platform/core-impl/src/com/intellij/psi/impl/source/tree/RecursiveTreeElementVisitor.java

/*
 * Copyright 2000-2009 JetBrains s.r.o.
 *
 * 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.intellij.psi.impl.source.tree;

public abstract class RecursiveTreeElementVisitor extends TreeElementVisitor{
  @Override public void visitLeaf(LeafElement leaf) {
    visitNode(leaf);
  }

  @Override public void visitComposite(CompositeElement composite) {
    if(!visitNode(composite)) return;
    TreeElement child = composite.getFirstChildNode();
    while(child != null) {
      final TreeElement treeNext = child.getTreeNext();
      child.acceptTree(this);
      child = treeNext;
    }
  }

  protected abstract boolean visitNode(TreeElement element);
}