source: trunk/yao/share/antlr-2.7.7/lib/csharp/antlr.runtime/antlr/TokenStreamBasicFilter.cs @ 1

using System;
using BitSet = antlr.collections.impl.BitSet;
        
namespace antlr
{
        /*ANTLR Translator Generator
        * Project led by Terence Parr at http://www.jGuru.com
        * Software rights: http://www.antlr.org/license.html
        *
        * $Id:$
        */

        //
        // ANTLR C# Code Generator by Micheal Jordan
        //                            Kunle Odutola       : kunle UNDERSCORE odutola AT hotmail DOT com
        //                            Anthony Oguntimehin
        //
        // With many thanks to Eric V. Smith from the ANTLR list.
        //

        /*This object is a TokenStream that passes through all
        *  tokens except for those that you tell it to discard.
        *  There is no buffering of the tokens.
        */
        public class TokenStreamBasicFilter : TokenStream
        {
                /*The set of token types to discard */
                protected internal BitSet discardMask;
                
                /*The input stream */
                protected internal TokenStream input;
                
                public TokenStreamBasicFilter(TokenStream input)
                {
                        this.input = input;
                        discardMask = new BitSet();
                }
                public virtual void  discard(int ttype)
                {
                        discardMask.add(ttype);
                }
                public virtual void  discard(BitSet mask)
                {
                        discardMask = mask;
                }
                public virtual IToken nextToken()
                {
                        IToken tok = input.nextToken();
                        while (tok != null && discardMask.member(tok.Type))
                        {
                                tok = input.nextToken();
                        }
                        return tok;
                }
        }
}