Debounce input from the search edit

This makes writing there a little bit more pleasant

third_party/KDToolBox/KDSignalThrottler.h

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+/****************************************************************************
+**                                MIT License
+**
+** Copyright (C) 2020-2023 Klarälvdalens Datakonsult AB, a KDAB Group company, info@kdab.com, author Giuseppe D'Angelo
+*<giuseppe.dangelo@kdab.com>
+**
+** This file is part of KDToolBox (https://github.com/KDAB/KDToolBox).
+**
+** Permission is hereby granted, free of charge, to any person obtaining a copy
+** of this software and associated documentation files (the "Software"), to deal
+** in the Software without restriction, including without limitation the rights
+** to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+** copies of the Software, ** and to permit persons to whom the Software is
+** furnished to do so, subject to the following conditions:
+**
+** The above copyright notice and this permission notice (including the next paragraph)
+** shall be included in all copies or substantial portions of the Software.
+**
+** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+** FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+** AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+** LIABILITY, WHETHER IN AN ACTION OF ** CONTRACT, TORT OR OTHERWISE,
+** ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+** DEALINGS IN THE SOFTWARE.
+****************************************************************************/
+
+#ifndef KDSIGNALTHROTTLER_H
+#define KDSIGNALTHROTTLER_H
+
+#include <QObject>
+#include <QTimer>
+
+#include <chrono>
+
+namespace KDToolBox
+{
+
+class KDGenericSignalThrottler : public QObject
+{
+    Q_OBJECT
+
+    Q_PROPERTY(Kind kind READ kind CONSTANT)
+    Q_PROPERTY(EmissionPolicy emissionPolicy READ emissionPolicy CONSTANT)
+    Q_PROPERTY(int timeout READ timeout WRITE setTimeout NOTIFY timeoutChanged)
+    Q_PROPERTY(Qt::TimerType timerType READ timerType WRITE setTimerType NOTIFY timerTypeChanged)
+
+public:
+    enum class Kind
+    {
+        Throttler,
+        Debouncer,
+    };
+    Q_ENUM(Kind)
+
+    enum class EmissionPolicy
+    {
+        Trailing,
+        Leading,
+    };
+    Q_ENUM(EmissionPolicy)
+
+    explicit KDGenericSignalThrottler(Kind kind, EmissionPolicy emissionPolicy, QObject *parent = nullptr);
+    ~KDGenericSignalThrottler() override;
+
+    Kind kind() const;
+    EmissionPolicy emissionPolicy() const;
+
+    int timeout() const;
+    void setTimeout(int timeout);
+    void setTimeout(std::chrono::milliseconds timeout);
+
+    Qt::TimerType timerType() const;
+    void setTimerType(Qt::TimerType timerType);
+
+public Q_SLOTS:
+    void throttle();
+
+Q_SIGNALS:
+    void triggered();
+    void timeoutChanged(int timeout);
+    void timerTypeChanged(Qt::TimerType timerType);
+
+private:
+    void maybeEmitTriggered();
+    void emitTriggered();
+
+    QTimer m_timer;
+    Kind m_kind;
+    EmissionPolicy m_emissionPolicy;
+    bool m_hasPendingEmission;
+};
+
+// Convenience subclasses, e.g. for registering into QML
+
+class KDSignalThrottler : public KDGenericSignalThrottler
+{
+    Q_OBJECT
+public:
+    explicit KDSignalThrottler(QObject *parent = nullptr);
+    ~KDSignalThrottler() override;
+};
+
+class KDSignalLeadingThrottler : public KDGenericSignalThrottler
+{
+    Q_OBJECT
+public:
+    explicit KDSignalLeadingThrottler(QObject *parent = nullptr);
+    ~KDSignalLeadingThrottler() override;
+};
+
+class KDSignalDebouncer : public KDGenericSignalThrottler
+{
+    Q_OBJECT
+public:
+    explicit KDSignalDebouncer(QObject *parent = nullptr);
+    ~KDSignalDebouncer() override;
+};
+
+class KDSignalLeadingDebouncer : public KDGenericSignalThrottler
+{
+    Q_OBJECT
+public:
+    explicit KDSignalLeadingDebouncer(QObject *parent = nullptr);
+    ~KDSignalLeadingDebouncer() override;
+};
+
+} // namespace KDToolBox
+
+#endif // KDSIGNALTHROTTLER_H