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 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You 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

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 *      http://www.apache.org/licenses/LICENSE-2.0

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package com.sun.org.apache.xpath.internal;

import javax.xml.transform.SourceLocator;

/**

 * A class that implements this interface can construct expressions,

 * give information about child and parent expressions,

 * and give the originating source information.  A class that implements

 * this interface does not lay any claim to being directly executable.

 *

 * <p>Note: This interface should not be considered stable.  Only exprSetParent

 * and exprGetParent can be counted on to work reliably.  Work in progress.</p>

 */

public interface ExpressionNode extends SourceLocator

{

  /** This pair of methods are used to inform the node of its

    parent. */

  public void exprSetParent(ExpressionNode n);

  public ExpressionNode exprGetParent();

  /** This method tells the node to add its argument to the node's

    list of children.  */

  public void exprAddChild(ExpressionNode n, int i);

  /** This method returns a child node.  The children are numbered

     from zero, left to right. */

  public ExpressionNode exprGetChild(int i);

  /** Return the number of children the node has. */

  public int exprGetNumChildren();

}