Ensure we run the observable transform on PolymerElement (fixes issue 14942)

pkg/observe/lib/transform.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.
 
 /**
- * Code transform for @observable. The core transformation is relatively
- * straightforward, and essentially like an editor refactoring.
+ * Code transform for @observable. This library will be removed soon, it simply
+ * reexports `observe.transformer`.
  */
+// TODO(sigmund): deprecate and delete.
 library observe.transform;
 
-import 'dart:async';
-
-import 'package:analyzer/src/generated/java_core.dart' show CharSequence;
-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: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") || c.contains("@published"));
-  }
-
-  Future apply(Transform transform) {
-    return transform.primaryInput.readAsString().then((content) {
-      var id = transform.primaryInput.id;
-      // 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(transform.primaryInput);
-        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);
-  var code = new TextEditTransaction(inputCode, 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.',
-          span: _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.',
-            span: _getSpan(sourceFile, declaration));
-      }
-    }
-  }
-  return code;
-}
-
-/** Parse [code] using analyzer. */
-CompilationUnit _parseCompilationUnit(String code) {
-  var errorListener = new _ErrorCollector();
-  var reader = new CharSequenceReader(new CharSequence(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);
-}
-
-_getSpan(SourceFile file, ASTNode node) => file.span(node.offset, node.end);
-
-/** True if the node has the `@observable` or `@published` annotation. */
-// TODO(jmesserly): it is not good to be hard coding Polymer support here.
-bool _hasObservable(AnnotatedNode node) =>
-    node.metadata.any(_isObservableAnnotation);
-
-// 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 in analyzer, so it isn't feasible yet.
-bool _isObservableAnnotation(Annotation node) =>
-    _isAnnotationContant(node, 'observable') ||
-    _isAnnotationContant(node, 'published') ||
-    _isAnnotationType(node, 'ObservableProperty') ||
-    _isAnnotationType(node, 'PublishedProperty');
-
-bool _isAnnotationContant(Annotation m, String name) =>
-    m.name.name == name && m.constructorName == null && m.arguments == null;
-
-bool _isAnnotationType(Annotation m, String name) => m.name == name;
-
-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.',
-        span: _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 explicitObservable = false;
-  var implicitObservable = false;
-  if (cls.extendsClause != null) {
-    var id = _getSimpleIdentifier(cls.extendsClause.superclass.name);
-    if (id.name == 'Observable') {
-      code.edit(id.offset, id.end, 'ChangeNotifier');
-      explicitObservable = true;
-    } else if (id.name == 'ChangeNotifier') {
-      explicitObservable = true;
-    } else if (id.name != 'HtmlElement' && id.name != 'CustomElement'
-        && id.name != 'Object') {
-      // TODO(sigmund): this is conservative, consider using type-resolution to
-      // improve this check.
-      implicitObservable = true;
-    }
-  }
-
-  if (cls.withClause != null) {
-    for (var type in cls.withClause.mixinTypes) {
-      var id = _getSimpleIdentifier(type.name);
-      if (id.name == 'Observable') {
-        code.edit(id.offset, id.end, 'ChangeNotifier');
-        explicitObservable = true;
-        break;
-      } else if (id.name == 'ChangeNotifier') {
-        explicitObservable = true;
-        break;
-      } else {
-        // TODO(sigmund): this is conservative, consider using type-resolution
-        // to improve this check.
-        implicitObservable = true;
-      }
-    }
-  }
-
-  if (cls.implementsClause != null) {
-    // TODO(sigmund): consider adding type-resolution to give a more precise
-    // answer.
-    implicitObservable = true;
-  }
-
-  var declaresObservable = explicitObservable || implicitObservable;
-
-  // 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) {
-      if (member.isStatic) {
-        if (_hasObservable(member)){
-          logger.warning('Static fields can no longer be observable. '
-              'Observable fields should be put in an observable objects.',
