Add a public API for the results of constant evaluation

pkg/analyzer/lib/src/generated/element.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.
 
 library engine.element;
 
 import 'dart:collection';
 import 'dart:math' show min;
 
 import 'package:analyzer/src/generated/utilities_general.dart';
 import 'package:analyzer/src/task/dart.dart';
 import 'package:analyzer/task/model.dart'
     show AnalysisTarget, ConstantEvaluationTarget;
 
 import 'ast.dart';
-import 'constant.dart' show EvaluationResultImpl;
+import 'constant.dart' show DartObject, EvaluationResultImpl;
 import 'engine.dart' show AnalysisContext, AnalysisEngine, AnalysisException;
 import 'html.dart' show XmlAttributeNode, XmlTagNode;
 import 'java_core.dart';
 import 'java_engine.dart';
 import 'resolver.dart';
 import 'scanner.dart' show Keyword;
 import 'sdk.dart' show DartSdk;
 import 'source.dart';
 import 'utilities_collection.dart';
 import 'utilities_dart.dart';
@@ skipping 1726 matching lines @@
    */
   @deprecated // Use new ConstFieldElementImpl(name, offset)
   ConstFieldElementImpl.con2(String name, int offset) : super(name, offset);
 
   /**
    * Initialize a newly created field element to have the given [name].
    */
   ConstFieldElementImpl.forNode(Identifier name) : super.forNode(name);
 
   @override
+  DartObject get constantValue => _result.value;
+
+  @override
   EvaluationResultImpl get evaluationResult => _result;
 
   @override
   void set evaluationResult(EvaluationResultImpl result) {
     this._result = result;
   }
 }
 
 /**
  * A [LocalVariableElement] for a local 'const' variable that has an
@@ skipping 11 matching lines @@
    * and [offset].
    */
   ConstLocalVariableElementImpl(String name, int offset) : super(name, offset);
 
   /**
    * Initialize a newly created local variable element to have the given [name].
    */
   ConstLocalVariableElementImpl.forNode(Identifier name) : super.forNode(name);
 
   @override
+  DartObject get constantValue => _result.value;
+
+  @override
   EvaluationResultImpl get evaluationResult => _result;
 
   @override
   void set evaluationResult(EvaluationResultImpl result) {
     this._result = result;
   }
 }
 
 /**
  * An element representing a constructor or a factory method defined within a
@@ skipping 298 matching lines @@
    */
   EvaluationResultImpl _result;
 
   /**
    * Initialize a newly created top-level variable element to have the given
    * [name].
    */
   ConstTopLevelVariableElementImpl(Identifier name) : super.forNode(name);
 
   @override
+  DartObject get constantValue => _result.value;
+
+  @override
   EvaluationResultImpl get evaluationResult => _result;
 
   @override
   void set evaluationResult(EvaluationResultImpl result) {
     this._result = result;
   }
 }
 
 /**
  * Mixin used by elements that represent constant variables and have
@@ skipping 144 matching lines @@
    * The result of evaluating this variable's initializer.
    */
   EvaluationResultImpl _result;
 
   /**
    * Initialize a newly created parameter element to have the given [name].
    */
   DefaultFieldFormalParameterElementImpl(Identifier name) : super(name);
 
   @override
+  DartObject get constantValue => _result.value;
+
+  @override
   EvaluationResultImpl get evaluationResult => _result;
 
   @override
   void set evaluationResult(EvaluationResultImpl result) {
     this._result = result;
   }
 }
 
 /**
  * A [ParameterElement] for parameters that have an initializer.
  */
 class DefaultParameterElementImpl extends ParameterElementImpl
     with ConstVariableElement {
   /**
    * The result of evaluating this variable's initializer.
    */
   EvaluationResultImpl _result;
 
   /**
    * Initialize a newly created parameter element to have the given [name].
    */
   DefaultParameterElementImpl(Identifier name) : super.forNode(name);
 
   @override
+  DartObject get constantValue => _result.value;
+
+  @override
   EvaluationResultImpl get evaluationResult => _result;
 
   @override
   void set evaluationResult(EvaluationResultImpl result) {
     this._result = result;
   }
 
   @override
   DefaultFormalParameter computeNode() =>
       getNodeMatching((node) => node is DefaultFormalParameter);
@@ skipping 342 matching lines @@
 /**
  * A single annotation associated with an element.
  */
 abstract class ElementAnnotation {
   /**
    * An empty list of annotations.
    */
   static const List<ElementAnnotation> EMPTY_LIST = const <ElementAnnotation>[];
 
   /**
+   * Return a representation of the value of this annotation.
+   *
+   * Return `null` if the value of this annotation could not be computed because
+   * of errors.
+   */
+  DartObject get constantValue;
+
+  /**
    * Return the element representing the field, variable, or const constructor
    * being used as an annotation.
    */
   Element get element;
 
   /**
    * Return `true` if this annotation marks the associated element as being
    * deprecated.
    */
   bool get isDeprecated;
@@ skipping 59 matching lines @@
   EvaluationResultImpl evaluationResult;
 
   /**
    * Initialize a newly created annotation. The given [element] is the element
    * representing the field, variable, or constructor being used as an
    * annotation.
    */
   ElementAnnotationImpl(this.element);
 
   @override
+  DartObject get constantValue => evaluationResult.value;
+
+  @override
   bool get isDeprecated {
     if (element != null) {
       LibraryElement library = element.library;
       if (library != null && library.isDartCore) {
         if (element is ConstructorElement) {
           ConstructorElement constructorElement = element as ConstructorElement;
           if (constructorElement.enclosingElement.name ==
               _DEPRECATED_CLASS_NAME) {
             return true;
           }
@@ skipping 7852 matching lines @@
 /**
  * A variable. There are concrete subclasses for different kinds of variables.
  */
 abstract class VariableElement implements Element, ConstantEvaluationTarget {
   /**
    * An empty list of variable elements.
    */
   static const List<VariableElement> EMPTY_LIST = const <VariableElement>[];
 
   /**
+   * Return a representation of the value of this variable.
+   *
+   * Return `null` if either this variable was not declared with the 'const'
+   * modifier or if the value of this variable could not be computed because of
+   * errors.
+   */
+  DartObject get constantValue;
+
+  /**
    * Return `true` if this variable element did not have an explicit type
    * specified for it.
    */
   bool get hasImplicitType;
 
   /**
    * Return a synthetic function representing this variable's initializer, or
    * `null` if this variable does not have an initializer. The function will
    * have no parameters. The return type of the function will be the
    * compile-time type of the initialization expression.
@@ skipping 82 matching lines @@
    */
   VariableElementImpl.forNode(Identifier name) : super.forNode(name);
 
   /**
    * Set whether this variable is const.
    */
   void set const3(bool isConst) {
     setModifier(Modifier.CONST, isConst);
   }
 
+  @override
+  DartObject get constantValue => null;
+
   /**
    * Return the result of evaluating this variable's initializer as a
    * compile-time constant expression, or `null` if this variable is not a
    * 'const' variable, if it does not have an initializer, or if the compilation
    * unit containing the variable has not been resolved.
    */
   EvaluationResultImpl get evaluationResult => null;
 
   /**
    * Set the result of evaluating this variable's initializer as a compile-time
@@ skipping 192 matching lines @@
 
   @override
   void visitElement(Element element) {
     int offset = element.nameOffset;
     if (offset != -1) {
       map[offset] = element;
     }
     super.visitElement(element);
   }
 }