UnbufferedTokenStream.cs revision 324c4644fee44b9898524c09511bd33c3f12e2df 
1/*
2 * [The "BSD licence"]
3 * Copyright (c) 2005-2008 Terence Parr
4 * All rights reserved.
5 *
6 * Conversion to C#:
7 * Copyright (c) 2009 Sam Harwell
8 * All rights reserved.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. The name of the author may not be used to endorse or promote products
19 *    derived from this software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33namespace Antlr.Runtime {
34    using Antlr.Runtime.Misc;
35    using CLSCompliant = System.CLSCompliantAttribute;
36    using NotSupportedException = System.NotSupportedException;
37    using IndexOutOfRangeException = System.IndexOutOfRangeException;
38
39    /** A token stream that pulls tokens from the code source on-demand and
40     *  without tracking a complete buffer of the tokens. This stream buffers
41     *  the minimum number of tokens possible.  It's the same as
42     *  OnDemandTokenStream except that OnDemandTokenStream buffers all tokens.
43     *
44     *  You can't use this stream if you pass whitespace or other off-channel
45     *  tokens to the parser. The stream can't ignore off-channel tokens.
46     *
47     *  You can only look backwards 1 token: LT(-1).
48     *
49     *  Use this when you need to read from a socket or other infinite stream.
50     *
51     *  @see BufferedTokenStream
52     *  @see CommonTokenStream
53     */
54    public class UnbufferedTokenStream : LookaheadStream<IToken>, ITokenStream {
55        [CLSCompliant(false)]
56        protected ITokenSource tokenSource;
57        protected int tokenIndex; // simple counter to set token index in tokens
58
59        /** Skip tokens on any channel but this one; this is how we skip whitespace... */
60        protected int channel = TokenChannels.Default;
61
62        public UnbufferedTokenStream(ITokenSource tokenSource) {
63            this.tokenSource = tokenSource;
64        }
65
66        public ITokenSource TokenSource {
67            get {
68                return this.tokenSource;
69            }
70        }
71
72        public string SourceName {
73            get {
74                return TokenSource.SourceName;
75            }
76        }
77
78        public override IToken NextElement() {
79            IToken t = this.tokenSource.NextToken();
80            t.TokenIndex = this.tokenIndex++;
81            return t;
82        }
83
84        public override bool IsEndOfFile(IToken o) {
85            return o.Type == CharStreamConstants.EndOfFile;
86        }
87
88        public IToken Get(int i) {
89            throw new NotSupportedException("Absolute token indexes are meaningless in an unbuffered stream");
90        }
91
92        public int LA(int i) {
93            return LT(i).Type;
94        }
95
96        public string ToString(int start, int stop) {
97            return "n/a";
98        }
99
100        public string ToString(IToken start, IToken stop) {
101            return "n/a";
102        }
103    }
104}
105