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#ifndef INC_TokenBuffer_hpp__ |
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#define INC_TokenBuffer_hpp__ |
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|
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/* ANTLR Translator Generator |
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* Project led by Terence Parr at http://www.jGuru.com |
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* Software rights: http://www.antlr.org/license.html |
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* |
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* $Id: TokenBuffer.hpp,v 1.1 2005-12-02 15:38:02 tim Exp $ |
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*/ |
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|
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#include <antlr/config.hpp> |
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#include <antlr/TokenStream.hpp> |
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#include <antlr/CircularQueue.hpp> |
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|
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#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE |
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namespace antlr { |
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#endif |
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|
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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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* @todo: see if we can integrate this one with InputBuffer into one template |
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* or so. |
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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 ANTLR_API TokenBuffer { |
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public: |
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/** Create a token buffer */ |
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TokenBuffer(TokenStream& input_); |
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virtual ~TokenBuffer(); |
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|
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/// Reset the input buffer to empty state |
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inline void reset( void ) |
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{ |
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nMarkers = 0; |
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markerOffset = 0; |
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numToConsume = 0; |
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queue.clear(); |
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} |
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|
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/** Get a lookahead token value */ |
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int LA( unsigned int i ); |
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|
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/** Get a lookahead token */ |
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RefToken LT( unsigned int i ); |
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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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unsigned int mark(); |
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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 rewind(unsigned int mark); |
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|
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/** Mark another token for deferred consumption */ |
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inline void consume() |
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{ |
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numToConsume++; |
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} |
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|
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/// Return the number of entries in the TokenBuffer |
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virtual unsigned int entries() const; |
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|
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private: |
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/** Ensure that the token buffer is sufficiently full */ |
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void fill(unsigned int amount); |
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/** Sync up deferred consumption */ |
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void syncConsume(); |
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|
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protected: |
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/// Token source |
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TokenStream& input; |
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|
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/// Number of active markers |
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unsigned int nMarkers; |
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|
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/// Additional offset used when markers are active |
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unsigned int markerOffset; |
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|
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/// Number of calls to consume() since last LA() or LT() call |
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unsigned int numToConsume; |
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|
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/// Circular queue with Tokens |
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CircularQueue<RefToken> queue; |
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|
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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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}; |
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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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if (numToConsume > 0) |
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{ |
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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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|
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#ifdef ANTLR_CXX_SUPPORTS_NAMESPACE |
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} |
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#endif |
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|
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#endif //INC_TokenBuffer_hpp__ |
