From: Heesob Park <phasis@...>
Date: 2010-11-08T10:19:26+09:00
Subject: Re: irb misbehaviour with arrow keys on Windows

Hi,

2010/11/7 Marvin Gülker <sutniuq@gmx.net>:
> Hi there,
>
> It seems that irb has problems with the arrow keys on Windows. Steps to
> reproduce:
>
> 1. Start up CMD.
> 2. Type "irb" and press return
> 3. Type "abc" and *do not* press return
> 4. Press the right arrow key
> 5. Now try typing "defg" - the characters don't show up anymore. If you
> press return followed by the up arrow key, the whole sequence you typed,
> including the mysteriously invisible characters, shows up.
>
> I'm using ruby 1.9.2p0 (2010-08-18) [i386-mingw32] on Windows Vista
> 32-bit, installed by extracting the 7z archive provided by the
> RubyInstaller team to C:\Rubies\ruby-1.9.2-p0-i386-mingw32. Of course I
> added the bin\ subdirectory to my PATH variable.
> I don't know wheather in matters, but I don't have the RubyInstaller's
> devkit installed, but a separate MinGW+MSYS installation in C:\MinGW
> which is up-to-date.
>
> Anyone experiencing the same problem?
>
This is a bug of rbreadline.

Here is a patch for rbrealine.rb
--- rbreadline.rb       2010-11-08 10:10:28.000000000 +0900
+++ rbreadline.rb.new   2010-11-08 10:10:11.000000000 +0900
@@ -8435,21 +8435,20 @@
          count -= 1
       end

+      str = (flags == MB_FIND_NONZERO) ? string.strip : string
+
       case @encoding
       when 'E'
-         point += string[point..-1].scan(/./me)[0,count].to_s.length
+         point += str[point..-1].scan(/./me)[0,count].to_s.length
       when 'S'
-         point += string[point..-1].scan(/./ms)[0,count].to_s.length
+         point += str[point..-1].scan(/./ms)[0,count].to_s.length
       when 'U'
-         point += string[point..-1].scan(/./mu)[0,count].to_s.length
+         point += str[point..-1].scan(/./mu)[0,count].to_s.length
       when 'X'
-         point += string[point..-1].force_encoding(@encoding_name)[0,count].byt
+         point += str[point..-1].force_encoding(@encoding_name)[0,count].bytesi
       else
          point += count
       end
-      if flags == MB_FIND_NONZERO
-         point = string.length if point>=string.length
-      end
       point
    end


Regards,
Park Heesob