mirror of
https://github.com/lua/lua.git
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264 lines
6.0 KiB
C
264 lines
6.0 KiB
C
/*
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** $Id: ltm.c,v 1.11 1997/12/11 17:21:11 roberto Exp roberto $
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** Tag methods
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** See Copyright Notice in lua.h
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*/
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#include <stdio.h>
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#include <string.h>
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#include "lauxlib.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lstate.h"
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#include "ltm.h"
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char *luaT_eventname[] = { /* ORDER IM */
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"gettable", "settable", "index", "getglobal", "setglobal", "add",
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"sub", "mul", "div", "pow", "unm", "lt", "le", "gt", "ge",
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"concat", "gc", "function", NULL
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};
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static int luaI_checkevent (char *name, char *list[])
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{
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int e = luaO_findstring(name, list);
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if (e < 0)
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luaL_verror("`%.50s' is not a valid event name", name);
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return e;
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}
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/* events in LUA_T_NIL are all allowed, since this is used as a
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* 'placeholder' for "default" fallbacks
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*/
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static char validevents[NUM_TAGS][IM_N] = { /* ORDER LUA_T, ORDER IM */
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{1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1}, /* LUA_T_USERDATA */
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{1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1}, /* LUA_T_NUMBER */
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{1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}, /* LUA_T_STRING */
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{0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, /* LUA_T_ARRAY */
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{1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0}, /* LUA_T_PROTO */
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{1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0}, /* LUA_T_CPROTO */
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{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1} /* LUA_T_NIL */
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};
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static int validevent (int t, int e)
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{ /* ORDER LUA_T */
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return (t < LUA_T_NIL) ? 1 : validevents[-t][e];
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}
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static void init_entry (int tag)
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{
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int i;
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for (i=0; i<IM_N; i++)
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ttype(luaT_getim(tag, i)) = LUA_T_NIL;
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}
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void luaT_init (void)
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{
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int t;
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L->IMtable_size = NUM_TAGS*2;
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L->last_tag = -(NUM_TAGS-1);
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L->IMtable = luaM_newvector(L->IMtable_size, struct IM);
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for (t=L->last_tag; t<=0; t++)
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init_entry(t);
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}
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int lua_newtag (void)
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{
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--L->last_tag;
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if ((-L->last_tag) >= L->IMtable_size)
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L->IMtable_size = luaM_growvector(&L->IMtable, L->IMtable_size,
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struct IM, memEM, MAX_INT);
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init_entry(L->last_tag);
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return L->last_tag;
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}
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static void checktag (int tag)
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{
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if (!(L->last_tag <= tag && tag <= 0))
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luaL_verror("%d is not a valid tag", tag);
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}
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void luaT_realtag (int tag)
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{
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if (!(L->last_tag <= tag && tag < LUA_T_NIL))
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luaL_verror("tag %d is not result of `newtag'", tag);
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}
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int lua_copytagmethods (int tagto, int tagfrom)
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{
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int e;
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checktag(tagto);
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checktag(tagfrom);
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for (e=0; e<IM_N; e++) {
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if (validevent(tagto, e))
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*luaT_getim(tagto, e) = *luaT_getim(tagfrom, e);
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}
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return tagto;
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}
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int luaT_efectivetag (TObject *o)
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{
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int t;
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switch (t = ttype(o)) {
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case LUA_T_ARRAY:
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return o->value.a->htag;
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case LUA_T_USERDATA: {
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int tag = o->value.ts->u.d.tag;
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return (tag >= 0) ? LUA_T_USERDATA : tag;
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}
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case LUA_T_CLOSURE:
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return o->value.cl->consts[0].ttype;
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#ifdef DEBUG
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case LUA_T_PMARK: case LUA_T_CMARK:
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case LUA_T_CLMARK: case LUA_T_LINE:
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lua_error("internal error");
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#endif
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default:
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return t;
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}
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}
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TObject *luaT_gettagmethod (int t, char *event)
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{
