Update require() behaviour

The behaviour of `require()` has been changed to align more closely with standard Lua (caching return results).

Barotrauma/BarotraumaShared/SharedSource/LuaCs/Lua/LuaRequire.cs

@@ -0,0 +1,41 @@
+
+
+using System;
+using System.Collections.Generic;
+using MoonSharp.Interpreter;
+
+namespace Barotrauma
+{
+  class LuaRequire {
+    private Script lua { get; set; }
+    private Dictionary<Tuple<string, Table>, DynValue> LoadedModules { get; set; }
+
+    private bool GetExistingReturnValue(Tuple<string, Table> key, ref DynValue returnValue) {
+      return LoadedModules.TryGetValue(key, out returnValue);
+    }
+
+    private void ExecuteModule(Tuple<string, Table> key, ref DynValue returnValue) {
+      string moduleName = key.Item1;
+      Table globalContext = key.Item2;
+      returnValue = lua.Call(lua.RequireModule(moduleName, globalContext));
+      LoadedModules[key] = returnValue;
+    }
+
+    // Lua modules that have been previously loaded by require() will
+    // not be loaded again; instead, their initial return value is
+    // preserved and returned again on subsequent attempts.
+    public DynValue Require(string moduleName, Table globalContext) {
+      DynValue returnValue = DynValue.Nil;
+      var key = new Tuple<string, Table>(moduleName, globalContext);
+
+      if (GetExistingReturnValue(key, ref returnValue)) return returnValue;
+      ExecuteModule(key, ref returnValue);
+      return returnValue;
+    }
+
+    public LuaRequire(Script lua) {
+      this.lua = lua;
+      LoadedModules = new Dictionary<Tuple<string, Table>, DynValue>();
+    }
+  }
+}

Barotrauma/BarotraumaShared/SharedSource/LuaCs/LuaCsSetup.cs

@@ -29,6 +29,7 @@ namespace Barotrauma
 		public LuaCsHook Hook { get; private set; }
 		public LuaCsNetworking Networking { get; private set; }
 		public LuaCsModStore ModStore { get; private set; }
+		private LuaRequire require { get; set; }
 
 		public CsScriptLoader NetScriptLoader { get; private set; }
 		public CsLua Lua { get; private set; }
@@ -236,22 +237,18 @@ namespace Barotrauma
 
 			return null;
 		}
-
-		private DynValue Require(string modname, Table globalContext)
+		public DynValue Require(string moduleName, Table globalContexts)
 		{
 			try
 			{
-				return lua.Call(lua.RequireModule(modname, globalContext));
-
+				return require.Require(moduleName, globalContexts);
 			}
 			catch (Exception e)
 			{
 				HandleException(e);
 			}
-
 			return null;
 		}
-
 		public object CallLuaFunction(object function, params object[] arguments)
 		{
 			try
@@ -310,6 +307,8 @@ namespace Barotrauma
 			Lua = new CsLua(this);
 			CsScript = new CsScriptRunner(this);
 
+			require = new LuaRequire(lua);
+
 			Game = new LuaGame();
 			Networking = new LuaCsNetworking();
 			Hook.Initialize();