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

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

    private class MSymbolData
    {
      public string name;
      public object value;
      public MPlist plist;

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

    private MSymbolData data;

    public static MSymbol nil = new MSymbol ("nil");
    public static MSymbol t = new MSymbol ("t");
    public static MSymbol symbol = new MSymbol ("symbol");
    public static MSymbol mtext = new MSymbol ("mtext");
    public static MSymbol plist = new MSymbol ("plist");
    public static MSymbol integer = new MSymbol ("integer");

    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 ()
    {
      string str = "";

      foreach (char c in data.name)
	{
	  if (c == '\\' || c == ' ' || c == '\'' || c == '\"' || c == ':')
	    str += "\\";
	  str += c;
	}
      return str;
    }

    public static bool operator== (MSymbol sym1, MSymbol sym2)
    {
      if (System.Object.ReferenceEquals(sym1, sym2))
        return true;
      if (((object) sym1 == null) || ((object) sym2 == null))
        return false;
      return sym1.data == sym2.data;
    }

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

    public override bool Equals (object sym)
    {
      if (sym == null)
	return false;
      return (this.data == ((MSymbol) sym).data);
    }

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

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

    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);
    }
  }
}