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cLuaState::Call() uses variadic templates.

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(doesn't compile)
This commit is contained in:
Mattes D 2014-10-15 18:50:32 +02:00
parent eeb580a74e
commit f58d44ea50
1 changed files with 75 additions and 3 deletions
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78
src/Bindings/LuaState.h
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@ -240,10 +240,24 @@ public:
/** Retrieve value at a_StackPos, if it is a valid cWorld class. If not, a_Value is unchanged */
void GetStackValue(int a_StackPos, pWorld & a_Value);
/** Call the specified Lua function.
Returns true if call succeeded, false if there was an error.
A special param of cRet & signifies the end of param list and the start of return values.
Example call: Call(Fn, Param1, Param2, Param3, cLuaState::Return, Ret1, Ret2) */
template <typename FnT, typename... Args>
bool Call(const FnT & a_Function, Args &... args)
{
PushFunction(a_Function);
return PushCallPop(args...);
}
// Include the cLuaState::Call() overload implementation that is generated by the gen_LuaState_Call.lua script:
#include "LuaState_Call.inc"
/** Retrieves a list of values from the Lua stack, starting at the specified index. */
template <typename T, typename... Args>
inline void GetStackValues(int a_StartStackPos, T & a_Ret, Args &... args)
{
GetStackValue(a_StartStackPos, a_Ret);
GetStackValues(a_StartStackPos + 1, args...);
}
/** Returns true if the specified parameters on the stack are of the specified usertable type; also logs warning if not. Used for static functions */
bool CheckParamUserTable(int a_StartParam, const char * a_UserTable, int a_EndParam = -1);
@ -310,6 +324,7 @@ public:
static void LogStack(lua_State * a_LuaState, const char * a_Header = NULL);
protected:
lua_State * m_LuaState;
/** If true, the state is owned by this object and will be auto-Closed. False => attached state */
@ -327,6 +342,63 @@ protected:
int m_NumCurrentFunctionArgs;
/** Variadic template terminator: Counting zero args returns zero. */
int CountArgs(void)
{
return 0;
}
/** Variadic template: Counting args means add one to the count of the rest. */
template <typename T, typename... Args>
int CountArgs(T, Args... args)
{
return 1 + CountArgs(args...);
}
/** Variadic template terminator: If there's nothing more to push / pop, just call the function.
Note that there are no return values either, because those are prefixed by a cRet value, so the arg list is never empty. */
bool PushCallPop(void)
{
return CallFunction(0);
}
/** Variadic template recursor: More params to push. Push them and recurse. */
template<typename T, typename... Args>
inline bool PushCallPop(T a_Param, Args &... args)
{
Push(a_Param);
return PushCallPop(args...);
}
/** Variadic template terminator: If there's nothing more to push, but return values to collect, call the function and collect the returns. */
template <typename... Args>
bool PushCallPop(cLuaState::cRet, Args &... args)
{
// Calculate the number of return values (number of args left):
int NumReturns = CountArgs(args...);
// Call the function:
if (!CallFunction(NumReturns))
{
return false;
}
// Collect the return values:
GetStackValues(-NumReturns, args...);
lua_pop(m_LuaState, NumReturns);
// All successful:
return true;
}
/** Variadic template terminator: If there are no more values to get, bail out.
This function is not available in the public API, because it's an error to request no values directly; only internal functions can do that.
If you get a compile error saying this function is not accessible, check your calling code, you aren't reading any stack values. */
void GetStackValues(int a_StartingStackPos)
{
// Do nothing
}
/** Pushes the function of the specified name onto the stack.
Returns true if successful. Logs a warning on failure (incl. m_SubsystemName)
*/