Home | History | Annotate | Download | only in h 
      1 // FILE:        BufFileInput.cpp
      2 // AUTHOR:      Alexey Demakov (AVD) demakov (at) kazbek.ispras.ru
      3 // CREATION:    26-JAN-1998
      4 // DESCRIPTION: File Input Stream with lookahead for Scanner.
      5 //   See file BufFileInput.h for details
      6 
      7 // Change History:
      8 //
      9 //   22-Jun-1998    assert.h -> PCCTS_ASSERT_H
     10 //                  string.h -> PCCTS_STRING_H
     11 //
     12 //   28-May-1998    Add virtual destructor to release buffer.
     13 //
     14 //                  Add dummy definition for ANTLRTokenType
     15 //                  to allow compilation without knowing
     16 //                  token type codes.
     17 //
     18 //                  Manfred Kogler (km (at) cast.uni-linz.ac.at)
     19 //                  (1.33MR14)
     20 //
     21 //   20-Jul-1998    MR14a - Reorder initialization list for ctor.
     22 //
     23 
     24 enum ANTLRTokenType {TER_HATES_CPP=0, SO_DO_OTHERS=9999 };
     25 
     26 #include "pcctscfg.h"
     27 #include "pccts_assert.h"
     28 #include "pccts_string.h"
     29 
     30 PCCTS_NAMESPACE_STD
     31 
     32 #include "BufFileInput.h"
     33 
     34 BufFileInput::BufFileInput( FILE *f, int buf_size )
     35 : input( f ),
     36   buf( new int[buf_size] ),
     37   size( buf_size ),
     38   start( 0 ),
     39   len( 0 )
     40 {
     41 }
     42 
     43 BufFileInput::~BufFileInput()
     44 {
     45   delete [] buf;
     46 }
     47 
     48 int BufFileInput::nextChar( void )
     49 {
     50     if( len > 0 )
     51     {
     52         // get char from buffer
     53         int c = buf[start];
     54 
     55         if( c != EOF )
     56         {
     57             start++; start %= size;
     58             len--;
     59         }
     60         return c;
     61     } else {
     62         // get char from file
     63         int c = getc( input );
     64 
     65         if( c == EOF )
     66         {
     67             // if EOF - put it in the buffer as indicator
     68             buf[start] = EOF;
     69             len++;
     70         }
     71         return c;
     72     }
     73 }
     74 
     75 int BufFileInput::lookahead( char* s )
     76 {
     77     int l = strlen( s );
     78 
     79     assert( 0 < l && l <= size );
     80 
     81     while( len < l )
     82     {
     83         int c = getc( input );
     84 
     85         buf[ (start+len) % size ] = c;
     86 
     87         len++;
     88 
     89         if( c == EOF ) return 0;
     90     }
     91 
     92     for( int i = 0; i < l; i++ )
     93     {
     94         if( s[i] != buf[ (start+i) % size ] ) return 0;
     95     }
     96     return 1;
     97 }
     98 
     99 // End of file BufFileInput.cpp
    100 
    101