Move file_path.h to base/files.
TBR=sky
git-svn-id: svn://svn.chromium.org/chrome/trunk/src@184344 0039d316-1c4b-4281-b951-d872f2087c98
CrOS-Libchrome-Original-Commit: 57999817d30c384de8974a2c64c0356e71fde63c
diff --git a/base/files/file_path.h b/base/files/file_path.h
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+++ b/base/files/file_path.h
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+// 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.
+
+// 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.
+// Chrome OS also uses UTF-8.
+// Linux does not specify an encoding, but in practice, the locale's
+// character set may be used.
+//
+// For more arcane bits of path trivia, see below.
+//
+// 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.
+//
+// Paths can't contain NULs as a precaution agaist premature truncation.
+//
+// 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);
+// | [...]
+// | }
+//
+// WARNING: FilePaths should ALWAYS be displayed with LTR directionality, even
+// when the UI language is RTL. This means you always need to pass filepaths
+// through base::i18n::WrapPathWithLTRFormatting() before displaying it in the
+// RTL UI.
+//
+// This is a very common source of bugs, please try to keep this in mind.
+//
+// ARCANE BITS OF PATH TRIVIA
+//
+// - A double leading slash is actually part of the POSIX standard. Systems
+// are allowed to treat // as an alternate root, as Windows does for UNC
+// (network share) paths. Most POSIX systems don't do anything special
+// with two leading slashes, but FilePath handles this case properly
+// in case it ever comes across such a system. FilePath needs this support
+// for Windows UNC paths, anyway.
+// References:
+// The Open Group Base Specifications Issue 7, sections 3.266 ("Pathname")
+// and 4.12 ("Pathname Resolution"), available at:
+// http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap03.html#tag_03_266
+// http://www.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap04.html#tag_04_12
+//
+// - Windows treats c:\\ the same way it treats \\. This was intended to
+// allow older applications that require drive letters to support UNC paths
+// like \\server\share\path, by permitting c:\\server\share\path as an
+// equivalent. Since the OS treats these paths specially, FilePath needs
+// to do the same. Since Windows can use either / or \ as the separator,
+// FilePath treats c://, c:\\, //, and \\ all equivalently.
+// Reference:
+// The Old New Thing, "Why is a drive letter permitted in front of UNC
+// paths (sometimes)?", available at:
+// http://blogs.msdn.com/oldnewthing/archive/2005/11/22/495740.aspx
+
+#ifndef BASE_FILES_FILE_PATH_H_
+#define BASE_FILES_FILE_PATH_H_
+
+#include <stddef.h>
+#include <string>
+#include <vector>
+
+#include "base/base_export.h"
+#include "base/compiler_specific.h"
+#include "base/hash_tables.h"
+#include "base/string16.h"
+#include "base/string_piece.h" // For implicit conversions.
+#include "build/build_config.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
+
+class Pickle;
+class PickleIterator;
+
+namespace base {
+
+// An abstraction to isolate users from the differences between native
+// pathnames on different platforms.
+class BASE_EXPORT 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);
+ explicit FilePath(const StringType& path);
+ ~FilePath();
+ FilePath& operator=(const FilePath& that);
+
+ bool operator==(const FilePath& that) const;
+
+ bool operator!=(const FilePath& that) const;
+
+ // 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(); }
+
+ void clear() { path_.clear(); }
+
+ // Returns true if |character| is in kSeparators.
+ static bool IsSeparator(CharType character);
+
+ // Returns a vector of all of the components of the provided path. It is
+ // equivalent to calling DirName().value() on the path's root component,
+ // and BaseName().value() on each child component.
+ void GetComponents(std::vector<FilePath::StringType>* components) const;
+
+ // Returns true if this FilePath is a strict parent of the |child|. Absolute
+ // and relative paths are accepted i.e. is /foo parent to /foo/bar and
+ // is foo parent to foo/bar. Does not convert paths to absolute, follow
+ // symlinks or directory navigation (e.g. ".."). A path is *NOT* its own
+ // parent.
