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142 lines
3.8 KiB
142 lines
3.8 KiB
#ifndef INC_TokenBuffer_hpp__
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#define INC_TokenBuffer_hpp__
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/**
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* <b>SOFTWARE RIGHTS</b>
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* <p>
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* ANTLR 2.6.0 MageLang Insitute, 1999
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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, 1999
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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/config.h"
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#include "antlr/TokenStream.h"
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#include "antlr/CircularQueue.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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class TokenBuffer {
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protected:
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// Token source
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TokenStream& input;
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private:
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// Number of active markers
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int nMarkers;
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// Additional offset used when markers are active
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int markerOffset;
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// Number of calls to consume() since last LA() or LT() call
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int numToConsume;
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// Circular queue
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CircularQueue<RefToken> queue;
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public:
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/** Create a token buffer */
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TokenBuffer(TokenStream& input_);
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/** Mark another token for deferred consumption */
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void consume();
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private:
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/** Ensure that the token buffer is sufficiently full */
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void fill(int amount);
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public:
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/** Get a lookahead token value */
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int LA(int i);
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/** Get a lookahead token */
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RefToken LT(int i);
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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 mark();
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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 rewind(int mark);
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private:
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/** Sync up deferred consumption */
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void syncConsume();
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private:
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TokenBuffer(const TokenBuffer& other);
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const TokenBuffer& operator=(const TokenBuffer& other);
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public:
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// virtual ~TokenBuffer() {}
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};
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/** Sync up deferred consumption */
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inline void TokenBuffer::syncConsume()
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{
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#ifdef OLD_CODE
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while (numToConsume > 0) {
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if (nMarkers > 0) {
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// guess mode -- leave leading tokens and bump offset.
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markerOffset++;
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} else {
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// normal mode -- remove first token
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queue.removeFirst();
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}
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numToConsume--;
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}
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#endif
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if (numToConsume > 0) {
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if (nMarkers > 0) {
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markerOffset += numToConsume;
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} else {
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queue.removeItems( numToConsume );
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}
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numToConsume = 0;
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}
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}
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ANTLR_END_NAMESPACE
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#endif //INC_TokenBuffer_hpp__
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