cLuaState: Added direct support for pushing a nil constant.

src/Bindings/LuaJson.cpp

@@ -82,7 +82,7 @@ void PushJsonValue(const Json::Value & a_Value, cLuaState & a_LuaState)
 	{
 		case Json::nullValue:
 		{
-			a_LuaState.PushNil();
+			a_LuaState.Push(cLuaState::Nil);
 			break;
 		}
 
@@ -228,8 +228,7 @@ static int tolua_cJson_Parse(lua_State * a_LuaState)
 	Json::Reader reader;
 	if (!reader.parse(input, root, false))
 	{
-		L.PushNil();
-		L.Push(Printf("Parsing Json failed: %s", reader.getFormattedErrorMessages().c_str()));
+		L.Push(cLuaState::Nil, Printf("Parsing Json failed: %s", reader.getFormattedErrorMessages().c_str()));
 		return 2;
 	}
 

src/Bindings/LuaState.cpp

@@ -42,6 +42,7 @@ extern "C"
 
 
 const cLuaState::cRet cLuaState::Return = {};
+const cLuaState::cNil cLuaState::Nil = {};
 
 /** Each Lua state stores a pointer to its creating cLuaState in Lua globals, under this name.
 This way any cLuaState can reference the main cLuaState's TrackedCallbacks, mutex etc. */
@@ -751,18 +752,6 @@ bool cLuaState::PushFunction(const cRef & a_TableRef, const char * a_FnName)
 
 
 
-void cLuaState::PushNil(void)
-{
-	ASSERT(IsValid());
-
-	lua_pushnil(m_LuaState);
-	m_NumCurrentFunctionArgs += 1;
-}
-
-
-
-
-
 void cLuaState::Push(const AString & a_String)
 {
 	ASSERT(IsValid());
@@ -860,6 +849,18 @@ void cLuaState::Push(const cItems & a_Items)
 
 
 
+void cLuaState::Push(const cNil & a_Nil)
+{
+	ASSERT(IsValid());
+
+	lua_pushnil(m_LuaState);
+	m_NumCurrentFunctionArgs += 1;
+}
+
+
+
+
+
 void cLuaState::Push(const cPlayer * a_Player)
 {
 	ASSERT(IsValid());

src/Bindings/LuaState.h

@@ -327,14 +327,21 @@ public:
 		T & m_Dest;
 	};
 
+
 	/** A dummy class that's used only to delimit function args from return values for cLuaState::Call() */
 	class cRet
 	{
 	} ;
-
 	static const cRet Return;  // Use this constant to delimit function args from return values for cLuaState::Call()
 
 
+	/** A dummy class that's used only to push a constant nil as a function parameter in Call(). */
+	class cNil
+	{
+	};
+	static const cNil Nil;  // Use this constant to give a function a nil parameter in Call()
+
+
 	/** A RAII class for values pushed onto the Lua stack.
 	Will pop the value off the stack in the destructor. */
 	class cStackValue
@@ -489,8 +496,6 @@ public:
 		Push(std::forward<Arg2>(a_Arg2), std::forward<Args>(a_Args)...);
 	}
 
-	void PushNil(void);
-
 	// Push a const value onto the stack (keep alpha-sorted):
 	void Push(const AString & a_String);
 	void Push(const AStringMap & a_Dictionary);
@@ -499,6 +504,7 @@ public:
 	void Push(const cCraftingRecipe * a_Recipe);
 	void Push(const char * a_Value);
 	void Push(const cItems & a_Items);
+	void Push(const cNil & a_Nil);
 	void Push(const cPlayer * a_Player);
 	void Push(const cRef & a_Ref);
 	void Push(const HTTPRequest * a_Request);

src/Bindings/ManualBindings.cpp

@@ -2058,8 +2058,7 @@ static int tolua_cUrlParser_Parse(lua_State * a_LuaState)
 	if (!res.first)
 	{
 		// Error, return nil and error msg:
-		L.PushNil();
-		L.Push(res.second);
+		L.Push(cLuaState::Nil, res.second);
 		return 2;
 	}
 	L.Push(scheme, username, password, host, port, path, query, fragment);
@@ -2099,8 +2098,7 @@ static int tolua_cUrlParser_ParseAuthorityPart(lua_State * a_LuaState)
 	if (!res.first)
 	{
 		// Error, return nil and error msg:
-		L.PushNil();
-		L.Push(res.second);
+		L.Push(cLuaState::Nil, res.second);
 		return 2;
 	}
 	L.Push(username, password, host, port);

src/Bindings/ManualBindings_Network.cpp

@@ -649,8 +649,7 @@ static int tolua_cTCPLink_StartTLSClient(lua_State * L)
 	AString res = Link->StartTLSClient(OwnCert, OwnPrivKey, OwnPrivKeyPassword);
 	if (!res.empty())
 	{
-		S.PushNil();
-		S.Push(Printf("Cannot start TLS on link to %s:%d: %s", Link->GetRemoteIP().c_str(), Link->GetRemotePort(), res.c_str()));
+		S.Push(cLuaState::Nil, Printf("Cannot start TLS on link to %s:%d: %s", Link->GetRemoteIP().c_str(), Link->GetRemotePort(), res.c_str()));
 		return 2;
 	}
 	return 1;
@@ -695,10 +694,10 @@ static int tolua_cTCPLink_StartTLSServer(lua_State * L)
 	AString res = Link->StartTLSServer(OwnCert, OwnPrivKey, OwnPrivKeyPassword, StartTLSData);
 	if (!res.empty())
 	{
-		S.PushNil();
-		S.Push(Printf("Cannot start TLS on link to %s:%d: %s", Link->GetRemoteIP().c_str(), Link->GetRemotePort(), res.c_str()));
+		S.Push(cLuaState::Nil, Printf("Cannot start TLS on link to %s:%d: %s", Link->GetRemoteIP().c_str(), Link->GetRemotePort(), res.c_str()));
 		return 2;
 	}
+	S.Push(true);
 	return 1;
 }