Add codegen support in smoke

pkg/smoke/lib/codegen/recorder.dart

+// Copyright (c) 2014, 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.
+
+/// Records accesses to Dart program declarations and generates code that will
+/// allow to do the same accesses at runtime using `package:smoke/static.dart`.
+/// Internally, this library relies on the `analyzer` to extract data from the
+/// program, and then uses [SmokeCodeGenerator] to produce the code needed by
+/// the smoke system.
+///
+/// This library only uses the analyzer to consume data previously produced by
+/// running the resolver. This library does not provide any hooks to integrate
+/// running the analyzer itself. See `package:code_transformers` to integrate
+/// the analyzer into pub transformers.
+library smoke.codegen.recorder;
+
+import 'package:analyzer/src/generated/element.dart';
+import 'package:analyzer/src/generated/ast.dart';
+import 'generator.dart';
+
+typedef String ImportUrlResolver(LibraryElement lib);
+
+/// A recorder that tracks how elements are accessed in order to generate code
+/// that replicates those accesses with the smoke runtime.
+class Recorder {
+  /// Underlying code generator.
+  SmokeCodeGenerator generator;
+
+  /// Function that provides the import url for a library element. This may
+  /// internally use the resolver to resolve the import url.
+  ImportUrlResolver importUrlFor;
+
+  Recorder(this.generator, this.importUrlFor);
+
+  /// Stores mixins that have been recorded and associates a type identifier
+  /// with them. Mixins don't have an associated identifier in the code, so we
+  /// generate a unique identifier for them and use it throughout the code.
+  Map<TypeIdentifier, Map<ClassElement, TypeIdentifier>> _mixins = {};
+
+  /// Adds the superclass information of [type] (including intermediate mixins).
+  /// This will not generate data for direct subtypes of Object, as that is
+  /// considered redundant information.
+  void lookupParent(ClassElement type) {
+    var parent = type.supertype;
+    var mixins = type.mixins;
+    if (parent == null && mixins.isEmpty) return; // type is Object
+    var baseType = parent.element;
+    var baseId = _typeFor(baseType);
+    if (mixins.isNotEmpty) {
+      _mixins.putIfAbsent(baseId, () => {});
+      for (var m in mixins) {
+        var mixinType = m.element;
+        var mixinId = _mixins[baseId].putIfAbsent(mixinType, () {
+          var comment = '${baseId.name} & ${mixinType.name}';
+          return generator.createMixinType(comment);
+        });
+        if (!baseType.type.isObject) generator.addParent(mixinId, baseId);
+        baseType = mixinType;
+        baseId = mixinId;
+        _mixins.putIfAbsent(mixinId, () => {});
+      }
+    }
+    if (!baseType.type.isObject) generator.addParent(_typeFor(type), baseId);
+  }
+
+  TypeIdentifier _typeFor(ClassElement type) =>
+      new TypeIdentifier(importUrlFor(type.library), type.displayName);
+
+  /// Adds any declaration and superclass information that is needed to answer a
+  /// query on [type] that matches [options].
+  void runQuery(ClassElement type, QueryOptions options) {
+    if (type.type.isObject) return; // We don't include Object in query results.
+    var id = _typeFor(type);
+    var parent = type.supertype != null ? type.supertype.element : null;
+    if (options.includeInherited && parent != null &&
+        parent != options.includeUpTo) {
+      lookupParent(type);
+      runQuery(parent, options);
+      var parentId = _typeFor(parent);
+      for (var m in type.mixins) {
+        var mixinClass = m.element;
+        var mixinId = _mixins[parentId][mixinClass];
+        _runQueryInternal(mixinClass, mixinId, options);
+        parentId = mixinId;
+      }
+    }
+    _runQueryInternal(type, id, options);
+  }
+
+  /// Helper for [runQuery]. This runs the query only on a specific [type],
+  /// which could be a class or a mixin labeled by [id].
+  // TODO(sigmund): currently we materialize mixins in smoke/static.dart,
+  // we should consider to include the mixin declaration information directly,
+  // and remove the duplication we have for mixins today.
