// FILE:        BufFileInput.cpp

// AUTHOR:      Alexey Demakov (AVD) demakov@kazbek.ispras.ru

// CREATION:    26-JAN-1998

// DESCRIPTION: File Input Stream with lookahead for Scanner.

//   See file BufFileInput.h for details

// Change History:

//

//   22-Jun-1998    assert.h -> PCCTS_ASSERT_H

//                  string.h -> PCCTS_STRING_H

//

//   28-May-1998    Add virtual destructor to release buffer.

//

//                  Add dummy definition for ANTLRTokenType

//                  to allow compilation without knowing

//                  token type codes.

//

//                  Manfred Kogler (km@cast.uni-linz.ac.at)

//                  (1.33MR14)

//

//   20-Jul-1998    MR14a - Reorder initialization list for ctor.

//

enum ANTLRTokenType {TER_HATES_CPP=0, SO_DO_OTHERS=9999 };

#include "pcctscfg.h"

#include "pccts_assert.h"

#include "pccts_string.h"

PCCTS_NAMESPACE_STD

#include "BufFileInput.h"

BufFileInput::BufFileInput( FILE *f, int buf_size )

: input( f ),

  buf( new int[buf_size] ),

  size( buf_size ),

  start( 0 ),

  len( 0 )

{

}

BufFileInput::~BufFileInput()

{

  delete [] buf;

}

int BufFileInput::nextChar( void )

{

    if( len > 0 )

    {

        // get char from buffer

        int c = buf[start];

        if( c != EOF )

        {

            start++; start %= size;

            len--;

        }

        return c;

    } else {

        // get char from file

        int c = getc( input );

        if( c == EOF )

        {

            // if EOF - put it in the buffer as indicator

            buf[start] = EOF;

            len++;

        }

        return c;

    }

}

int BufFileInput::lookahead( char* s )

{

    int l = strlen( s );

    assert( 0 < l && l <= size );

    while( len < l )

    {

        int c = getc( input );

        buf[ (start+len) % size ] = c;

        len++;

        if( c == EOF ) return 0;

    }

    for( int i = 0; i < l; i++ )

    {

        if( s[i] != buf[ (start+i) % size ] ) return 0;

    }

    return 1;

}

// End of file BufFileInput.cpp