LuaState: Added support for config-style usage.

Globals and table values can be queried from the Lua state easily.
Use perfect forwarding.

src/Bindings/LuaState.cpp

@@ -211,23 +211,31 @@ void cLuaState::AddPackagePath(const AString & a_PathVariable, const AString & a
 
 
 
-bool cLuaState::LoadFile(const AString & a_FileName)
+bool cLuaState::LoadFile(const AString & a_FileName, bool a_LogWarnings)
 {
 	ASSERT(IsValid());
 	
 	// Load the file:
 	int s = luaL_loadfile(m_LuaState, a_FileName.c_str());
-	if (ReportErrors(s))
+	if (s != 0)
 	{
-		LOGWARNING("Can't load %s because of an error in file %s", m_SubsystemName.c_str(), a_FileName.c_str());
+		if (a_LogWarnings)
+		{
+			LOGWARNING("Can't load %s because of a load error in file %s: %d (%s)", m_SubsystemName.c_str(), a_FileName.c_str(), s, lua_tostring(m_LuaState, -1));
+		}
+		lua_pop(m_LuaState, 1);
 		return false;
 	}
 
 	// Execute the globals:
 	s = lua_pcall(m_LuaState, 0, LUA_MULTRET, 0);
-	if (ReportErrors(s))
+	if (s != 0)
 	{
-		LOGWARNING("Error in %s in file %s", m_SubsystemName.c_str(), a_FileName.c_str());
+		if (a_LogWarnings)
+		{
+			LOGWARNING("Can't load %s because of an initialization error in file %s: %d (%s)", m_SubsystemName.c_str(), a_FileName.c_str(), s, lua_tostring(m_LuaState, -1));
+		}
+		lua_pop(m_LuaState, 1);
 		return false;
 	}
 	
@@ -446,6 +454,18 @@ void cLuaState::Push(const cPlayer * a_Player)
 
 
 
+void cLuaState::Push(const cLuaState::cRef & a_Ref)
+{
+	ASSERT(IsValid());
+
+	lua_rawgeti(m_LuaState, LUA_REGISTRYINDEX, static_cast<int>(a_Ref));
+	m_NumCurrentFunctionArgs += 1;
+}
+
+
+
+
+
 void cLuaState::Push(const HTTPRequest * a_Request)
 {
 	ASSERT(IsValid());
@@ -765,14 +785,17 @@ bool cLuaState::GetStackValue(int a_StackPos, double & a_ReturnedVal)
 
 
 
-bool cLuaState::GetStackValue(int a_StackPos, float & a_ReturnedVal)
+bool cLuaState::GetStackValue(int a_StackPos, eBlockFace & a_ReturnedVal)
 {
-	if (lua_isnumber(m_LuaState, a_StackPos))
+	if (!lua_isnumber(m_LuaState, a_StackPos))
 	{
-		a_ReturnedVal = static_cast<float>(tolua_tonumber(m_LuaState, a_StackPos, a_ReturnedVal));
+		return false;
-		return true;
 	}
-	return false;
+	a_ReturnedVal = static_cast<eBlockFace>(Clamp(
+		static_cast<int>(tolua_tonumber(m_LuaState, a_StackPos, a_ReturnedVal)),
+		static_cast<int>(BLOCK_FACE_MIN), static_cast<int>(BLOCK_FACE_MAX))
+	);
+	return true;
 }
 
 
@@ -796,6 +819,46 @@ bool cLuaState::GetStackValue(int a_StackPos, eWeather & a_ReturnedVal)
 
 
 
