[AVR] Moonsilver Spear, extract common ability

Mage/src/mage/abilities/common/AttacksEquippedTriggeredAbility.java

@@ -0,0 +1,39 @@
+package mage.abilities.common;
+
+import mage.Constants;
+import mage.abilities.TriggeredAbilityImpl;
+import mage.abilities.effects.Effect;
+import mage.game.Game;
+import mage.game.events.GameEvent;
+import mage.game.permanent.Permanent;
+
+public class AttacksEquippedTriggeredAbility extends TriggeredAbilityImpl<AttacksEquippedTriggeredAbility> {
+    public AttacksEquippedTriggeredAbility(Effect effect) {
+        super(Constants.Zone.BATTLEFIELD, effect);
+    }
+
+    public AttacksEquippedTriggeredAbility(final AttacksEquippedTriggeredAbility abiltity) {
+        super(abiltity);
+    }
+
+    @Override
+    public AttacksEquippedTriggeredAbility copy() {
+        return new AttacksEquippedTriggeredAbility(this);
+    }
+
+    @Override
+    public boolean checkTrigger(GameEvent event, Game game) {
+        Permanent equipment = game.getPermanent(this.sourceId);
+        if (equipment != null && equipment.getAttachedTo() != null
+                && event.getType() == GameEvent.EventType.ATTACKER_DECLARED
+                && event.getSourceId().equals(equipment.getAttachedTo())) {
+            return true;
+        }
+        return false;
+    }
+
+    @Override
+    public String getRule() {
+        return "Whenever equipped creature attacks, " + super.getRule();
+    }
+}