OSX/libsecurity_codesigning/antlr2/src/TokenBuffer.cpp

   1 /* ANTLR Translator Generator
   2  * Project led by Terence Parr at http://www.jGuru.com
   3  * Software rights: http://www.antlr.org/license.html
   4  *
   5  * $Id: //depot/code/org.antlr/release/antlr-2.7.7/lib/cpp/src/TokenBuffer.cpp#2 $
   6  */
   7
   8 #include "antlr/TokenBuffer.hpp"
   9
  10 #ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
  11 namespace antlr {
  12 #endif
  13
  14 /**A Stream of Token objects fed to the parser from a TokenStream that can
  15  * be rewound via mark()/rewind() methods.
  16  * <p>
  17  * A dynamic array is used to buffer up all the input tokens.  Normally,
  18  * "k" tokens are stored in the buffer.  More tokens may be stored during
  19  * guess mode (testing syntactic predicate), or when LT(i>k) is referenced.
  20  * Consumption of tokens is deferred.  In other words, reading the next
  21  * token is not done by conume(), but deferred until needed by LA or LT.
  22  * <p>
  23  *
  24  * @see antlr.Token
  25  * @see antlr.TokenStream
  26  * @see antlr.TokenQueue
  27  */
  28
  29 /** Create a token buffer */
  30 TokenBuffer::TokenBuffer( TokenStream& inp )
  31 : input(inp)
  32 , nMarkers(0)
  33 , markerOffset(0)
  34 , numToConsume(0)
  35 {
  36 }
  37
  38 TokenBuffer::~TokenBuffer( void )
  39 {
  40 }
  41
  42 /** Ensure that the token buffer is sufficiently full */
  43 void TokenBuffer::fill(unsigned int amount)
  44 {
  45         syncConsume();
  46         // Fill the buffer sufficiently to hold needed tokens
  47         while (queue.entries() < (amount + markerOffset))
  48         {
  49                 // Append the next token
  50                 queue.append(input.nextToken());
  51         }
  52 }
  53
  54 /** Get a lookahead token value */
  55 int TokenBuffer::LA(unsigned int i)
  56 {
  57         fill(i);
  58         return queue.elementAt(markerOffset+i-1)->getType();
  59 }
  60
  61 /** Get a lookahead token */
  62 RefToken TokenBuffer::LT(unsigned int i)
  63 {
  64         fill(i);
  65         return queue.elementAt(markerOffset+i-1);
  66 }
  67
  68 /** Return an integer marker that can be used to rewind the buffer to
  69  * its current state.
  70  */
  71 unsigned int TokenBuffer::mark()
  72 {
  73         syncConsume();
  74         nMarkers++;
  75         return markerOffset;
  76 }
  77
  78 /**Rewind the token buffer to a marker.
  79  * @param mark Marker returned previously from mark()
  80  */
  81 void TokenBuffer::rewind(unsigned int mark)
  82 {
  83         syncConsume();
  84         markerOffset=mark;
  85         nMarkers--;
  86 }
  87
  88 /// Get number of non-consumed tokens
  89 unsigned int TokenBuffer::entries() const
  90 {
  91         return (unsigned int)queue.entries() - markerOffset;
  92 }
  93
  94 #ifdef ANTLR_CXX_SUPPORTS_NAMESPACE
  95         }
  96 #endif