1 : // Copyright (c) 2008 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 : // FilePath is a container for pathnames stored in a platform's native string
6 : // type, providing containers for manipulation in according with the
7 : // platform's conventions for pathnames. It supports the following path
8 : // types:
9 : //
10 : // POSIX Windows
11 : // --------------- ----------------------------------
12 : // Fundamental type char[] wchar_t[]
13 : // Encoding unspecified* UTF-16
14 : // Separator / \, tolerant of /
15 : // Drive letters no case-insensitive A-Z followed by :
16 : // Alternate root // (surprise!) \\, for UNC paths
17 : //
18 : // * The encoding need not be specified on POSIX systems, although some
19 : // POSIX-compliant systems do specify an encoding. Mac OS X uses UTF-8.
20 : // Linux does not specify an encoding, but in practice, the locale's
21 : // character set may be used.
22 : //
23 : // FilePath objects are intended to be used anywhere paths are. An
24 : // application may pass FilePath objects around internally, masking the
25 : // underlying differences between systems, only differing in implementation
26 : // where interfacing directly with the system. For example, a single
27 : // OpenFile(const FilePath &) function may be made available, allowing all
28 : // callers to operate without regard to the underlying implementation. On
29 : // POSIX-like platforms, OpenFile might wrap fopen, and on Windows, it might
30 : // wrap _wfopen_s, perhaps both by calling file_path.value().c_str(). This
31 : // allows each platform to pass pathnames around without requiring conversions
32 : // between encodings, which has an impact on performance, but more imporantly,
33 : // has an impact on correctness on platforms that do not have well-defined
34 : // encodings for pathnames.
35 : //
36 : // Several methods are available to perform common operations on a FilePath
37 : // object, such as determining the parent directory (DirName), isolating the
38 : // final path component (BaseName), and appending a relative pathname string
39 : // to an existing FilePath object (Append). These methods are highly
40 : // recommended over attempting to split and concatenate strings directly.
41 : // These methods are based purely on string manipulation and knowledge of
42 : // platform-specific pathname conventions, and do not consult the filesystem
43 : // at all, making them safe to use without fear of blocking on I/O operations.
44 : // These methods do not function as mutators but instead return distinct
45 : // instances of FilePath objects, and are therefore safe to use on const
46 : // objects. The objects themselves are safe to share between threads.
47 : //
48 : // To aid in initialization of FilePath objects from string literals, a
49 : // FILE_PATH_LITERAL macro is provided, which accounts for the difference
50 : // between char[]-based pathnames on POSIX systems and wchar_t[]-based
51 : // pathnames on Windows.
52 : //
53 : // Because a FilePath object should not be instantiated at the global scope,
54 : // instead, use a FilePath::CharType[] and initialize it with
55 : // FILE_PATH_LITERAL. At runtime, a FilePath object can be created from the
56 : // character array. Example:
57 : //
58 : // | const FilePath::CharType kLogFileName[] = FILE_PATH_LITERAL("log.txt");
59 : // |
60 : // | void Function() {
61 : // | FilePath log_file_path(kLogFileName);
62 : // | [...]
63 : // | }
64 :
65 : #ifndef BASE_FILE_PATH_H_
66 : #define BASE_FILE_PATH_H_
67 :
68 : #include <string>
69 :
70 : #include "base/basictypes.h"
71 : #include "base/compiler_specific.h"
72 : #include "base/hash_tables.h"
73 :
74 : // Windows-style drive letter support and pathname separator characters can be
75 : // enabled and disabled independently, to aid testing. These #defines are
76 : // here so that the same setting can be used in both the implementation and
77 : // in the unit test.
78 : #if defined(OS_WIN)
79 : #define FILE_PATH_USES_DRIVE_LETTERS
80 : #define FILE_PATH_USES_WIN_SEPARATORS
81 : #endif // OS_WIN
82 :
83 : // An abstraction to isolate users from the differences between native
84 : // pathnames on different platforms.
85 0 : class FilePath {
86 : public:
87 : #if defined(OS_POSIX)
88 : // On most platforms, native pathnames are char arrays, and the encoding
89 : // may or may not be specified. On Mac OS X, native pathnames are encoded
90 : // in UTF-8.
