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
13namespace base {
14
15inline 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
23inline 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.
40BASE_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.
46BASE_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.
53BASE_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.
64BASE_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.
69BASE_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.
74inline 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.
87template<typename CHAR>
88void 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().
92template<typename STRING>
93void 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