+ bool IsParent(const FilePath& child) const;
+
+ // If IsParent(child) holds, appends to path (if non-NULL) the
+ // relative path to child and returns true. For example, if parent
+ // holds "/Users/johndoe/Library/Application Support", child holds
+ // "/Users/johndoe/Library/Application Support/Google/Chrome/Default", and
+ // *path holds "/Users/johndoe/Library/Caches", then after
+ // parent.AppendRelativePath(child, path) is called *path will hold
+ // "/Users/johndoe/Library/Caches/Google/Chrome/Default". Otherwise,
+ // returns false.
+ bool AppendRelativePath(const FilePath& child, FilePath* path) const;
+
+ // 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 WARN_UNUSED_RESULT;
+
+ // 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 WARN_UNUSED_RESULT;
+
+ // 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 WARN_UNUSED_RESULT;
+
+ // 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 WARN_UNUSED_RESULT;
+ FilePath InsertBeforeExtensionASCII(
+ const base::StringPiece& suffix) const WARN_UNUSED_RESULT;
+
+ // Adds |extension| to |file_name|. Returns the current FilePath if
+ // |extension| is empty. Returns "" if BaseName() == "." or "..".
+ FilePath AddExtension(
+ const StringType& extension) const WARN_UNUSED_RESULT;
+
+ // Replaces the extension of |file_name| with |extension|. If |file_name|
+ // does not have an extension, then |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 WARN_UNUSED_RESULT;
+
+ // Returns true if the file path matches the specified extension. The test is
+ // case insensitive. Don't forget the leading period if appropriate.
+ bool MatchesExtension(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 base::StringPiece& 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 WARN_UNUSED_RESULT;
+
+ // Returns true if this FilePath contains any attempt to reference a parent
+ // directory (i.e. has a path component that is ".."
+ bool ReferencesParent() const;
+
+ // Return a Unicode human-readable version of this path.
+ // Warning: you can *not*, in general, go from a display name back to a real
+ // path. Only use this when displaying paths to users, not just when you
+ // want to stuff a string16 into some other API.
+ string16 LossyDisplayName() const;
+
+ // Return the path as ASCII, or the empty string if the path is not ASCII.
+ // This should only be used for cases where the FilePath is representing a
+ // known-ASCII filename.
+ std::string MaybeAsASCII() const;
+
+ // Return the path as UTF-8.
+ //
+ // This function is *unsafe* as there is no way to tell what encoding is
+ // used in file names on POSIX systems other than Mac and Chrome OS,
+ // although UTF-8 is practically used everywhere these days. To mitigate
+ // the encoding issue, this function internally calls
+ // SysNativeMBToWide() on POSIX systems other than Mac and Chrome OS,
+ // per assumption that the current locale's encoding is used in file
+ // names, but this isn't a perfect solution.
+ //
+ // Once it becomes safe to to stop caring about non-UTF-8 file names,
+ // the SysNativeMBToWide() hack will be removed from the code, along
+ // with "Unsafe" in the function name.
+ std::string AsUTF8Unsafe() const;
+
+ // Older Chromium code assumes that paths are always wstrings.
+ // This function converts wstrings to FilePaths, and is
+ // useful to smooth porting that old code to the FilePath API.
+ // It has "Hack" its name so people feel bad about using it.
+ // http://code.google.com/p/chromium/issues/detail?id=24672
+ //
+ // If you are trying to be a good citizen and remove these, ask yourself:
+ // - Am I interacting with other Chrome code that deals with files? Then
+ // try to convert the API into using FilePath.
+ // - Am I interacting with OS-native calls? Then use value() to get at an
+ // OS-native string format.
+ // - Am I using well-known file names, like "config.ini"? Then use the
+ // ASCII functions (we require paths to always be supersets of ASCII).
+ // - Am I displaying a string to the user in some UI? Then use the
+ // LossyDisplayName() function, but keep in mind that you can't
+ // ever use the result of that again as a path.
