1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
|
// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
// This is a partial implementation of Chromium's source file
// base/file/file_path.cc.
#include "base/files/file_path.h"
namespace base {
using StringType = FilePath::StringType;
using StringPieceType = FilePath::StringPieceType;
namespace {
const FilePath::CharType kStringTerminator = FILE_PATH_LITERAL('\0');
// If this FilePath contains a drive letter specification, returns the
// position of the last character of the drive letter specification,
// otherwise returns npos. This can only be true on Windows, when a pathname
// begins with a letter followed by a colon. On other platforms, this always
// returns npos.
StringPieceType::size_type FindDriveLetter(StringPieceType path) {
#if defined(FILE_PATH_USES_DRIVE_LETTERS)
// This is dependent on an ASCII-based character set, but that's a
// reasonable assumption. iswalpha can be too inclusive here.
if (path.length() >= 2 && path[1] == L':' &&
((path[0] >= L'A' && path[0] <= L'Z') ||
(path[0] >= L'a' && path[0] <= L'z'))) {
return 1;
}
#endif // FILE_PATH_USES_DRIVE_LETTERS
return StringType::npos;
}
bool IsPathAbsolute(StringPieceType path) {
#if defined(FILE_PATH_USES_DRIVE_LETTERS)
StringType::size_type letter = FindDriveLetter(path);
if (letter != StringType::npos) {
// Look for a separator right after the drive specification.
return path.length() > letter + 1 &&
FilePath::IsSeparator(path[letter + 1]);
}
// Look for a pair of leading separators.
return path.length() > 1 &&
FilePath::IsSeparator(path[0]) && FilePath::IsSeparator(path[1]);
#else // FILE_PATH_USES_DRIVE_LETTERS
// Look for a separator in the first position.
return path.length() > 0 && FilePath::IsSeparator(path[0]);
#endif // FILE_PATH_USES_DRIVE_LETTERS
}
} // namespace
FilePath::FilePath() = default;
FilePath::FilePath(const FilePath& that) = default;
FilePath::FilePath(FilePath&& that) noexcept = default;
FilePath::FilePath(StringPieceType path) : path_(path) {
StringType::size_type nul_pos = path_.find(kStringTerminator);
if (nul_pos != StringType::npos)
path_.erase(nul_pos, StringType::npos);
}
FilePath::~FilePath() = default;
FilePath& FilePath::operator=(const FilePath& that) = default;
FilePath& FilePath::operator=(FilePath&& that) = default;
// static
bool FilePath::IsSeparator(CharType character) {
for (size_t i = 0; i < kSeparatorsLength - 1; ++i) {
if (character == kSeparators[i]) {
return true;
}
}
return false;
}
// libgen's dirname and basename aren't guaranteed to be thread-safe and aren't
// guaranteed to not modify their input strings, and in fact are implemented
// differently in this regard on different platforms. Don't use them, but
// adhere to their behavior.
FilePath FilePath::DirName() const {
FilePath new_path(path_);
new_path.StripTrailingSeparatorsInternal();
// The drive letter, if any, always needs to remain in the output. If there
// is no drive letter, as will always be the case on platforms which do not
// support drive letters, letter will be npos, or -1, so the comparisons and
// resizes below using letter will still be valid.
StringType::size_type letter = FindDriveLetter(new_path.path_);
StringType::size_type last_separator =
new_path.path_.find_last_of(kSeparators, StringType::npos,
kSeparatorsLength - 1);
if (last_separator == StringType::npos) {
// path_ is in the current directory.
new_path.path_.resize(letter + 1);
} else if (last_separator == letter + 1) {
// path_ is in the root directory.
new_path.path_.resize(letter + 2);
} else if (last_separator == letter + 2 &&
IsSeparator(new_path.path_[letter + 1])) {
// path_ is in "//" (possibly with a drive letter); leave the double
// separator intact indicating alternate root.
new_path.path_.resize(letter + 3);
} else if (last_separator != 0) {
// path_ is somewhere else, trim the basename.
new_path.path_.resize(last_separator);
}
new_path.StripTrailingSeparatorsInternal();
if (!new_path.path_.length())
new_path.path_ = kCurrentDirectory;
return new_path;
}
FilePath FilePath::BaseName() const {
FilePath new_path(path_);
new_path.StripTrailingSeparatorsInternal();
// The drive letter, if any, is always stripped.
StringType::size_type letter = FindDriveLetter(new_path.path_);
if (letter != StringType::npos) {
new_path.path_.erase(0, letter + 1);
}
// Keep everything after the final separator, but if the pathname is only
// one character and it's a separator, leave it alone.
StringType::size_type last_separator =
new_path.path_.find_last_of(kSeparators, StringType::npos,
kSeparatorsLength - 1);
if (last_separator != StringType::npos &&
last_separator < new_path.path_.length() - 1) {
new_path.path_.erase(0, last_separator + 1);
}
return new_path;
}
FilePath FilePath::Append(StringPieceType component) const {
StringPieceType appended = component;
StringType without_nuls;
StringType::size_type nul_pos = component.find(kStringTerminator);
if (nul_pos != StringPieceType::npos) {
without_nuls = StringType(component.substr(0, nul_pos));
appended = StringPieceType(without_nuls);
}
DCHECK(!IsPathAbsolute(appended));
if (path_.compare(kCurrentDirectory) == 0 && !appended.empty()) {
// Append normally doesn't do any normalization, but as a special case,
// when appending to kCurrentDirectory, just return a new path for the
// component argument. Appending component to kCurrentDirectory would
// serve no purpose other than needlessly lengthening the path, and
// it's likely in practice to wind up with FilePath objects containing
// only kCurrentDirectory when calling DirName on a single relative path
// component.
return FilePath(appended);
}
FilePath new_path(path_);
new_path.StripTrailingSeparatorsInternal();
// Don't append a separator if the path is empty (indicating the current
// directory) or if the path component is empty (indicating nothing to
// append).
if (!appended.empty() && !new_path.path_.empty()) {
// Don't append a separator if the path still ends with a trailing
// separator after stripping (indicating the root directory).
if (!IsSeparator(new_path.path_.back())) {
// Don't append a separator if the path is just a drive letter.
if (FindDriveLetter(new_path.path_) + 1 != new_path.path_.length()) {
new_path.path_.append(1, kSeparators[0]);
}
}
}
new_path.path_.append(appended.data(), appended.size());
return new_path;
}
FilePath FilePath::Append(const FilePath& component) const {
return Append(component.value());
}
void FilePath::StripTrailingSeparatorsInternal() {
// If there is no drive letter, start will be 1, which will prevent stripping
// the leading separator if there is only one separator. If there is a drive
// letter, start will be set appropriately to prevent stripping the first
// separator following the drive letter, if a separator immediately follows
// the drive letter.
StringType::size_type start = FindDriveLetter(path_) + 2;
StringType::size_type last_stripped = StringType::npos;
for (StringType::size_type pos = path_.length();
pos > start && IsSeparator(path_[pos - 1]);
--pos) {
// If the string only has two separators and they're at the beginning,
// don't strip them, unless the string began with more than two separators.
if (pos != start + 1 || last_stripped == start + 2 ||
!IsSeparator(path_[start - 1])) {
path_.resize(pos - 1);
last_stripped = pos;
}
}
}
} // namespace base
|
