static Buffer unescapeBytes()

in activemq-protobuf/src/main/java/org/apache/activemq/protobuf/compiler/TextFormat.java [517:584]
65 lines of code
24 McCabe index (conditional complexity)

  static Buffer unescapeBytes(CharSequence input)
      throws InvalidEscapeSequence {
    byte[] result = new byte[input.length()];
    int pos = 0;
    for (int i = 0; i < input.length(); i++) {
      char c = input.charAt(i);
      if (c == '\\') {
        if (i + 1 < input.length()) {
          ++i;
          c = input.charAt(i);
          if (isOctal(c)) {
            // Octal escape.
            int code = digitValue(c);
            if (i + 1 < input.length() && isOctal(input.charAt(i + 1))) {
              ++i;
              code = code * 8 + digitValue(input.charAt(i));
            }
            if (i + 1 < input.length() && isOctal(input.charAt(i + 1))) {
              ++i;
              code = code * 8 + digitValue(input.charAt(i));
            }
            result[pos++] = (byte)code;
          } else {
            switch (c) {
              case 'a' : result[pos++] = 0x07; break;
              case 'b' : result[pos++] = '\b'; break;
              case 'f' : result[pos++] = '\f'; break;
              case 'n' : result[pos++] = '\n'; break;
              case 'r' : result[pos++] = '\r'; break;
              case 't' : result[pos++] = '\t'; break;
              case 'v' : result[pos++] = 0x0b; break;
              case '\\': result[pos++] = '\\'; break;
              case '\'': result[pos++] = '\''; break;
              case '"' : result[pos++] = '\"'; break;

              case 'x':
                // hex escape
                int code = 0;
                if (i + 1 < input.length() && isHex(input.charAt(i + 1))) {
                  ++i;
                  code = digitValue(input.charAt(i));
                } else {
                  throw new InvalidEscapeSequence(
                    "Invalid escape sequence: '\\x' with no digits");
                }
                if (i + 1 < input.length() && isHex(input.charAt(i + 1))) {
                  ++i;
                  code = code * 16 + digitValue(input.charAt(i));
                }
                result[pos++] = (byte)code;
                break;

              default:
                throw new InvalidEscapeSequence(
                  "Invalid escape sequence: '\\" + c + "'");
            }
          }
        } else {
          throw new InvalidEscapeSequence(
            "Invalid escape sequence: '\\' at end of string.");
        }
      } else {
        result[pos++] = (byte)c;
      }
    }

    return new Buffer(result, 0, pos);
  }