Distinguish between line build nodes and segments.

OpenRA.Mods.Common/Traits/Buildings/LineBuild.cs

@@ -10,19 +10,91 @@
 #endregion
 
 using System.Collections.Generic;
+using System.Linq;
 using OpenRA.Traits;
 
 namespace OpenRA.Mods.Common.Traits
 {
+	public class LineBuildParentInit : IActorInit<Actor[]>
+	{
+		[FieldFromYamlKey] public readonly string[] ParentNames = new string[0];
+		readonly Actor[] parents = null;
+
+		public LineBuildParentInit() { }
+		public LineBuildParentInit(Actor[] init) { parents = init; }
+		public Actor[] Value(World world)
+		{
+			if (parents != null)
+				return parents;
+
+			var sma = world.WorldActor.Trait<SpawnMapActors>();
+			return ParentNames.Select(n => sma.Actors[n]).ToArray();
+		}
+	}
+
+	public interface INotifyLineBuildSegmentsChanged
+	{
+		void SegmentAdded(Actor self, Actor segment);
+		void SegmentRemoved(Actor self, Actor segment);
+	}
+
 	[Desc("Place the second actor in line to build more of the same at once (used for walls).")]
-	public class LineBuildInfo : TraitInfo<LineBuild>
+	public class LineBuildInfo : ITraitInfo
 	{
 		[Desc("The maximum allowed length of the line.")]
 		public readonly int Range = 5;
 
 		[Desc("LineBuildNode 'Types' to attach to.")]
 		public readonly HashSet<string> NodeTypes = new HashSet<string> { "wall" };
+
+		[ActorReference(typeof(LineBuildInfo))]
+		[Desc("Actor type for line-built segments (defaults to same actor).")]
+		public readonly string SegmentType = null;
+
+		public object Create(ActorInitializer init) { return new LineBuild(init, this); }
 	}
 
-	public class LineBuild { }
+	public class LineBuild : INotifyAddedToWorld, INotifyRemovedFromWorld, INotifyLineBuildSegmentsChanged
+	{
+		readonly Actor[] parentNodes = new Actor[0];
+		HashSet<Actor> segments;
+
+		public LineBuild(ActorInitializer init, LineBuildInfo info)
+		{
+			if (init.Contains<LineBuildParentInit>())
+				parentNodes = init.Get<LineBuildParentInit>().Value(init.World);
+		}
+
+		void INotifyLineBuildSegmentsChanged.SegmentAdded(Actor self, Actor segment)
+		{
+			if (segments == null)
+				segments = new HashSet<Actor>();
+
+			segments.Add(segment);
+		}
+
+		void INotifyLineBuildSegmentsChanged.SegmentRemoved(Actor self, Actor segment)
+		{
+			if (segments == null)
+				return;
+
+			segments.Remove(segment);
+		}
+
+		void INotifyAddedToWorld.AddedToWorld(Actor self)
+		{
+			foreach (var parent in parentNodes)
+				if (!parent.Disposed)
+					foreach (var n in parent.TraitsImplementing<INotifyLineBuildSegmentsChanged>())
+						n.SegmentAdded(parent, self);
+		}
+
+		void INotifyRemovedFromWorld.RemovedFromWorld(Actor self)
+		{
+			foreach (var parent in parentNodes)
+				if (!parent.Disposed)
+					foreach (var n in parent.TraitsImplementing<INotifyLineBuildSegmentsChanged>())
+						n.SegmentRemoved(parent, self);
+		}
+	}
 }