From 5999e6e0c32e6897b88f59f0743b4bb1fc9c521c Mon Sep 17 00:00:00 2001
From: Florent Le Coz <louiz@louiz.org>
Date: Tue, 27 May 2014 01:12:46 +0200
Subject: Introduce the timed events

---
 src/utils/timed_events.hpp | 111 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 src/utils/timed_events.hpp

(limited to 'src/utils/timed_events.hpp')

diff --git a/src/utils/timed_events.hpp b/src/utils/timed_events.hpp
new file mode 100644
index 0000000..9be747d
--- /dev/null
+++ b/src/utils/timed_events.hpp
@@ -0,0 +1,111 @@
+#ifndef TIMED_EVENTS_HPP
+# define TIMED_EVENTS_HPP
+
+#include <functional>
+#include <chrono>
+#include <list>
+
+using namespace std::literals::chrono_literals;
+
+namespace utils {
+static constexpr std::chrono::milliseconds no_timeout = std::chrono::milliseconds(-1);
+}
+
+class TimedEventsManager;
+
+/**
+ * A callback with an associated date.
+ */
+
+class TimedEvent
+{
+  friend class TimedEventsManager;
+public:
+  /**
+   * An event the occurs only once, at the given time_point
+   */
+  explicit TimedEvent(std::chrono::steady_clock::time_point&& time_point,
+                      std::function<void()> callback);
+  explicit TimedEvent(std::chrono::milliseconds&& duration,
+                      std::function<void()> callback);
+
+  explicit TimedEvent(TimedEvent&&);
+  ~TimedEvent();
+  /**
+   * Whether or not this event happens after the other one.
+   */
+  bool is_after(const TimedEvent& other) const;
+  bool is_after(const std::chrono::steady_clock::time_point& time_point) const;
+  /**
+   * Return the duration difference between now and the event time point.
+   * If the difference would be negative (i.e. the event is expired), the
+   * returned value is 0 instead. The value cannot then be negative.
+   */
+  std::chrono::milliseconds get_timeout() const;
+  void execute();
+
+private:
+  /**
+   * The next time point at which the event is executed.
+   */
+  std::chrono::steady_clock::time_point time_point;
+  /**
+   * The function to execute.
+   */
+  const std::function<void()> callback;
+  /**
+   * Whether or not this events repeats itself until it is destroyed.
+   */
+  const bool repeat;
+  /**
+   * This value is added to the time_point each time the event is executed,
+   * if repeat is true. Otherwise it is ignored.
+   */
+  const std::chrono::milliseconds repeat_delay;
+
+  TimedEvent(const TimedEvent&) = delete;
+  TimedEvent& operator=(const TimedEvent&) = delete;
+  TimedEvent& operator=(TimedEvent&&) = delete;
+};
+
+/**
+ * A class managing a list of TimedEvents.
+ * They are sorted, new events can be added, removed, fetch, etc.
+ */
+
+class TimedEventsManager
+{
+public:
+  explicit TimedEventsManager();
+  ~TimedEventsManager();
+  /**
+   * Add an event to the list of managed events. The list is sorted after
+   * this call.
+   */
+  void add_event(TimedEvent&& event);
+  /**
+   * Returns the duration, in milliseconds, between now and the next
+   * available event. If the event is already expired (the duration is
+   * negative), 0 is returned instead (as in “it's not too late, execute it
+   * now”)
+   * Returns a negative value if no event is available.
+   */
+  std::chrono::milliseconds get_timeout() const;
+  /**
+   * Execute all the expired events (if their expiration time is exactly
+   * now, or before now). The event is then removed from the list. If the
+   * event does repeat, its expiration time is updated and it is reinserted
+   * in the list at the correct position.
+   * Returns the number of executed events.
+   */
+  std::size_t execute_expired_events();
+
+private:
+  std::list<TimedEvent> events;
+  TimedEventsManager(const TimedEventsManager&) = delete;
+  TimedEventsManager(TimedEventsManager&&) = delete;
+  TimedEventsManager& operator=(const TimedEventsManager&) = delete;
+  TimedEventsManager& operator=(TimedEventsManager&&) = delete;
+};
+
+#endif // TIMED_EVENTS_HPP
-- 
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