* Copyright 2008 Google Inc.

*

* 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.

*/

* Creates a JavaScript AST from a <code>JProgram</code> node.

*/

  /**

   * The GWT Java AST might contain different local variables with the same name in the same

   * scope. This fixup pass renames variables in the case they clash in a scope.

   */

  private static class FixNameClashesVisitor extends JVisitor {

    /**

     * Represents the scope tree defined by nested statement blocks. It is a temporary

     * structure to track local variable lifetimes.

     */

    private static class Scope {

      private Scope parent;

      // Keeps track what names are used in children.

      private Set<String> usedInChildScope = Sets.newHashSet();

      // Keeps track what names have this scope as its lifetime.

      private Set<String> namesInThisScope = Sets.newHashSet();

      /**

       * The depth at which this scope is in the tree.

       */

      private int level;

      private Scope() {

        this.parent = null;

        this.level = 0;

      }

      private Scope(Scope parent) {

        this.parent = parent;

        this.level = parent.level + 1;

      }

      private static Scope getInnermostEnclosingScope(Scope thisScope, Scope thatScope) {

        if (thisScope == null) {

          return thatScope;

        }

        if (thatScope == null) {

          return thisScope;

        }

        if (thisScope == thatScope) {

          return thisScope;

        }

        if (thisScope.level > thatScope.level) {

          return getInnermostEnclosingScope(thatScope, thisScope);

        }

        if (thisScope.level == thatScope.level) {

          return getInnermostEnclosingScope(thisScope.parent, thatScope.parent);

        }

        return getInnermostEnclosingScope(thisScope, thatScope.parent);

      }

      private void addChildUsage(String name) {

        usedInChildScope.add(name);

        if (parent != null) {

          parent.addChildUsage(name);