PrefixedIdentifier ? (id as PrefixedIdentifier).identifier : id;


	bool _hasKeyword(Token token, Keyword keyword) =>
	token is KeywordToken && (token as KeywordToken).keyword == keyword;

	String _getOriginalCode(TextEditTransaction code, ASTNode node) =>
	code.original.substring(node.offset, node.end);

	void _fixConstructor(ConstructorDeclaration ctor, TextEditTransaction code,
	Set<String> changedFields) {

	// Fix normal initializers
	for (var initializer in ctor.initializers) {
	if (initializer is ConstructorFieldInitializer) {
	var field = initializer.fieldName;
	if (changedFields.contains(field.name)) {
	code.edit(field.offset, field.end, '__\$${field.name}');
	}
	}
	}

	// Fix "this." initializer in parameter list. These are tricky:
	// we need to preserve the name and add an initializer.
	// Preserving the name is important for named args, and for dartdoc.
	// BEFORE: Foo(this.bar, this.baz) { ... }
	// AFTER: Foo(bar, baz) : __$bar = bar, __$baz = baz { ... }

	var thisInit = [];
	for (var param in ctor.parameters.parameters) {
	if (param is DefaultFormalParameter) {
	param = param.parameter;
	}
	if (param is FieldFormalParameter) {
	var name = param.identifier.name;
	if (changedFields.contains(name)) {
	thisInit.add(name);
	// Remove "this." but keep everything else.
	code.edit(param.thisToken.offset, param.period.end, '');
	}
	}
	}

	if (thisInit.length == 0) return;

	// TODO(jmesserly): smarter formatting with indent, etc.
	var inserted = thisInit.map((i) => '__\$$i = $i').join(', ');

	int offset;
	if (ctor.separator != null) {
	offset = ctor.separator.end;
	inserted = ' $inserted,';
	} else {
	offset = ctor.parameters.end;
	inserted = ' : $inserted';
	}

	code.edit(offset, offset, inserted);
	}

	bool _isReadOnly(VariableDeclarationList fields) {
	return _hasKeyword(fields.keyword, Keyword.CONST) \|\|
	_hasKeyword(fields.keyword, Keyword.FINAL);
	}

	void _transformFields(VariableDeclarationList fields, TextEditTransaction code,
	int begin, int end) {

	if (_isReadOnly(fields)) return;

	var indent = guessIndent(code.original, begin);
	var replace = new StringBuffer();

	// Unfortunately "var" doesn't work in all positions where type annotations
	// are allowed, such as "var get name". So we use "dynamic" instead.
	var type = 'dynamic';
	if (fields.type != null) {
	type = _getOriginalCode(code, fields.type);
	}

	for (var field in fields.variables) {
	var initializer = '';
	if (field.initializer != null) {
	initializer = ' = ${_getOriginalCode(code, field.initializer)}';
	}

	var name = field.name.name;

	// TODO(jmesserly): should we generate this one one line, so source maps
	// don't break?
	if (replace.length > 0) replace.write('\n\n$indent');
	replace.write('''
	$type __\$$name$initializer;
	$type get $name => __\$$name;
	set $name($type value) {
	__\$$name = notifyPropertyChange(const Symbol('$name'), __\$$name, value);
	}
	'''.replaceAll('\n', '\n$indent'));
	}

	code.edit(begin, end, '$replace');
	}