using System;
using System.Collections;
using M17N.Core;

namespace M17N.Core
{
  public class MSymbol
  {
    static private Hashtable pool = new Hashtable ();

    internal class MSymbolData
    {
      public string name;
      public Object value;
      public MPlist plist;

      public MSymbolData (string name)
      {
	this.name = name;
      }
    }

    static public MSymbol nil = new MSymbol ("nil");
    static public MSymbol t = new MSymbol ("t");

    private MSymbolData data;

    public MSymbol (string name)
    {
      if (! pool.ContainsKey (name))
	{
	  data = new MSymbolData (name);
	  pool.Add (name, data);
	}
      else
	data = (MSymbolData) pool[name];
    }

    public override string ToString () { return data.name; }

    public override bool Equals (Object sym)
    {
      return (this.data == ((MSymbol) sym).data);
    }

    public override int GetHashCode ()
    {
      return (data.name.GetHashCode ());
    }

    public static bool operator== (MSymbol sym1, MSymbol sym2)
    {
      return ((object) sym1.data == (object) sym2.data);
    }

    public static bool operator!= (MSymbol sym1, MSymbol sym2)
    {
      return ((object) sym1.data != (object) sym2.data);
    }

    public object get (MSymbol key)
    {
      return (data.plist == null ? null : data.plist.get (key));
    }

    public object put (MSymbol key, object val)
    {
      if (data.plist == null)
	data.plist = new MPlist ();
      return data.plist.put (key, val);
    }
  }
}