Added callback line of sight methods. Thanks xZise!

src/main/java/org/bukkit/craftbukkit/entity/CraftLivingEntity.java

@@ -18,6 +18,7 @@ import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Snowball;
 import org.bukkit.entity.Vehicle;
 import org.bukkit.util.BlockIterator;
+import org.bukkit.util.Callback;
 
 import java.util.List;
 import java.util.HashSet;
@@ -86,6 +87,45 @@ public class CraftLivingEntity extends CraftEntity implements LivingEntity {
         return getEyeHeight();
     }
 
+    private List<Block> getLineOfSight(Callback<Boolean, Block> callback, int maxDistance, int maxLength) {
+        if (maxDistance > 120) {
+            maxDistance = 120;
+        }
+        ArrayList<Block> blocks = new ArrayList<Block>(maxLength == 0 ? 10 : maxLength);
+        Iterator<Block> itr = new BlockIterator(this, maxDistance);
+        while (itr.hasNext()) {
+            Block block = itr.next();
+            if (maxLength != 0 && blocks.size() + 1 > maxLength) {
+                blocks.remove(0);
+            }
+            blocks.add(block);
+            if (callback == null) {
+                if (block.getTypeId() != 0) {
+                    break;
+                }
+            } else {
+                Boolean result = callback.call(block);
+                if (result != null && !result) {
+                    break;
+                }
+            }
+        }
+        return blocks;
+    }
+
+    public List<Block> getLineOfSight(Callback<Boolean, Block> callback, int maxDistance) {
+        return getLineOfSight(callback, maxDistance, 0);
+    }
+
+    public Block getTargetBlock(Callback<Boolean, Block> callback, int maxDistance) {
+        List<Block> blocks = getLineOfSight(callback, maxDistance, 1);
+        return blocks.get(0);
+    }
+
+    public List<Block> getLastTwoTargetBlocks(Callback<Boolean, Block> callback, int maxDistance) {
+        return getLineOfSight(callback, maxDistance, 2);
+    }
+
     private List<Block> getLineOfSight(HashSet<Byte> transparent, int maxDistance, int maxLength) {
         if (maxDistance > 120) {
             maxDistance = 120;