-              span: _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 '
-              'Observable, includes Observable, or implements '
-              'Observable.',
-              span: _getSpan(file, member));
-        }
-        _transformFields(file, member, code, logger);
-
-        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;
-
-  if (!explicitObservable) _mixinObservable(cls, code);
-
-  // 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);
-    }
-  }
-}
-
-/** Adds "with ChangeNotifier" and associated implementation. */
-void _mixinObservable(ClassDeclaration cls, TextEditTransaction code) {
-  // Note: we need to be careful to put the with clause after extends, but
-  // before implements clause.
-  if (cls.withClause != null) {
-    var pos = cls.withClause.end;
-    code.edit(pos, pos, ', ChangeNotifier');
-  } else if (cls.extendsClause != null) {
-    var pos = cls.extendsClause.end;
-    code.edit(pos, pos, ' with ChangeNotifier ');
-  } else {
-    var params = cls.typeParameters;
-    var pos =  params != null ? params.end : cls.name.end;
-    code.edit(pos, pos, ' extends ChangeNotifier ');
-  }
-}
-
-SimpleIdentifier _getSimpleIdentifier(Identifier id) =>
-    id is PrefixedIdentifier ? id.identifier : id;
-
-
-bool _hasKeyword(Token token, Keyword keyword) =>
-    token is KeywordToken && token.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(SourceFile file, FieldDeclaration member,
-    TextEditTransaction code, TransformLogger logger) {
-
-  final fields = member.fields;
-  if (_isReadOnly(fields)) return;
-
-  // Private fields aren't supported:
-  for (var field in fields.variables) {
-    final name = field.name.name;
-    if (Identifier.isPrivateName(name)) {
-      logger.warning('Cannot make private field $name observable.',
-          span: _getSpan(file, field));
-      return;
-    }
-  }
-
-  // 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);
-  } else if (_hasKeyword(fields.keyword, Keyword.VAR)) {
-    // Replace 'var' with 'dynamic'
-    code.edit(fields.keyword.offset, fields.keyword.end, type);
-  }
-
-  // Note: the replacements here are a bit subtle. It needs to support multiple
-  // fields declared via the same @observable, as well as preserving newlines.
-  // (Preserving newlines is important because it allows the generated code to
-  // be debugged without needing a source map.)
-  //
-  // For example:
-  //
-  //     @observable
-  //     @otherMetaData
-  //         Foo
-  //             foo = 1, bar = 2,
-  //             baz;
-  //
-  // Will be transformed into something like:
-  //
-  //     @reflectable @observable
-  //     @OtherMetaData()
-  //         Foo
-  //             get foo => __foo; Foo __foo = 1; @reflectable set foo ...; ...
-  //             @observable @OtherMetaData() Foo get baz => __baz; Foo baz; ...
-  //
-  // Metadata is moved to the getter.
-
-  String metadata = '';
-  if (fields.variables.length > 1) {
-    metadata = member.metadata
-      .map((m) => _getOriginalCode(code, m))
-      .join(' ');
-    metadata = '@reflectable $metadata';
-  }
-
-  for (int i = 0; i < fields.variables.length; i++) {
-    final field = fields.variables[i];
-    final name = field.name.name;
-
-    var beforeInit = 'get $name => __\$$name; $type __\$$name';
-
-    // The first field is expanded differently from subsequent fields, because
-    // we can reuse the metadata and type annotation.
-    if (i == 0) {
-      final begin = member.metadata.first.offset;
-      code.edit(begin, begin, '@reflectable ');
-    } else {
-      beforeInit = '$metadata $type $beforeInit';
-    }
-
-    code.edit(field.name.offset, field.name.end, beforeInit);
-
-    // Replace comma with semicolon
-    final end = _findFieldSeperator(field.endToken.next);
-    if (end.type == TokenType.COMMA) code.edit(end.offset, end.end, ';');
-
-    code.edit(end.end, end.end, ' @reflectable set $name($type value) { '
-        '__\$$name = notifyPropertyChange(#$name, __\$$name, value); }');
-  }
-}
-
-Token _findFieldSeperator(Token token) {
-  while (token != null) {
-    if (token.type == TokenType.COMMA || token.type == TokenType.SEMICOLON) {
-      break;
-    }
-    token = token.next;
-  }
-  return token;
-}
+export 'transformer.dart';