Revert "Revert "Allow patch files to add top-level declarations to the patched library.""

lib/compiler/implementation/elements/elements.dart

 // Copyright (c) 2012, 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.
 
 #library('elements');
 
 #import('../tree/tree.dart');
 #import('../scanner/scannerlib.dart');
 #import('../leg.dart');  // TODO(karlklose): we only need type.
 #import('../util/util.dart');
@@ skipping 65 matching lines @@
   static final ElementKind GETTER =
     const ElementKind('getter', ElementCategory.NONE);
   static final ElementKind SETTER =
     const ElementKind('setter', ElementCategory.NONE);
   static final ElementKind TYPE_VARIABLE =
     const ElementKind('type_variable', ElementCategory.TYPE_VARIABLE);
   static final ElementKind ABSTRACT_FIELD =
     const ElementKind('abstract_field', ElementCategory.VARIABLE);
   static final ElementKind LIBRARY =
     const ElementKind('library', ElementCategory.NONE);
+  static final ElementKind COMPILATION_UNIT_OVERRIDE =
+    const ElementKind('compilation_unit_override', ElementCategory.NONE);
   static final ElementKind PREFIX =
     const ElementKind('prefix', ElementCategory.PREFIX);
   static final ElementKind TYPEDEF =
     const ElementKind('typedef', ElementCategory.ALIAS);
 
   static final ElementKind STATEMENT =
     const ElementKind('statement', ElementCategory.NONE);
   static final ElementKind LABEL =
     const ElementKind('label', ElementCategory.NONE);
   static final ElementKind VOID =
     const ElementKind('void', ElementCategory.NONE);
 
   toString() => id;
 }
 
 class Element implements Hashable {
   final SourceString name;
   final ElementKind kind;
   final Element enclosingElement;
   Link<Node> metadata = const EmptyLink<Node>();
+
+
+  Element(this.name, this.kind, this.enclosingElement) {
+    assert(getLibrary() !== null);
+  }
+
   Modifiers get modifiers() => null;
 
   Node parseNode(DiagnosticListener listener) {
     listener.cancel("Internal Error: $this.parseNode", token: position());
   }
 
   Type computeType(Compiler compiler) {
     compiler.internalError("$this.computeType.", token: position());
   }
 
   void addMetadata(Node node) {
     metadata = metadata.prepend(node);
   }
 
   bool isFunction() => kind === ElementKind.FUNCTION;
   bool isConstructor() => isFactoryConstructor() || isGenerativeConstructor();
   bool isClosure() => false;
   bool isMember() {
     // Check that this element is defined in the scope of a Class.
     Element enclosing = enclosingElement;
+    if (enclosing !== null &&
+        enclosing.kind === ElementKind.COMPILATION_UNIT_OVERRIDE) {
+      enclosing = enclosing.enclosingElement;
+    }
     // TODO(lrn): Skip any synthetic elements inserted, e.g.,
     // a compilation unit override.
     return enclosing !== null && enclosing.isClass();
   }
   bool isInstanceMember() => false;
   bool isFactoryConstructor() => modifiers !== null && modifiers.isFactory();
   bool isGenerativeConstructor() => kind === ElementKind.GENERATIVE_CONSTRUCTOR;
   bool isGenerativeConstructorBody() =>
       kind === ElementKind.GENERATIVE_CONSTRUCTOR_BODY;
   bool isCompilationUnit() {
     return kind === ElementKind.COMPILATION_UNIT ||
-           kind === ElementKind.LIBRARY;
+           kind === ElementKind.LIBRARY ||
+           kind === ElementKind.COMPILATION_UNIT_OVERRIDE;
   }
+  /**
+   * Provides the compilation unit corresponding to this element.
+   * Returns non-null for elements where [isCompilationUnit] returns true,
+   * but may not return the current [Element].
+   */
+  CompilationUnitElement asCompilationUnit() => null;
   bool isClass() => kind === ElementKind.CLASS;
   bool isPrefix() => kind === ElementKind.PREFIX;
   bool isVariable() => kind === ElementKind.VARIABLE;
   bool isParameter() => kind === ElementKind.PARAMETER;
   bool isStatement() => kind === ElementKind.STATEMENT;
   bool isTypedef() => kind === ElementKind.TYPEDEF;
   bool isTypeVariable() => kind === ElementKind.TYPE_VARIABLE;
   bool isField() => kind === ElementKind.FIELD;
   bool isGetter() => kind === ElementKind.GETTER;
   bool isSetter() => kind === ElementKind.SETTER;
@@ skipping 17 matching lines @@
 
