smugglys/translatomatic

module Translatomatic
  # String escaping/unescaping code from syck/encoding.rb
  module StringEscaping
    ESCAPES = %w[\x00 \x01 \x02 \x03 \x04 \x05 \x06 \a
                 \x08 \t \n \v \f
                 \r \x0e \x0f
                 \x10 \x11 \x12 \x13 \x14 \x15 \x16 \x17
                 \x18 \x19 \x1a \e \x1c \x1d \x1e \x1f].freeze
    UNESCAPES = {
      'a' => "\x07", 'b' => "\x08", 't' => "\x09",
      'n' => "\x0a", 'v' => "\x0b", 'f' => "\x0c",
      'r' => "\x0d", 'e' => "\x1b", '\\' => '\\'
    }.freeze

    private_constant :ESCAPES
    private_constant :UNESCAPES

    class << self
      # Escape unprintable characters such as newlines.
      # @param value [String] The string to escape
      # @param include [String] Extra characters to escape
      # @return [String] The string with special characters escaped.
      def escape(value, include = '"')
        return nil if value.nil?
        new_value = value.dup
        new_value.gsub!(/\\/, '\\\\\\')
        if include.present?
          new_value.gsub!(/([#{include}])/) { '\\' + Regexp.last_match(1) }
        end
        new_value.gsub!(/([\x00-\x1f])/) { ESCAPES[ $&.unpack('C')[0] ] }
        new_value
      end

      # Unescape character escapes such as "\n" to their character equivalents.
      # @param value [String] The string to unescape
      # @return [String] The string with special characters unescaped.
      def unescape(value)
        return nil if value.nil?
        regex = /\\(?:([nevfbart\\])|0?x([0-9a-fA-F]{2})|u([0-9a-fA-F]{4}))/
        value.gsub(regex) do
          if Regexp.last_match(3)
            [Regexp.last_match(3).to_s.hex].pack('U*')
          elsif Regexp.last_match(2)
            [Regexp.last_match(2)].pack('H2')
          else
            UNESCAPES[Regexp.last_match(1)]
          end
        end
      end

      # Unescape as above, and also convert all occurrences of \$char to $char
      # @param value [String] The string to unescape
      # @return [String] The string with all characters unescaped.
      def unescape_all(value)
        return nil if value.nil?
        value = unescape(value).gsub(/\\(.)/) { Regexp.last_match(1) }
        value
      end
    end
  end
end