content: /*******************************************************************************
  * Copyright (c) 2010 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,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  ******************************************************************************/
  package org.luaj.vm2.ast;
  
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.Map;
  import java.util.Set;
  
  
  public class NameScope {
  
  	private static final Set<String> LUA_KEYWORDS = new HashSet<String>();
  	
  	static { 
  		String[] k = new String[] { 
  	        "and", "break", "do", "else", "elseif", "end", 
  	        "false", "for", "function", "if", "in", "local",
  	        "nil", "not", "or", "repeat", "return", 
  	        "then", "true", "until", "while" };
  		for ( int i=0; i<k.length; i++ )
  			LUA_KEYWORDS.add( k[i] );
  	}
  	
  	public final Map<String,Variable> namedVariables = new HashMap<String,Variable>();
  
  	public final NameScope outerScope;
  
  	public int functionNestingCount;
  	
  	/** Construct default names scope */
  	public NameScope() {
  		this.outerScope = null;
  		this.functionNestingCount = 0;
  	}
  	
  	/** Construct name scope within another scope*/
  	public NameScope(NameScope outerScope) {
  		this.outerScope = outerScope;
  		this.functionNestingCount = outerScope!=null? outerScope.functionNestingCount: 0;
  	}
  	
  	/** Look up a name.  If it is a global name, then throw IllegalArgumentException. */
  	public Variable find( String name ) throws IllegalArgumentException {
  		validateIsNotKeyword(name);
  		for ( NameScope n = this; n!=null; n=n.outerScope )
  			if ( n.namedVariables.containsKey(name) )
  				return (Variable)n.namedVariables.get(name);
  		Variable value = new Variable(name);
  		this.namedVariables.put(name, value);
  		return value;
  	}
  	
  	/** Define a name in this scope.  If it is a global name, then throw IllegalArgumentException. */
  	public Variable define( String name ) throws IllegalStateException, IllegalArgumentException {
  		validateIsNotKeyword(name);
  		Variable value = new Variable(name, this);
  		this.namedVariables.put(name, value);
  		return value;
  	}
  	
  	private void validateIsNotKeyword(String name) {
  		if ( LUA_KEYWORDS.contains(name) )
  			throw new IllegalArgumentException("name is a keyword: '"+name+"'");
  	}
  }
  