Remove backends.

compiler/java/com/google/dart/compiler/backend/js/analysis/DependencyComputer.java

-// Copyright (c) 2011, 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.
-
-package com.google.dart.compiler.backend.js.analysis;
-
-import org.mozilla.javascript.Token;
-import org.mozilla.javascript.ast.AstNode;
-import org.mozilla.javascript.ast.FunctionNode;
-import org.mozilla.javascript.ast.Name;
-import org.mozilla.javascript.ast.NewExpression;
-import org.mozilla.javascript.ast.NodeVisitor;
-import org.mozilla.javascript.ast.PropertyGet;
-import org.mozilla.javascript.ast.Scope;
-import org.mozilla.javascript.ast.Symbol;
-
-import java.util.ArrayList;
-import java.util.HashSet;
-import java.util.List;
-import java.util.Map;
-import java.util.Set;
-
-/**
- * Computes the set of dependencies that a given AstNode node has.
- */
-class DependencyComputer {
-  /**
-   * Visitor for determining what dependencies an AstNode has.
-   */
-  class DependencyComputingVisitor implements NodeVisitor {
-    /**
-     * Adds a dependency on the given identifier.  If the identifier is virtual then then a 
-     * dependency is only added if the enclosing "class" has been instantiated.
-     */
-    private void addDependency(String identifier, boolean isVirtual) {
-      List<JavascriptElement> members = namesToElements.get(identifier);
-      if (members != null) {
-        for (JavascriptElement member : members) {
-          if (isVirtual && member.isVirtual()) {
-            JavascriptElement enclosingElement = member.getEnclosingElement();
-            if (enclosingElement != null && enclosingElement.isInstantiated()) {
-              dependencies.add(member);
-            }
-          } else {
-            if (!member.isVirtual()) {
-              if (member.getEnclosingElement() != null) {
-                dependencies.add(member.getEnclosingElement());
-              }
-            }
-            dependencies.add(member);
-          }
-        }
-      }
-    }
-
-    /**
-     * Record that we saw a new of a given identifier.
-     */
-    private void addInstantiation(String identifier) {
-      List<JavascriptElement> instantiatedClasses = namesToElements.get(identifier);
-      if (instantiatedClasses != null) {
-        for (JavascriptElement instantiatedClass : instantiatedClasses) {
-          instantiatedClass.setInstantiated(true);
-
-          /*
-           * Whenever we see an instantiation we must check it and any super type for members that
-           * match the virtual names seen to date and we must ensure that the corresponding inherits
-           * get emitted. 
-           */
-          while (instantiatedClass != null) {
-            JavascriptElement inheritsInvocation = instantiatedClass.getInheritsInvocation();
-            if (inheritsInvocation != null) {
-              dependencies.add(inheritsInvocation);
-            }
-            
-            for (JavascriptElement member : instantiatedClass.getMembers()) {
-              if (virtualNames.contains(member.getName())) {
-                dependencies.add(member);
-              }
-            }
-            
-            instantiatedClass = instantiatedClass.getInheritsElement();
-          }
-        }
-      }
-    }
-
-    private void addStaticDependency(String identifier) {
-      addDependency(identifier, false);
-    }
-
-    private void addVirtualDependency(String identifier) {
-      virtualNames.add(identifier);
-      addDependency(identifier, true);
-    }
-
-    Symbol findSymbol(Scope scope, String name) {
-      if (scope == null) {
-        return null;
-      }
-
-      Symbol symbol = scope.getSymbol(name);
-      if (symbol == null) {
-        Scope parentScope = scope.getParentScope();
-        if (parentScope == null && (scope != scope.getAstRoot())) {
-          return findSymbol(scope.getAstRoot(), name);
-        } else {
-          return findSymbol(parentScope, name);
-        }
-      }
-
-      return symbol;
-    }
-
-    /**
-     * Returns true if the name is a local or parameter name.  However, if the name is on the 
-     * right hand side of a property get then we don't consider this name to be a local variable.
-     */
-    boolean isLocalVariableOrParameter(Name name) {
-      Scope definingScope = name.getDefiningScope();
-      Scope enclosingScope = name.getEnclosingScope();
-      if (definingScope != null) {
-        Symbol symbol = definingScope.getSymbol(name.getIdentifier());
-        if (definingScope.getType() == Token.FUNCTION) {
-          if (symbol != null && (symbol.getDeclType() == Token.VAR)
-              || (symbol.getDeclType() == Token.LP)) {
-            
-            if (name.getParent().getType() == Token.GETPROP) {
-              PropertyGet propertyGet = (PropertyGet) name.getParent();
-              return propertyGet.getRight() != name;
-            }
-            
-            return true;
-          } 
-        }
-      }
-
-      return false;
-    }
-
-    /**
-     * Returns <code>true</code> if the name is associated with a native
-     * function or a top level function.
