ltm.c
(5.5.0)
/*
** $Id: ltm.c $
** Tag methods
** See Copyright Notice in lua.h
*/
#define ltm_c
#define LUA_CORE
#include "lprefix.h"
#include <string.h>
#include "lua.h"
#include "ldebug.h"
#include "ldo.h"
#include "lgc.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_TOTALTYPES] = {
"no value",
"nil", "boolean", udatatypename, "number",
"string", "table", "function", udatatypename, "thread",
"upvalue", "proto" /* these last 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", "__mod", "__pow",
"__div", "__idiv",
"__band", "__bor", "__bxor", "__shl", "__shr",
"__unm", "__bnot", "__lt", "__le",
"__concat", "__call", "__close"
};
int i;
for (i=0; i<TM_N; i++) {
G(L)->tmname[i] = luaS_new(L, luaT_eventname[i]);
luaC_fix(L, obj2gco(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_Hgetshortstr(events, ename);
lua_assert(event <= TM_EQ);
if (notm(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 (ttype(o)) {
case LUA_TTABLE:
mt = hvalue(o)->metatable;
break;
case LUA_TUSERDATA:
mt = uvalue(o)->metatable;
break;
default:
mt = G(L)->mt[ttype(o)];
}
return (mt ? luaH_Hgetshortstr(mt, G(L)->tmname[event]) : &G(L)->nilvalue);
}
/*
** Return the name of the type of an object. For tables and userdata
** with metatable, use their '__name' metafield, if present.
*/
const char *luaT_objtypename (lua_State *L, const TValue *o) {
Table *mt;
if ((ttistable(o) && (mt = hvalue(o)->metatable) != NULL) ||
(ttisfulluserdata(o) && (mt = uvalue(o)->metatable) != NULL)) {
const TValue *name = luaH_Hgetshortstr(mt, luaS_new(L, "__name"));
if (ttisstring(name)) /* is '__name' a string? */
return getstr(tsvalue(name)); /* use it as type name */
}
return ttypename(ttype(o)); /* else use standard type name */
}
void luaT_callTM (lua_State *L, const TValue *f, const TValue *p1,
const TValue *p2, const TValue *p3) {
StkId func = L->top.p;
setobj2s(L, func, f); /* push function (assume EXTRA_STACK) */
setobj2s(L, func + 1, p1); /* 1st argument */
setobj2s(L, func + 2, p2); /* 2nd argument */
setobj2s(L, func + 3, p3); /* 3rd argument */
L->top.p = func + 4;
/* metamethod may yield only when called from Lua code */
if (isLuacode(L->ci))
luaD_call(L, func, 0);
else
luaD_callnoyield(L, func, 0);
}
lu_byte luaT_callTMres (lua_State *L, const TValue *f, const TValue *p1,
const TValue *p2, StkId res) {
ptrdiff_t result = savestack(L, res);
StkId func = L->top.p;
setobj2s(L, func, f); /* push function (assume EXTRA_STACK) */
setobj2s(L, func + 1, p1); /* 1st argument */
setobj2s(L, func + 2, p2); /* 2nd argument */
L->top.p += 3;
/* metamethod may yield only when called from Lua code */
if (isLuacode(L->ci))
luaD_call(L, func, 1);
else
luaD_callnoyield(L, func, 1);
res = restorestack(L, result);
setobjs2s(L, res, --L->top.p); /* move result to its place */
return ttypetag(s2v(res)); /* return tag of the result */
}
static int 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 (notm(tm))
tm = luaT_gettmbyobj(L, p2, event); /* try second operand */
if (notm(tm))
return -1; /* tag method not found */
else /* call tag method and return the tag of the result */
return luaT_callTMres(L, tm, p1, p2, res);
}
void luaT_trybinTM (lua_State *L, const TValue *p1, const TValue *p2,
StkId res, TMS event) {
if (l_unlikely(callbinTM(L, p1, p2, res, event) < 0)) {
switch (event) {
case TM_BAND: case TM_BOR: case TM_BXOR:
case TM_SHL: case TM_SHR: case TM_BNOT: {
if (ttisnumber(p1) && ttisnumber(p2))
luaG_tointerror(L, p1, p2);
else
luaG_opinterror(L, p1, p2, "perform bitwise operation on");
}
/* calls never return, but to avoid warnings: *//* FALLTHROUGH */
default:
luaG_opinterror(L, p1, p2, "perform arithmetic on");
