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/*
** $Id: ltm.c,v 2.16 2013/04/25 15:59:42 roberto Exp roberto $
** Tag methods
** See Copyright Notice in lua.h
*/
#include <string.h>
#define ltm_c
#define LUA_CORE
#include "lua.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", "upval" /* these last two cases are 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", "__div", "__mod",
"__pow", "__unm", "__lt", "__le",
"__concat", "__call"
};
int i;
for (i=0; i<TM_N; i++) {
G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
luaS_fix(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_getstr(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_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
}
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);
setobj2s(L, L->top++, f); /* push function */
setobj2s(L, L->top++, p1); /* 1st argument */
setobj2s(L, L->top++, p2); /* 2nd argument */
if (!hasres) /* no result? 'p3' is third argument */
setobj2s(L, L->top++, p3); /* 3rd argument */
/* metamethod may yield only when called from Lua code */
luaD_call(L, L->top - (4 - hasres), hasres, isLua(L->ci));
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;
}
const TValue *luaT_getequalTM (lua_State *L, Table *mt1, Table *mt2) {
const TValue *tm1 = fasttm(L, mt1, TM_EQ);
const TValue *tm2;
if (tm1 == NULL) return NULL; /* no metamethod */
if (mt1 == mt2) return tm1; /* same metatables => same metamethods */
tm2 = fasttm(L, mt2, TM_EQ);
if (tm2 == NULL) return NULL; /* no metamethod */
if (luaV_rawequalobj(tm1, tm2)) /* same metamethods? */
return tm1;
return NULL;
}
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);
}
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