// Copyright 2008 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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// FilePath is a container for pathnames stored in a platform's native string
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// type, providing containers for manipulation in according with the
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// platform's conventions for pathnames. It supports the following path
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// types:
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//
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// POSIX Windows
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// --------------- ----------------------------------
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// Fundamental type char[] wchar_t[]
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// Encoding unspecified* UTF-16
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// Separator / \, tolerant of /
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// Drive letters no case-insensitive A-Z followed by :
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// Alternate root // (surprise!) \\, for UNC paths
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//
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// * The encoding need not be specified on POSIX systems, although some
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// POSIX-compliant systems do specify an encoding. Mac OS X uses UTF-8.
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// Chrome OS also uses UTF-8.
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// Linux does not specify an encoding, but in practice, the locale's
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// character set may be used.
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//
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// For more arcane bits of path trivia, see below.
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//
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// FilePath objects are intended to be used anywhere paths are. An
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// application may pass FilePath objects around internally, masking the
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// underlying differences between systems, only differing in implementation
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// where interfacing directly with the system. For example, a single
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// OpenFile(const FilePath &) function may be made available, allowing all
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// callers to operate without regard to the underlying implementation. On
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// POSIX-like platforms, OpenFile might wrap fopen, and on Windows, it might
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// wrap _wfopen_s, perhaps both by calling file_path.value().c_str(). This
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// allows each platform to pass pathnames around without requiring conversions
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// between encodings, which has an impact on performance, but more imporantly,
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// has an impact on correctness on platforms that do not have well-defined
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// encodings for pathnames.
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//
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// Several methods are available to perform common operations on a FilePath
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// object, such as determining the parent directory (DirName), isolating the
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// final path component (BaseName), and appending a relative pathname string
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// to an existing FilePath object (Append). These methods are highly
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// recommended over attempting to split and concatenate strings directly.
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// These methods are based purely on string manipulation and knowledge of
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// platform-specific pathname conventions, and do not consult the filesystem
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// at all, making them safe to use without fear of blocking on I/O operations.
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// These methods do not function as mutators but instead return distinct
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// instances of FilePath objects, and are therefore safe to use on const
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// objects. The objects themselves are safe to share between threads.
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//
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// To aid in initialization of FilePath objects from string literals, a
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// FILE_PATH_LITERAL macro is provided, which accounts for the difference
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// between char[]-based pathnames on POSIX systems and wchar_t[]-based
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// pathnames on Windows.
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//
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// Paths can't contain NULs as a precaution agaist premature truncation.
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//
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// Because a FilePath object should not be instantiated at the global scope,
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// instead, use a FilePath::CharType[] and initialize it with
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// FILE_PATH_LITERAL. At runtime, a FilePath object can be created from the
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// character array. Example:
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//
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// | const FilePath::CharType kLogFileName[] = FILE_PATH_LITERAL("log.txt");
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// |
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// | void Function() {
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// | FilePath log_file_path(kLogFileName);
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// | [...]
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// | }
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//
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// WARNING: FilePaths should ALWAYS be displayed with LTR directionality, even
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// when the UI language is RTL. This means you always need to pass filepaths
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// through base::i18n::WrapPathWithLTRFormatting() before displaying it in the
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// RTL UI.
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//
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// This is a very common source of bugs, please try to keep this in mind.
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//
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// ARCANE BITS OF PATH TRIVIA
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//
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// - A double leading slash is actually part of the POSIX standard. Systems
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// are allowed to treat // as an alternate root, as Windows does for UNC
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// (network share) paths. Most POSIX systems don't do anything special
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// with two leading slashes, but FilePath handles this case properly
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// in case it ever comes across such a system. FilePath needs this support
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// for Windows UNC paths, anyway.
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// References:
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// The Open Group Base Specifications Issue 7, sections 3.266 ("Pathname")
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// and 4.12 ("Pathname Resolution"), available at:
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// http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_266
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// http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_12
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//
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// - Windows treats c:\\ the same way it treats \\. This was intended to
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// allow older applications that require drive letters to support UNC paths
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// like \\server\share\path, by permitting c:\\server\share\path as an
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// equivalent. Since the OS treats these paths specially, FilePath needs
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// to do the same. Since Windows can use either / or \ as the separator,
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// FilePath treats c://, c:\\, //, and \\ all equivalently.
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// Reference:
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// The Old New Thing, "Why is a drive letter permitted in front of UNC
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// paths (sometimes)?", available at:
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// http://blogs.msdn.com/oldnewthing/archive/2005/11/22/495740.aspx
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#ifndef MINI_CHROMIUM_BASE_FILES_FILE_PATH_H_
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#define MINI_CHROMIUM_BASE_FILES_FILE_PATH_H_
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#include <stddef.h>
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#include <iosfwd>
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#include <string>
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#include "base/compiler_specific.h"
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#include "build/build_config.h"
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// Windows-style drive letter support and pathname separator characters can be
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// enabled and disabled independently, to aid testing. These #defines are
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// here so that the same setting can be used in both the implementation and
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// in the unit test.
