Index: pkg/observe/lib/transform.dart |
diff --git a/pkg/observe/lib/transform.dart b/pkg/observe/lib/transform.dart |
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+// 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'); |
+} |