Move constant implementation out of generated

pkg/analyzer/lib/src/dart/constant/utilities.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 analyzer.src.dart.constant.utilities;
+
+import 'dart:collection';
+
+import 'package:analyzer/dart/ast/ast.dart';
+import 'package:analyzer/dart/ast/visitor.dart';
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/src/dart/ast/utilities.dart';
+import 'package:analyzer/src/dart/element/element.dart';
+import 'package:analyzer/src/dart/element/handle.dart'
+    show ConstructorElementHandle;
+import 'package:analyzer/src/dart/element/member.dart';
+import 'package:analyzer/src/generated/engine.dart';
+import 'package:analyzer/src/generated/source.dart' show Source;
+import 'package:analyzer/src/task/dart.dart';
+
+ConstructorElementImpl getConstructorImpl(ConstructorElement constructor) {
+  while (constructor is ConstructorMember) {
+    constructor = (constructor as ConstructorMember).baseElement;
+  }
+  if (constructor is ConstructorElementHandle) {
+    constructor = (constructor as ConstructorElementHandle).actualElement;
+  }
+  return constructor;
+}
+
+/**
+ * Callback used by [ReferenceFinder] to report that a dependency was found.
+ */
+typedef void ReferenceFinderCallback(ConstantEvaluationTarget dependency);
+
+/**
+ * An [AstCloner] that copies the necessary information from the AST to allow
+ * constants to be evaluated.
+ */
+class ConstantAstCloner extends AstCloner {
+  ConstantAstCloner() : super(true);
+
+  @override
+  ConstructorName visitConstructorName(ConstructorName node) {
+    ConstructorName name = super.visitConstructorName(node);
+    name.staticElement = node.staticElement;
+    return name;
+  }
+
+  @override
+  InstanceCreationExpression visitInstanceCreationExpression(
+      InstanceCreationExpression node) {
+    InstanceCreationExpression expression =
+        super.visitInstanceCreationExpression(node);
+    expression.staticElement = node.staticElement;
+    return expression;
+  }
+
+  @override
+  RedirectingConstructorInvocation visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
+    RedirectingConstructorInvocation invocation =
+        super.visitRedirectingConstructorInvocation(node);
+    invocation.staticElement = node.staticElement;
+    return invocation;
+  }
+
+  @override
+  SimpleIdentifier visitSimpleIdentifier(SimpleIdentifier node) {
+    SimpleIdentifier identifier = super.visitSimpleIdentifier(node);
+    identifier.staticElement = node.staticElement;
+    return identifier;
+  }
+
+  @override
+  SuperConstructorInvocation visitSuperConstructorInvocation(
+      SuperConstructorInvocation node) {
+    SuperConstructorInvocation invocation =
+        super.visitSuperConstructorInvocation(node);
+    invocation.staticElement = node.staticElement;
+    return invocation;
+  }
+
+  @override
+  TypeName visitTypeName(TypeName node) {
+    TypeName typeName = super.visitTypeName(node);
+    typeName.type = node.type;
+    return typeName;
+  }
+}
+
+/**
+ * A visitor used to traverse the AST structures of all of the compilation units
+ * being resolved and build the full set of dependencies for all constant
+ * expressions.
+ */
+class ConstantExpressionsDependenciesFinder extends RecursiveAstVisitor {
+  /**
+   * The constants whose values need to be computed.
+   */
+  HashSet<ConstantEvaluationTarget> dependencies =
+      new HashSet<ConstantEvaluationTarget>();
+
+  @override
+  void visitInstanceCreationExpression(InstanceCreationExpression node) {
+    if (node.isConst) {
+      _find(node);
+    } else {
+      super.visitInstanceCreationExpression(node);
+    }
+  }
+
+  @override
+  void visitListLiteral(ListLiteral node) {
+    if (node.constKeyword != null) {
+      _find(node);
+    } else {
+      super.visitListLiteral(node);
+    }
+  }
+
+  @override
+  void visitMapLiteral(MapLiteral node) {
+    if (node.constKeyword != null) {
+      _find(node);
+    } else {
+      super.visitMapLiteral(node);
+    }
+  }
+
+  @override
+  void visitSwitchCase(SwitchCase node) {
+    _find(node.expression);
+    node.statements.accept(this);
+  }
+
+  void _find(Expression node) {
+    if (node != null) {
+      ReferenceFinder referenceFinder = new ReferenceFinder(dependencies.add);
+      node.accept(referenceFinder);
+    }
+  }
+}
+
+/**
+ * A visitor used to traverse the AST structures of all of the compilation units
+ * being resolved and build tables of the constant variables, constant
+ * constructors, constant constructor invocations, and annotations found in
+ * those compilation units.
+ */
+class ConstantFinder extends RecursiveAstVisitor<Object> {
+  final AnalysisContext context;
+  final Source source;
+  final Source librarySource;
+
+  /**
+   * The elements and AST nodes whose constant values need to be computed.
