102 lines
2.9 KiB
C++
102 lines
2.9 KiB
C++
/* This file is part of Clementine.
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Copyright 2011, David Sansome <me@davidsansome.com>
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Clementine is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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Clementine is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with Clementine. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef CACHEDLIST_H
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#define CACHEDLIST_H
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#include <QDateTime>
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#include <QSettings>
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template <typename T>
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class CachedList {
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public:
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// Use a CachedList when you want to download and save a list of things from a
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// remote service, updating it only periodically.
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// T must be a registered metatype and must support being stored in
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// QSettings. This usually means you have to implement QDataStream streaming
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// operators, and use qRegisterMetaTypeStreamOperators.
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typedef QList<T> ListType;
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CachedList(const QString& settings_group, const QString& name,
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int cache_duration_secs)
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: settings_group_(settings_group),
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name_(name),
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cache_duration_secs_(cache_duration_secs) {}
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void Load() {
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QSettings s;
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s.beginGroup(settings_group_);
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last_updated_ = s.value("last_refreshed_" + name_).toDateTime();
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data_.clear();
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const int count = s.beginReadArray(name_ + "_data");
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for (int i = 0; i < count; ++i) {
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s.setArrayIndex(i);
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data_ << s.value("value").value<T>();
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}
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s.endArray();
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}
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void Save() const {
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QSettings s;
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s.beginGroup(settings_group_);
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s.setValue("last_refreshed_" + name_, last_updated_);
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s.beginWriteArray(name_ + "_data", data_.size());
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for (int i = 0; i < data_.size(); ++i) {
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s.setArrayIndex(i);
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s.setValue("value", QVariant::fromValue(data_[i]));
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}
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s.endArray();
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}
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void Update(const ListType& data) {
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data_ = data;
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last_updated_ = QDateTime::currentDateTime();
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Save();
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}
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bool IsStale() const {
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return last_updated_.isNull() ||
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last_updated_.secsTo(QDateTime::currentDateTime()) >
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cache_duration_secs_;
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}
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void Sort() { qSort(data_); }
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const ListType& Data() const { return data_; }
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operator ListType() const { return data_; }
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// Q_FOREACH support
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typedef typename ListType::const_iterator const_iterator;
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const_iterator begin() const { return data_.begin(); }
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const_iterator end() const { return data_.end(); }
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private:
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const QString settings_group_;
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const QString name_;
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const int cache_duration_secs_;
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QDateTime last_updated_;
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ListType data_;
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};
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#endif // CACHEDLIST_H
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