rebase to origin/unstable-tests

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>();
+    }
+  }
+}