OSX/libsecurity_codesigning/antlr2/antlr/InputBuffer.hpp

   1 #ifndef INC_InputBuffer_hpp__
   2 #define INC_InputBuffer_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/InputBuffer.hpp#2 $
   9  */
  10
  11 #include <antlr/config.hpp>
  12 #include <antlr/CircularQueue.hpp>
  13 #include <string>
  14
  15 #ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
  16 namespace antlr {
  17 #endif
  18
  19 /** A Stream of characters fed to the lexer from a InputStream that can
  20  * be rewound via mark()/rewind() methods.
  21  * <p>
  22  * A dynamic array is used to buffer up all the input characters.  Normally,
  23  * "k" characters are stored in the buffer.  More characters may be stored during
  24  * guess mode (testing syntactic predicate), or when LT(i>k) is referenced.
  25  * Consumption of characters is deferred.  In other words, reading the next
  26  * character is not done by conume(), but deferred until needed by LA or LT.
  27  * <p>
  28  *
  29  * @see antlr.CharQueue
  30  */
  31 class ANTLR_API InputBuffer {
  32 public:
  33         /** Create a character buffer */
  34         InputBuffer()
  35         : nMarkers(0)
  36         , markerOffset(0)
  37         , numToConsume(0)
  38         {
  39         }
  40
  41         virtual ~InputBuffer()
  42         {
  43         }
  44
  45         /// Reset the input buffer to empty state
  46         virtual inline void reset( void )
  47         {
  48                 nMarkers = 0;
  49                 markerOffset = 0;
  50                 numToConsume = 0;
  51                 queue.clear();
  52         }
  53
  54         /** This method updates the state of the input buffer so that
  55          * the text matched since the most recent mark() is no longer
  56          * held by the buffer.  So, you either do a mark/rewind for
  57          * failed predicate or mark/commit to keep on parsing without
  58          * rewinding the input.
  59          */
  60         inline void commit( void )
  61         {
  62                 nMarkers--;
  63         }
  64
  65         /** Mark another character for deferred consumption */
  66         virtual inline void consume()
  67         {
  68                 numToConsume++;
  69         }
  70
  71         /** Ensure that the character buffer is sufficiently full */
  72         virtual void fill(unsigned int amount);
  73
  74         /** Override this in subclasses to get the next character */
  75         virtual int getChar()=0;
  76
  77         /** Get a lookahead character */
  78         virtual inline int LA(unsigned int i)
  79         {
  80                 fill(i);
  81                 return queue.elementAt(markerOffset + i - 1);
  82         }
  83
  84         /** Return an integer marker that can be used to rewind the buffer to
  85          * its current state.
  86          */
  87         virtual unsigned int mark();
  88         /// Are there any marks active in the InputBuffer
  89         virtual inline bool isMarked() const
  90         {
  91                 return (nMarkers != 0);
  92         }
  93         /** Rewind the character buffer to a marker.
  94          * @param mark Marker returned previously from mark()
  95          */
  96         virtual void rewind(unsigned int mark);
  97
  98         /** Get the number of non-consumed characters
  99          */
 100         virtual unsigned int entries() const;
 101
 102         ANTLR_USE_NAMESPACE(std)string getLAChars() const;
 103
 104         ANTLR_USE_NAMESPACE(std)string getMarkedChars() const;
 105
 106 protected:
 107         // char source
 108         // leave to subclasses
 109
 110         // Number of active markers
 111         unsigned int nMarkers; // = 0;
 112
 113         // Additional offset used when markers are active
 114         unsigned int markerOffset; // = 0;
 115
 116         // Number of calls to consume() since last LA() or LT() call
 117         unsigned int numToConsume; // = 0;
 118
 119         // Circular queue
 120         CircularQueue<int> queue;
 121
 122         /** Sync up deferred consumption */
 123         void syncConsume();
 124
 125 private:
 126         InputBuffer(const InputBuffer& other);
 127         InputBuffer& operator=(const InputBuffer& other);
 128 };
 129
 130 /** Sync up deferred consumption */
 131 inline void InputBuffer::syncConsume() {
 132         if (numToConsume > 0)
 133         {
 134                 if (nMarkers > 0)
 135                         markerOffset += numToConsume;
 136                 else
 137                         queue.removeItems( numToConsume );
 138                 numToConsume = 0;
 139         }
 140 }
 141
 142 #ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
 143 }
 144 #endif
 145
 146 #endif //INC_InputBuffer_hpp__