Module: Rfc2047

Defined in:
lib/sup/rfc2047.rb

Overview

$Id: rfc2047.rb,v 1.4 2003/04/18 20:55:56 sam Exp $ MODIFIED slightly by William Morgan

An implementation of RFC 2047 decoding.

This module depends on the iconv library by Nobuyoshi Nakada, which I’ve heard may be distributed as a standard part of Ruby 1.8. Many thanks to him for helping with building and using iconv.

Thanks to “Josef ‘Jupp’ Schugt” <jupp / gmx.de> for pointing out an error with stateful character sets.

Copyright © Sam Roberts <sroberts / uniserve.com> 2004

This file is distributed under the same terms as Ruby.

Constant Summary collapse

WORD =

:nodoc: ‘stupid ruby-mode

%r{=\?([!\#$%&'*+-/0-9A-Z\\^\`a-z{|}~]+)\?([BbQq])\?([!->@-~ ]+)\?=}
WORDSEQ = 
%r{(#{WORD.source})\s+(?=#{WORD.source})}

Class Method Summary collapse

Class Method Details

.decode_to(target, from) ⇒ Object

Decodes a string, from, containing RFC 2047 encoded words into a target character set, target. See iconv_open(3) for information on the supported target encodings. If one of the encoded words cannot be converted to the target encoding, it is left in its encoded form.



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# File 'lib/sup/rfc2047.rb', line 29

def Rfc2047.decode_to(target, from)
  from = from.gsub(WORDSEQ, '\1')
  from.gsub(WORD) do
    |word|
    charset, encoding, text = $1, $2, $3

    # B64 or QP decode, as necessary:
    case encoding
      when 'b', 'B'
        ## Padding is optional in RFC 2047 words. Add some extra padding
        ## before decoding the base64, otherwise on Ruby 2.0 the final byte
        ## might be discarded.
        text = (text + '===').unpack('m*')[0]

      when 'q', 'Q'
        # RFC 2047 has a variant of quoted printable where a ' ' character
        # can be represented as an '_', rather than =32, so convert
        # any of these that we find before doing the QP decoding.
        text = text.tr("_", " ")
        text = text.unpack('M*')[0]

      # Don't need an else, because no other values can be matched in a
      # WORD.
    end

    # Handle UTF-7 specially because Ruby doesn't actually support it as
    # a normal character encoding.
    if charset == 'UTF-7'
      begin
        next text.decode_utf7.encode(target)
      rescue ArgumentError, EncodingError
        next word
      end
    end

    begin
      text.force_encoding(charset).encode(target)
    rescue ArgumentError, EncodingError
      word
    end
  end
end

.is_encoded?(s) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/sup/rfc2047.rb', line 23

def Rfc2047.is_encoded? s; s =~ WORD end