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
16namespace base {
17
18inline 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
26inline 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.
43BASE_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.
49BASE_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.
56BASE_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.
66BASE_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.
71BASE_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.
76inline 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.
89template<typename CHAR>
90void 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().
94template<typename STRING>
95void 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