From 3cf09e656f41a5ebb39e41b2a59e263347696fbe Mon Sep 17 00:00:00 2001
From: Chris Forbes <chrisf@ijw.co.nz>
Date: Sat, 11 Feb 2012 11:13:39 +1300
Subject: [PATCH] Add support for negative prerequisites (#1323)

---
 .../Lint/LintBuildablePrerequisites.cs          |  2 +-
 OpenRA.Mods.RA/Player/TechTree.cs               | 17 ++++++++++-------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs b/OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs
index 7ce5ffc4bd..c615167fd3 100644
--- a/OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs
+++ b/OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs
@@ -29,7 +29,7 @@ namespace OpenRA.Mods.RA
 				var bi = i.Value.Traits.GetOrDefault<BuildableInfo>();
 				if (bi != null)
 					foreach( var prereq in bi.Prerequisites )
-						if ( !providedPrereqs.Contains(prereq) )
+						if ( !providedPrereqs.Contains(prereq.Replace("!","")) )
 							emitError( "Buildable actor {0} has prereq {1} not provided by anything.".F( i.Key, prereq ) );
 			}
 		}
diff --git a/OpenRA.Mods.RA/Player/TechTree.cs b/OpenRA.Mods.RA/Player/TechTree.cs
index 92f897b90a..cfd4ba225e 100755
--- a/OpenRA.Mods.RA/Player/TechTree.cs
+++ b/OpenRA.Mods.RA/Player/TechTree.cs
@@ -86,15 +86,18 @@ namespace OpenRA.Mods.RA
 				this.hasPrerequisites = false;
 			}
 
+			bool HasPrerequisites(Cache<string, List<Actor>> buildings)
+			{
+				foreach (var p in prerequisites)
+					if (p.StartsWith("!") ^
+						!buildings.Keys.Contains(p.Replace("!","")))
+						return false;
+				return true;
+			}
+
 			public void Update(Cache<string, List<Actor>> buildings)
 			{
-				var nowHasPrerequisites = true;
-				foreach (var p in prerequisites)
-					if (!buildings.Keys.Contains(p))
-					{
-						nowHasPrerequisites = false;
-						break;
-					}
+				var nowHasPrerequisites = HasPrerequisites(buildings);
 
 				if( nowHasPrerequisites && !hasPrerequisites )
 					watcher.PrerequisitesAvailable(key);