   Token position() => null;
 
   Token findMyName(Token token) {
     for (Token t = token; t.kind !== EOF_TOKEN; t = t.next) {
       if (t.value == name) return t;
     }
     return token;
   }
 
-  Element(this.name, this.kind, this.enclosingElement) {
-    assert(getLibrary() !== null);
-  }
-
   // TODO(kasperl): This is a very bad hash code for the element and
   // there's no reason why two elements with the same name should have
   // the same hash code. Replace this with a simple id in the element?
   int hashCode() => name === null ? 0 : name.hashCode();
 
+  Script getScript() {
+    return getCompilationUnit().script;
+  }
+
   CompilationUnitElement getCompilationUnit() {
     Element element = this;
     while (element !== null && !element.isCompilationUnit()) {
       element = element.enclosingElement;
     }
-    return element;
+    return element.asCompilationUnit();
   }
 
   LibraryElement getLibrary() {
     Element element = this;
     while (element.kind !== ElementKind.LIBRARY) {
       element = element.enclosingElement;
     }
     return element;
   }
 
@@ skipping 44 matching lines @@
     } else {
       return '$kind(${nameText})';
     }
   }
 
   bool _isNative = false;
   void setNative() { _isNative = true; }
   bool isNative() => _isNative;
 
   FunctionElement asFunctionElement() => null;
+
+  Element cloneTo(Element enclosing, DiagnosticListener listener) {
+    listener.cancel("Unimplemented cloneTo", element: this);
+  }
 }
 
 class ContainerElement extends Element {
   ContainerElement(name, kind, enclosingElement) :
     super(name, kind, enclosingElement);
 
   abstract void addMember(Element element, DiagnosticListener listener);
 
   void addGetterOrSetter(Element element,
                          Element existing,
@@ skipping 40 matching lines @@
   CompilationUnitElement(Script script, Element enclosing)
     : this.script = script,
       super(new SourceString(script.name),
             ElementKind.COMPILATION_UNIT,
             enclosing);
 
   CompilationUnitElement.library(Script script)
     : this.script = script,
       super(new SourceString(script.name), ElementKind.LIBRARY, null);
 
+  CompilationUnitElement asCompilationUnit() => this;
+
   void addMember(Element element, DiagnosticListener listener) {
     LibraryElement library = enclosingElement;
     library.addMember(element, listener);
     topLevelElements = topLevelElements.prepend(element);
   }
 
   void define(Element element, DiagnosticListener listener) {
     LibraryElement library = enclosingElement;
     library.define(element, listener);
   }
 
   void addTag(ScriptTag tag, DiagnosticListener listener) {
     listener.cancel("script tags not allowed here", node: tag);
   }
 }
 
+class CompilationUnitOverrideElement extends Element {
+  final CompilationUnitElement compilationUnit;
+
+  CompilationUnitOverrideElement(CompilationUnitElement compilationUnit,
+                                 Element enclosing)
+      : this.compilationUnit = compilationUnit,
+        super(compilationUnit.name,
+              ElementKind.COMPILATION_UNIT_OVERRIDE,
+              enclosing);
+
+  CompilationUnitElement asCompilationUnit() => compilationUnit;
+}
+
 class LibraryElement extends CompilationUnitElement {
   // TODO(ahe): Library element should not be a subclass of
   // CompilationUnitElement.
 
