Listing 1 Definition of class filefilter

// class FileFilter:
// The FileFilter class encapsulates reading an
// input file, filtering its contents through a function,
// and writing the result to an output file. It uses two
// threads of execution, one for reading the file, the other
// for writing the output file.
// Author:     Michael Kelly
// Date:       July 26, 1993
// Copyright:  Copyright (c) 1993 Michael Kelly,
//             all rights reserved.
#if !defined(FFILTER_HPP)

#if !defined(INCL_DOSPROCESS)
#if !defined(INCL_DOSQUEUES)
#include <os2.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <process.h>

#define INBUF_SIZE 4096
#define QNAME_LEN 32

struct data_block {
  int data_size;
  char *block;

class FileFilter {
    HEV   done_sem;
    HQUEUE qhandle;
    char   qname[ QNAME_LEN ];
    ULONG max_sem_wait;

    static int count;
    int in_line_mode:
    int blocks2read;
    int blocks2write;
    int filter_valid;
    data_block* (*filter)( data_block *inblock );

    ULONG filter_error;
    FILE *rfile;
    FILE *wfile;

    friend void read_thread( void *filterptr );
    friend void write_thread( void *filterptr );
    int create_sem();

    int          create_queue();
    data_block  *get_queue();
    int          put_queue( data_block *data );

    FileFilter() {}
    FileFilter( const char *file2read,
              const char *file2write,
              data_block* (*filter_func)

                     ( data_block *inblock ) );


    ULONG        error_code()    { return filter_error; }
    int          valid()         { return filter_valid; }
    APIRET       wait4completion( ULONG max_wait );


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