1 // Copyright (c) 2011 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 #ifndef BASE_STRINGS_UTF_STRING_CONVERSION_UTILS_H_ 6 #define BASE_STRINGS_UTF_STRING_CONVERSION_UTILS_H_ 7 8 // This should only be used by the various UTF string conversion files. 9 10 #include <stddef.h> 11 #include <stdint.h> 12 13 #include "base/base_export.h" 14 #include "base/strings/string16.h" 15 16 namespace base { 17 18 inline bool IsValidCodepoint(uint32_t code_point) { 19 // Excludes the surrogate code points ([0xD800, 0xDFFF]) and 20 // codepoints larger than 0x10FFFF (the highest codepoint allowed). 21 // Non-characters and unassigned codepoints are allowed. 22 return code_point < 0xD800u || 23 (code_point >= 0xE000u && code_point <= 0x10FFFFu); 24 } 25 26 inline bool IsValidCharacter(uint32_t code_point) { 27 // Excludes non-characters (U+FDD0..U+FDEF, and all codepoints ending in 28 // 0xFFFE or 0xFFFF) from the set of valid code points. 29 return code_point < 0xD800u || (code_point >= 0xE000u && 30 code_point < 0xFDD0u) || (code_point > 0xFDEFu && 31 code_point <= 0x10FFFFu && (code_point & 0xFFFEu) != 0xFFFEu); 32 } 33 34 // ReadUnicodeCharacter -------------------------------------------------------- 35 36 // Reads a UTF-8 stream, placing the next code point into the given output 37 // |*code_point|. |src| represents the entire string to read, and |*char_index| 38 // is the character offset within the string to start reading at. |*char_index| 39 // will be updated to index the last character read, such that incrementing it 40 // (as in a for loop) will take the reader to the next character. 41 // 42 // Returns true on success. On false, |*code_point| will be invalid. 43 BASE_EXPORT bool ReadUnicodeCharacter(const char* src, 44 int32_t src_len, 45 int32_t* char_index, 46 uint32_t* code_point_out); 47 48 // Reads a UTF-16 character. The usage is the same as the 8-bit version above. 49 BASE_EXPORT bool ReadUnicodeCharacter(const char16* src, 50 int32_t src_len, 51 int32_t* char_index, 52 uint32_t* code_point); 53 54 #if defined(WCHAR_T_IS_UTF32) 55 // Reads UTF-32 character. The usage is the same as the 8-bit version above. 56 BASE_EXPORT bool ReadUnicodeCharacter(const wchar_t* src, 57 int32_t src_len, 58 int32_t* char_index, 59 uint32_t* code_point); 60 #endif // defined(WCHAR_T_IS_UTF32) 61 62 // WriteUnicodeCharacter ------------------------------------------------------- 63 64 // Appends a UTF-8 character to the given 8-bit string. Returns the number of 65 // bytes written. 66 BASE_EXPORT size_t WriteUnicodeCharacter(uint32_t code_point, 67 std::string* output); 68 69 // Appends the given code point as a UTF-16 character to the given 16-bit 70 // string. Returns the number of 16-bit values written. 71 BASE_EXPORT size_t WriteUnicodeCharacter(uint32_t code_point, string16* output); 72 73 #if defined(WCHAR_T_IS_UTF32) 74 // Appends the given UTF-32 character to the given 32-bit string. Returns the 75 // number of 32-bit values written. 76 inline size_t WriteUnicodeCharacter(uint32_t code_point, std::wstring* output) { 77 // This is the easy case, just append the character. 78 output->push_back(code_point); 79 return 1; 80 } 81 #endif // defined(WCHAR_T_IS_UTF32) 82 83 // Generalized Unicode converter ----------------------------------------------- 84 85 // Guesses the length of the output in UTF-8 in bytes, clears that output 86 // string, and reserves that amount of space. We assume that the input 87 // character types are unsigned, which will be true for UTF-16 and -32 on our 88 // systems. 89 template<typename CHAR> 90 void PrepareForUTF8Output(const CHAR* src, size_t src_len, std::string* output); 91 92 // Prepares an output buffer (containing either UTF-16 or -32 data) given some 93 // UTF-8 input that will be converted to it. See PrepareForUTF8Output(). 94 template<typename STRING> 95 void PrepareForUTF16Or32Output(const char* src, size_t src_len, STRING* output); 96 97 } // namespace base 98 99 #endif // BASE_STRINGS_UTF_STRING_CONVERSION_UTILS_H_ 100
