unescape_value

# File ext/openssl/lib/openssl/config.rb, line 97
      def unescape_value(data, section, value)
        scanned = []
        while m = value.match(/['"\\$]/)
          scanned << m.pre_match
          c = m[0]
          value = m.post_match
          case c
          when "'"
            if m = value.match(QUOTE_REGEXP_SQ)
              scanned << m[1].gsub(/\\(.)/, '\1')
              value = m.post_match
            else
              break
            end
          when '"'
            if m = value.match(QUOTE_REGEXP_DQ)
              scanned << m[1].gsub(/""/, '').gsub(/\\(.)/, '\1')
              value = m.post_match
            else
              break
            end
          when "\\"
            c = value.slice!(0, 1)
            scanned << (ESCAPE_MAP[c] || c)
          when "$"
            ref, value = extract_reference(value)
            refsec = section
            if ref.index('::')
              refsec, ref = ref.split('::', 2)
            end
            if v = get_key_string(data, refsec, ref)
              scanned << v
            else
              raise ConfigError, "variable has no value"
            end
          else
            raise 'must not reaced'
          end
        end
        scanned << value
        scanned.join
      end