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TMessagesProj/jni/voip/webrtc/base/path_service.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.
+
+#ifndef BASE_PATH_SERVICE_H_
+#define BASE_PATH_SERVICE_H_
+
+#include <string>
+
+#include "base/base_export.h"
+#include "base/base_paths.h"
+#include "base/gtest_prod_util.h"
+#include "build/build_config.h"
+
+namespace base {
+
+class FilePath;
+class ScopedPathOverride;
+
+// The path service is a global table mapping keys to file system paths.  It is
+// OK to use this service from multiple threads.
+//
+class BASE_EXPORT PathService {
+ public:
+  // Populates |path| with a special directory or file. Returns true on success,
+  // in which case |path| is guaranteed to have a non-empty value. On failure,
+  // |path| will not be changed.
+  static bool Get(int key, FilePath* path);
+
+  // Overrides the path to a special directory or file.  This cannot be used to
+  // change the value of DIR_CURRENT, but that should be obvious.  Also, if the
+  // path specifies a directory that does not exist, the directory will be
+  // created by this method.  This method returns true if successful.
+  //
+  // If the given path is relative, then it will be resolved against
+  // DIR_CURRENT.
+  //
+  // WARNING: Consumers of PathService::Get may expect paths to be constant
+  // over the lifetime of the app, so this method should be used with caution.
+  //
+  // Unit tests generally should use ScopedPathOverride instead. Overrides from
+  // one test should not carry over to another.
+  static bool Override(int key, const FilePath& path);
+
+  // This function does the same as PathService::Override but it takes extra
+  // parameters:
+  // - |is_absolute| indicates that |path| has already been expanded into an
+  // absolute path, otherwise MakeAbsoluteFilePath() will be used. This is
+  // useful to override paths that may not exist yet, since MakeAbsoluteFilePath
+  // fails for those. Note that MakeAbsoluteFilePath also expands symbolic
+  // links, even if path.IsAbsolute() is already true.
+  // - |create| guides whether the directory to be overriden must
+  // be created in case it doesn't exist already.
+  static bool OverrideAndCreateIfNeeded(int key,
+                                        const FilePath& path,
+                                        bool is_absolute,
+                                        bool create);
+
+  // To extend the set of supported keys, you can register a path provider,
+  // which is just a function mirroring PathService::Get.  The ProviderFunc
+  // returns false if it cannot provide a non-empty path for the given key.
+  // Otherwise, true is returned.
+  //
+  // WARNING: This function could be called on any thread from which the
+  // PathService is used, so a the ProviderFunc MUST BE THREADSAFE.
+  //
+  typedef bool (*ProviderFunc)(int, FilePath*);
+
+  // Call to register a path provider.  You must specify the range "[key_start,
+  // key_end)" of supported path keys.
+  static void RegisterProvider(ProviderFunc provider,
+                               int key_start,
+                               int key_end);
+
+  // Disable internal cache.
+  static void DisableCache();
+
+ private:
+  friend class ScopedPathOverride;
+  FRIEND_TEST_ALL_PREFIXES(PathServiceTest, RemoveOverride);
+
+  // Removes an override for a special directory or file. Returns true if there
+  // was an override to remove or false if none was present.
+  // NOTE: This function is intended to be used by tests only!
+  static bool RemoveOverride(int key);
+};
+
+}  // namespace base
+
+#endif  // BASE_PATH_SERVICE_H_