+ static FilePath FromWStringHack(const std::wstring& wstring);
+
+ // Returns a FilePath object from a path name in UTF-8. This function
+ // should only be used for cases where you are sure that the input
+ // string is UTF-8.
+ //
+ // Like AsUTF8Unsafe(), this function is unsafe. This function
+ // internally calls SysWideToNativeMB() on POSIX systems other than Mac
+ // and Chrome OS, to mitigate the encoding issue. See the comment at
+ // AsUTF8Unsafe() for details.
+ static FilePath FromUTF8Unsafe(const std::string& utf8);
+
+ void WriteToPickle(Pickle* pickle) const;
+ bool ReadFromPickle(PickleIterator* iter);
+
+ // Normalize all path separators to backslash on Windows
+ // (if FILE_PATH_USES_WIN_SEPARATORS is true), or do nothing on POSIX systems.
+ FilePath NormalizePathSeparators() const;
+
+ // Compare two strings in the same way the file system does.
+ // Note that these always ignore case, even on file systems that are case-
+ // sensitive. If case-sensitive comparison is ever needed, add corresponding
+ // methods here.
+ // The methods are written as a static method so that they can also be used
+ // on parts of a file path, e.g., just the extension.
+ // CompareIgnoreCase() returns -1, 0 or 1 for less-than, equal-to and
+ // greater-than respectively.
+ static int CompareIgnoreCase(const StringType& string1,
+ const StringType& string2);
+ static bool CompareEqualIgnoreCase(const StringType& string1,
+ const StringType& string2) {
+ return CompareIgnoreCase(string1, string2) == 0;
+ }
+ static bool CompareLessIgnoreCase(const StringType& string1,
+ const StringType& string2) {
+ return CompareIgnoreCase(string1, string2) < 0;
+ }
+
+#if defined(OS_MACOSX)
+ // Returns the string in the special canonical decomposed form as defined for
+ // HFS, which is close to, but not quite, decomposition form D. See
+ // http://developer.apple.com/mac/library/technotes/tn/tn1150.html#UnicodeSubtleties
+ // for further comments.
+ // Returns the epmty string if the conversion failed.
+ static StringType GetHFSDecomposedForm(const FilePath::StringType& string);
+
+ // Special UTF-8 version of FastUnicodeCompare. Cf:
+ // http://developer.apple.com/mac/library/technotes/tn/tn1150.html#StringComparisonAlgorithm
+ // IMPORTANT: The input strings must be in the special HFS decomposed form!
+ // (cf. above GetHFSDecomposedForm method)
+ static int HFSFastUnicodeCompare(const StringType& string1,
+ const StringType& string2);
+#endif
+
+ 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_;
+};
+
+} // namespace base
+
+// This is required by googletest to print a readable output on test failures.
+BASE_EXPORT extern void PrintTo(const base::FilePath& path, std::ostream* out);
+
+// Macros for string literal initialization of FilePath::CharType[], and for
+// using a FilePath::CharType[] in a printf-style format string.
+#if defined(OS_POSIX)
+#define FILE_PATH_LITERAL(x) x
+#define PRFilePath "s"
+#define PRFilePathLiteral "%s"
+#elif defined(OS_WIN)
+#define FILE_PATH_LITERAL(x) L ## x
+#define PRFilePath "ls"
+#define PRFilePathLiteral L"%ls"
+#endif // OS_WIN
+
+// Provide a hash function so that hash_sets and maps can contain FilePath
+// objects.
+namespace BASE_HASH_NAMESPACE {
+#if defined(COMPILER_GCC)
+
+template<>
+struct hash<base::FilePath> {
+ size_t operator()(const base::FilePath& f) const {
+ return hash<base::FilePath::StringType>()(f.value());
+ }
+};
+
+#elif defined(COMPILER_MSVC)
+
+inline size_t hash_value(const base::FilePath& f) {
+ return hash_value(f.value());
+}
+
+#endif // COMPILER
+
+} // namespace BASE_HASH_NAMESPACE
+
+#endif // BASE_FILES_FILE_PATH_H_