OSX/libsecurity_codesigning/antlr2/antlr/TokenBuffer.hpp

   1 #ifndef INC_TokenBuffer_hpp__
   2 #define INC_TokenBuffer_hpp__
   3
   4 /* ANTLR Translator Generator
   5  * Project led by Terence Parr at http://www.jGuru.com
   6  * Software rights: http://www.antlr.org/license.html
   7  *
   8  * $Id: //depot/code/org.antlr/release/antlr-2.7.7/lib/cpp/antlr/TokenBuffer.hpp#2 $
   9  */
  10
  11 #include <antlr/config.hpp>
  12 #include <antlr/TokenStream.hpp>
  13 #include <antlr/CircularQueue.hpp>
  14
  15 #ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
  16 namespace antlr {
  17 #endif
  18
  19 /**A Stream of Token objects fed to the parser from a TokenStream that can
  20  * be rewound via mark()/rewind() methods.
  21  * <p>
  22  * A dynamic array is used to buffer up all the input tokens.  Normally,
  23  * "k" tokens are stored in the buffer.  More tokens may be stored during
  24  * guess mode (testing syntactic predicate), or when LT(i>k) is referenced.
  25  * Consumption of tokens is deferred.  In other words, reading the next
  26  * token is not done by conume(), but deferred until needed by LA or LT.
  27  * <p>
  28  *
  29  * @todo: see if we can integrate this one with InputBuffer into one template
  30  * or so.
  31  *
  32  * @see antlr.Token
  33  * @see antlr.TokenStream
  34  * @see antlr.TokenQueue
  35  */
  36 class ANTLR_API TokenBuffer {
  37 public:
  38         /** Create a token buffer */
  39         TokenBuffer(TokenStream& input_);
  40         virtual ~TokenBuffer();
  41
  42         /// Reset the input buffer to empty state
  43         inline void reset( void )
  44         {
  45                 nMarkers = 0;
  46                 markerOffset = 0;
  47                 numToConsume = 0;
  48                 queue.clear();
  49         }
  50
  51         /** Get a lookahead token value */
  52         int LA( unsigned int i );
  53
  54         /** Get a lookahead token */
  55         RefToken LT( unsigned int i );
  56
  57         /** Return an integer marker that can be used to rewind the buffer to
  58          * its current state.
  59          */
  60         unsigned int mark();
  61
  62         /**Rewind the token buffer to a marker.
  63          * @param mark Marker returned previously from mark()
  64          */
  65         void rewind(unsigned int mark);
  66
  67         /** Mark another token for deferred consumption */
  68         inline void consume()
  69         {
  70                 numToConsume++;
  71         }
  72
  73         /// Return the number of entries in the TokenBuffer
  74         virtual unsigned int entries() const;
  75
  76 private:
  77         /** Ensure that the token buffer is sufficiently full */
  78         void fill(unsigned int amount);
  79         /** Sync up deferred consumption */
  80         void syncConsume();
  81
  82 protected:
  83         /// Token source
  84         TokenStream& input;
  85
  86         /// Number of active markers
  87         unsigned int nMarkers;
  88
  89         /// Additional offset used when markers are active
  90         unsigned int markerOffset;
  91
  92         /// Number of calls to consume() since last LA() or LT() call
  93         unsigned int numToConsume;
  94
  95         /// Circular queue with Tokens
  96         CircularQueue<RefToken> queue;
  97
  98 private:
  99         TokenBuffer(const TokenBuffer& other);
 100         const TokenBuffer& operator=(const TokenBuffer& other);
 101 };
 102
 103 /** Sync up deferred consumption */
 104 inline void TokenBuffer::syncConsume()
 105 {
 106         if (numToConsume > 0)
 107         {
 108                 if (nMarkers > 0)
 109                         markerOffset += numToConsume;
 110                 else
 111                         queue.removeItems( numToConsume );
 112
 113                 numToConsume = 0;
 114         }
 115 }
 116
 117 #ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
 118 }
 119 #endif
 120
 121 #endif //INC_TokenBuffer_hpp__