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 // Copyright (c) 2008 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.

 // FilePath is a container for pathnames stored in a platform's native string

 // type, providing containers for manipulation in according with the

 // platform's conventions for pathnames.  It supports the following path

 // types:

 //

 //                   POSIX            Windows

 //                   ---------------  ----------------------------------

 // Fundamental type  char[]           wchar_t[]

 // Encoding          unspecified*     UTF-16

 // Separator         /                \, tolerant of /

 // Drive letters     no               case-insensitive A-Z followed by :

 // Alternate root    // (surprise!)   \\, for UNC paths

 //

 // * The encoding need not be specified on POSIX systems, although some

 //   POSIX-compliant systems do specify an encoding.  Mac OS X uses UTF-8.

 //   Linux does not specify an encoding, but in practice, the locale's

 //   character set may be used.

 //

 // FilePath objects are intended to be used anywhere paths are.  An

 // application may pass FilePath objects around internally, masking the

 // underlying differences between systems, only differing in implementation

 // where interfacing directly with the system.  For example, a single

 // OpenFile(const FilePath &) function may be made available, allowing all

 // callers to operate without regard to the underlying implementation.  On

 // POSIX-like platforms, OpenFile might wrap fopen, and on Windows, it might

 // wrap _wfopen_s, perhaps both by calling file_path.value().c_str().  This

 // allows each platform to pass pathnames around without requiring conversions

 // between encodings, which has an impact on performance, but more imporantly,

 // has an impact on correctness on platforms that do not have well-defined

 // encodings for pathnames.

 //

 // Several methods are available to perform common operations on a FilePath

 // object, such as determining the parent directory (DirName), isolating the

 // final path component (BaseName), and appending a relative pathname string

 // to an existing FilePath object (Append).  These methods are highly

 // recommended over attempting to split and concatenate strings directly.

 // These methods are based purely on string manipulation and knowledge of

 // platform-specific pathname conventions, and do not consult the filesystem

 // at all, making them safe to use without fear of blocking on I/O operations.

 // These methods do not function as mutators but instead return distinct

 // instances of FilePath objects, and are therefore safe to use on const

 // objects.  The objects themselves are safe to share between threads.

 //

 // To aid in initialization of FilePath objects from string literals, a

 // FILE_PATH_LITERAL macro is provided, which accounts for the difference

 // between char[]-based pathnames on POSIX systems and wchar_t[]-based

 // pathnames on Windows.

 //

 // Because a FilePath object should not be instantiated at the global scope,

 // instead, use a FilePath::CharType[] and initialize it with

 // FILE_PATH_LITERAL.  At runtime, a FilePath object can be created from the

 // character array.  Example:

 //

 // | const FilePath::CharType kLogFileName[] = FILE_PATH_LITERAL("log.txt");

 // |

 // | void Function() {

 // |   FilePath log_file_path(kLogFileName);

 // |   [...]

 // | }

 #ifndef BASE_FILE_PATH_H_

 #define BASE_FILE_PATH_H_

 #include <string>

 #include "base/basictypes.h"

 #include "base/compiler_specific.h"

 #include "base/hash_tables.h"

 // Windows-style drive letter support and pathname separator characters can be

 // enabled and disabled independently, to aid testing.  These #defines are

 // here so that the same setting can be used in both the implementation and

 // in the unit test.

 #if defined(OS_WIN)

 #define FILE_PATH_USES_DRIVE_LETTERS

 #define FILE_PATH_USES_WIN_SEPARATORS

 #endif  // OS_WIN

 // An abstraction to isolate users from the differences between native

 // pathnames on different platforms.

 class FilePath {

  public:

 #if defined(OS_POSIX)

   // On most platforms, native pathnames are char arrays, and the encoding

   // may or may not be specified.  On Mac OS X, native pathnames are encoded

   // in UTF-8.

   typedef std::string StringType;

 #elif defined(OS_WIN)

   // On Windows, for Unicode-aware applications, native pathnames are wchar_t

   // arrays encoded in UTF-16.

   typedef std::wstring StringType;

 #endif  // OS_WIN

   typedef StringType::value_type CharType;

   // Null-terminated array of separators used to separate components in

   // hierarchical paths.  Each character in this array is a valid separator,

   // but kSeparators[0] is treated as the canonical separator and will be used

   // when composing pathnames.

   static const CharType kSeparators[];

   // A special path component meaning "this directory."

   static const CharType kCurrentDirectory[];

   // A special path component meaning "the parent directory."

   static const CharType kParentDirectory[];

   // The character used to identify a file extension.

   static const CharType kExtensionSeparator;

   FilePath() {}

   FilePath(const FilePath& that) : path_(that.path_) {}

   explicit FilePath(const StringType& path) : path_(path) {}

   FilePath& operator=(const FilePath& that) {

     path_ = that.path_;

     return *this;

   }

   bool operator==(const FilePath& that) const {

     return path_ == that.path_;

   }

   bool operator!=(const FilePath& that) const {

     return path_ != that.path_;

   }

   // Required for some STL containers and operations

   bool operator<(const FilePath& that) const {

     return path_ < that.path_;

   }

   const StringType& value() const { return path_; }

   bool empty() const { return path_.empty(); }

   // Returns true if |character| is in kSeparators.

   static bool IsSeparator(CharType character);

   // Returns a FilePath corresponding to the directory containing the path

   // named by this object, stripping away the file component.  If this object

   // only contains one component, returns a FilePath identifying

   // kCurrentDirectory.  If this object already refers to the root directory,

   // returns a FilePath identifying the root directory.

