/*
 * [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 stream of tokens accessing tokens from a TokenSource</summary> */
    public interface ITokenStream : IIntStream {
        /** <summary>Get Token at current input pointer + i ahead where i=1 is next Token.
         *  i&lt;0 indicates tokens in the past.  So -1 is previous token and -2 is
         *  two tokens ago. LT(0) is undefined.  For i&gt;=n, return Token.EOFToken.
         *  Return null for LT(0) and any index that results in an absolute address
         *  that is negative.</summary>
         */
        IToken LT(int k);

        /// <summary>
        /// How far ahead has the stream been asked to look?  The return
        /// value is a valid index from 0..n-1.
        /// </summary>
        int Range {
            get;
        }

        /** <summary>
         *  Get a token at an absolute index i; 0..n-1.  This is really only
         *  needed for profiling and debugging and token stream rewriting.
         *  If you don't want to buffer up tokens, then this method makes no
         *  sense for you.  Naturally you can't use the rewrite stream feature.
         *  I believe DebugTokenStream can easily be altered to not use
         *  this method, removing the dependency.
         *  </summary>
         */
        IToken Get(int i);

        /** <summary>
         *  Where is this stream pulling tokens from?  This is not the name, but
         *  the object that provides Token objects.
         *  </summary>
         */
        ITokenSource TokenSource {
            get;
        }

        /** <summary>
         *  Return the text of all tokens from start to stop, inclusive.
         *  If the stream does not buffer all the tokens then it can just
         *  return "" or null;  Users should not access $ruleLabel.text in
         *  an action of course in that case.
         *  </summary>
         */
        string ToString(int start, int stop);

        /** <summary>
         *  Because the user is not required to use a token with an index stored
         *  in it, we must provide a means for two token objects themselves to
         *  indicate the start/end location.  Most often this will just delegate
         *  to the other toString(int,int).  This is also parallel with
         *  the TreeNodeStream.toString(Object,Object).
         *  </summary>
         */
        string ToString(IToken start, IToken stop);
    }
}