xref: /external/antlr/antlr-3.4/runtime/CSharp3/Sources/Antlr3.Runtime/ITokenSource.cs

/*
 * [The "BSD licence"]
 * Copyright (c) 2005-2008 Terence Parr
 * All rights reserved.
 *
 * Conversion to C#:
 * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

namespace Antlr.Runtime
{

    /** <summary>
     *  A source of tokens must provide a sequence of tokens via nextToken()
     *  and also must reveal it's source of characters; CommonToken's text is
     *  computed from a CharStream; it only store indices into the char stream.
     *  </summary>
     *
     *  <remarks>
     *  Errors from the lexer are never passed to the parser.  Either you want
     *  to keep going or you do not upon token recognition error.  If you do not
     *  want to continue lexing then you do not want to continue parsing.  Just
     *  throw an exception not under RecognitionException and Java will naturally
     *  toss you all the way out of the recognizers.  If you want to continue
     *  lexing then you should not throw an exception to the parser--it has already
     *  requested a token.  Keep lexing until you get a valid one.  Just report
     *  errors and keep going, looking for a valid token.
     *  </summary>
     */
    public interface ITokenSource
    {
        /** <summary>
         *  Return a Token object from your input stream (usually a CharStream).
         *  Do not fail/return upon lexing error; keep chewing on the characters
         *  until you get a good one; errors are not passed through to the parser.
         *  </summary>
         */
        IToken NextToken();

        /** <summary>
         *  Where are you getting tokens from? normally the implication will simply
         *  ask lexers input stream.
         *  </summary>
         */
        string SourceName
        {
            get;
        }

        string[] TokenNames
        {
            get;
        }
    }
}