wrapper for creating node-powered js "binaries" with emcc

cc.rb

#!/usr/bin/env ruby
# %% -*- ruby -*-

# This script adds a wrapper to emcc: when the value of -o option is an
# executable file without extensions(such as mrbc), we would first use
# emcc to generate a .js file, then adds a "#!/usr/bin/env node" line at
# the top, finally removes the extension and mark the file mode as
# executable to pretend creating a binary file.

WEBRUBY_ROOT = File.join(File.dirname(__FILE__), '..')
EMCC = File.join(WEBRUBY_ROOT, 'modules', 'emscripten', 'emcc')

def mark_file_executable(original_filename, js_filename)
  File.open(original_filename, "w", 0755) do |f|
    f.puts "#!/usr/bin/env node"
    File.foreach(js_filename) do |l|
      f.puts l
    end
  end
end

if (i = ARGV.index('-o')) &&
    (i + 1 < ARGV.length) &&
    (!ARGV[i + 1].split('/').last.include?('.'))

  original_filename = ARGV[i + 1]
  js_filename = original_filename + ".js"
  ARGV[i + 1] = js_filename

  ret = 255
  if system(EMCC, *ARGV)
    # normal execution
    mark_file_executable(original_filename, js_filename)
    ret = 0
  end
  File.delete(js_filename) if File.exists?(js_filename)
  exit(ret)
else
  exec(EMCC, *ARGV)
end

gistfile1.rb

#!/usr/bin/env ruby
# -*- Ruby -*-

require 'fileutils'

EXECUTABLES = ['mrbc']

CURRENT_PATH = File.dirname(__FILE__)
WEBRUBY_ROOT = File.join(CURRENT_PATH, '..')
EMCC_ROOT = File.join(WEBRUBY_ROOT, 'modules', 'emscripten')
EMCC_MAP = {
  :cc => File.join(EMCC_ROOT, 'emcc'),
  :ll => File.join(EMCC_ROOT, 'emcc'),
  :ar => File.join(EMCC_ROOT, 'emar')}

EXE = EMCC_MAP[ARGV.first.to_sym]
if !EXE
  puts "Unknown program: ${ARGV.first}!"
  exit 1
end

# Removes optimization arguments since this is not used in emcc
args = ARGV.drop(1).select { |i| (i != "-g") && (!i.start_with?("-O")) }

if (i = args.index('-o')) &&
    (i + 1 < args.length) &&
    (program_name = File.basename(args[i + 1])) &&
    (EXECUTABLES.index(program_name))
  original_file = args[i + 1]
  args[i + 1] = original_file + ".js"

  ret = 255
  if system(EXE, *args)
    # normal execution
    FileUtils.cp(File.join(CURRENT_PATH, program_name),
                 original_file)
    FileUtils.touch original_file
    ret = 0
  end
  exit(ret)
else
  exec(EXE, *args)
end