| // Copyright (c) 2009 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #include "base/strings/utf_string_conversion_utils.h" |
| |
| #include "base/third_party/icu/icu_utf.h" |
| |
| namespace base { |
| |
| // ReadUnicodeCharacter -------------------------------------------------------- |
| |
| bool ReadUnicodeCharacter(const char* src, |
| int32_t src_len, |
| int32_t* char_index, |
| uint32_t* code_point_out) { |
| // U8_NEXT expects to be able to use -1 to signal an error, so we must |
| // use a signed type for code_point. But this function returns false |
| // on error anyway, so code_point_out is unsigned. |
| int32_t code_point; |
| CBU8_NEXT(src, *char_index, src_len, code_point); |
| *code_point_out = static_cast<uint32_t>(code_point); |
| |
| // The ICU macro above moves to the next char, we want to point to the last |
| // char consumed. |
| (*char_index)--; |
| |
| // Validate the decoded value. |
| return IsValidCodepoint(code_point); |
| } |
| |
| // WriteUnicodeCharacter ------------------------------------------------------- |
| |
| size_t WriteUnicodeCharacter(uint32_t code_point, std::string* output) { |
| if (code_point <= 0x7f) { |
| // Fast path the common case of one byte. |
| output->push_back(static_cast<char>(code_point)); |
| return 1; |
| } |
| |
| |
| // CBU8_APPEND_UNSAFE can append up to 4 bytes. |
| size_t char_offset = output->length(); |
| size_t original_char_offset = char_offset; |
| output->resize(char_offset + CBU8_MAX_LENGTH); |
| |
| CBU8_APPEND_UNSAFE(&(*output)[0], char_offset, code_point); |
| |
| // CBU8_APPEND_UNSAFE will advance our pointer past the inserted character, so |
| // it will represent the new length of the string. |
| output->resize(char_offset); |
| return char_offset - original_char_offset; |
| } |
| |
| // Generalized Unicode converter ----------------------------------------------- |
| |
| template<typename CHAR> |
| void PrepareForUTF8Output(const CHAR* src, |
| size_t src_len, |
| std::string* output) { |
| output->clear(); |
| if (src_len == 0) |
| return; |
| if (src[0] < 0x80) { |
| // Assume that the entire input will be ASCII. |
| output->reserve(src_len); |
| } else { |
| // Assume that the entire input is non-ASCII and will have 3 bytes per char. |
| output->reserve(src_len * 3); |
| } |
| } |
| |
| template<typename STRING> |
| void PrepareForUTF16Or32Output(const char* src, |
| size_t src_len, |
| STRING* output) { |
| output->clear(); |
| if (src_len == 0) |
| return; |
| if (static_cast<unsigned char>(src[0]) < 0x80) { |
| // Assume the input is all ASCII, which means 1:1 correspondence. |
| output->reserve(src_len); |
| } else { |
| // Otherwise assume that the UTF-8 sequences will have 2 bytes for each |
| // character. |
| output->reserve(src_len / 2); |
| } |
| } |
| |
| } // namespace base |