+  void _runQueryInternal(ClassElement type, TypeIdentifier id,
+      QueryOptions options) {
+
+    skipBecauseOfAnnotations(Element e) {
+      if (options.withAnnotations == null) return false;
+      return !_matchesAnnotation(e.metadata, options.withAnnotations);
+    }
+
+    if (options.includeFields) {
+      for (var f in type.fields) {
+        if (f.isStatic) continue;
+        if (f.isSynthetic) continue; // exclude getters
+        if (options.excludeFinal && f.isFinal) continue;
+        if (skipBecauseOfAnnotations(f)) continue;
+        generator.addDeclaration(id, f.displayName, _typeFor(f.type.element),
+            isField: true, isFinal: f.isFinal,
+            annotations: _copyAnnotations(f));
+      }
+    }
+
+    if (options.includeProperties) {
+      for (var a in type.accessors) {
+        if (a is! PropertyAccessorElement) continue;
+        if (a.isStatic || !a.isGetter) continue;
+        var v = a.variable;
+        if (v is FieldElement && !v.isSynthetic) continue; // exclude fields
+        if (options.excludeFinal && v.isFinal) continue;
+        if (skipBecauseOfAnnotations(v)) continue;
+        generator.addDeclaration(id, v.displayName, _typeFor(v.type.element),
+            isProperty: true, isFinal: v.isFinal,
+            annotations: _copyAnnotations(a));
+      }
+    }
+
+    if (options.includeMethods) {
+      for (var m in type.methods) {
+        if (m.isStatic) continue;
+        if (skipBecauseOfAnnotations(m)) continue;
+        generator.addDeclaration(id, m.displayName,
+            new TypeIdentifier('dart:core', 'Function'), isMethod: true,
+            annotations: _copyAnnotations(m));
+      }
+    }
+  }
+
+  /// Adds the declaration of [name] if it was found in [type]. If [recursive]
+  /// is true, then we continue looking up [name] in the parent classes until we
+  /// find it or we reach Object.
+  void lookupMember(ClassElement type, String name, {bool recursive: false}) {
+    _lookupMemberInternal(type, _typeFor(type), name, recursive);
+  }
+
+  /// Helper for [lookupMember] that walks up the type hierarchy including mixin
+  /// classes.
+  bool _lookupMemberInternal(ClassElement type, TypeIdentifier id, String name,
+      bool recursive) {
+    // Exclude members from [Object].
+    if (type.type.isObject) return false;
+    generator.addEmptyDeclaration(id);
+    for (var f in type.fields) {
+      if (f.displayName != name) continue;
+      if (f.isSynthetic) continue; // exclude getters
+      generator.addDeclaration(id, f.displayName,
+          _typeFor(f.type.element), isField: true, isFinal: f.isFinal,
+          isStatic: f.isStatic, annotations: _copyAnnotations(f));
+      return true;
+    }
+
+    for (var a in type.accessors) {
+      if (a is! PropertyAccessorElement) continue;
+      // TODO(sigmund): support setters without getters.
+      if (!a.isGetter) continue;
+      if (a.displayName != name) continue;
+      var v = a.variable;
+      if (v is FieldElement && !v.isSynthetic) continue; // exclude fields
+      generator.addDeclaration(id, v.displayName,
+          _typeFor(v.type.element), isProperty: true, isFinal: v.isFinal,
+          isStatic: v.isStatic, annotations: _copyAnnotations(a));
+      return true;
+    }
+
+    for (var m in type.methods) {
+      if (m.displayName != name) continue;
+      generator.addDeclaration(id, m.displayName,
+          new TypeIdentifier('dart:core', 'Function'), isMethod: true,
+          isStatic: m.isStatic, annotations: _copyAnnotations(m));
+      return true;
+    }
+
+    if (recursive) {
+      lookupParent(type);
+      var parent = type.supertype != null ? type.supertype.element : null;
+      if (parent == null) return false;
+      var parentId = _typeFor(parent);
+      for (var m in type.mixins) {
+        var mixinClass = m.element;
+        var mixinId = _mixins[parentId][mixinClass];
+        if (_lookupMemberInternal(mixinClass, mixinId, name, false)) {
+          return true;
+        }
+        parentId = mixinId;
+      }
+      return _lookupMemberInternal(parent, parentId, name, true);
+    }
+    return false;
+  }
+
+
+  /// Copy metadata associated with the declaration of [target].
+  List<ConstExpression> _copyAnnotations(Element target) {
+    var node = target.node;
+    // [node] is the initialization expression, we walk up to get to the actual
+    // member declaration where the metadata is attached to.
+    while (node is! ClassMember) node = node.parent;
+    return node.metadata.map(_convertAnnotation).toList();
+  }
+
+  /// Converts annotations into [ConstExpression]s supported by the codegen
+  /// library.