+bool cLuaState::GetStackValue(int a_StackPos, float & a_ReturnedVal)
+{
+	if (lua_isnumber(m_LuaState, a_StackPos))
+	{
+		a_ReturnedVal = static_cast<float>(tolua_tonumber(m_LuaState, a_StackPos, a_ReturnedVal));
+		return true;
+	}
+	return false;
+}
+
+
+
+
+
+cLuaState::cStackValue cLuaState::WalkToValue(const AString & a_Name)
+{
+	auto path = StringSplit(a_Name, ".");
+	lua_pushvalue(m_LuaState, -1);  // Copy the stack value into the "working area"
+	for (const auto & elem: path)
+	{
+		// If the value is not a table, bail out (error):
+		if (!lua_istable(m_LuaState, -1))
+		{
+			lua_pop(m_LuaState, 1);
+			return cStackValue();
+		}
+
+		// Get the next part of the path:
+		lua_getfield(m_LuaState, -1, elem.c_str());
+
+		// Remove the previous value from the stack (keep only the new one):
+		lua_remove(m_LuaState, -2);
+	}  // for elem - path[]
+	return std::move(cStackValue(*this));
+}
+
+
+
+
+
 bool cLuaState::CallFunction(int a_NumResults)
 {
 	ASSERT (m_NumCurrentFunctionArgs >= 0);  // A function must be pushed to stack first

src/Bindings/LuaState.h

@@ -78,11 +78,14 @@ public:
 		bool IsValid(void) const {return (m_Ref != LUA_REFNIL); }
 		
 		/** Allows to use this class wherever an int (i. e. ref) is to be used */
-		operator int(void) const { return m_Ref; }
+		explicit operator int(void) const { return m_Ref; }
 
 	protected:
 		cLuaState * m_LuaState;
 		int m_Ref;
+
+		// Remove the copy-constructor:
+		cRef(const cRef &) = delete;
 	} ;
 	
 	
@@ -98,6 +101,12 @@ public:
 		{
 		}
 		
+		cTableRef(const cRef & a_TableRef, const char * a_FnName) :
+			m_TableRef(static_cast<int>(a_TableRef)),
+			m_FnName(a_FnName)
+		{
+		}
+
 		int GetTableRef(void) const { return m_TableRef; }
 		const char * GetFnName(void) const { return m_FnName; }
 	} ;
@@ -111,6 +120,61 @@ public:
 	static const cRet Return;  // Use this constant to delimit function args from return values for cLuaState::Call()
 
 
+	/** A RAII class for values pushed onto the Lua stack.
+	Will pop the value off the stack in the destructor. */
+	class cStackValue
+	{
+	public:
+		cStackValue(void):
+			m_LuaState(nullptr)
+		{
+		}
+
+		cStackValue(cLuaState & a_LuaState):
+			m_LuaState(a_LuaState)
+		{
+			m_StackLen = lua_gettop(a_LuaState);
+		}
+
+		cStackValue(cStackValue && a_Src):
+			m_LuaState(nullptr),
+			m_StackLen(-1)
+		{
+			std::swap(m_LuaState, a_Src.m_LuaState);
+			std::swap(m_StackLen, a_Src.m_StackLen);
+		}
+
+		~cStackValue()
+		{
+			if (m_LuaState != nullptr)
+			{
+				auto top = lua_gettop(m_LuaState);
+				ASSERT(m_StackLen == top);
+				lua_pop(m_LuaState, 1);
+			}
+		}
+
+		void Set(cLuaState & a_LuaState)
+		{
+			m_LuaState = a_LuaState;
+			m_StackLen = lua_gettop(a_LuaState);
+		}
+
+		bool IsValid(void) const
+		{
+			return (m_LuaState != nullptr);
+		}
+
+	protected:
+		lua_State * m_LuaState;
+
+		int m_StackLen;
+
+		// Remove the copy-constructor:
+		cStackValue(const cStackValue &) = delete;
+	};
+
+
 	/** Creates a new instance. The LuaState is not initialized.
 	a_SubsystemName is used for reporting problems in the console, it is "plugin %s" for plugins,
 	or "LuaScript" for the cLuaScript template
@@ -151,10 +215,9 @@ public:
 	void AddPackagePath(const AString & a_PathVariable, const AString & a_Path);
 	
 	/** Loads the specified file
-	Returns false and logs a warning to the console if not successful (but the LuaState is kept open).
+	Returns false and optionally logs a warning to the console if not successful (but the LuaState is kept open).
-	m_SubsystemName is displayed in the warning log message.
+	m_SubsystemName is displayed in the warning log message. */
-	*/
+	bool LoadFile(const AString & a_FileName, bool a_LogWarnings = true);
-	bool LoadFile(const AString & a_FileName);
 	
