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Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.

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/*
 * Copyright 2009 The Closure Compiler Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.javascript.jscomp;

import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.Token;

/**
 * Rewrites
 * new JSCompiler_ObjectPropertyString(window, foo.prototype.bar)
 * to new JSCompiler_ObjectPropertyString(foo.prototype, 'bar')
 *
 * Rewrites
 * new JSCompiler_ObjectPropertyString(window, foo[bar])
 * to new JSCompiler_ObjectPropertyString(foo, bar)

 * Rewrites
 * new JSCompiler_ObjectPropertyString(window, foo$bar$baz) to
 * new JSCompiler_ObjectPropertyString(window, 'foo$bar$baz')
 *
 * @see ObjectPropertyStringPreprocess
 *
 */
class ObjectPropertyStringPostprocess implements CompilerPass {
  private final AbstractCompiler compiler;

  public ObjectPropertyStringPostprocess(AbstractCompiler compiler) {
    this.compiler = compiler;
  }

  @Override
  public void process(Node externs, Node root) {
    NodeTraversal.traverseEs6(compiler, root, new Callback());
  }

  private class Callback extends AbstractPostOrderCallback {
    @Override
    public void visit(NodeTraversal t, Node n, Node parent) {
      if (!n.isNew()) {
        return;
      }

      Node objectName = n.getFirstChild();

      if (!objectName.matchesQualifiedName(
          SimpleDefinitionFinder.EXTERN_OBJECT_PROPERTY_STRING)) {
        return;
      }

      Node firstArgument = objectName.getNext();
      Node secondArgument = firstArgument.getNext();
      int secondArgumentType = secondArgument.getType();
      if (secondArgumentType == Token.GETPROP) {
        // Rewrite "new goog.testing.ObjectPropertyString(window, foo.bar)"
        // as "new goog.testing.ObjectPropertyString(foo, 'bar')".
        Node newChild = secondArgument.getFirstChild();
        secondArgument.removeChild(newChild);
        n.replaceChild(firstArgument, newChild);
        n.replaceChild(secondArgument,
            IR.string(secondArgument.getFirstChild().getString()));
      } else if (secondArgumentType == Token.GETELEM) {
        // Rewrite "new goog.testing.ObjectPropertyString(window, foo[bar])"
        // as "new goog.testing.ObjectPropertyString(foo, bar)".
        Node newFirstArgument = secondArgument.getFirstChild();
        secondArgument.removeChild(newFirstArgument);
        Node newSecondArgument = secondArgument.getLastChild();
        secondArgument.removeChild(newSecondArgument);
        n.replaceChild(firstArgument, newFirstArgument);
        n.replaceChild(secondArgument, newSecondArgument);
      } else {
        // Rewrite "new goog.testing.ObjectPropertyString(window, foo)" as
        // "new goog.testing.ObjectPropertyString(window, 'foo')"
        n.replaceChild(secondArgument,
            IR.string(secondArgument.getString()));
      }
      compiler.reportCodeChange();
    }
  }
}