   Link<CompilationUnitElement> compilationUnits =
     const EmptyLink<CompilationUnitElement>();
   Link<ScriptTag> tags = const EmptyLink<ScriptTag>();
   ScriptTag libraryTag;
   Map<SourceString, Element> elements;
   bool canUseNative = false;
@@ skipping 72 matching lines @@
       return path.substring(path.lastIndexOf('/') + 1);
     }
   }
 
   Scope buildEnclosingScope() => new TopScope(this);
 }
 
 class PrefixElement extends Element {
   Map<SourceString, Element> imported;
   Token firstPosition;
-  final CompilationUnitElement patchSource;
 
-  PrefixElement(SourceString prefix, Element enclosing, this.firstPosition,
-                [this.patchSource])
-    : imported = new Map<SourceString, Element>(),
-      super(prefix, ElementKind.PREFIX, enclosing);
-
-  CompilationUnitElement getCompilationUnit() {
-    if (patchSource !== null) return patchSource;
-    return super.getCompilationUnit();
-  }
+  PrefixElement(SourceString prefix, Element enclosing, this.firstPosition)
+      : imported = new Map<SourceString, Element>(),
+        super(prefix, ElementKind.PREFIX, enclosing);
 
   lookupLocalMember(SourceString memberName) => imported[memberName];
 
   Type computeType(Compiler compiler) => compiler.types.dynamicType;
 
   Token position() => firstPosition;
+
+  PrefixElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    return new PrefixElement(name, enclosing, firstPosition);
+  }
 }
 
 class TypedefElement extends Element implements TypeDeclarationElement {
   Type cachedType;
   Typedef cachedNode;
 
   TypedefElement(SourceString name, Element enclosing)
       : super(name, ElementKind.TYPEDEF, enclosing);
 
   Type computeType(Compiler compiler) {
     if (cachedType !== null) return cachedType;
     cachedType = compiler.computeFunctionType(
         this, compiler.resolveTypedef(this));
     return cachedType;
   }
 
   Link<Type> get typeVariables() => const EmptyLink<Type>();
 
   Scope buildScope() =>
       new TypeDeclarationScope(enclosingElement.buildScope(), this);
+
+  TypedefElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    TypedefElement result = new TypedefElement(name, enclosing);
+    return result;
+  }
 }
 
 class VariableElement extends Element {
   final VariableListElement variables;
   Expression cachedNode; // The send or the identifier in the variables list.
 
   Modifiers get modifiers() => variables.modifiers;
 
   VariableElement(SourceString name,
                   VariableListElement this.variables,
@@ skipping 26 matching lines @@
 
   Type get type() => variables.type;
 
   bool isInstanceMember() {
     return isMember() && !modifiers.isStatic();
   }
 
   // Note: cachedNode.getBeginToken() will not be correct in all
   // cases, for example, for function typed parameters.
   Token position() => findMyName(variables.position());
+
+  VariableElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    VariableListElement clonedVariables =
+        variables.cloneTo(enclosing, listener);
+    VariableElement result = new VariableElement(
+        name, clonedVariables, kind, enclosing, cachedNode);
+    return result;
+  }
 }
 
 /**
  * Parameters in constructors that directly initialize fields. For example:
  * [:A(this.field):].
  */
 class FieldParameterElement extends VariableElement {
   VariableElement fieldElement;
 
   FieldParameterElement(SourceString name,
                         this.fieldElement,
                         VariableListElement variables,
                         Element enclosing,
                         Node node)
       : super(name, variables, ElementKind.FIELD_PARAMETER, enclosing, node);
+
+  FieldParameterElement cloneTo(Element enclosing,
+                                DiagnosticListener listener) {
+    FieldParameterElement result =
+      new FieldParameterElement(name, fieldElement,
+                                variables.cloneTo(enclosing, listener),
+                                enclosing, cachedNode);
+    return result;
+  }
 }
 
