1 // Copyright (C) 2013 Google Inc. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 // An object to retrieve data. 16 17 #ifndef I18N_ADDRESSINPUT_RETRIEVER_H_ 18 #define I18N_ADDRESSINPUT_RETRIEVER_H_ 19 20 #include <libaddressinput/callback.h> 21 #include <libaddressinput/util/basictypes.h> 22 #include <libaddressinput/util/scoped_ptr.h> 23 24 #include <map> 25 #include <string> 26 27 namespace i18n { 28 namespace addressinput { 29 30 class Downloader; 31 class Storage; 32 33 // Manages downloading data and caching it locally. Sample usage: 34 // scoped_ptr<Downloader> downloader(new Downloader); 35 // scoped_ptr<Storage> storage(new Storage); 36 // Retriever retriever("https://i18napis.appspot.com/ssl-aggregate-address/", 37 // downloader.Pass(), storage.Pass()); 38 // retriever.Retrieve("data/CA/AB--fr", 39 // BuildCallback(this, &MyClass::OnDataRetrieved)); 40 class Retriever { 41 public: 42 // The return value indicates whether the data is valid (should be kept) or is 43 // invalid (should be discarded). 44 typedef i18n::addressinput::Callback<bool(std::string, std::string)> Callback; 45 46 Retriever(const std::string& validation_data_url, 47 scoped_ptr<Downloader> downloader, 48 scoped_ptr<Storage> storage); 49 ~Retriever(); 50 51 // Retrieves the data for |key| and invokes the |retrieved| callback. Checks 52 // for the data in storage first. If storage does not have the data for |key|, 53 // then downloads the data and places it in storage. 54 void Retrieve(const std::string& key, scoped_ptr<Callback> retrieved); 55 56 private: 57 friend class RetrieverTest; 58 59 // Callback for when a rule is retrieved from |storage_|. 60 void OnDataRetrievedFromStorage(bool success, 61 const std::string& key, 62 const std::string& stored_data); 63 64 // Callback for when a rule is retrieved by |downloader_|. 65 void OnDownloaded(bool success, 66 const std::string& url, 67 scoped_ptr<std::string> downloaded_data); 68 69 // Returns the URL where the |key| can be retrieved. For example, returns 70 // "https://i18napis.appspot.com/ssl-aggregate-address/data/US" for input 71 // "data/US". Assumes that the input string is a valid URL segment. 72 std::string GetUrlForKey(const std::string& key) const; 73 74 // Returns the key for the |url|. For example, returns "data/US" for 75 // "https://i18napis.appspot.com/ssl-aggregate-address/data/US". If the |url| 76 // does not start with |validation_data_url| that was passed to the 77 // constructor, then returns an empty string. (This can happen if the user of 78 // the library returns a bad URL in their Downloader implementation.) 79 std::string GetKeyForUrl(const std::string& url) const; 80 81 // Returns true if the |url| starts with |validation_data_url| that was passed 82 // to the constructor. 83 bool IsValidationDataUrl(const std::string& url) const; 84 85 // Looks up the callback for |key| in |requests_|, removes it from the map and 86 // invokes it with |key|, |success|, and |data| parameters. 87 bool InvokeCallbackForKey(const std::string& key, 88 bool success, 89 const std::string& data); 90 91 const std::string validation_data_url_; 92 scoped_ptr<Downloader> downloader_; 93 scoped_ptr<Storage> storage_; 94 95 // Holds pending requests. The callback pointers are owned. 96 std::map<std::string, Callback*> requests_; 97 98 // Holds data from storage that has expired timestamps. If a download fails, 99 // then this data is used as fallback. 100 std::map<std::string, std::string> stale_data_; 101 102 DISALLOW_COPY_AND_ASSIGN(Retriever); 103 }; 104 105 } // namespace addressinput 106 } // namespace i18n 107 108 #endif // I18N_ADDRESSINPUT_RETRIEVER_H_ 109
