source: doc/papers/concurrency/examples/Format.cfa@ 9b55aa3

#if 1
#include <fstream.hfa>
#include <coroutine.hfa>

coroutine Fmt {
        char ch;                                                                // communication variables
        int g, b;                                                               // needed in destructor
};
void main( Fmt & fmt ) with( fmt ) {
        for () {                                                                // for as many characters
                for ( g = 0; g < 5; g += 1 ) {          // groups of 5 blocks
                        for ( b = 0; b < 4; b += 1 ) {  // blocks of 4 characters
                                do {
                                        suspend();
                                } while ( ch == '\n' || ch == '\t' );
                                sout | ch;                                      // print character
                        }
                        sout | "  ";                                    // block separator
                }
                sout | nl;                                                      // group separator
        }
}
void ?{}( Fmt & fmt ) { resume( fmt ); } // prime (start) coroutine
void ^?{}( Fmt & fmt ) with( fmt ) { // destructor
        if ( g != 0 || b != 0 ) // special case
                sout | nl; }
void send( Fmt & fmt, char c ) { fmt.ch = c; resume( fmt ); }
int main() {
        Fmt fmt;
        sout | nlOff;                                                   // turn off auto newline
        for ( 41 )
                send( fmt, 'a' );
  //    sout | nlOff;                                                   // turn off auto newline
  // eof: for () {                                                              // read until end of file
  //            sin | fmt.ch;                                           // read one character
  //      if ( eof( sin ) ) break eof;                  // eof ?
  //            format( fmt );                                          // push character for formatting
  //    }
}
#else

#include <stdio.h>

struct Format {
        char ch;                                                                // used for communication
        int g, b;                                                               // global because used in destructor
};

void format( struct Format * fmt ) {
        if ( fmt->ch != -1 ) { // not EOF ?
//              if ( fmt->ch == '\n' || fmt->ch == '\t' ) return;
//              printf( "%c %d %d", fmt->ch, fmt->g, fmt->b );          // character
                printf( "%c", fmt->ch );                // character
                fmt->b += 1;
                if ( fmt->b == 4 ) {    // block ?
                        printf( "  " ); // separator
                        fmt->b = 0;
                        fmt->g += 1;
                }
                if ( fmt->g == 5 ) {    // group ?
                        printf( "\n" ); // separator
                        fmt->g = 0;
                }
        } else {
                if ( fmt->g != 0 || fmt->b != 0 ) printf( "\n" );
        }
}
int main() {
        struct Format fmt = { 0, 0, 0 };
        for ( ;; ) {
                scanf( "%c", &fmt.ch );
          if ( feof( stdin ) ) break;
                format( &fmt );
        }
        fmt.ch = -1;
        format( &fmt );
}
#endif

// Local Variables: //
// tab-width: 4 //
// fill-column: 120 //
// compile-command: "cfa Format.cfa" //
// End: //