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/*
* Demonstrate the use of goto, call and return. This machine expects either a
* lower case char or a digit as a command then a space followed by the command
* arg. If the command is a char, then the arg must be an a string of chars.
* If the command is a digit, then the arg must be a string of digits. This
* choice is determined by action code, rather than though transition
* desitinations.
*/
#include <iostream>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
using namespace std;
struct GotoCallRet
{
char comm;
int cs, top, stack[32];
int init( );
int execute( const char *data, int len, bool isEof );
int finish( );
};
%%{
machine GotoCallRet;
# Error machine, consumes to end of
# line, then starts the main line over.
garble_line := (
(any-'\n')*'\n'
) >{cout << "error: garbling line" << endl;} @{fgoto main;};
# Look for a string of alphas or of digits,
# on anything else, hold the character and return.
alp_comm := alpha+ $!{fhold;fret;};
dig_comm := digit+ $!{fhold;fret;};
# Choose which to machine to call into based on the command.
action comm_arg {
if ( comm >= 'a' )
fcall alp_comm;
else
fcall dig_comm;
}
# Specifies command string. Note that the arg is left out.
command = (
[a-z0-9] @{comm = fc;} ' ' @comm_arg '\n'
) @{cout << "correct command" << endl;};
# Any number of commands. If there is an
# error anywhere, garble the line.
main := command* $!{fhold;fgoto garble_line;};
}%%
%% write data;
int GotoCallRet::init( )
{
%% write init;
return 1;
}
int GotoCallRet::execute( const char *data, int len, bool isEof )
{
const char *p = data;
const char *pe = data + len;
const char *eof = isEof ? pe : 0;
%% write exec;
if ( cs == GotoCallRet_error )
return -1;
if ( cs >= GotoCallRet_first_final )
return 1;
return 0;
}
#define BUFSIZE 1024
int main()
{
char buf[BUFSIZE];
GotoCallRet gcr;
gcr.init();
while ( fgets( buf, sizeof(buf), stdin ) != 0 )
gcr.execute( buf, strlen(buf), false );
gcr.execute( 0, 0, true );
if ( gcr.cs < GotoCallRet_first_final )
cerr << "gotocallret: error: parsing input" << endl;
return 0;
}
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