RawObject FUNC()

in runtime/under-codecs-module.cpp [1239:1345]
105 lines of code
21 McCabe index (conditional complexity)

RawObject FUNC(_codecs, backslashreplace_errors)(Thread* thread,
                                                 Arguments args) {
  HandleScope scope(thread);
  Runtime* runtime = thread->runtime();
  Object error(&scope, args.get(0));
  Object object(&scope, NoneType::object());
  word start;
  word end;
  if (runtime->isInstanceOfUnicodeDecodeError(*error)) {
    UnicodeErrorBase unicode_error(&scope, *error);
    start = SmallInt::cast(unicode_error.start()).value();
    end = SmallInt::cast(unicode_error.end()).value();
    object = unicode_error.object();
    if (!runtime->isInstanceOfBytes(*object)) {
      return thread->raiseWithFmt(LayoutId::kTypeError,
                                  "object attribute must be bytes");
    }
    Bytes bytes(&scope, bytesUnderlying(*object));
    word length = bytes.length();
    if (start >= length) start = length - 1;
    if (start < 0) start = 0;
    if (end >= length) end = length;
    if (end < 1) end = 1;
    word result_size = end - start;
    if (result_size < 0) {
      return thread->raiseWithFmt(LayoutId::kValueError, "end before start");
    }
    result_size *= 4;
    MutableBytes result(&scope,
                        runtime->newMutableBytesUninitialized(result_size));
    word pos = 0;
    for (word i = start; i < end; i++) {
      byte b = bytes.byteAt(i);
      result.byteAtPut(pos++, '\\');
      result.byteAtPut(pos++, 'x');
      uwordToHexadecimalWithMutableBytes(*result, pos, /*num_digits=*/2, b);
      pos += 2;
    }
    DCHECK(pos == result.length(), "size mismatch");
    Object result_str(&scope, result.becomeStr());
    Object end_obj(&scope, SmallInt::fromWord(end));
    return runtime->newTupleWith2(result_str, end_obj);
  }

  if (runtime->isInstanceOfUnicodeEncodeError(*error) ||
      runtime->isInstanceOfUnicodeTranslateError(*error)) {
    UnicodeErrorBase unicode_error(&scope, *error);
    start = SmallInt::cast(unicode_error.start()).value();
    end = SmallInt::cast(unicode_error.end()).value();
    object = unicode_error.object();
    if (!runtime->isInstanceOfStr(*object)) {
      return thread->raiseWithFmt(LayoutId::kTypeError,
                                  "object attribute must be unicode");
    }
    Str str(&scope, strUnderlying(*object));

    if (start < 0) start = 0;
    if (end < 1) end = 1;
    if (end < start) {
      return thread->raiseWithFmt(LayoutId::kValueError, "end before start");
    }
    word start_byte = str.offsetByCodePoints(0, start);
    word end_byte = str.offsetByCodePoints(start_byte, end - start);
    word result_size = 0;
    for (word i = start_byte; i < end_byte;) {
      word num_bytes;
      int32_t cp = str.codePointAt(i, &num_bytes);
      i += num_bytes;
      if (cp > kMaxUint16) {
        result_size += 10;  // Will replace with `\Uxxxxxxxx`
      } else if (cp > kMaxByte) {
        result_size += 6;  // Will replace with `\uxxxx`
      } else {
        result_size += 4;  // Will replace with `\xyy`
      }
    }
    MutableBytes result(&scope,
                        runtime->newMutableBytesUninitialized(result_size));
    word pos = 0;
    for (word i = start_byte; i < end_byte;) {
      word num_bytes;
      int32_t cp = str.codePointAt(i, &num_bytes);
      i += num_bytes;
      result.byteAtPut(pos++, '\\');
      if (cp > kMaxUint16) {
        result.byteAtPut(pos++, 'U');
        uwordToHexadecimalWithMutableBytes(*result, pos, /*num_digits=*/8, cp);
        pos += 8;
      } else if (cp > kMaxByte) {
        result.byteAtPut(pos++, 'u');
        uwordToHexadecimalWithMutableBytes(*result, pos, /*num_digits=*/4, cp);
        pos += 4;
      } else {
        result.byteAtPut(pos++, 'x');
        uwordToHexadecimalWithMutableBytes(*result, pos, /*num_digits=*/2, cp);
        pos += 2;
      }
    }
    DCHECK(pos == result.length(), "size mismatch");
    Object result_bytes(&scope, result.becomeStr());
    Object end_obj(&scope, SmallInt::fromWord(end));
    return runtime->newTupleWith2(result_bytes, end_obj);
  }
  return thread->raiseWithFmt(LayoutId::kTypeError,
                              "don't know how to handle %T in error callback",
                              &error);
}