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 "base/base_export.h"
11 #include "base/strings/string16.h"
12
13 namespace base {
14
IsValidCodepoint(uint32 code_point)15 inline bool IsValidCodepoint(uint32 code_point) {
16 // Excludes the surrogate code points ([0xD800, 0xDFFF]) and
17 // codepoints larger than 0x10FFFF (the highest codepoint allowed).
18 // Non-characters and unassigned codepoints are allowed.
19 return code_point < 0xD800u ||
20 (code_point >= 0xE000u && code_point <= 0x10FFFFu);
21 }
22
IsValidCharacter(uint32 code_point)23 inline bool IsValidCharacter(uint32 code_point) {
24 // Excludes non-characters (U+FDD0..U+FDEF, and all codepoints ending in
25 // 0xFFFE or 0xFFFF) from the set of valid code points.
26 return code_point < 0xD800u || (code_point >= 0xE000u &&
27 code_point < 0xFDD0u) || (code_point > 0xFDEFu &&
28 code_point <= 0x10FFFFu && (code_point & 0xFFFEu) != 0xFFFEu);
29 }
30
31 // ReadUnicodeCharacter --------------------------------------------------------
32
33 // Reads a UTF-8 stream, placing the next code point into the given output
34 // |*code_point|. |src| represents the entire string to read, and |*char_index|
35 // is the character offset within the string to start reading at. |*char_index|
36 // will be updated to index the last character read, such that incrementing it
37 // (as in a for loop) will take the reader to the next character.
38 //
39 // Returns true on success. On false, |*code_point| will be invalid.
40 BASE_EXPORT bool ReadUnicodeCharacter(const char* src,
41 int32 src_len,
42 int32* char_index,
43 uint32* code_point_out);
44
45 // Reads a UTF-16 character. The usage is the same as the 8-bit version above.
46 BASE_EXPORT bool ReadUnicodeCharacter(const char16* src,
47 int32 src_len,
48 int32* char_index,
49 uint32* code_point);
50
51 #if defined(WCHAR_T_IS_UTF32)
52 // Reads UTF-32 character. The usage is the same as the 8-bit version above.
53 BASE_EXPORT bool ReadUnicodeCharacter(const wchar_t* src,
54 int32 src_len,
55 int32* char_index,
56 uint32* code_point);
57 #endif // defined(WCHAR_T_IS_UTF32)
58
59 // WriteUnicodeCharacter -------------------------------------------------------
60
61 // Appends a UTF-8 character to the given 8-bit string. Returns the number of
62 // bytes written.
63 // TODO(brettw) Bug 79631: This function should not be exposed.
64 BASE_EXPORT size_t WriteUnicodeCharacter(uint32 code_point,
65 std::string* output);
66
67 // Appends the given code point as a UTF-16 character to the given 16-bit
68 // string. Returns the number of 16-bit values written.
69 BASE_EXPORT size_t WriteUnicodeCharacter(uint32 code_point, string16* output);
70
71 #if defined(WCHAR_T_IS_UTF32)
72 // Appends the given UTF-32 character to the given 32-bit string. Returns the
73 // number of 32-bit values written.
WriteUnicodeCharacter(uint32 code_point,std::wstring * output)74 inline size_t WriteUnicodeCharacter(uint32 code_point, std::wstring* output) {
75 // This is the easy case, just append the character.
76 output->push_back(code_point);
77 return 1;
78 }
79 #endif // defined(WCHAR_T_IS_UTF32)
80
81 // Generalized Unicode converter -----------------------------------------------
82
83 // Guesses the length of the output in UTF-8 in bytes, clears that output
84 // string, and reserves that amount of space. We assume that the input
85 // character types are unsigned, which will be true for UTF-16 and -32 on our
86 // systems.
87 template<typename CHAR>
88 void PrepareForUTF8Output(const CHAR* src, size_t src_len, std::string* output);
89
90 // Prepares an output buffer (containing either UTF-16 or -32 data) given some
91 // UTF-8 input that will be converted to it. See PrepareForUTF8Output().
92 template<typename STRING>
93 void PrepareForUTF16Or32Output(const char* src, size_t src_len, STRING* output);
94
95 } // namespace base
96
97 #endif // BASE_STRINGS_UTF_STRING_CONVERSION_UTILS_H_
98