obj_c.rb

require "readline"
require "pry"
require "fileutils"

class CompileObjectiveC
  attr_accessor :code_lines

  TMP_DIR = "/tmp"

  def initialize
    @code_lines = []
  end

  def start_reading
    while buf = Readline.readline("obj-c> ", true)
      process_input(buf)
    end
  end

  def process_input(raw_data)
    raw_data.strip!
    return if !raw_data || raw_data.empty?
    case raw_data
    when 'clear'
      @code_lines = []
    when /print/
      if print_stuff(raw_data)
        @code_lines.pop
      end
    when /^NSLog/
      add_and_remove_old_log(raw_data)
      if compile_and_run
        @code_lines.pop
      end
    else
      @code_lines << raw_data
      compile_and_run
    end
  end

  def print_stuff(raw_data)
    print_arg = raw_data.split(' ',2).last
    print_arg.strip!
    return false if !print_arg || print_arg.empty?

    current_line = %Q{IFPrint(@"\%@\\n",#{print_arg})}
    @code_lines.reject! { |line| line =~ /IFPrint/ }
    @code_lines << current_line
    compile_and_run
  end

  def add_and_remove_old_log(raw_data)
    @code_lines.reject! { |line| line =~ /NSLog/ }
    @code_lines << raw_data
  end

  def compile_and_run
    File.open("/tmp/foo.m","w") do |fl|
      fl.puts <<-EOD
#import <Foundation/Foundation.h>
void IFPrint (NSString *format, ...) {
    va_list args;
    va_start(args, format);

    fputs([[[[NSString alloc] initWithFormat:format arguments:args] autorelease] UTF8String], stdout);

    va_end(args);
}

int main (int args, const char *arv[])
{
  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
      EOD
      code_lines.each do |line|
        if line =~ /;$/
          fl.puts "#{line}"
        else
          fl.puts "#{line};"
        end
      end

      fl.puts <<-EOD
  [pool drain];
  return 0;
}
      EOD

    end

    success_flag = false
    FileUtils.cd("/tmp") do
      success_flag = system("clang -framework Foundation foo.m")
      if success_flag
        success_flag = system("./a.out")
      else
        @code_lines.pop
      end
    end
    success_flag
  end

end

if __FILE__ == $0
  CompileObjectiveC.new().start_reading
end