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108 lines
3.1 KiB
108 lines
3.1 KiB
/**
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* <b>SOFTWARE RIGHTS</b>
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* <p>
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* ANTLR 2.6.0 MageLang Insitute, 1998
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* <p>
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* We reserve no legal rights to the ANTLR--it is fully in the
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* public domain. An individual or company may do whatever
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* they wish with source code distributed with ANTLR or the
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* code generated by ANTLR, including the incorporation of
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* ANTLR, or its output, into commerical software.
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* <p>
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* We encourage users to develop software with ANTLR. However,
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* we do ask that credit is given to us for developing
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* ANTLR. By "credit", we mean that if you use ANTLR or
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* incorporate any source code into one of your programs
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* (commercial product, research project, or otherwise) that
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* you acknowledge this fact somewhere in the documentation,
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* research report, etc... If you like ANTLR and have
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* developed a nice tool with the output, please mention that
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* you developed it using ANTLR. In addition, we ask that the
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* headers remain intact in our source code. As long as these
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* guidelines are kept, we expect to continue enhancing this
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* system and expect to make other tools available as they are
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* completed.
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* <p>
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* The ANTLR gang:
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* @version ANTLR 2.6.0 MageLang Insitute, 1998
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* @author Terence Parr, <a href=http://www.MageLang.com>MageLang Institute</a>
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* @author <br>John Lilley, <a href=http://www.Empathy.com>Empathy Software</a>
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* @author <br><a href="mailto:pete@yamuna.demon.co.uk">Pete Wells</a>
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*/
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#include "antlr/TokenBuffer.h"
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ANTLR_BEGIN_NAMESPACE(antlr)
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/**A Stream of Token objects fed to the parser from a TokenStream that can
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* be rewound via mark()/rewind() methods.
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* <p>
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* A dynamic array is used to buffer up all the input tokens. Normally,
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* "k" tokens are stored in the buffer. More tokens may be stored during
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* guess mode (testing syntactic predicate), or when LT(i>k) is referenced.
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* Consumption of tokens is deferred. In other words, reading the next
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* token is not done by conume(), but deferred until needed by LA or LT.
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* <p>
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*
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* @see antlr.Token
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* @see antlr.TokenStream
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* @see antlr.TokenQueue
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*/
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/** Create a token buffer */
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TokenBuffer::TokenBuffer(TokenStream& input_)
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: input(input_)
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{ nMarkers=0; markerOffset=0; numToConsume=0; }
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/** Mark another token for deferred consumption */
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void TokenBuffer::consume()
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{ numToConsume++; }
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/** Ensure that the token buffer is sufficiently full */
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void TokenBuffer::fill(int amount)
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{
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syncConsume();
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// Fill the buffer sufficiently to hold needed tokens
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while (queue.entries() < amount + markerOffset) {
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// Append the next token
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queue.append(input.nextToken());
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}
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}
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/** Get a lookahead token value */
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int TokenBuffer::LA(int i)
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{
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fill(i);
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return queue.elementAt(markerOffset+i-1)->type;
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}
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/** Get a lookahead token */
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RefToken TokenBuffer::LT(int i)
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{
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fill(i);
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return queue.elementAt(markerOffset+i-1);
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}
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/**Return an integer marker that can be used to rewind the buffer to
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* its current state.
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*/
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int TokenBuffer::mark()
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{
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syncConsume();
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nMarkers++;
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return markerOffset;
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}
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/**Rewind the token buffer to a marker.
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* @param mark Marker returned previously from mark()
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*/
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void TokenBuffer::rewind(int mark)
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{
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syncConsume();
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markerOffset=mark;
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nMarkers--;
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}
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ANTLR_END_NAMESPACE
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