91 : typedef std::string StringType;
92 : #elif defined(OS_WIN)
93 : // On Windows, for Unicode-aware applications, native pathnames are wchar_t
94 : // arrays encoded in UTF-16.
95 : typedef std::wstring StringType;
96 : #endif // OS_WIN
97 :
98 : typedef StringType::value_type CharType;
99 :
100 : // Null-terminated array of separators used to separate components in
101 : // hierarchical paths. Each character in this array is a valid separator,
102 : // but kSeparators[0] is treated as the canonical separator and will be used
103 : // when composing pathnames.
104 : static const CharType kSeparators[];
105 :
106 : // A special path component meaning "this directory."
107 : static const CharType kCurrentDirectory[];
108 :
109 : // A special path component meaning "the parent directory."
110 : static const CharType kParentDirectory[];
111 :
112 : // The character used to identify a file extension.
113 : static const CharType kExtensionSeparator;
114 :
115 0 : FilePath() {}
116 0 : FilePath(const FilePath& that) : path_(that.path_) {}
117 0 : explicit FilePath(const StringType& path) : path_(path) {}
118 :
119 0 : FilePath& operator=(const FilePath& that) {
120 0 : path_ = that.path_;
121 0 : return *this;
122 : }
123 :
124 0 : bool operator==(const FilePath& that) const {
125 0 : return path_ == that.path_;
126 : }
127 :
128 : bool operator!=(const FilePath& that) const {
129 : return path_ != that.path_;
130 : }
131 :
132 : // Required for some STL containers and operations
133 : bool operator<(const FilePath& that) const {
134 : return path_ < that.path_;
135 : }
136 :
137 0 : const StringType& value() const { return path_; }
138 :
139 0 : bool empty() const { return path_.empty(); }
140 :
141 : // Returns true if |character| is in kSeparators.
142 : static bool IsSeparator(CharType character);
143 :
144 : // Returns a FilePath corresponding to the directory containing the path
145 : // named by this object, stripping away the file component. If this object
146 : // only contains one component, returns a FilePath identifying
147 : // kCurrentDirectory. If this object already refers to the root directory,
148 : // returns a FilePath identifying the root directory.
149 : FilePath DirName() const;
150 :
151 : // Returns a FilePath corresponding to the last path component of this
152 : // object, either a file or a directory. If this object already refers to
153 : // the root directory, returns a FilePath identifying the root directory;
154 : // this is the only situation in which BaseName will return an absolute path.
155 : FilePath BaseName() const;
156 :
157 : // Returns ".jpg" for path "C:\pics\jojo.jpg", or an empty string if
158 : // the file has no extension. If non-empty, Extension() will always start
159 : // with precisely one ".". The following code should always work regardless
160 : // of the value of path.
161 : // new_path = path.RemoveExtension().value().append(path.Extension());
162 : // ASSERT(new_path == path.value());
163 : // NOTE: this is different from the original file_util implementation which
164 : // returned the extension without a leading "." ("jpg" instead of ".jpg")
165 : StringType Extension() const;
166 :
167 : // Returns "C:\pics\jojo" for path "C:\pics\jojo.jpg"
168 : // NOTE: this is slightly different from the similar file_util implementation
169 : // which returned simply 'jojo'.
170 : FilePath RemoveExtension() const;
171 :
172 : // Inserts |suffix| after the file name portion of |path| but before the
173 : // extension. Returns "" if BaseName() == "." or "..".
174 : // Examples:
175 : // path == "C:\pics\jojo.jpg" suffix == " (1)", returns "C:\pics\jojo (1).jpg"
176 : // path == "jojo.jpg" suffix == " (1)", returns "jojo (1).jpg"
177 : // path == "C:\pics\jojo" suffix == " (1)", returns "C:\pics\jojo (1)"
178 : // path == "C:\pics.old\jojo" suffix == " (1)", returns "C:\pics.old\jojo (1)"
179 : FilePath InsertBeforeExtension(const StringType& suffix) const;
180 :
181 : // Replaces the extension of |file_name| with |extension|. If |file_name|
182 : // does not have an extension, them |extension| is added. If |extension| is
183 : // empty, then the extension is removed from |file_name|.
