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/*
* [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 simple stream of integers used when all I care about is the char
* or token type sequence (such as interpretation).
* </summary>
*/
public interface IIntStream
{
void Consume();
/** <summary>
* Get int at current input pointer + i ahead where i=1 is next int.
* Negative indexes are allowed. LA(-1) is previous token (token
* just matched). LA(-i) where i is before first token should
* yield -1, invalid char / EOF.
* </summary>
*/
int LA( int i );
/** <summary>
* Tell the stream to start buffering if it hasn't already. Return
* current input position, Index, or some other marker so that
* when passed to rewind() you get back to the same spot.
* rewind(mark()) should not affect the input cursor. The Lexer
* track line/col info as well as input index so its markers are
* not pure input indexes. Same for tree node streams.
* </summary>
*/
int Mark();
/** <summary>
* Return the current input symbol index 0..n where n indicates the
* last symbol has been read. The index is the symbol about to be
* read not the most recently read symbol.
* </summary>
*/
int Index
{
get;
}
/** <summary>
* Reset the stream so that next call to index would return marker.
* The marker will usually be Index but it doesn't have to be. It's
* just a marker to indicate what state the stream was in. This is
* essentially calling release() and seek(). If there are markers
* created after this marker argument, this routine must unroll them
* like a stack. Assume the state the stream was in when this marker
* was created.
* </summary>
*/
void Rewind( int marker );
/** <summary>
* Rewind to the input position of the last marker.
* Used currently only after a cyclic DFA and just
* before starting a sem/syn predicate to get the
* input position back to the start of the decision.
* Do not "pop" the marker off the state. mark(i)
* and rewind(i) should balance still. It is
* like invoking rewind(last marker) but it should not "pop"
* the marker off. It's like seek(last marker's input position).
* </summary>
*/
void Rewind();
/** <summary>
* You may want to commit to a backtrack but don't want to force the
* stream to keep bookkeeping objects around for a marker that is
* no longer necessary. This will have the same behavior as
* rewind() except it releases resources without the backward seek.
* This must throw away resources for all markers back to the marker
* argument. So if you're nested 5 levels of mark(), and then release(2)
* you have to release resources for depths 2..5.
* </summary>
*/
void Release( int marker );
/** <summary>
* Set the input cursor to the position indicated by index. This is
* normally used to seek ahead in the input stream. No buffering is
* required to do this unless you know your stream will use seek to
* move backwards such as when backtracking.
* </summary>
*
* <remarks>
* This is different from rewind in its multi-directional
* requirement and in that its argument is strictly an input cursor (index).
*
* For char streams, seeking forward must update the stream state such
* as line number. For seeking backwards, you will be presumably
* backtracking using the mark/rewind mechanism that restores state and
* so this method does not need to update state when seeking backwards.
*
* Currently, this method is only used for efficient backtracking using
* memoization, but in the future it may be used for incremental parsing.
*
* The index is 0..n-1. A seek to position i means that LA(1) will
* return the ith symbol. So, seeking to 0 means LA(1) will return the
* first element in the stream.
* </remarks>
*/
void Seek( int index );
/** <summary>
* Only makes sense for streams that buffer everything up probably, but
* might be useful to display the entire stream or for testing. This
* value includes a single EOF.
* </summary>
*/
int Count
{
get;
}
/** <summary>
* Where are you getting symbols from? Normally, implementations will
* pass the buck all the way to the lexer who can ask its input stream
* for the file name or whatever.
* </summary>
*/
string SourceName
{
get;
}
}
}
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