 // This element represents a list of variable or field declaration.
 // It contains the node, and the type. A [VariableElement] always
 // references its [VariableListElement]. It forwards its
 // [computeType] and [parseNode] methods to this element.
 class VariableListElement extends Element {
   VariableDefinitions cachedNode;
   Type type;
   final Modifiers modifiers;
@@ skipping 42 matching lines @@
                                             functionSignature);
       } else {
         type = compiler.types.dynamicType;
       }
     }
     assert(type != null);
     return type;
   }
 
   Token position() => cachedNode.getBeginToken();
+
+  VariableListElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    VariableListElement result;
+    if (cachedNode !== null) {
+      result = new VariableListElement(cachedNode, kind, enclosing);
+    } else {
+      result = new VariableListElement(kind, modifiers, enclosing);
+    }
+    return result;
+  }
 }
 
 class ForeignElement extends Element {
   ForeignElement(SourceString name, ContainerElement enclosingElement)
     : super(name, ElementKind.FOREIGN, enclosingElement);
 
   Type computeType(Compiler compiler) {
     return compiler.types.dynamicType;
   }
 
   parseNode(DiagnosticListener listener) {
     throw "internal error: ForeignElement has no node";
   }
+
+  ForeignElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    ForeignElement result = new ForeignElement(name, kind, enclosing);
+    return result;
+  }
 }
 
 class AbstractFieldElement extends Element {
   FunctionElement getter;
   FunctionElement setter;
 
   AbstractFieldElement(SourceString name, Element enclosing)
       : super(name, ElementKind.ABSTRACT_FIELD, enclosing);
 
   Type computeType(Compiler compiler) {
@@ skipping 24 matching lines @@
     if (getter !== null) {
       return new Modifiers.withFlags(
           getter.modifiers.nodes,
           getter.modifiers.flags | Modifiers.FLAG_ABSTRACT);
     } else {
       return new Modifiers.withFlags(
           setter.modifiers.nodes,
           setter.modifiers.flags | Modifiers.FLAG_ABSTRACT);
     }
   }
+
+  AbstractFieldElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    listener.cancel("Cannot clone synthetic AbstractFieldElement",
+                    element: this);
+  }
 }
 
 // TODO(johnniwinther): [FunctionSignature] should be merged with
 // [FunctionType].
 class FunctionSignature {
   Link<Element> requiredParameters;
   Link<Element> optionalParameters;
   Type returnType;
   int requiredParameterCount;
   int optionalParameterCount;
@@ skipping 64 matching lines @@
   FunctionElement.tooMuchOverloading(SourceString name,
                                      FunctionExpression this.cachedNode,
                                      ElementKind kind,
                                      Modifiers this.modifiers,
                                      Element enclosing,
                                      FunctionSignature this.functionSignature)
       : super(name, kind, enclosing) {
     defaultImplementation = this;
   }
 
-  CompilationUnitElement getCompilationUnit() {
-    if (patch !== null) return patch.getCompilationUnit();
-    return super.getCompilationUnit();
+  Script getScript() {
+    if (patch !== null) return patch.getScript();
+    return super.getScript();
   }
 
   bool get isPatched() => patch !== null;
 
   /**
    * Applies a patch function to this function. The patch function's body
    * is used as replacement when parsing this function's body.
    * This method must not be called after the function has been parsed,
    * and it must be called at most once.
    */
@@ skipping 47 matching lines @@
       }
       return null;
     }
     cachedNode = patch.parseNode(listener);
     return cachedNode;
   }
 
   Token position() => cachedNode.getBeginToken();
 
   FunctionElement asFunctionElement() => this;
+
+  FunctionElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    FunctionElement result = new FunctionElement.tooMuchOverloading(
+        name, cachedNode, kind, modifiers, enclosing, functionSignature);
+    result.defaultImplementation = defaultImplementation;
+    result.type = type;
+    return result;
+  }
 }
 
