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Reimplement LuaCountArgs with template specialization to make it constexpr

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This commit is contained in:
jyelon
2023-05-08 15:49:47 -04:00
parent b233db4227
commit d70b9f0d13
1 changed files with 43 additions and 48 deletions
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91
luprex/cpp/core/luastack.hpp
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@@ -206,6 +206,41 @@ public:
friend class LuaDefStack;
};
struct LuaArgCounts {
int nret;
int narg;
int nvar;
int nextra;
constexpr LuaArgCounts(int nr, int na, int nv, int ne) : nret(nr), narg(na), nvar(nv), nextra(ne) {}
constexpr LuaArgCounts operator +(LuaArgCounts b) const {
return LuaArgCounts(nret + b.nret, narg + b.narg, nvar + b.nvar, nextra + b.nextra);
}
};
template<class... Ts>
struct LuaCountArgs;
template<>
struct LuaCountArgs<> {
static constexpr LuaArgCounts value = LuaArgCounts(0,0,0,0);
};
template<class... Ts>
struct LuaCountArgs<LuaRet, Ts...> {
static constexpr LuaArgCounts value = LuaArgCounts(1, 0, 0, 0) + LuaCountArgs<Ts...>::value;
};
template<class... Ts>
struct LuaCountArgs<LuaArg, Ts...> {
static constexpr LuaArgCounts value = LuaArgCounts(0, 1, 0, 0) + LuaCountArgs<Ts...>::value;
};
template<class... Ts>
struct LuaCountArgs<LuaVar, Ts...> {
static constexpr LuaArgCounts value = LuaArgCounts(0, 0, 1, 0) + LuaCountArgs<Ts...>::value;
};
template<class... Ts>
struct LuaCountArgs<LuaExtraArgs, Ts...> {
static constexpr LuaArgCounts value = LuaArgCounts(0, 0, 0, 1) + LuaCountArgs<Ts...>::value;
};
class LuaNilMarker {};
extern LuaNilMarker LuaNil;
@@ -291,51 +326,8 @@ protected:
lua_State *L_;
protected:
struct Counts {
int nret;
int narg;
int nvar;
int nextra;
constexpr Counts(int nr, int na, int nv, int ne) : nret(nr), narg(na), nvar(nv), nextra(ne) {}
constexpr Counts(Counts a, Counts b)
: nret(a.nret+b.nret), narg(a.narg+b.narg), nvar(a.nvar+b.nvar), nextra(a.nextra+b.nextra) {}
};
template<class... SS>
constexpr static Counts count_slots(LuaRet &v, SS && ... stackslots)
{
return Counts(Counts(1, 0, 0, 0), count_slots(stackslots...));
}
template<class... SS>
constexpr static Counts count_slots(LuaArg &v, SS && ... stackslots)
{
return Counts(Counts(0, 1, 0, 0), count_slots(stackslots...));
}
template<class... SS>
constexpr static Counts count_slots(LuaVar &v, SS && ... stackslots)
{
return Counts(Counts(0, 0, 1, 0), count_slots(stackslots...));
}
template<class... SS>
constexpr static Counts count_slots(LuaExtraArgs &v, SS && ... stackslots)
{
return Counts(Counts(0, 0, 0, 1), count_slots(stackslots...));
}
constexpr static Counts count_slots() {
return Counts(0, 0, 0, 0);
}
template<class... SS>
constexpr static int count_vars(LuaVar &v, SS && ... stackslots)
{
return 1 + count_vars(stackslots...);
}
constexpr static int count_vars() {
return 0;
}
private:
private:
// Push any value on the stack, by type.
void push_any_value(LuaNewTableMarker s) const { lua_newtable(L_); }
void push_any_value(LuaNilMarker s) const { lua_pushnil(L_); }
@@ -599,7 +591,7 @@ private:
public:
template<class... SS>
inline LuaDefStack(lua_State *L, SS & ... stackslots) : LuaCoreStack(L) {
Counts counts = count_slots(stackslots...);
constexpr LuaArgCounts counts = LuaCountArgs<SS...>::value;
int nargs = lua_gettop(L);
if (counts.nextra == 0) {
if (nargs != counts.narg) {
@@ -657,10 +649,13 @@ private:
public:
template<class... SS>
LuaExtStack(lua_State *L, SS & ... stackslots) : LuaCoreStack(L) {
int nvars = count_vars(stackslots...);
lua_checkstack(L_, nvars + 20);
constexpr LuaArgCounts counts = LuaCountArgs<SS...>::value;
static_assert(counts.narg == 0, "LuaExtStack only allows LuaVar, not LuaArg");
static_assert(counts.nret == 0, "LuaExtStack only allows LuaVar, not LuaRet");
static_assert(counts.nextra == 0, "LuaExtStack only allows LuaVar, not LuaExtraArgs");
lua_checkstack(L_, counts.nvar + 20);
oldtop_ = lua_gettop(L_);
for (int i = 0; i < nvars; i++) {
for (int i = 0; i < counts.nvar; i++) {
lua_pushnil(L_);
}
assign_slots(oldtop_ + 1, stackslots...);