abseil-cpp/absl/strings/internal/utf8.cc

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// Copyright 2017 The Abseil Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
// UTF8 utilities, implemented to reduce dependencies.
 
#include "absl/strings/internal/utf8.h"
 
namespace absl {
ABSL_NAMESPACE_BEGIN
namespace strings_internal {
 
size_t EncodeUTF8Char(char *buffer, char32_t utf8_char) {
  if (utf8_char <= 0x7F) {
    *buffer = static_cast<char>(utf8_char);
    return 1;
  } else if (utf8_char <= 0x7FF) {
    buffer[1] = static_cast<char>(0x80 | (utf8_char & 0x3F));
    utf8_char >>= 6;
    buffer[0] = static_cast<char>(0xC0 | utf8_char);
    return 2;
  } else if (utf8_char <= 0xFFFF) {
    buffer[2] = static_cast<char>(0x80 | (utf8_char & 0x3F));
    utf8_char >>= 6;
    buffer[1] = static_cast<char>(0x80 | (utf8_char & 0x3F));
    utf8_char >>= 6;
    buffer[0] = static_cast<char>(0xE0 | utf8_char);
    return 3;
  } else {
    buffer[3] = static_cast<char>(0x80 | (utf8_char & 0x3F));
    utf8_char >>= 6;
    buffer[2] = static_cast<char>(0x80 | (utf8_char & 0x3F));
    utf8_char >>= 6;
    buffer[1] = static_cast<char>(0x80 | (utf8_char & 0x3F));
    utf8_char >>= 6;
    buffer[0] = static_cast<char>(0xF0 | utf8_char);
    return 4;
  }
}
 
}  // namespace strings_internal
ABSL_NAMESPACE_END
}  // namespace absl