antlr/Antlr4.Runtime/IToken.cs

/*
 * [The "BSD license"]
 *  Copyright (c) 2013 Terence Parr
 *  Copyright (c) 2013 Sam Harwell
 *  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,
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 *  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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using Antlr4.Runtime;
using Sharpen;

namespace Antlr4.Runtime
{
    /// <summary>
    /// A token has properties: text, type, line, character position in the line
    /// (so we can ignore tabs), token channel, index, and source from which
    /// we obtained this token.
    /// </summary>
    /// <remarks>
    /// A token has properties: text, type, line, character position in the line
    /// (so we can ignore tabs), token channel, index, and source from which
    /// we obtained this token.
    /// </remarks>
    public abstract class IToken
    {
        public const int InvalidType = 0;

        /// <summary>
        /// During lookahead operations, this "token" signifies we hit rule end ATN state
        /// and did not follow it despite needing to.
        /// </summary>
        /// <remarks>
        /// During lookahead operations, this "token" signifies we hit rule end ATN state
        /// and did not follow it despite needing to.
        /// </remarks>
        public const int Epsilon = -2;

        public const int MinUserTokenType = 1;

        public const int Eof = IIntStream.Eof;

        /// <summary>
        /// All tokens go to the parser (unless skip() is called in that rule)
        /// on a particular "channel".
        /// </summary>
        /// <remarks>
        /// All tokens go to the parser (unless skip() is called in that rule)
        /// on a particular "channel".  The parser tunes to a particular channel
        /// so that whitespace etc... can go to the parser on a "hidden" channel.
        /// </remarks>
        public const int DefaultChannel = 0;

        /// <summary>
        /// Anything on different channel than DEFAULT_CHANNEL is not parsed
        /// by parser.
        /// </summary>
        /// <remarks>
        /// Anything on different channel than DEFAULT_CHANNEL is not parsed
        /// by parser.
        /// </remarks>
        public const int HiddenChannel = 1;

        /// <summary>Get the text of the token.</summary>
        /// <remarks>Get the text of the token.</remarks>
        internal abstract string Text
        {
            get;
        }

        /// <summary>Get the token type of the token.</summary>
        /// <remarks>Get the token type of the token.</remarks>
        internal abstract int Type
        {
            get;
        }

        /// <summary>
        /// The line number on which the 1st character of this token was matched,
        /// line=1..n
        /// </summary>
        internal abstract int Line
        {
            get;
        }

        /// <summary>
        /// The index of the first character of this token relative to the
        /// beginning of the line at which it occurs, 0..n-1
        /// </summary>
        internal abstract int Column
        {
            get;
        }

        /// <summary>Return the channel this token.</summary>
        /// <remarks>
        /// Return the channel this token. Each token can arrive at the parser
        /// on a different channel, but the parser only "tunes" to a single channel.
        /// The parser ignores everything not on DEFAULT_CHANNEL.
        /// </remarks>
        internal abstract int Channel
        {
            get;
        }

        /// <summary>An index from 0..n-1 of the token object in the input stream.</summary>
        /// <remarks>
        /// An index from 0..n-1 of the token object in the input stream.
        /// This must be valid in order to print token streams and
        /// use TokenRewriteStream.
        /// Return -1 to indicate that this token was conjured up since
        /// it doesn't have a valid index.
        /// </remarks>
        internal abstract int TokenIndex
        {
            get;
        }

        /// <summary>
        /// The starting character index of the token
        /// This method is optional; return -1 if not implemented.
        /// </summary>
        /// <remarks>
        /// The starting character index of the token
        /// This method is optional; return -1 if not implemented.
        /// </remarks>
        internal abstract int StartIndex
        {
            get;
        }

        /// <summary>The last character index of the token.</summary>
        /// <remarks>
        /// The last character index of the token.
        /// This method is optional; return -1 if not implemented.
        /// </remarks>
        internal abstract int StopIndex
        {
            get;
        }

        /// <summary>
        /// Gets the
        /// <see cref="ITokenSource">ITokenSource</see>
        /// which created this token.
        /// </summary>
        internal abstract ITokenSource TokenSource
        {
            get;
        }

        /// <summary>
        /// Gets the
        /// <see cref="ICharStream">ICharStream</see>
        /// from which this token was derived.
        /// </summary>
        internal abstract ICharStream InputStream
        {
            get;
        }
    }
}