add jtk.timer module

src/jtk/package.d

@@ -3,4 +3,5 @@ module jtk;
 public import jtk.event;
 public import jtk.init;
 public import jtk.time;
+public import jtk.timer;
 public import jtk.window;

src/jtk/timer.d

@@ -0,0 +1,69 @@
+module jtk.timer;
+
+import jtk.time;
+import std.algorithm;
+
+class Timer
+{
+    private static Timer[Timer] timers;
+
+    ulong next;
+
+    ulong interval;
+
+    void * user;
+
+    this(ulong delay, ulong interval, void * user)
+    {
+        ulong current_time = ms_time();
+        this.next = current_time + delay;
+        this.interval = interval;
+        this.user = user;
+        timers[this] = this;
+    }
+
+    void remove()
+    {
+        timers.remove(this);
+    }
+
+    void service()
+    {
+        if (this.interval == 0u)
+        {
+            remove();
+        }
+        else
+        {
+            this.next += this.interval;
+        }
+    }
+
+    static Timer get_expired_timer()
+    {
+        ulong current_time = ms_time();
+        foreach (Timer timer; timers)
+        {
+            if (timer.next <= current_time)
+            {
+                return timer;
+            }
+        }
+        return null;
+    }
+
+    static ulong time_to_next_timer_expiration()
+    {
+        ulong rv = cast(ulong)-1;
+        ulong current_time = ms_time();
+        foreach (Timer timer; timers)
+        {
+            if (timer.next <= current_time)
+            {
+                return 0u;
+            }
+            rv = min(rv, timer.next - current_time);
+        }
+        return rv;
+    }
+}