#include <stdio.h>
#include <ruby.h>
#include <stdbool.h>

VALUE ruby_protect_eval_string_rescue(VALUE exception, VALUE exception_object)
{
    *(bool *)exception = true;
    fprintf(stderr, "exception: %s\n",
            rb_obj_classname(exception_object));
    return Qnil;
}

VALUE ruby_protect_eval_string(const char * ruby_expression, bool * exception)
{
    *exception = false;
    return rb_rescue(rb_eval_string, (VALUE)ruby_expression,
            ruby_protect_eval_string_rescue, (VALUE)exception);
}

int main(int argc, char **argv)
{
    if (argc < 2)
    {
        fprintf(stderr, "Usage: %s <ruby-expression>\n", argv[0]);
        return -1;
    }
    VALUE v = INT2FIX(0);
    bool exception;
    {
        RUBY_INIT_STACK;
        ruby_init();
        v = ruby_protect_eval_string(argv[1], &exception);
    }
    if (exception)
    {
        fprintf(stderr, "Exception!\n");
    }
    else
    {
        if (FIXNUM_P(v))
        {
            printf("Success! Result is %d\n", FIX2INT(v));
        }
        else
        {
            printf("Success! Non-Fixnum result\n");
        }
    }
    return 0;
}