+   */
+  List<ConstantEvaluationTarget> constantsToCompute =
+      <ConstantEvaluationTarget>[];
+
+  /**
+   * A flag indicating whether instance variables marked as "final" should be
+   * treated as "const".
+   */
+  bool treatFinalInstanceVarAsConst = false;
+
+  ConstantFinder(this.context, this.source, this.librarySource);
+
+  @override
+  Object visitAnnotation(Annotation node) {
+    super.visitAnnotation(node);
+    ElementAnnotation elementAnnotation = node.elementAnnotation;
+    if (elementAnnotation == null) {
+      // Analyzer ignores annotations on "part of" directives.
+      assert(node.parent is PartOfDirective);
+    } else {
+      constantsToCompute.add(elementAnnotation);
+    }
+    return null;
+  }
+
+  @override
+  Object visitClassDeclaration(ClassDeclaration node) {
+    bool prevTreatFinalInstanceVarAsConst = treatFinalInstanceVarAsConst;
+    if (node.element.constructors.any((ConstructorElement e) => e.isConst)) {
+      // Instance vars marked "final" need to be included in the dependency
+      // graph, since constant constructors implicitly use the values in their
+      // initializers.
+      treatFinalInstanceVarAsConst = true;
+    }
+    try {
+      return super.visitClassDeclaration(node);
+    } finally {
+      treatFinalInstanceVarAsConst = prevTreatFinalInstanceVarAsConst;
+    }
+  }
+
+  @override
+  Object visitConstructorDeclaration(ConstructorDeclaration node) {
+    super.visitConstructorDeclaration(node);
+    if (node.constKeyword != null) {
+      ConstructorElement element = node.element;
+      if (element != null) {
+        constantsToCompute.add(element);
+        constantsToCompute.addAll(element.parameters);
+      }
+    }
+    return null;
+  }
+
+  @override
+  Object visitDefaultFormalParameter(DefaultFormalParameter node) {
+    super.visitDefaultFormalParameter(node);
+    Expression defaultValue = node.defaultValue;
+    if (defaultValue != null && node.element != null) {
+      constantsToCompute.add(node.element);
+    }
+    return null;
+  }
+
+  @override
+  Object visitVariableDeclaration(VariableDeclaration node) {
+    super.visitVariableDeclaration(node);
+    Expression initializer = node.initializer;
+    VariableElement element = node.element;
+    if (initializer != null &&
+        (node.isConst ||
+            treatFinalInstanceVarAsConst &&
+                element is FieldElement &&
+                node.isFinal &&
+                !element.isStatic)) {
+      if (element != null) {
+        constantsToCompute.add(element);
+      }
+    }
+    return null;
+  }
+}
+
+/**
+ * An object used to add reference information for a given variable to the
+ * bi-directional mapping used to order the evaluation of constants.
+ */
+class ReferenceFinder extends RecursiveAstVisitor<Object> {
+  /**
+   * The callback which should be used to report any dependencies that were
+   * found.
+   */
+  final ReferenceFinderCallback _callback;
+
+  /**
+   * Initialize a newly created reference finder to find references from a given
+   * variable to other variables and to add those references to the given graph.
+   * The [_callback] will be invoked for every dependency found.
+   */
+  ReferenceFinder(this._callback);
+
+  @override
+  Object visitInstanceCreationExpression(InstanceCreationExpression node) {
+    if (node.isConst) {
+      ConstructorElement constructor = getConstructorImpl(node.staticElement);
+      if (constructor != null) {
+        _callback(constructor);
+      }
+    }
+    return super.visitInstanceCreationExpression(node);
+  }
+
+  @override
+  Object visitLabel(Label node) {
+    // We are visiting the "label" part of a named expression in a function
+    // call (presumably a constructor call), e.g. "const C(label: ...)".  We
+    // don't want to visit the SimpleIdentifier for the label because that's a
+    // reference to a function parameter that needs to be filled in; it's not a
+    // constant whose value we depend on.
+    return null;
+  }
+
+  @override
+  Object visitRedirectingConstructorInvocation(
+      RedirectingConstructorInvocation node) {
+    super.visitRedirectingConstructorInvocation(node);
+    ConstructorElement target = getConstructorImpl(node.staticElement);
+    if (target != null) {
+      _callback(target);
+    }
+    return null;
+  }
+
+  @override
+  Object visitSimpleIdentifier(SimpleIdentifier node) {
+    Element element = node.staticElement;
+    if (element is PropertyAccessorElement) {
+      element = (element as PropertyAccessorElement).variable;
+    }
+    if (element is VariableElement && element.isConst) {
+      _callback(element);
+    }
+    return null;
+  }
+
+  @override
+  Object visitSuperConstructorInvocation(SuperConstructorInvocation node) {
+    super.visitSuperConstructorInvocation(node);
+    ConstructorElement constructor = getConstructorImpl(node.staticElement);
+    if (constructor != null) {
+      _callback(constructor);
+    }
+    return null;
+  }
+}