+
 class ConstructorBodyElement extends FunctionElement {
   FunctionElement constructor;
 
   ConstructorBodyElement(FunctionElement constructor)
       : this.constructor = constructor,
         super(constructor.name,
               ElementKind.GENERATIVE_CONSTRUCTOR_BODY,
               null,
               constructor.enclosingElement) {
     functionSignature = constructor.functionSignature;
   }
 
   bool isInstanceMember() => true;
 
   FunctionType computeType(Compiler compiler) {
     compiler.reportFatalError('Internal error: $this.computeType', this);
   }
 
   Node parseNode(DiagnosticListener listener) {
     if (cachedNode !== null) return cachedNode;
     cachedNode = constructor.parseNode(listener);
     assert(cachedNode !== null);
     return cachedNode;
   }
 
   Token position() => constructor.position();
+
+  ConstructorBodyElement cloneTo(Element enclosing,
+                                 DiagnosticListener listener) {
+    ConstructorBodyElement result =
+      new ConstructorBodyElement(constructor.cloneTo(enclosing, listener));
+    return result;
+  }
 }
 
 class SynthesizedConstructorElement extends FunctionElement {
   SynthesizedConstructorElement(Element enclosing)
     : super(enclosing.name, ElementKind.GENERATIVE_CONSTRUCTOR,
             null, enclosing);
 
   Token position() => enclosingElement.position();
+
+  SynthesizedConstructorElement cloneTo(Element enclosing,
+                                        DiagnosticListener listener) {
+    return new SynthesizedConstructorElement(enclosing);
+  }
 }
 
 class VoidElement extends Element {
   VoidElement(Element enclosing)
       : super(const SourceString('void'), ElementKind.VOID, enclosing);
   Type computeType(compiler) => compiler.types.voidType;
   Node parseNode(_) {
     throw 'internal error: parseNode on void';
   }
   bool impliesType() => true;
@@ skipping 42 matching lines @@
 class ClassElement extends ContainerElement
     implements TypeDeclarationElement {
   final int id;
   InterfaceType type;
   Type supertype;
   Type defaultClass;
   Link<Element> members = const EmptyLink<Element>();
   Map<SourceString, Element> localMembers;
   Map<SourceString, Element> constructors;
   Link<Type> interfaces = const EmptyLink<Type>();
+
+  LinkedHashMap<SourceString, TypeVariableElement> typeParameters;
+  SourceString nativeName;
+
   bool isResolved = false;
   bool isBeingResolved = false;
   // backendMembers are members that have been added by the backend to simplify
   // compilation. They don't have any user-side counter-part.
   Link<Element> backendMembers = const EmptyLink<Element>();
 
   Link<Type> allSupertypes;
-  ClassElement patch = null;
 
-  ClassElement(SourceString name, CompilationUnitElement enclosing, this.id)
+  ClassElement(SourceString name, Element enclosing, this.id)
     : localMembers = new Map<SourceString, Element>(),
       constructors = new Map<SourceString, Element>(),
       super(name, ElementKind.CLASS, enclosing);
 
   void addMember(Element element, DiagnosticListener listener) {
     members = members.prepend(element);
     if (element.kind == ElementKind.GENERATIVE_CONSTRUCTOR ||
         element.modifiers.isFactory()) {
       constructors[element.name] = element;
     } else if (element.kind == ElementKind.GETTER
@@ skipping 67 matching lines @@
       // lookupMember will work.
       while (lookupClass.getLibrary() != memberLibrary) {
         lookupClass = lookupClass.superclass;
       }
     }
     SourceString fieldName = fieldMember.name;
     while (true) {
       Element foundMember = lookupClass.lookupMember(fieldName);
       if (foundMember == fieldMember) return false;
       if (foundMember.isField()) return true;
-      lookupClass = (foundMember.enclosingElement as ClassElement).superclass;
+      lookupClass = foundMember.getEnclosingClass().superclass;
     }
   }
 
