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Re: Parser Combinators

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luser droog <luser.droog@gmail.com> writes:
<snip>
> #include <stdio.h>
> #include <stdlib.h>
>
> typedef struct parser *parser;
> typedef int (*parser_handler)( parser p, char *input );
>
> struct parser {
>     parser_handler test;
>     parser a, b;
>     int c;
> };
>
> int debug_parse_term = 1;
>
>
> int parse( parser p, char *input ){    return p->test( p, input ); }
>
> int parse_fail   ( parser p, char *input ){    return  0; }
> int parse_succeed( parser p, char *input ){    return  1; }
>
> int parse_term( parser p, char *input ){
>     return  debug_parse_term && printf( "%c", p->c ),
>             *input == p->c;
> }
> int parse_alt ( parser p, char *input ){
>     return  parse( p->a, input ) || parse( p->b, input );
> }
> int parse_seq ( parser p, char *input ){
>     return  parse( p->a, input )  ?  parse( p->b, input + 1 )  :  0;
> }
>
>
> parser new_parser( struct parser ps ){
>     parser p = malloc( sizeof *p );
>     return  p  ?  ( *p = ps ), p  :  p;
> }
>
> parser fail   (){    return  new_parser( (struct parser){ .test = parse_fail } ); }
> parser succeed(){    return  new_parser( (struct parser){ .test = parse_succeed } ); }
>
> parser term( int c ){
>     return  new_parser( (struct parser){ .test = parse_term, .c = c } );
> }
> parser alternate( parser a, parser b ){
>     return  new_parser( (struct parser){ .test = parse_alt, .a = a, .b = b } );
> }
> parser sequence ( parser a, parser b ){
>     return  new_parser( (struct parser){ .test = parse_seq, .a = a, .b = b } );
> }
>
>
> parser char_class( char *str ){
>     return  *str  ?  alternate( term( *str ), char_class( str + 1 ) )
>                   :  fail();
> }
>
> parser string( char *str ){
>     return  *str  ?  sequence( term(*str), string( str + 1 ) )
>                   :  succeed();
> }
>
>
> int main( void ){
>     parser p = sequence( char_class( "Hh" ), string( "ello" ) );
>     
>     printf("%d\n", parse( p, "hello"  ) );
>     printf("%d\n", parse( p, "Hello"  ) );
>     printf("%d\n", parse( p, "YaMaMa" ) );

Try:

        parser p = sequence( string( "ab" ), term( 'c' ) );
        printf("%d\n", parse( p, "abc" ) );

>     return 0;
> }

-- 
Ben.

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Parser Combinators luser droog <luser.droog@gmail.com> - 2017-05-30 00:34 -0700
  Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-04 19:34 -0700
    Re: Parser Combinators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-05 12:46 +0100
      Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-05 07:55 -0700
  Re: Parser Combinators bartc <bc@freeuk.com> - 2017-06-05 15:06 +0100
    Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-05 08:00 -0700
      Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-06 21:54 -0700
        Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-06 22:32 -0700
          Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-06 23:03 -0700
            Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-06 23:24 -0700
            Re: Parser Combinators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-07 20:57 +0100
              Re: Parser Combinators Melzzzzz <Melzzzzz@zzzzz.com> - 2017-06-08 00:55 +0000
              Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-07 20:17 -0700
                Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-11 00:29 -0700
                Re: Parser Combinators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-11 12:11 +0100
                Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-11 21:21 -0700
                Re: Parser Combinators Ben Bacarisse <ben.usenet@bsb.me.uk> - 2017-06-12 12:25 +0100
                Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-12 13:53 -0700
                Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-13 04:43 -0700
                Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-16 02:22 -0700
                Re: Parser Combinators Melzzzzz <Melzzzzz@zzzzz.com> - 2017-06-17 04:04 +0000
                Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-06-16 23:05 -0700
                Re: Parser Combinators Melzzzzz <Melzzzzz@zzzzz.com> - 2017-06-17 06:16 +0000
                Re: Parser Combinators tkook11@gmail.com - 2017-08-10 06:38 -0700
                Re: Parser Combinators Steve Carroll <tmelmosfire@gmail.com> - 2017-08-12 13:07 -0700
                Re: Parser Combinators luser droog <luser.droog@gmail.com> - 2017-08-20 18:45 -0700
          Re: Parser Combinators bartc <bc@freeuk.com> - 2017-06-07 12:22 +0100
        Re: Parser Combinators Melzzzzz <Melzzzzz@zzzzz.com> - 2017-06-07 12:43 +0000
          Re: Parser Combinators bartc <bc@freeuk.com> - 2017-06-07 14:43 +0100

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