Ragel quickstartEdit

Created , updated

This article demonstrates the basic work flow for Ragel development.

simple.rl

Start with the simplest code possible, a recognizer for strings of letters (taken from the Ragel user guide):

#include <stdio.h>

%% machine foo;

int main(int argc, char **argv)
{
    %% write data noerror nofinal;
    int cs, res = 0;
    if (argc > 1)
    {
        char *p = argv[1];
        %%{
            main := [a-z]+ 0 @{ res = 1; fbreak; };
            write init;
            write exec noend;
        }%%
    }
    printf("execute = %i\n", res );
    return 0;
}

Run ragel

Now run the ragel on the file:

$ ragel simple.rl

Compile the C code

$ gcc simple.c -o simple

Run

A sample session; 0 is printed if no match occurs, 1 is printed on success:

$ ./simple
execute = 0
$ ./simple foo
execute = 1
$ ./simple fo4
execute = 0

See also