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# lua/ltm.c

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    00001 /*
    00002 ** $Id: ltm.c,v 2.8 2006/01/10 12:50:00 roberto Exp $
    00003 ** Tag methods
    00004 ** See Copyright Notice in lua.h
    00005 */
    00006
    00007
    00008 #include <string.h>
    00009
    00010 #define ltm_c
    00011 #define LUA_CORE
    00012
    00013 #include "lua.h"
    00014
    00015 #include "lobject.h"
    00016 #include "lstate.h"
    00017 #include "lstring.h"
    00018 #include "ltable.h"
    00019 #include "ltm.h"
    00020
    00021
    00022
    00023 const char *const luaT_typenames[] = {
    00024   "nil", "boolean", "userdata", "number",
    00025   "string", "table", "function", "userdata", "thread",
    00026   "proto", "upval"
    00027 };
    00028
    00029
    00030 void luaT_init (lua_State *L) {
    00031   static const char *const luaT_eventname[] = {  /* ORDER TM */
    00032     "__index", "__newindex",
    00033     "__gc", "__mode", "__eq",
    00034     "__add", "__sub", "__mul", "__div", "__mod",
    00035     "__pow", "__unm", "__len", "__lt", "__le",
    00036     "__concat", "__call"
    00037   };
    00038   int i;
    00039   for (i=0; i<TM_N; i++) {
    00040     G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
    00041     luaS_fix(G(L)->tmname[i]);  /* never collect these names */
    00042   }
    00043 }
    00044
    00045
    00046 /*
    00047 ** function to be used with macro "fasttm": optimized for absence of
    00048 ** tag methods
    00049 */
    00050 const TValue *luaT_gettm (Table *events, TMS event, TString *ename) {
    00051   const TValue *tm = luaH_getstr(events, ename);
    00052   lua_assert(event <= TM_EQ);
    00053   if (ttisnil(tm)) {  /* no tag method? */
    00054     events->flags |= cast_byte(1u<<event);  /* cache this fact */
    00055     return NULL;
    00056   }
    00057   else return tm;
    00058 }
    00059
    00060
    00061 const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS event) {
    00062   Table *mt;
    00063   switch (ttype(o)) {
    00064     case LUA_TTABLE:
    00065       mt = hvalue(o)->metatable;
    00066       break;
    00067     case LUA_TUSERDATA:
    00068       mt = uvalue(o)->metatable;
    00069       break;
    00070     default:
    00071       mt = G(L)->mt[ttype(o)];
    00072   }
    00073   return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : luaO_nilobject);
    00074 }
    00075