| // Copyright (C) 2013 Google Inc. |
| // |
| // Licensed under the Apache License, Version 2.0 (the "License"); |
| // you may not use this file except in compliance with the License. |
| // You may obtain a copy of the License at |
| // |
| // http://www.apache.org/licenses/LICENSE-2.0 |
| // |
| // Unless required by applicable law or agreed to in writing, software |
| // distributed under the License is distributed on an "AS IS" BASIS, |
| // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| // See the License for the specific language governing permissions and |
| // limitations under the License. |
| // |
| // An object to retrieve data. |
| |
| #ifndef I18N_ADDRESSINPUT_RETRIEVER_H_ |
| #define I18N_ADDRESSINPUT_RETRIEVER_H_ |
| |
| #include <libaddressinput/callback.h> |
| |
| #include <memory> |
| #include <string> |
| |
| namespace i18n { |
| namespace addressinput { |
| |
| class Source; |
| class Storage; |
| class ValidatingStorage; |
| |
| // Retrieves data. Sample usage: |
| // Source* source = ...; |
| // Storage* storage = ...; |
| // Retriever retriever(source, storage); |
| // const std::unique_ptr<const Retriever::Callback> retrieved( |
| // BuildCallback(this, &MyClass::OnDataRetrieved)); |
| // retriever.Retrieve("data/CA/AB--fr", *retrieved); |
| class Retriever { |
| public: |
| using Callback = |
| i18n::addressinput::Callback<const std::string&, const std::string&>; |
| |
| Retriever(const Retriever&) = delete; |
| Retriever& operator=(const Retriever&) = delete; |
| |
| // Takes ownership of |source| and |storage|. |
| Retriever(const Source* source, Storage* storage); |
| ~Retriever(); |
| |
| // Retrieves the data for |key| and invokes the |retrieved| callback. Checks |
| // for the data in |storage_| first. If storage does not have the data for |
| // |key|, then gets the data from |source_| and places it in storage. If the |
| // data in storage is corrupted, then it's discarded and requested anew. If |
| // the data is stale, then it's requested anew. If the request fails, then |
| // stale data will be returned this one time. Any subsequent call to |
| // Retrieve() will attempt to get fresh data again. |
| void Retrieve(const std::string& key, const Callback& retrieved) const; |
| |
| private: |
| std::unique_ptr<const Source> source_; |
| std::unique_ptr<ValidatingStorage> storage_; |
| }; |
| |
| } // namespace addressinput |
| } // namespace i18n |
| |
| #endif // I18N_ADDRESSINPUT_RETRIEVER_H_ |