184 : // Returns "" if BaseName() == "." or "..".
185 : FilePath ReplaceExtension(const StringType& extension) const;
186 :
187 : // Returns a FilePath by appending a separator and the supplied path
188 : // component to this object's path. Append takes care to avoid adding
189 : // excessive separators if this object's path already ends with a separator.
190 : // If this object's path is kCurrentDirectory, a new FilePath corresponding
191 : // only to |component| is returned. |component| must be a relative path;
192 : // it is an error to pass an absolute path.
193 : FilePath Append(const StringType& component) const WARN_UNUSED_RESULT;
194 : FilePath Append(const FilePath& component) const WARN_UNUSED_RESULT;
195 :
196 : // Although Windows StringType is std::wstring, since the encoding it uses for
197 : // paths is well defined, it can handle ASCII path components as well.
198 : // Mac uses UTF8, and since ASCII is a subset of that, it works there as well.
199 : // On Linux, although it can use any 8-bit encoding for paths, we assume that
200 : // ASCII is a valid subset, regardless of the encoding, since many operating
201 : // system paths will always be ASCII.
202 : FilePath AppendASCII(const std::string& component) const WARN_UNUSED_RESULT;
203 :
204 : // Returns true if this FilePath contains an absolute path. On Windows, an
205 : // absolute path begins with either a drive letter specification followed by
206 : // a separator character, or with two separator characters. On POSIX
207 : // platforms, an absolute path begins with a separator character.
208 : bool IsAbsolute() const;
209 :
210 : // Returns a copy of this FilePath that does not end with a trailing
211 : // separator.
212 : FilePath StripTrailingSeparators() const;
213 :
214 : // Calls open on given ifstream instance
215 : void OpenInputStream(std::ifstream &stream) const;
216 :
217 : // Older Chromium code assumes that paths are always wstrings.
218 : // This function converts a wstring to a FilePath, and is useful to smooth
219 : // porting that old code to the FilePath API.
220 : // It has "Hack" in its name so people feel bad about using it.
221 : // TODO(port): remove these functions.
222 : static FilePath FromWStringHack(const std::wstring& wstring);
223 :
224 : // Older Chromium code assumes that paths are always wstrings.
225 : // This function produces a wstring from a FilePath, and is useful to smooth
226 : // porting that old code to the FilePath API.
227 : // It has "Hack" in its name so people feel bad about using it.
228 : // TODO(port): remove these functions.
229 : std::wstring ToWStringHack() const;
230 :
231 : private:
232 : // Remove trailing separators from this object. If the path is absolute, it
233 : // will never be stripped any more than to refer to the absolute root
234 : // directory, so "////" will become "/", not "". A leading pair of
235 : // separators is never stripped, to support alternate roots. This is used to
236 : // support UNC paths on Windows.
237 : void StripTrailingSeparatorsInternal();
238 :
239 : StringType path_;
240 : };
241 :
242 : // Macros for string literal initialization of FilePath::CharType[].
243 : #if defined(OS_POSIX)
244 : #define FILE_PATH_LITERAL(x) x
245 : #elif defined(OS_WIN)
246 : #define FILE_PATH_LITERAL(x) L ## x
247 : #endif // OS_WIN
248 :
249 : // Implement hash function so that we can use FilePaths in hashsets and maps.
250 : #if defined(COMPILER_GCC) && !defined(ANDROID)
251 : namespace __gnu_cxx {
252 :
253 : template<>
254 : struct hash<FilePath> {
255 : size_t operator()(const FilePath& f) const {
256 : return hash<FilePath::StringType>()(f.value());
257 : }
258 : };
259 :
260 : } // namespace __gnu_cxx
261 : #elif defined(COMPILER_MSVC)
262 : namespace stdext {
263 :
264 : inline size_t hash_value(const FilePath& f) {
265 : return hash_value(f.value());
266 : }
267 :
268 : } // namespace stdext
269 : #endif // COMPILER
270 :
271 : #endif // BASE_FILE_PATH_H_
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