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int e = luaI_checkevent(event, luaT_eventname);
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checktag(t);
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if (validevent(t, e))
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return luaT_getim(t,e);
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else
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return &luaO_nilobject;
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}
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void luaT_settagmethod (int t, char *event, TObject *func)
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{
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TObject temp = *func;
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int e = luaI_checkevent(event, luaT_eventname);
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checktag(t);
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if (!validevent(t, e))
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luaL_verror("settagmethod: cannot change internal method `%.20s' for tag %d",
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luaT_eventname[e], t);
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*func = *luaT_getim(t,e);
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*luaT_getim(t, e) = temp;
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}
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char *luaT_travtagmethods (int (*fn)(TObject *))
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{
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int e;
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if (fn(&L->errorim))
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return "error";
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for (e=IM_GETTABLE; e<=IM_FUNCTION; e++) { /* ORDER IM */
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int t;
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for (t=0; t>=L->last_tag; t--)
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if (fn(luaT_getim(t,e)))
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return luaT_eventname[e];
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}
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return NULL;
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}
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/*
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* ===================================================================
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* compatibility with old fallback system
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*/
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#if LUA_COMPAT2_5
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#include "lapi.h"
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static void errorFB (void)
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{
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lua_Object o = lua_getparam(1);
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if (lua_isstring(o))
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fprintf(stderr, "lua: %s\n", lua_getstring(o));
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else
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fprintf(stderr, "lua: unknown error\n");
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}
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static void nilFB (void) { }
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static void typeFB (void)
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{
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lua_error("unexpected type");
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}
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static void fillvalids (IMS e, TObject *func)
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{
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int t;
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for (t=LUA_T_NIL; t<=LUA_T_USERDATA; t++)
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if (validevent(t, e))
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*luaT_getim(t, e) = *func;
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}
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void luaT_setfallback (void)
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{
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static char *oldnames [] = {"error", "getglobal", "arith", "order", NULL};
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TObject oldfunc;
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lua_CFunction replace;
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char *name = luaL_check_string(1);
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lua_Object func = lua_getparam(2);
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luaL_arg_check(lua_isfunction(func), 2, "function expected");
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switch (luaO_findstring(name, oldnames)) {
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case 0: /* old error fallback */
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oldfunc = L->errorim;
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L->errorim = *luaA_Address(func);
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replace = errorFB;
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break;
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case 1: /* old getglobal fallback */
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oldfunc = *luaT_getim(LUA_T_NIL, IM_GETGLOBAL);
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*luaT_getim(LUA_T_NIL, IM_GETGLOBAL) = *luaA_Address(func);
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replace = nilFB;
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break;
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case 2: { /* old arith fallback */
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int i;
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oldfunc = *luaT_getim(LUA_T_NUMBER, IM_POW);
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for (i=IM_ADD; i<=IM_UNM; i++) /* ORDER IM */
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fillvalids(i, luaA_Address(func));
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replace = typeFB;
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break;
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}
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case 3: { /* old order fallback */
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int i;
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oldfunc = *luaT_getim(LUA_T_NIL, IM_LT);
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for (i=IM_LT; i<=IM_GE; i++) /* ORDER IM */
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fillvalids(i, luaA_Address(func));
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replace = typeFB;
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break;
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}
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default: {
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int e;
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if ((e = luaO_findstring(name, luaT_eventname)) >= 0) {
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oldfunc = *luaT_getim(LUA_T_NIL, e);
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fillvalids(e, luaA_Address(func));
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replace = (e == IM_GC || e == IM_INDEX) ? nilFB : typeFB;
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}
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else {
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luaL_verror("`%.50s' is not a valid fallback name", name);
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replace = NULL; /* to avoid warnings */
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}
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}
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}
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if (oldfunc.ttype != LUA_T_NIL)
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luaA_pushobject(&oldfunc);
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else
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lua_pushcfunction(replace);
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}
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#endif
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