 	/** Returns true if a_FunctionName is a valid Lua function that can be called */
 	bool HasFunction(const char * a_FunctionName);
@@ -169,6 +232,7 @@ public:
 	void Push(const char * a_Value);
 	void Push(const cItems & a_Items);
 	void Push(const cPlayer * a_Player);
+	void Push(const cRef & a_Ref);
 	void Push(const HTTPRequest * a_Request);
 	void Push(const HTTPTemplateRequest * a_Request);
 	void Push(const Vector3d & a_Vector);
@@ -188,12 +252,13 @@ public:
 	
 	// GetStackValue() retrieves the value at a_StackPos, if it is a valid type. If not, a_Value is unchanged.
 	// Returns whether value was changed
-	// Enum values are clamped to their allowed range.
+	// Enum values are checked for their allowed values and fail if the value is not assigned.
 	bool GetStackValue(int a_StackPos, AString & a_Value);
 	bool GetStackValue(int a_StackPos, bool & a_Value);
 	bool GetStackValue(int a_StackPos, cPluginManager::CommandResult & a_Result);
 	bool GetStackValue(int a_StackPos, cRef & a_Ref);
 	bool GetStackValue(int a_StackPos, double & a_Value);
+	bool GetStackValue(int a_StackPos, eBlockFace & a_Value);
 	bool GetStackValue(int a_StackPos, eWeather & a_Value);
 	bool GetStackValue(int a_StackPos, float & a_ReturnedVal);
 
@@ -202,21 +267,53 @@ public:
 	bool GetStackValue(int a_StackPos, T & a_ReturnedVal, typename std::enable_if<std::is_integral<T>::value>::type * unused = nullptr)
 	{
 		UNUSED(unused);
-		if (lua_isnumber(m_LuaState, a_StackPos))
+		if (!lua_isnumber(m_LuaState, a_StackPos))  // Also accepts strings representing a number: http://pgl.yoyo.org/luai/i/lua_isnumber
 		{
-			lua_Number Val = tolua_tonumber(m_LuaState, a_StackPos, a_ReturnedVal);
+			return false;
-			if (Val > std::numeric_limits<T>::max())
-			{
-				return false;
-			}
-			if (Val < std::numeric_limits<T>::min())
-			{
-				return false;
-			}
-			a_ReturnedVal = static_cast<T>(Val);
-			return true;
 		}
-		return false;
+		lua_Number Val = lua_tonumber(m_LuaState, a_StackPos);
+		if (Val > std::numeric_limits<T>::max())
+		{
+			return false;
+		}
+		if (Val < std::numeric_limits<T>::min())
+		{
+			return false;
+		}
+		a_ReturnedVal = static_cast<T>(Val);
+		return true;
+	}
+
+	/** Pushes the named value in the table at the top of the stack.
+	a_Name may be a path containing multiple table levels, such as "_G.cChatColor.Blue".
+	If the value is found, it is pushed on top of the stack and the returned cStackValue is valid.
+	If the value is not found, the stack is unchanged and the returned cStackValue is invalid. */
+	cStackValue WalkToValue(const AString & a_Name);
+
+	/** Retrieves the named value in the table at the top of the Lua stack.
+	a_Name may be a path containing multiple table levels, such as "_G.cChatColor.Blue".
+	Returns true if the value was successfully retrieved, false on error. */
+	template <typename T> bool GetNamedValue(const AString & a_Name, T & a_Value)
+	{
+		auto stk = WalkToValue(a_Name);
+		if (!stk.IsValid())
+		{
+			// Name not found
+			return false;
+		}
+		return GetStackValue(-1, a_Value);
+	}
+
+	/** Retrieves the named global value. a_Name may be a path containing multiple table levels, such as "_G.cChatColor.Blue".
+	Returns true if the value was successfully retrieved, false on error. */
+	template <typename T> bool GetNamedGlobal(const AString & a_Name, T & a_Value)
+	{
+		// Push the globals table onto the stack and make it RAII-removed:
+		lua_getglobal(m_LuaState, "_G");
+		cStackValue stk(*this);
+
+		// Get the named global:
+		return GetNamedValue(a_Name, a_Value);
 	}
 