   Element lookupConstructor(SourceString className,
                             [SourceString constructorName =
                                  const SourceString(''),
                             Element noMatch(Element)]) {
     // TODO(karlklose): have a map from class names to a map of constructors
     //                  instead of creating the name here?
     SourceString normalizedName;
@@ skipping 88 matching lines @@
    */
   bool isSubclassOf(ClassElement cls) {
     for (ClassElement s = this; s != null; s = s.superclass) {
       if (s === cls) return true;
     }
     return false;
   }
 
   bool isInterface() => false;
   bool isNative() => nativeName != null;
-  SourceString nativeName;
   int hashCode() => id;
 
   Scope buildScope() =>
       new ClassScope(enclosingElement.buildScope(), this);
+
+  void cloneMembersTo(Element target, DiagnosticListener listener) {
+    target.type = type;
+    target.supertype = supertype;
+    target.defaultClass = defaultClass;
+    target.interfaces = interfaces;
+    if (typeParameters !== null) {
+      target.typeParameters =
+          new LinkedHashMap<SourceString, TypeVariableElement>();
+      typeParameters.forEach((SourceString name, TypeVariableElement type) {
+        target.typeParameters[name] = type.cloneTo(target, listener);
+      });
+    }
+    target.nativeName = nativeName;
+    target.isResolved = isResolved;
+    target.isBeingResolved = isBeingResolved;
+    target.allSupertypes = allSupertypes;
+    if (!backendMembers.isEmpty()) {
+      listener.cancel("Cloning backend-modified class.", element: this);
+    }
+
+    Link<Element> elementList = this.members;
+    while (!elementList.isEmpty()) {
+      target.addMember(elementList.head.cloneTo(target, listener), listener);
+      elementList = elementList.tail;
+    }
+  }
+
+  ClassElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    // TODO(lrn): Is copying id acceptable?
+    ClassElement result = new ClassElement(name, enclosing, id);
+    cloneMembersTo(result, listener);
+    return result;
+  }
 }
 
 class Elements {
   static bool isLocal(Element element) {
     return ((element !== null)
             && !element.isInstanceMember()
             && !isStaticOrTopLevelField(element)
             && !isStaticOrTopLevelFunction(element)
             && (element.kind === ElementKind.VARIABLE ||
                 element.kind === ElementKind.PARAMETER ||
@@ skipping 99 matching lines @@
         || (element == coreLibrary.find(const SourceString('Pattern')));
   }
 
   static bool isListSupertype(Element element, Compiler compiler) {
     LibraryElement coreLibrary = compiler.coreLibrary;
     return (element == coreLibrary.find(const SourceString('Collection')))
         || (element == coreLibrary.find(const SourceString('Iterable')));
   }
 }
 
-
 class LabelElement extends Element {
   // We store the original label here so it can be returned by [parseNode].
   final Label label;
   final String labelName;
   final TargetElement target;
   bool isBreakTarget = false;
   bool isContinueTarget = false;
   LabelElement(Label label, this.labelName, this.target,
                Element enclosingElement)
       : this.label = label,
@@ skipping 50 matching lines @@
 
   TypeVariableElement(name, Element enclosing, this.cachedNode,
                       [this.type, this.bound])
     : super(name, ElementKind.TYPE_VARIABLE, enclosing);
 
   TypeVariableType computeType(compiler) => type;
 
   Node parseNode(compiler) => cachedNode;
 
   String toString() => "${enclosingElement.toString()}.${name.slowToString()}";
+
+  TypeVariableElement cloneTo(Element enclosing, DiagnosticListener listener) {
+    TypeVariableElement result =
+        new TypeVariableElement(name, enclosing, node, type, bound);
+    return result;
+  }
 }