   FilePath DirName() const;

   // Returns a FilePath corresponding to the last path component of this

   // object, either a file or a directory.  If this object already refers to

   // the root directory, returns a FilePath identifying the root directory;

   // this is the only situation in which BaseName will return an absolute path.

   FilePath BaseName() const;

   // Returns ".jpg" for path "C:\pics\jojo.jpg", or an empty string if

   // the file has no extension.  If non-empty, Extension() will always start

   // with precisely one ".".  The following code should always work regardless

   // of the value of path.

   // new_path = path.RemoveExtension().value().append(path.Extension());

   // ASSERT(new_path == path.value());

   // NOTE: this is different from the original file_util implementation which

   // returned the extension without a leading "." ("jpg" instead of ".jpg")

   StringType Extension() const;

   // Returns "C:\pics\jojo" for path "C:\pics\jojo.jpg"

   // NOTE: this is slightly different from the similar file_util implementation

   // which returned simply 'jojo'.

   FilePath RemoveExtension() const;

   // Inserts |suffix| after the file name portion of |path| but before the

   // extension.  Returns "" if BaseName() == "." or "..".

   // Examples:

   // path == "C:\pics\jojo.jpg" suffix == " (1)", returns "C:\pics\jojo (1).jpg"

   // path == "jojo.jpg"         suffix == " (1)", returns "jojo (1).jpg"

   // path == "C:\pics\jojo"     suffix == " (1)", returns "C:\pics\jojo (1)"

   // path == "C:\pics.old\jojo" suffix == " (1)", returns "C:\pics.old\jojo (1)"

   FilePath InsertBeforeExtension(const StringType& suffix) const;

   // Replaces the extension of |file_name| with |extension|.  If |file_name|

   // does not have an extension, them |extension| is added.  If |extension| is

   // empty, then the extension is removed from |file_name|.

   // Returns "" if BaseName() == "." or "..".

   FilePath ReplaceExtension(const StringType& extension) const;

   // Returns a FilePath by appending a separator and the supplied path

   // component to this object's path.  Append takes care to avoid adding

   // excessive separators if this object's path already ends with a separator.

   // If this object's path is kCurrentDirectory, a new FilePath corresponding

   // only to |component| is returned.  |component| must be a relative path;

   // it is an error to pass an absolute path.

   FilePath Append(const StringType& component) const WARN_UNUSED_RESULT;

   FilePath Append(const FilePath& component) const WARN_UNUSED_RESULT;

   // Although Windows StringType is std::wstring, since the encoding it uses for

   // paths is well defined, it can handle ASCII path components as well.

   // Mac uses UTF8, and since ASCII is a subset of that, it works there as well.

   // On Linux, although it can use any 8-bit encoding for paths, we assume that

   // ASCII is a valid subset, regardless of the encoding, since many operating

   // system paths will always be ASCII.

   FilePath AppendASCII(const std::string& component) const WARN_UNUSED_RESULT;

   // Returns true if this FilePath contains an absolute path.  On Windows, an

   // absolute path begins with either a drive letter specification followed by

   // a separator character, or with two separator characters.  On POSIX

   // platforms, an absolute path begins with a separator character.

   bool IsAbsolute() const;

   // Returns a copy of this FilePath that does not end with a trailing

   // separator.

   FilePath StripTrailingSeparators() const;

   // Calls open on given ifstream instance

   void OpenInputStream(std::ifstream &stream) const;

   // Older Chromium code assumes that paths are always wstrings.

   // This function converts a wstring to a FilePath, and is useful to smooth

   // porting that old code to the FilePath API.

   // It has "Hack" in its name so people feel bad about using it.

   // TODO(port): remove these functions.

   static FilePath FromWStringHack(const std::wstring& wstring);

   // Older Chromium code assumes that paths are always wstrings.

   // This function produces a wstring from a FilePath, and is useful to smooth

   // porting that old code to the FilePath API.

   // It has "Hack" in its name so people feel bad about using it.

   // TODO(port): remove these functions.

   std::wstring ToWStringHack() const;

  private:

   // Remove trailing separators from this object.  If the path is absolute, it

   // will never be stripped any more than to refer to the absolute root

   // directory, so "////" will become "/", not "".  A leading pair of

   // separators is never stripped, to support alternate roots.  This is used to

   // support UNC paths on Windows.

   void StripTrailingSeparatorsInternal();

   StringType path_;

 };

 // Macros for string literal initialization of FilePath::CharType[].

 #if defined(OS_POSIX)

 #define FILE_PATH_LITERAL(x) x

 #elif defined(OS_WIN)

 #define FILE_PATH_LITERAL(x) L ## x

 #endif  // OS_WIN

 // Implement hash function so that we can use FilePaths in hashsets and maps.

 #if defined(COMPILER_GCC) && !defined(ANDROID)

 namespace __gnu_cxx {

 template<>

 struct hash<FilePath> {

   size_t operator()(const FilePath& f) const {

     return hash<FilePath::StringType>()(f.value());

   }

 };

 }  // namespace __gnu_cxx

 #elif defined(COMPILER_MSVC)

 namespace stdext {

 inline size_t hash_value(const FilePath& f) {

   return hash_value(f.value());

 }

 }  // namespace stdext

 #endif  // COMPILER

 #endif  // BASE_FILE_PATH_H_