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 // Low-level UTF handling functions. Most code will want to use the functions
9 // in utf_string_conversions.h
10
11 #include <stddef.h>
12 #include <stdint.h>
13
14 #include "base/base_export.h"
15 #include "base/strings/string16.h"
16
17 namespace base {
18
IsValidCodepoint(uint32_t code_point)19 inline bool IsValidCodepoint(uint32_t code_point) {
20 // Excludes the surrogate code points ([0xD800, 0xDFFF]) and
21 // codepoints larger than 0x10FFFF (the highest codepoint allowed).
22 // Non-characters and unassigned codepoints are allowed.
23 return code_point < 0xD800u ||
24 (code_point >= 0xE000u && code_point <= 0x10FFFFu);
25 }
26
IsValidCharacter(uint32_t code_point)27 inline bool IsValidCharacter(uint32_t code_point) {
28 // Excludes non-characters (U+FDD0..U+FDEF, and all codepoints ending in
29 // 0xFFFE or 0xFFFF) from the set of valid code points.
30 return code_point < 0xD800u || (code_point >= 0xE000u &&
31 code_point < 0xFDD0u) || (code_point > 0xFDEFu &&
32 code_point <= 0x10FFFFu && (code_point & 0xFFFEu) != 0xFFFEu);
33 }
34
35 // ReadUnicodeCharacter --------------------------------------------------------
36
37 // Reads a UTF-8 stream, placing the next code point into the given output
38 // |*code_point|. |src| represents the entire string to read, and |*char_index|
39 // is the character offset within the string to start reading at. |*char_index|
40 // will be updated to index the last character read, such that incrementing it
41 // (as in a for loop) will take the reader to the next character.
42 //
43 // Returns true on success. On false, |*code_point| will be invalid.
44 BASE_EXPORT bool ReadUnicodeCharacter(const char* src,
45 int32_t src_len,
46 int32_t* char_index,
47 uint32_t* code_point_out);
48
49 // Reads a UTF-16 character. The usage is the same as the 8-bit version above.
50 BASE_EXPORT bool ReadUnicodeCharacter(const char16* src,
51 int32_t src_len,
52 int32_t* char_index,
53 uint32_t* code_point);
54
55 #if defined(WCHAR_T_IS_UTF32)
56 // Reads UTF-32 character. The usage is the same as the 8-bit version above.
57 BASE_EXPORT bool ReadUnicodeCharacter(const wchar_t* src,
58 int32_t src_len,
59 int32_t* char_index,
60 uint32_t* code_point);
61 #endif // defined(WCHAR_T_IS_UTF32)
62
63 // WriteUnicodeCharacter -------------------------------------------------------
64
65 // Appends a UTF-8 character to the given 8-bit string. Returns the number of
66 // bytes written.
67 BASE_EXPORT size_t WriteUnicodeCharacter(uint32_t code_point,
68 std::string* output);
69
70 // Appends the given code point as a UTF-16 character to the given 16-bit
71 // string. Returns the number of 16-bit values written.
72 BASE_EXPORT size_t WriteUnicodeCharacter(uint32_t code_point, string16* output);
73
74 #if defined(WCHAR_T_IS_UTF32)
75 // Appends the given UTF-32 character to the given 32-bit string. Returns the
76 // number of 32-bit values written.
WriteUnicodeCharacter(uint32_t code_point,std::wstring * output)77 inline size_t WriteUnicodeCharacter(uint32_t code_point, std::wstring* output) {
78 // This is the easy case, just append the character.
79 output->push_back(code_point);
80 return 1;
81 }
82 #endif // defined(WCHAR_T_IS_UTF32)
83
84 // Generalized Unicode converter -----------------------------------------------
85
86 // Guesses the length of the output in UTF-8 in bytes, clears that output
87 // string, and reserves that amount of space. We assume that the input
88 // character types are unsigned, which will be true for UTF-16 and -32 on our
89 // systems.
90 template<typename CHAR>
91 void PrepareForUTF8Output(const CHAR* src, size_t src_len, std::string* output);
92
93 // Prepares an output buffer (containing either UTF-16 or -32 data) given some
94 // UTF-8 input that will be converted to it. See PrepareForUTF8Output().
95 template<typename STRING>
96 void PrepareForUTF16Or32Output(const char* src, size_t src_len, STRING* output);
97
98 } // namespace base
99
100 #endif // BASE_STRINGS_UTF_STRING_CONVERSION_UTILS_H_
101