 	// Include the auto-generated Push and GetStackValue() functions:
@@ -229,12 +326,12 @@ public:
 	template <typename FnT, typename... Args>
 	bool Call(const FnT & a_Function, Args &&... args)
 	{
-		if (!PushFunction(a_Function))
+		if (!PushFunction(std::forward<const FnT &>(a_Function)))
 		{
 			// Pushing the function failed
 			return false;
 		}
-		return PushCallPop(args...);
+		return PushCallPop(std::forward<Args>(args)...);
 	}
 
 	/** Retrieves a list of values from the Lua stack, starting at the specified index. */
@@ -343,10 +440,10 @@ protected:
 
 	/** Variadic template recursor: More params to push. Push them and recurse. */
 	template <typename T, typename... Args>
-	inline bool PushCallPop(T a_Param, Args &&... args)
+	inline bool PushCallPop(T && a_Param, Args &&... args)
 	{
-		Push(a_Param);
+		Push(std::forward<T>(a_Param));
-		return PushCallPop(args...);
+		return PushCallPop(std::forward<Args>(args)...);
 	}
 
 	/** Variadic template terminator: If there's nothing more to push, but return values to collect, call the function and collect the returns. */
@@ -363,7 +460,7 @@ protected:
 		}
 
 		// Collect the return values:
-		GetStackValues(-NumReturns, args...);
+		GetStackValues(-NumReturns, std::forward<Args>(args)...);
 		lua_pop(m_LuaState, NumReturns);
 
 		// All successful:

src/Defines.h

@@ -29,16 +29,16 @@ enum
 
 
 
-/// Block face constants, used in PlayerDigging and PlayerBlockPlacement packets and bbox collision calc
+/** Block face constants, used in PlayerDigging and PlayerBlockPlacement packets and bbox collision calc */
 enum eBlockFace
 {
 	BLOCK_FACE_NONE = -1,  // Interacting with no block face - swinging the item in the air
-	BLOCK_FACE_XM   = 4,   // Interacting with the X- face of the block
+	BLOCK_FACE_XM   =  4,  // Interacting with the X- face of the block
-	BLOCK_FACE_XP   = 5,   // Interacting with the X+ face of the block
+	BLOCK_FACE_XP   =  5,  // Interacting with the X+ face of the block
-	BLOCK_FACE_YM   = 0,   // Interacting with the Y- face of the block
+	BLOCK_FACE_YM   =  0,  // Interacting with the Y- face of the block
-	BLOCK_FACE_YP   = 1,   // Interacting with the Y+ face of the block
+	BLOCK_FACE_YP   =  1,  // Interacting with the Y+ face of the block
-	BLOCK_FACE_ZM   = 2,   // Interacting with the Z- face of the block
+	BLOCK_FACE_ZM   =  2,  // Interacting with the Z- face of the block
-	BLOCK_FACE_ZP   = 3,   // Interacting with the Z+ face of the block
+	BLOCK_FACE_ZP   =  3,  // Interacting with the Z+ face of the block
 
 	// Synonyms using the (deprecated) world directions:
 	BLOCK_FACE_BOTTOM = BLOCK_FACE_YM,  // Interacting with the bottom   face of the block
@@ -47,6 +47,10 @@ enum eBlockFace
 	BLOCK_FACE_SOUTH  = BLOCK_FACE_ZP,  // Interacting with the southern face of the block
 	BLOCK_FACE_WEST   = BLOCK_FACE_XM,  // Interacting with the western  face of the block
 	BLOCK_FACE_EAST   = BLOCK_FACE_XP,  // Interacting with the eastern  face of the block
+
+	// Bounds, used for range-checking:
+	BLOCK_FACE_MIN = -1,
+	BLOCK_FACE_MAX =  5,
 } ;