112 lines
4.9 KiB
PHP
112 lines
4.9 KiB
PHP
<?php
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/*
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[The "BSD licence"]
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Copyright (c) 2005-2008 Terence Parr
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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1. Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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3. The name of the author may not be used to endorse or promote products
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derived from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/** A simple stream of integers used when all I care about is the char
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* or token type sequence (such as interpretation).
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*/
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interface IntStream {
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function consume();
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/** Get int at current input pointer + i ahead where i=1 is next int.
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* Negative indexes are allowed. LA(-1) is previous token (token
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* just matched). LA(-i) where i is before first token should
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* yield -1, invalid char / EOF.
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*/
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function LA($i);
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/** Tell the stream to start buffering if it hasn't already. Return
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* current input position, index(), or some other marker so that
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* when passed to rewind() you get back to the same spot.
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* rewind(mark()) should not affect the input cursor. The Lexer
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* track line/col info as well as input index so its markers are
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* not pure input indexes. Same for tree node streams.
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*/
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function mark();
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/** Return the current input symbol index 0..n where n indicates the
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* last symbol has been read. The index is the symbol about to be
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* read not the most recently read symbol.
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*/
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function index();
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/** Reset the stream so that next call to index would return marker.
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* The marker will usually be index() but it doesn't have to be. It's
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* just a marker to indicate what state the stream was in. This is
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* essentially calling release() and seek(). If there are markers
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* created after this marker argument, this routine must unroll them
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* like a stack. Assume the state the stream was in when this marker
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* was created.
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*/
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function rewind($marker=null);
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/** You may want to commit to a backtrack but don't want to force the
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* stream to keep bookkeeping objects around for a marker that is
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* no longer necessary. This will have the same behavior as
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* rewind() except it releases resources without the backward seek.
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* This must throw away resources for all markers back to the marker
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* argument. So if you're nested 5 levels of mark(), and then release(2)
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* you have to release resources for depths 2..5.
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*/
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function release($marker);
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/** Set the input cursor to the position indicated by index. This is
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* normally used to seek ahead in the input stream. No buffering is
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* required to do this unless you know your stream will use seek to
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* move backwards such as when backtracking.
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*
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* This is different from rewind in its multi-directional
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* requirement and in that its argument is strictly an input cursor (index).
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*
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* For char streams, seeking forward must update the stream state such
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* as line number. For seeking backwards, you will be presumably
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* backtracking using the mark/rewind mechanism that restores state and
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* so this method does not need to update state when seeking backwards.
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*
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* Currently, this method is only used for efficient backtracking using
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* memoization, but in the future it may be used for incremental parsing.
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*
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* The index is 0..n-1. A seek to position i means that LA(1) will
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* return the ith symbol. So, seeking to 0 means LA(1) will return the
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* first element in the stream.
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*/
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function seek($index);
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/** Only makes sense for streams that buffer everything up probably, but
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* might be useful to display the entire stream or for testing. This
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* value includes a single EOF.
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*/
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function size();
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/** Where are you getting symbols from? Normally, implementations will
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* pass the buck all the way to the lexer who can ask its input stream
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* for the file name or whatever.
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*/
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public function getSourceName();
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}
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?>
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