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/*
** $Id: ltm.c,v 1.3 2001/11/26 23:00:26 darkgod Exp $
** Tag methods
** See Copyright Notice in lua.h
*/
#include <stdio.h>
#include <string.h>
#include "lua.h"
#include "ldo.h"
#include "lmem.h"
#include "lobject.h"
#include "lstate.h"
#include "ltm.h"
const char *const luaT_eventname[] = { /* ORDER TM */
"gettable", "settable", "index", "getglobal", "setglobal", "add", "sub",
"mul", "div", "pow", "unm", "lt", "concat", "gc", "function",
"le", "gt", "ge", /* deprecated options!! */
NULL
};
static int findevent (const char *name) {
int i;
for (i=0; luaT_eventname[i]; i++)
if (strcmp(luaT_eventname[i], name) == 0)
return i;
return -1; /* name not found */
}
static int luaI_checkevent (lua_State *L, const char *name, int t) {
int e = findevent(name);
if (e >= TM_N)
luaO_verror(L, "event `%.50s' is deprecated", name);
if (e == TM_GC && t == LUA_TTABLE)
luaO_verror(L, "event `gc' for tables is deprecated");
if (e < 0)
luaO_verror(L, "`%.50s' is not a valid event name", name);
return e;
}
/* events in LUA_TNIL are all allowed, since this is used as a
* 'placeholder' for "default" fallbacks
*/
/* ORDER LUA_T, ORDER TM */
static const char luaT_validevents[NUM_TAGS][TM_N] = {
{1, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1}, /* LUA_TUSERDATA */
{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1}, /* LUA_TNIL */
{1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1}, /* LUA_TNUMBER */
{1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1}, /* LUA_TSTRING */
{0, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1}, /* LUA_TTABLE */
{1, 1, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0} /* LUA_TFUNCTION */
};
int luaT_validevent (int t, int e) { /* ORDER LUA_T */
return (t >= NUM_TAGS) ? 1 : luaT_validevents[t][e];
}
static void init_entry (lua_State *L, int tag) {
int i;
for (i=0; i<TM_N; i++)
luaT_gettm(L, tag, i) = NULL;
L->TMtable[tag].collected = NULL;
}
void luaT_init (lua_State *L) {
int t;
luaM_growvector(L, L->TMtable, 0, NUM_TAGS, struct TM, "", MAX_INT);
L->nblocks += NUM_TAGS*sizeof(struct TM);
L->last_tag = NUM_TAGS-1;
for (t=0; t<=L->last_tag; t++)
init_entry(L, t);
}
LUA_API int lua_newtag (lua_State *L) {
luaM_growvector(L, L->TMtable, L->last_tag, 1, struct TM,
"tag table overflow", MAX_INT);
L->nblocks += sizeof(struct TM);
L->last_tag++;
init_entry(L, L->last_tag);
return L->last_tag;
}
static void checktag (lua_State *L, int tag) {
if (!(0 <= tag && tag <= L->last_tag))
luaO_verror(L, "%d is not a valid tag", tag);
}
void luaT_realtag (lua_State *L, int tag) {
if (!validtag(tag))
luaO_verror(L, "tag %d was not created by `newtag'", tag);
}
LUA_API int lua_copytagmethods (lua_State *L, int tagto, int tagfrom) {
int e;
checktag(L, tagto);
checktag(L, tagfrom);
for (e=0; e<TM_N; e++) {
if (luaT_validevent(tagto, e))
luaT_gettm(L, tagto, e) = luaT_gettm(L, tagfrom, e);
}
return tagto;
}
int luaT_tag (const TObject *o) {
int t = ttype(o);
switch (t) {
case LUA_TUSERDATA: return tsvalue(o)->u.d.tag;
case LUA_TTABLE: return hvalue(o)->htag;
default: return t;
}
}
LUA_API void lua_gettagmethod (lua_State *L, int t, const char *event) {
int e;
e = luaI_checkevent(L, event, t);
checktag(L, t);
if (luaT_validevent(t, e) && luaT_gettm(L, t, e)) {
clvalue(L->top) = luaT_gettm(L, t, e);
ttype(L->top) = LUA_TFUNCTION;
}
else
ttype(L->top) = LUA_TNIL;
incr_top;
}
LUA_API void lua_settagmethod (lua_State *L, int t, const char *event) {
int e = luaI_checkevent(L, event, t);
checktag(L, t);
if (!luaT_validevent(t, e))
luaO_verror(L, "cannot change `%.20s' tag method for type `%.20s'%.20s",
luaT_eventname[e], luaO_typenames[t],
(t == LUA_TTABLE || t == LUA_TUSERDATA) ?
" with default tag" : "");
switch (ttype(L->top - 1)) {
case LUA_TNIL:
luaT_gettm(L, t, e) = NULL;
break;
case LUA_TFUNCTION:
luaT_gettm(L, t, e) = clvalue(L->top - 1);
break;
default:
lua_error(L, "tag method must be a function (or nil)");
}
L->top--;
}
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