Lua2RTT/lua-5.1.4/ltm.c

/*
** $Id: ltm.c,v 2.8.1.1 2007/12/27 13:02:25 roberto Exp $
** Tag methods
** See Copyright Notice in lua.h
*/


#include <string.h>

#define ltm_c
#define LUA_CORE

#include "lua.h"

#include "lobject.h"
#include "lstate.h"
#include "lstring.h"
#include "ltable.h"
#include "ltm.h"
#include "lrotable.h"



const char *const luaT_typenames[] =
{
    "nil", "boolean", "romtable", "lightfunction", "userdata", "number",
    "string", "table", "function", "userdata", "thread",
    "proto", "upval"
};


void luaT_init(lua_State *L)
{
    static const char *const luaT_eventname[] =    /* ORDER TM */
    {
        "__index", "__newindex",
        "__gc", "__mode", "__eq",
        "__add", "__sub", "__mul", "__div", "__mod",
        "__pow", "__unm", "__len", "__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 = luaR_isrotable(events) ? luaH_getstr_ro(events, ename) : luaH_getstr(events, ename);
    lua_assert(event <= TM_EQ);
    if (ttisnil(tm))    /* no tag method? */
    {
        if (!luaR_isrotable(events))
            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 (ttype(o))
    {
    case LUA_TTABLE:
        mt = hvalue(o)->metatable;
        break;
    case LUA_TROTABLE:
        mt = (Table *)luaR_getmeta(rvalue(o));
        break;
    case LUA_TUSERDATA:
        mt = uvalue(o)->metatable;
        break;
    default:
        mt = G(L)->mt[ttype(o)];
    }
    if (!mt)
        return luaO_nilobject;
    else if (luaR_isrotable(mt))
        return luaH_getstr_ro(mt, G(L)->tmname[event]);
    else
        return luaH_getstr(mt, G(L)->tmname[event]);
}