embedded mruby Hello World

mruby_hello.c

/* Copyright (c) 2012 Jon Maken
 * License: 3-clause BSD
 * Revision: 2012-06-04 14:35:54 -0600
 *
 * typical Clang/MinGW build recipe:
 *    set CPATH=C:/devlibs/mruby/include
 *    set LIBRARY_PATH=C:/devlibs/mruby/lib
 *
 *    clang -Wall -O3 -march=native -o mruby_hello.exe mruby_hello.c -lmruby
 *
 * typical WinSDK 7.1 cmd line build recipe:
 *    set INCLUDE=C:\devlibs\mruby-vc1600\include;%INCLUDE%
 *    set LIB=C:\devlibs\mruby-vc1600\lib;%LIB%
 *
 *    cl /Wall /O2 /Femruby_hello.exe /MD mruby_hello.c mruby.lib
 */

#include <stdlib.h>

#include "mruby.h"
#include "mruby/compile.h"
#include "mruby/class.h"
#include "mruby/proc.h"

// Foo module implementation
static mrb_value
mrb_foo_now(mrb_state *mrb, mrb_value self)
{
  puts("Wake up, the foo is now...");

  return mrb_nil_value();
}

static void
mrb_init_foo(mrb_state *mrb)
{
  struct RClass *fc;
  fc = mrb_define_module(mrb, "Foo");
  mrb_define_class_method(mrb, fc, "now", mrb_foo_now, ARGS_NONE());
}


// TODO discover why mruby doesn't have a similar utility fcn
//      that makes client code nicer.
static int
mrb_run_string(mrb_state *mrb, char *str)
{
  int n = 0;
  //struct mrb_parser_state *p;

  //p = mrb_parse_string(mrb, str);
  //n = mrb_generate_code(mrb, p->tree);
  n = mrb_compile_string(mrb, str);
  mrb_run(mrb, mrb_proc_new(mrb, mrb->irep[n]), mrb_top_self(mrb));

  return mrb->exc ? 0 : 1; 
}


int
main(int argc, char *argv[])
{
  int rv = EXIT_SUCCESS;
  char *rb_code = "require 'foo'\n"
                  "\n"
                  "10.times do |i|\n"
                  "  puts %Q{[#{i}] Hello mruby!}\n"
                  "end"
                  "\n"
                  "# and now for something completely useless\n"
                  "Foo.now\n"
                  "\n"
                  "module Foo\n"
                  "  class Bar\n"
                  "    def say_baz; puts %Q{#{self.class} says baz...}; end\n"
                  "  end\n"
                  "end\n"
                  "\n"
                  "Foo::Bar.new.say_baz\n";

  // get an mruby VM instance
  mrb_state *mrb = mrb_open();
  if (mrb == NULL) return EXIT_FAILURE;

  // register Foo module with the mruby VM instance
  mrb_init_foo(mrb);

  // persuade the mruby VM to run the ruby source code string
  if (!mrb_run_string(mrb, rb_code)) {
    mrb_p(mrb, mrb_obj_value(mrb->exc));
    rv = EXIT_FAILURE;
  }

  mrb_close(mrb);

  return rv;
}

/* vim: set ts=2 sw=2 sts=2 et: */