1 /* 2 * [The "BSD licence"] 3 * Copyright (c) 2005-2008 Terence Parr 4 * All rights reserved. 5 * 6 * Conversion to C#: 7 * Copyright (c) 2008-2009 Sam Harwell, Pixel Mine, Inc. 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 33 namespace Antlr.Runtime 34 { 35 36 /** <summary> 37 * A simple stream of integers used when all I care about is the char 38 * or token type sequence (such as interpretation). 39 * </summary> 40 */ 41 public interface IIntStream 42 { 43 void Consume(); 44 45 /** <summary> 46 * Get int at current input pointer + i ahead where i=1 is next int. 47 * Negative indexes are allowed. LA(-1) is previous token (token 48 * just matched). LA(-i) where i is before first token should 49 * yield -1, invalid char / EOF. 50 * </summary> 51 */ 52 int LA( int i ); 53 54 /** <summary> 55 * Tell the stream to start buffering if it hasn't already. Return 56 * current input position, Index, or some other marker so that 57 * when passed to rewind() you get back to the same spot. 58 * rewind(mark()) should not affect the input cursor. The Lexer 59 * track line/col info as well as input index so its markers are 60 * not pure input indexes. Same for tree node streams. 61 * </summary> 62 */ 63 int Mark(); 64 65 /** <summary> 66 * Return the current input symbol index 0..n where n indicates the 67 * last symbol has been read. The index is the symbol about to be 68 * read not the most recently read symbol. 69 * </summary> 70 */ 71 int Index 72 { 73 get; 74 } 75 76 /** <summary> 77 * Reset the stream so that next call to index would return marker. 78 * The marker will usually be Index but it doesn't have to be. It's 79 * just a marker to indicate what state the stream was in. This is 80 * essentially calling release() and seek(). If there are markers 81 * created after this marker argument, this routine must unroll them 82 * like a stack. Assume the state the stream was in when this marker 83 * was created. 84 * </summary> 85 */ 86 void Rewind( int marker ); 87 88 /** <summary> 89 * Rewind to the input position of the last marker. 90 * Used currently only after a cyclic DFA and just 91 * before starting a sem/syn predicate to get the 92 * input position back to the start of the decision. 93 * Do not "pop" the marker off the state. mark(i) 94 * and rewind(i) should balance still. It is 95 * like invoking rewind(last marker) but it should not "pop" 96 * the marker off. It's like seek(last marker's input position). 97 * </summary> 98 */ 99 void Rewind(); 100 101 /** <summary> 102 * You may want to commit to a backtrack but don't want to force the 103 * stream to keep bookkeeping objects around for a marker that is 104 * no longer necessary. This will have the same behavior as 105 * rewind() except it releases resources without the backward seek. 106 * This must throw away resources for all markers back to the marker 107 * argument. So if you're nested 5 levels of mark(), and then release(2) 108 * you have to release resources for depths 2..5. 109 * </summary> 110 */ 111 void Release( int marker ); 112 113 /** <summary> 114 * Set the input cursor to the position indicated by index. This is 115 * normally used to seek ahead in the input stream. No buffering is 116 * required to do this unless you know your stream will use seek to 117 * move backwards such as when backtracking. 118 * </summary> 119 * 120 * <remarks> 121 * This is different from rewind in its multi-directional 122 * requirement and in that its argument is strictly an input cursor (index). 123 * 124 * For char streams, seeking forward must update the stream state such 125 * as line number. For seeking backwards, you will be presumably 126 * backtracking using the mark/rewind mechanism that restores state and 127 * so this method does not need to update state when seeking backwards. 128 * 129 * Currently, this method is only used for efficient backtracking using 130 * memoization, but in the future it may be used for incremental parsing. 131 * 132 * The index is 0..n-1. A seek to position i means that LA(1) will 133 * return the ith symbol. So, seeking to 0 means LA(1) will return the 134 * first element in the stream. 135 * </remarks> 136 */ 137 void Seek( int index ); 138 139 /** <summary> 140 * Only makes sense for streams that buffer everything up probably, but 141 * might be useful to display the entire stream or for testing. This 142 * value includes a single EOF. 143 * </summary> 144 */ 145 int Count 146 { 147 get; 148 } 149 150 /** <summary> 151 * Where are you getting symbols from? Normally, implementations will 152 * pass the buck all the way to the lexer who can ask its input stream 153 * for the file name or whatever. 154 * </summary> 155 */ 156 string SourceName 157 { 158 get; 159 } 160 } 161 } 162
