content: /*******************************************************************************
  * Copyright (c) 2009-2011 Luaj.org. All rights reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy
  * of this software and associated documentation files (the "Software"), to deal
  * in the Software without restriction, including without limitation the rights
  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  * copies of the Software, and to permit persons to whom the Software is
  * furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  * 
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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  * THE SOFTWARE.
  ******************************************************************************/
  package org.luaj.vm2;
  
  
  /** Upvalue used with Closure formulation
   * <p>
   * @see LuaClosure
   * @see Prototype
   */
  public final class UpValue {
  
  	LuaValue[] array; // initially the stack, becomes a holder 
  	int index;
  
  	/**
  	 *  Create an upvalue relative to a stack
  	 * @param stack the stack
  	 * @param index the index on the stack for the upvalue
  	 */
  	public UpValue( LuaValue[] stack, int index) {
  		this.array = stack;
  		this.index = index;
  	}
  
  	public String toString() {
  		return index + "/" + array.length + " " + array[index];
  	}
  	
  	/** 
  	 * Convert this upvalue to a Java String
  	 * @return the Java String for this upvalue.
  	 * @see LuaValue#tojstring()
  	 */
  	public String tojstring() {
  		return array[index].tojstring();
  	}
  	
  	/**
  	 * Get the value of the upvalue
  	 * @return the {@link LuaValue} for this upvalue
  	 */
  	public final LuaValue getValue() {
  		return array[index];
  	}
  	
  	/**
  	 * Set the value of the upvalue
  	 * @param the {@link LuaValue} to set it to
  	 */
  	public final void setValue( LuaValue value ) {
  		array[index] = value;
  	}
  	
  	/**
  	 * Close this upvalue so it is no longer on the stack
  	 */
  	public final void close() {
  		LuaValue[] old = array;
  		array = new LuaValue[] { old[index] };
  		old[index] = null;
  		index = 0;
  	}
  }
  