From: John Lam <drjflam@...>
Date: 2005-12-05T13:50:59+09:00
Subject: Re: IL Generator syntax proposal

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I had some free cycles this evening to do a first pass implementation of
some of the ideas that Wayne proposed, and here's the net result:

require 'RbDynamicMethod'
include RbDynamicMethod
include ILGenerator

create_ruby_method('say_hello') do
  ldstr    'Hello, World'
  call     'static System.Console.WriteLine(System.String)'
  ldc_i4_4
  ret
end

say_hello

This code generates a Ruby method with a VALUE (int, VALUE*, VALUE)
signature. The create_ruby_method yields to the block, and uses
method_missing to generate the IL instructions. Once the block has finished
executing, I bake the dynamic method into the RbDynamicMethod module.
Overall I'm pretty happy with this syntax. I'm attaching the implementation
of ILGenerator below for those who are curious. The MC++ part
(RbDynamicMethod) weighs in at about 160 lines of code.

Comments appreciated!

Thanks
-John
http://www.iunknown.com

module ILGenerator
  include RbDynamicMethod

  @@op_codes =3D {
    'ldstr'    =3D> 's',
    'call'     =3D> 'm',
    'ret'      =3D> nil,
    'ldc_i4_4' =3D> nil
  }

  def create_ruby_method(name)
    method =3D create_dynamic_method('', 'System.UInt32', 'System.Int32,
System.UInt32*,System.UInt32')
    @@g =3D get_cil_generator(method)
    yield if block_given?
    define_ruby_method(method, name)
  end

  def parse_method_ref(sig)
    re =3D /(static )?(.*)\.(\w+)\((.*)\)/
    m =3D re.match(sig)
    is_static   =3D m[1] =3D=3D 'static '
    type_name   =3D m[2]
    method_name =3D m[3]
    parameters  =3D m[4]
    return is_static, type_name, method_name, parameters
  end

  def method_missing(name, *parameters)
    op_code =3D name.to_s
    type =3D @@op_codes[op_code]
    case type
    when 's': emit_string(@@g, op_code, parameters[0])
    when 'm': emit_method_ref(@@g, op_code,
*parse_method_ref(parameters[0]))
    when nil: emit(@@g, op_code)
    end
  end
end

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