+  ConstExpression _convertAnnotation(Annotation annotation) {
+    var element = annotation.element;
+    if (element is ConstructorElement) {
+      if (!element.name.isEmpty) {
+        throw new UnimplementedError(
+            'named constructors are not implemented in smoke.codegen.recorder');
+      }
+
+      var positionalArgs = [];
+      for (var arg in annotation.arguments.arguments) {
+        if (arg is NamedExpression) {
+          throw new UnimplementedError(
+              'named arguments in constructors are not implemented in '
+              'smoke.codegen.recorder');
+        }
+        positionalArgs.add(_convertExpression(arg));
+      }
+
+      return new ConstructorExpression(importUrlFor(element.library),
+          element.enclosingElement.name, positionalArgs, const {});
+    }
+
+    if (element is PropertyAccessorElement) {
+      return new TopLevelIdentifier(
+          importUrlFor(element.library), element.name);
+    }
+
+    throw new UnsupportedError('unsupported annotation $annotation');
+  }
+
+  /// Converts [expression] into a [ConstExpression].
+  ConstExpression _convertExpression(Expression expression) {
+    if (expression is StringLiteral) {
+      return new ConstExpression.string(expression.stringValue);
+    }
+
+    if (expression is BooleanLiteral || expression is DoubleLiteral ||
+        expression is IntegerLiteral || expression is NullLiteral) {
+      return new CodeAsConstExpression("${(expression as dynamic).value}");
+    }
+
+    if (expression is Identifier) {
+      var element = expression.bestElement;
+      if (element == null || !element.isPublic) {
+        throw new UnsupportedError('private constants are not supported');
+      }
+
+      var url = importUrlFor(element.library);
+      if (element is ClassElement) {
+        return new TopLevelIdentifier(url, element.name);
+      }
+
+      if (element is PropertyAccessorElement) {
+        var variable = element.variable;
+        if (variable is FieldElement) {
+          var cls = variable.enclosingElement;
+          return new TopLevelIdentifier(url, '${cls.name}.${variable.name}');
+        } else if (variable is TopLevelVariableElement) {
+          return new TopLevelIdentifier(url, variable.name);
+        }
+      }
+    }
+
+    throw new UnimplementedError('expression convertion not implemented in '
+        'smoke.codegen.recorder (${expression.runtimeType} $expression)');
+  }
+}
+
+/// Returns whether [metadata] contains any annotation that is either equal to
+/// an annotation in [queryAnnotations] or whose type is a subclass of a type
+/// listed in [queryAnnotations]. This is equivalent to the check done in
+/// `src/common.dart#matchesAnnotation`, except that this is applied to
+/// static metadata as it was provided by the analyzer.
+bool _matchesAnnotation(Iterable<ElementAnnotation> metadata,
+    Iterable<Element> queryAnnotations) {
+  for (var meta in metadata) {
+    var element = meta.element;
+    var exp;
+    var type;
+    if (element is PropertyAccessorElement) {
+      exp = element.variable;
+      type = exp.evaluationResult.value.type;
+    } else if (element is ConstructorElement) {
+      exp = element;
+      type = element.enclosingElement.type;
+    } else {
+      throw new UnimplementedError('Unsupported annotation: ${meta}');
+    }
+    for (var queryMeta in queryAnnotations) {
+      if (exp == queryMeta) return true;
+      if (queryMeta is ClassElement && type.isSubtypeOf(queryMeta.type)) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+/// Options equivalent to `smoke.dart#QueryOptions`, except that type
+/// information and annotations are denoted by resolver's elements.
+class QueryOptions {
+  /// Whether to include fields (default is true).
+  final bool includeFields;
+
+  /// Whether to include getters and setters (default is true). Note that to
+  /// include fields you also need to enable [includeFields].
+  final bool includeProperties;
+
+  /// Whether to include symbols from the given type and its superclasses
+  /// (except [Object]).
+  final bool includeInherited;
+
+  /// If [includeInherited], walk up the type hierarchy up to this type
+  /// (defaults to [Object]).
+  final ClassElement includeUpTo;
+
+  /// Whether to include final fields and getter-only properties.
+  final bool excludeFinal;
+
+  /// Whether to include methods (default is false).
+  final bool includeMethods;
+
+  /// If [withAnnotation] is not null, then it should be a list of types, so
+  /// only symbols that are annotated with instances of those types are
+  /// included.
+  final List<Element> withAnnotations;
+
+  const QueryOptions({
+      this.includeFields: true,
+      this.includeProperties: true,
+      this.includeInherited: true,
+      this.includeUpTo: null,
+      this.excludeFinal: false,
+      this.includeMethods: false,
+      this.withAnnotations: null});
+}