1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef BASE_PATH_SERVICE_H_ 6 #define BASE_PATH_SERVICE_H_ 7 #pragma once 8 9 #include <string> 10 11 #include "base/base_api.h" 12 #include "base/base_paths.h" 13 #include "build/build_config.h" 14 15 class FilePath; 16 17 // The path service is a global table mapping keys to file system paths. It is 18 // OK to use this service from multiple threads. 19 // 20 class BASE_API PathService { 21 public: 22 // Retrieves a path to a special directory or file and places it into the 23 // string pointed to by 'path'. If you ask for a directory it is guaranteed 24 // to NOT have a path separator at the end. For example, "c:\windows\temp" 25 // Directories are also guaranteed to exist when this function succeeds. 26 // 27 // Returns true if the directory or file was successfully retrieved. On 28 // failure, 'path' will not be changed. 29 static bool Get(int key, FilePath* path); 30 31 // Overrides the path to a special directory or file. This cannot be used to 32 // change the value of DIR_CURRENT, but that should be obvious. Also, if the 33 // path specifies a directory that does not exist, the directory will be 34 // created by this method. This method returns true if successful. 35 // 36 // If the given path is relative, then it will be resolved against 37 // DIR_CURRENT. 38 // 39 // WARNING: Consumers of PathService::Get may expect paths to be constant 40 // over the lifetime of the app, so this method should be used with caution. 41 static bool Override(int key, const FilePath& path); 42 43 // To extend the set of supported keys, you can register a path provider, 44 // which is just a function mirroring PathService::Get. The ProviderFunc 45 // returns false if it cannot provide a non-empty path for the given key. 46 // Otherwise, true is returned. 47 // 48 // WARNING: This function could be called on any thread from which the 49 // PathService is used, so a the ProviderFunc MUST BE THREADSAFE. 50 // 51 typedef bool (*ProviderFunc)(int, FilePath*); 52 53 // Call to register a path provider. You must specify the range "[key_start, 54 // key_end)" of supported path keys. 55 static void RegisterProvider(ProviderFunc provider, 56 int key_start, 57 int key_end); 58 private: 59 static bool GetFromCache(int key, FilePath* path); 60 static bool GetFromOverrides(int key, FilePath* path); 61 static void AddToCache(int key, const FilePath& path); 62 }; 63 64 #endif // BASE_PATH_SERVICE_H_ 65