Add FilePath::FinalExtension and RemoveFinalExtension

base/files/file_path.h

 // Copyright 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
@@ skipping 129 matching lines @@
 
   // 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;
 
@@ skipping 17 matching lines @@
   // 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 the path's file extension. This does not have a special case for
+  // common double extensions, so FinalExtension() of "foo.tar.gz" is simply
+  // "foo.tar".

[Mark Mentovai, 2015/01/20 17:11:53]

I think this comment means “.gz”, not “foo.tar”. RemoveFinalExtension() would be
“foo.tar”.

The comment should also say that extensionless paths will return "". The
upstream copy says so on Extension(), but since we’re not bringing Extension()
over, we should say so here.

[scottmg, 2015/01/20 18:01:27]

Done.

+  StringType FinalExtension() const;

[Mark Mentovai, 2015/01/20 17:11:53]

Even though upstream’s not WARN_UNUSED_RESULT, it should be, and this could be
here.

[scottmg, 2015/01/20 18:01:27]

I think generally only the FilePath returning ones are marked that way as in
that case it can be unclear if it's mutating or copying. But I guess there's no
useful reason to call FinalExtension() and ignore the result either.

+
+  // Returns a FilePath with FinalExtension() removed.
+  FilePath RemoveFinalExtension() const WARN_UNUSED_RESULT;
+
   // 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;
 
   // Returns true if this FilePath contains an absolute path.  On Windows, an
@@ skipping 24 matching lines @@
 #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
 
 #endif  // MINI_CHROMIUM_BASE_FILES_FILE_PATH_H_