-     */
-    private boolean isNativeOrTopLevelFunction(Scope enclosingScope, String name) {
-      List<JavascriptElement> list = namesToElements.get(name);
-      if (list == null || list.isEmpty()) {
-        return false;
-      }
-
-      Symbol symbol = findSymbol(enclosingScope, name);
-      if (symbol != null
-          && (symbol.getDeclType() == Token.FUNCTION || symbol.getDeclType() == Token.VAR)) {
-        return true;
-      }
-
-      JavascriptElement javascriptElement = list.get(0);
-      return javascriptElement.isNative();
-    }
-
-    /**
-     * Return a static name if the {@link PropertyGet} matches the pattern x.y or
-     * x.prototype.y or <code>null</code> if it does not.
-     */
-    String maybeGetStaticName(PropertyGet propertyGet) {
-      AstNode right = propertyGet.getRight();
-      int rightType = right.getType();
-      if (rightType != Token.NAME) {
-        return null;
-      }
-
-      AstNode left = propertyGet.getLeft();
-      int leftType = left.getType();
-      if (leftType == Token.NAME) {
-        String qualifier = ((Name) left).getIdentifier();
-
-        if (isNativeOrTopLevelFunction(left.getEnclosingScope(), qualifier)) {
-          String targetName = ((Name) right).getIdentifier();
-          String qualifiedName = qualifier + "." + targetName;
-          if ("prototype".equals(targetName)) {
-            return qualifiedName;
-          } else if (namesToElements.containsKey(qualifiedName)) {
-            return qualifiedName;
-          }
-        }
-      } else if (leftType == Token.GETPROP) {
-        PropertyGet leftPropGet = (PropertyGet) left;
-        String handleSpecialCase = maybeGetStaticName(leftPropGet);
-        if (handleSpecialCase != null && handleSpecialCase.endsWith("prototype")) {
-          handleSpecialCase = handleSpecialCase + "." + ((Name) right).getIdentifier();
-          if (namesToElements.containsKey(handleSpecialCase)) {
-            return handleSpecialCase;
-          }
-        }
-      }
-
-      return null;
-    }
-
-    @Override
-    public boolean visit(AstNode node) {
-      switch (node.getType()) {
-        case Token.GETPROP:
-          PropertyGet propertyGet = (PropertyGet) node;
-          String staticName = maybeGetStaticName(propertyGet);
-          if (staticName != null) {
-            addStaticDependency(staticName);
-            return false;
-          }
-          break;
-
-        case Token.FUNCTION:
-          FunctionNode functionNode = (FunctionNode) node;
-          functionNode.getBody().visit(this);
-          // Don't process the parameters
-          return false;
-
-        case Token.NAME:
-          Name name = (Name) node;
-          if (!isLocalVariableOrParameter(name)) {
-            String identifier = name.getIdentifier();
-            addVirtualDependency(identifier);
-          }
-          break;
-
-        case Token.NEW:
-          NewExpression newExpression = (NewExpression) node;
-          Name target = (Name) newExpression.getTarget();
-          if (target != null) {
-            addInstantiation(target.getIdentifier());
-          }
-          break;
-
-        default:
-          break;
-      }
-
-      return true;
-    }
-
-  }
-
-  private final List<JavascriptElement> dependencies = new ArrayList<JavascriptElement>();
-  private final Map<String, List<JavascriptElement>> namesToElements;
-  
-  /**
-   * Names that have been referenced using virtual syntax, i.e. not using A.prototype.foo, but 
-   * as foo or this.foo, etc.
-   */
-  private final Set<String> virtualNames = new HashSet<String>();
-
-  public DependencyComputer(Map<String, List<JavascriptElement>> namesToElements) {
-    this.namesToElements = namesToElements;
-  }
-
-  public List<JavascriptElement> computeDependencies(AstNode node) {
-    // Clear the dependencies so this object can be reused.
-    dependencies.clear();
-    node.visit(new DependencyComputingVisitor());
-    return dependencies;
-  }
-}