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#if defined(OS_WIN)
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#define FILE_PATH_USES_DRIVE_LETTERS
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#define FILE_PATH_USES_WIN_SEPARATORS
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#endif // OS_WIN
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namespace base {
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// An abstraction to isolate users from the differences between native
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// pathnames on different platforms.
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class FilePath {
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public:
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#if defined(OS_POSIX)
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// On most platforms, native pathnames are char arrays, and the encoding
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// may or may not be specified. On Mac OS X, native pathnames are encoded
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// in UTF-8.
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typedef std::string StringType;
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#elif defined(OS_WIN)
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// On Windows, for Unicode-aware applications, native pathnames are wchar_t
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// arrays encoded in UTF-16.
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typedef std::wstring StringType;
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#endif // OS_WIN
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typedef StringType::value_type CharType;
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// Null-terminated array of separators used to separate components in
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// hierarchical paths. Each character in this array is a valid separator,
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// but kSeparators[0] is treated as the canonical separator and will be used
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// when composing pathnames.
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static const CharType kSeparators[];
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// A special path component meaning "this directory."
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static const CharType kCurrentDirectory[];
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// A special path component meaning "the parent directory."
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static const CharType kParentDirectory[];
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// The character used to identify a file extension.
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static const CharType kExtensionSeparator;
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FilePath();
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FilePath(const FilePath& that);
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explicit FilePath(const StringType& path);
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~FilePath();
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FilePath& operator=(const FilePath& that);
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bool operator==(const FilePath& that) const;
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bool operator!=(const FilePath& that) const;
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// Required for some STL containers and operations
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bool operator<(const FilePath& that) const {
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return path_ < that.path_;
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}
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const StringType& value() const { return path_; }
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bool empty() const { return path_.empty(); }
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void clear() { path_.clear(); }
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// Returns true if |character| is in kSeparators.
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static bool IsSeparator(CharType character);
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// Returns a FilePath corresponding to the directory containing the path
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// named by this object, stripping away the file component. If this object
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// only contains one component, returns a FilePath identifying
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// kCurrentDirectory. If this object already refers to the root directory,
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// returns a FilePath identifying the root directory.
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FilePath DirName() const WARN_UNUSED_RESULT;
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// Returns a FilePath corresponding to the last path component of this
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// object, either a file or a directory. If this object already refers to
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// the root directory, returns a FilePath identifying the root directory;
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// this is the only situation in which BaseName will return an absolute path.
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FilePath BaseName() const WARN_UNUSED_RESULT;
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// Returns the path's file extension. This does not have a special case for
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// common double extensions, so FinalExtension() of "foo.tar.gz" is simply
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// ".gz". If there is no extension, "" will be returned.
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StringType FinalExtension() const WARN_UNUSED_RESULT;
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// Returns a FilePath with FinalExtension() removed.
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FilePath RemoveFinalExtension() const WARN_UNUSED_RESULT;
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// Returns a FilePath by appending a separator and the supplied path
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// component to this object's path. Append takes care to avoid adding
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// excessive separators if this object's path already ends with a separator.
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// If this object's path is kCurrentDirectory, a new FilePath corresponding
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// only to |component| is returned. |component| must be a relative path;
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// it is an error to pass an absolute path.
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FilePath Append(const StringType& component) const WARN_UNUSED_RESULT;
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FilePath Append(const FilePath& component) const WARN_UNUSED_RESULT;
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// Returns true if this FilePath contains an absolute path. On Windows, an
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// absolute path begins with either a drive letter specification followed by
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// a separator character, or with two separator characters. On POSIX
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// platforms, an absolute path begins with a separator character.
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bool IsAbsolute() const;
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private:
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// Remove trailing separators from this object. If the path is absolute, it
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// will never be stripped any more than to refer to the absolute root
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// directory, so "////" will become "/", not "". A leading pair of
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// separators is never stripped, to support alternate roots. This is used to
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// support UNC paths on Windows.
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void StripTrailingSeparatorsInternal();
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StringType path_;
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};
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} // namespace base
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// This is required by googletest to print a readable output on test failures.
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extern void PrintTo(const base::FilePath& path, std::ostream* out);
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// Macros for string literal initialization of FilePath::CharType[], and for
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// using a FilePath::CharType[] in a printf-style format string.
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#if defined(OS_POSIX)
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#define FILE_PATH_LITERAL(x) x
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#define PRFilePath "s"
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#define PRFilePathLiteral "%s"
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#elif defined(OS_WIN)
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#define FILE_PATH_LITERAL(x) L ## x
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#define PRFilePath "ls"
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#define PRFilePathLiteral L"%ls"
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#endif // OS_WIN
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#endif // MINI_CHROMIUM_BASE_FILES_FILE_PATH_H_
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