Mesen-SX/Lua/ltm.c

/*
** $Id: ltm.c,v 2.38 2016/12/22 13:08:50 roberto Exp $
** Tag methods
** See Copyright Notice in lua.h
*/

#define ltm_c
#define LUA_CORE

#include "lprefix.h"


#include <string.h>

#include "lua.h"

#include "ldebug.h"
#include "ldo.h"
#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lvm.h"


static const char udatatypename[] = "userdata";

LUAI_DDEF const char* const luaT_typenames_[LUA_TOTALTAGS] = {
	"no value",
	"nil", "boolean", udatatypename, "number",
	"string", "table", "function", udatatypename, "thread",
	"proto" /* this last case is used for tests only */
};


void luaT_init(lua_State* L)
{
	static const char* const luaT_eventname[] = {
		/* ORDER TM */
		"__index", "__newindex",
		"__gc", "__mode", "__len", "__eq",
		"__add", "__sub", "__mul", "__mod", "__pow",
		"__div", "__idiv",
		"__band", "__bor", "__bxor", "__shl", "__shr",
		"__unm", "__bnot", "__lt", "__le",
		"__concat", "__call"
	};
	int i;
	for (i = 0; i < TM_N; i++)
	{
		G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
		luaC_fix(L, obj2gco(G(L)->tmname[i])); /* never collect these names */
	}
}


/*
** function to be used with macro "fasttm": optimized for absence of
** tag methods
*/
const TValue* luaT_gettm(Table* events, TMS event, TString* ename)
{
	const TValue* tm = luaH_getshortstr(events, ename);
	lua_assert(event <= TM_EQ);
	if (ttisnil(tm))
	{
		/* no tag method? */
		events->flags |= cast_byte(1u<<event); /* cache this fact */
		return NULL;
	}
	else return tm;
}


const TValue* luaT_gettmbyobj(lua_State* L, const TValue* o, TMS event)
{
	Table* mt;
	switch (ttnov(o))
	{
	case LUA_TTABLE:
		mt = hvalue(o)->metatable;
		break;
	case LUA_TUSERDATA:
		mt = uvalue(o)->metatable;
		break;
	default:
		mt = G(L)->mt[ttnov(o)];
	}
	return (mt ? luaH_getshortstr(mt, G(L)->tmname[event]) : luaO_nilobject);
}


/*
** Return the name of the type of an object. For tables and userdata
** with metatable, use their '__name' metafield, if present.
*/
const char* luaT_objtypename(lua_State* L, const TValue* o)
{
	Table* mt;
	if ((ttistable(o) && (mt = hvalue(o)->metatable) != NULL) ||
		(ttisfulluserdata(o) && (mt = uvalue(o)->metatable) != NULL))
	{
		const TValue* name = luaH_getshortstr(mt, luaS_new(L, "__name"));
		if (ttisstring(name)) /* is '__name' a string? */
			return getstr(tsvalue(name)); /* use it as type name */
	}
	return ttypename(ttnov(o)); /* else use standard type name */
}


void luaT_callTM(lua_State* L, const TValue* f, const TValue* p1,
                 const TValue* p2, TValue* p3, int hasres)
{
	ptrdiff_t result = savestack(L, p3);
	StkId func = L->top;
	setobj2s(L, func, f); /* push function (assume EXTRA_STACK) */
	setobj2s(L, func + 1, p1); /* 1st argument */
	setobj2s(L, func + 2, p2); /* 2nd argument */
	L->top += 3;
	if (!hasres) /* no result? 'p3' is third argument */
	setobj2s(L, L->top++, p3); /* 3rd argument */
	/* metamethod may yield only when called from Lua code */
	if (isLua(L->ci))
		luaD_call(L, func, hasres);
	else
		luaD_callnoyield(L, func, hasres);
	if (hasres)
	{
		/* if has result, move it to its place */
		p3 = restorestack(L, result);
		setobjs2s(L, p3, --L->top);
	}
}


int luaT_callbinTM(lua_State* L, const TValue* p1, const TValue* p2,
                   StkId res, TMS event)
{
	const TValue* tm = luaT_gettmbyobj(L, p1, event); /* try first operand */
	if (ttisnil(tm))
		tm = luaT_gettmbyobj(L, p2, event); /* try second operand */
	if (ttisnil(tm)) return 0;
	luaT_callTM(L, tm, p1, p2, res, 1);
	return 1;
}


void luaT_trybinTM(lua_State* L, const TValue* p1, const TValue* p2,
                   StkId res, TMS event)
{
	if (!luaT_callbinTM(L, p1, p2, res, event))
	{
		switch (event)
		{
		case TM_CONCAT:
			luaG_concaterror(L, p1, p2);
			/* call never returns, but to avoid warnings: */ /* FALLTHROUGH */
		case TM_BAND:
		case TM_BOR:
		case TM_BXOR:
		case TM_SHL:
		case TM_SHR:
		case TM_BNOT:
			{
				lua_Number dummy;
				if (tonumber(p1, &dummy) && tonumber(p2, &dummy))
					luaG_tointerror(L, p1, p2);
				else
					luaG_opinterror(L, p1, p2, "perform bitwise operation on");
			}
			/* calls never return, but to avoid warnings: */ /* FALLTHROUGH */
		default:
			luaG_opinterror(L, p1, p2, "perform arithmetic on");
		}
	}
}


int luaT_callorderTM(lua_State* L, const TValue* p1, const TValue* p2,
                     TMS event)
{
	if (!luaT_callbinTM(L, p1, p2, L->top, event))
		return -1; /* no metamethod */
	else
		return !l_isfalse(L->top);
}