MapPackage.java :  » Scripting » Pnuts » org » pnuts » lib » Java Open Source

/*
 * @(#)MapPackage.java 1.3 05/02/17
 *
 * Copyright (c) 1997-2005 Sun Microsystems, Inc. All Rights Reserved.
 *
 * See the file "LICENSE.txt" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 */
package org.pnuts.lib;

import java.util.Map;
import java.util.Collections;
import java.util.Enumeration;
import pnuts.lang.Pnuts;
import pnuts.lang.NamedValue;
import pnuts.lang.PnutsImpl;
import pnuts.lang.PnutsFunction;
import pnuts.lang.Context;
import pnuts.lang.Package;

/**
 * A wrapper class that makes pnuts.lang.Package from java.util.Map
 */
class MapPackage extends Package {

  private Map map;
  private static PnutsImpl pureImpl = new PnutsImpl();

  /*
   * Constructor
   *
   * @param map the map
   */
  public MapPackage(Map map){
    this.map = map;
  }

  /**
   * Add key-value mappings from a Pnuts expression <em>def</em> to the specified <em>map</em>.
   *
   * @param map the map
   * @param def a Pnuts expression
   * @param context the context in which the Pnuts expression is evaluated.
   */
  public static void defineMap(Map map, String def, Context context){
    Context ctx = new Context(context);
    ctx.setImplementation(pureImpl);
    ctx.setCurrentPackage(new MapPackage(map));
    Pnuts.eval(def, ctx);
  }

  public Object get(String symbol, Context context){
    return map.get(symbol);
  }

  public void set(String symbol, Object value, Context context){
    map.put(symbol, value);
  }

  public boolean defined(String name, Context context){
    return map.containsKey(name);
  }

  public Enumeration keys(){
    return Collections.enumeration(map.keySet());
  }

  public Enumeration values(){
    return Collections.enumeration(map.values());
  }

  public int size(){
    return map.size();
  }

  public NamedValue lookup(final String symbol, Context context){
    final Object value = map.get(symbol);
    if (value != null){
      return new NamedValue(){
          public String getName(){
            return symbol;
          }
          public Object get(){
            return value;
          }
          public void set(Object obj){
            map.put(symbol, obj);
          }
        };
    } else {
      return null;
    }
  }

  public static class Function extends PnutsFunction {
    protected Object exec(Object[] args, Context context){
      if (args.length != 2){
        undefined(args, context);
        return null;
      }
      Map m = (Map)args[0];
      String def = (String)args[1];
      defineMap(m, def, context);
      return m;
    }
  }
}