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
IsValidCodepoint(uint32_t code_point)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
IsValidCharacter(uint32_t code_point)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.
WriteUnicodeCharacter(uint32_t code_point,std::wstring * output)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