1// Copyright (c) 2009 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#include "base/utf_string_conversion_utils.h" 6 7#include "base/third_party/icu/icu_utf.h" 8 9namespace base { 10 11// ReadUnicodeCharacter -------------------------------------------------------- 12 13bool ReadUnicodeCharacter(const char* src, 14 int32 src_len, 15 int32* char_index, 16 uint32* code_point_out) { 17 // U8_NEXT expects to be able to use -1 to signal an error, so we must 18 // use a signed type for code_point. But this function returns false 19 // on error anyway, so code_point_out is unsigned. 20 int32 code_point; 21 CBU8_NEXT(src, *char_index, src_len, code_point); 22 *code_point_out = static_cast<uint32>(code_point); 23 24 // The ICU macro above moves to the next char, we want to point to the last 25 // char consumed. 26 (*char_index)--; 27 28 // Validate the decoded value. 29 return IsValidCodepoint(code_point); 30} 31 32bool ReadUnicodeCharacter(const char16* src, 33 int32 src_len, 34 int32* char_index, 35 uint32* code_point) { 36 if (CBU16_IS_SURROGATE(src[*char_index])) { 37 if (!CBU16_IS_SURROGATE_LEAD(src[*char_index]) || 38 *char_index + 1 >= src_len || 39 !CBU16_IS_TRAIL(src[*char_index + 1])) { 40 // Invalid surrogate pair. 41 return false; 42 } 43 44 // Valid surrogate pair. 45 *code_point = CBU16_GET_SUPPLEMENTARY(src[*char_index], 46 src[*char_index + 1]); 47 (*char_index)++; 48 } else { 49 // Not a surrogate, just one 16-bit word. 50 *code_point = src[*char_index]; 51 } 52 53 return IsValidCodepoint(*code_point); 54} 55 56#if defined(WCHAR_T_IS_UTF32) 57bool ReadUnicodeCharacter(const wchar_t* src, 58 int32 src_len, 59 int32* char_index, 60 uint32* code_point) { 61 // Conversion is easy since the source is 32-bit. 62 *code_point = src[*char_index]; 63 64 // Validate the value. 65 return IsValidCodepoint(*code_point); 66} 67#endif // defined(WCHAR_T_IS_UTF32) 68 69// WriteUnicodeCharacter ------------------------------------------------------- 70 71size_t WriteUnicodeCharacter(uint32 code_point, std::string* output) { 72 if (code_point <= 0x7f) { 73 // Fast path the common case of one byte. 74 output->push_back(code_point); 75 return 1; 76 } 77 78 79 // CBU8_APPEND_UNSAFE can append up to 4 bytes. 80 size_t char_offset = output->length(); 81 size_t original_char_offset = char_offset; 82 output->resize(char_offset + CBU8_MAX_LENGTH); 83 84 CBU8_APPEND_UNSAFE(&(*output)[0], char_offset, code_point); 85 86 // CBU8_APPEND_UNSAFE will advance our pointer past the inserted character, so 87 // it will represent the new length of the string. 88 output->resize(char_offset); 89 return char_offset - original_char_offset; 90} 91 92size_t WriteUnicodeCharacter(uint32 code_point, string16* output) { 93 if (CBU16_LENGTH(code_point) == 1) { 94 // Thie code point is in the Basic Multilingual Plane (BMP). 95 output->push_back(static_cast<char16>(code_point)); 96 return 1; 97 } 98 // Non-BMP characters use a double-character encoding. 99 size_t char_offset = output->length(); 100 output->resize(char_offset + CBU16_MAX_LENGTH); 101 CBU16_APPEND_UNSAFE(&(*output)[0], char_offset, code_point); 102 return CBU16_MAX_LENGTH; 103} 104 105// Generalized Unicode converter ----------------------------------------------- 106 107template<typename CHAR> 108void PrepareForUTF8Output(const CHAR* src, 109 size_t src_len, 110 std::string* output) { 111 output->clear(); 112 if (src_len == 0) 113 return; 114 if (src[0] < 0x80) { 115 // Assume that the entire input will be ASCII. 116 output->reserve(src_len); 117 } else { 118 // Assume that the entire input is non-ASCII and will have 3 bytes per char. 119 output->reserve(src_len * 3); 120 } 121} 122 123// Instantiate versions we know callers will need. 124template void PrepareForUTF8Output(const wchar_t*, size_t, std::string*); 125template void PrepareForUTF8Output(const char16*, size_t, std::string*); 126 127template<typename STRING> 128void PrepareForUTF16Or32Output(const char* src, 129 size_t src_len, 130 STRING* output) { 131 output->clear(); 132 if (src_len == 0) 133 return; 134 if (static_cast<unsigned char>(src[0]) < 0x80) { 135 // Assume the input is all ASCII, which means 1:1 correspondence. 136 output->reserve(src_len); 137 } else { 138 // Otherwise assume that the UTF-8 sequences will have 2 bytes for each 139 // character. 140 output->reserve(src_len / 2); 141 } 142} 143 144// Instantiate versions we know callers will need. 145template void PrepareForUTF16Or32Output(const char*, size_t, std::wstring*); 146template void PrepareForUTF16Or32Output(const char*, size_t, string16*); 147 148} // namespace base 149