}
}
}
/*
** The use of 'p1' after 'callbinTM' is safe because, when a tag
** method is not found, 'callbinTM' cannot change the stack.
*/
void luaT_tryconcatTM (lua_State *L) {
StkId p1 = L->top.p - 2; /* first argument */
if (l_unlikely(callbinTM(L, s2v(p1), s2v(p1 + 1), p1, TM_CONCAT) < 0))
luaG_concaterror(L, s2v(p1), s2v(p1 + 1));
}
void luaT_trybinassocTM (lua_State *L, const TValue *p1, const TValue *p2,
int flip, StkId res, TMS event) {
if (flip)
luaT_trybinTM(L, p2, p1, res, event);
else
luaT_trybinTM(L, p1, p2, res, event);
}
void luaT_trybiniTM (lua_State *L, const TValue *p1, lua_Integer i2,
int flip, StkId res, TMS event) {
TValue aux;
setivalue(&aux, i2);
luaT_trybinassocTM(L, p1, &aux, flip, res, event);
}
/*
** Calls an order tag method.
*/
int luaT_callorderTM (lua_State *L, const TValue *p1, const TValue *p2,
TMS event) {
int tag = callbinTM(L, p1, p2, L->top.p, event); /* try original event */
if (tag >= 0) /* found tag method? */
return !tagisfalse(tag);
luaG_ordererror(L, p1, p2); /* no metamethod found */
return 0; /* to avoid warnings */
}
int luaT_callorderiTM (lua_State *L, const TValue *p1, int v2,
int flip, int isfloat, TMS event) {
TValue aux; const TValue *p2;
if (isfloat) {
setfltvalue(&aux, cast_num(v2));
}
else
setivalue(&aux, v2);
if (flip) { /* arguments were exchanged? */
p2 = p1; p1 = &aux; /* correct them */
}
else
p2 = &aux;
return luaT_callorderTM(L, p1, p2, event);
}
/*
** Create a vararg table at the top of the stack, with 'n' elements
** starting at 'f'.
*/
static void createvarargtab (lua_State *L, StkId f, int n) {
int i;
TValue key, value;
Table *t = luaH_new(L);
sethvalue(L, s2v(L->top.p), t);
L->top.p++;
luaH_resize(L, t, cast_uint(n), 1);
setsvalue(L, &key, luaS_new(L, "n")); /* key is "n" */
setivalue(&value, n); /* value is n */
/* No need to anchor the key: Due to the resize, the next operation
cannot trigger a garbage collection */
luaH_set(L, t, &key, &value); /* t.n = n */
for (i = 0; i < n; i++)
luaH_setint(L, t, i + 1, s2v(f + i));
luaC_checkGC(L);
}
/*
** initial stack: func arg1 ... argn extra1 ...
** ^ ci->func ^ L->top
** final stack: func nil ... nil extra1 ... func arg1 ... argn
** ^ ci->func
*/
static void buildhiddenargs (lua_State *L, CallInfo *ci, const Proto *p,
int totalargs, int nfixparams, int nextra) {
int i;
ci->u.l.nextraargs = nextra;
luaD_checkstack(L, p->maxstacksize + 1);
/* copy function to the top of the stack, after extra arguments */
setobjs2s(L, L->top.p++, ci->func.p);
/* move fixed parameters to after the copied function */
for (i = 1; i <= nfixparams; i++) {
setobjs2s(L, L->top.p++, ci->func.p + i);
setnilvalue(s2v(ci->func.p + i)); /* erase original parameter (for GC) */
}
ci->func.p += totalargs + 1; /* 'func' now lives after hidden arguments */
ci->top.p += totalargs + 1;
}
void luaT_adjustvarargs (lua_State *L, CallInfo *ci, const Proto *p) {
int totalargs = cast_int(L->top.p - ci->func.p) - 1;
int nfixparams = p->numparams;
int nextra = totalargs - nfixparams; /* number of extra arguments */
if (p->flag & PF_VATAB) { /* does it need a vararg table? */
lua_assert(!(p->flag & PF_VAHID));
createvarargtab(L, ci->func.p + nfixparams + 1, nextra);
/* move table to proper place (last parameter) */
setobjs2s(L, ci->func.p + nfixparams + 1, L->top.p - 1);
}
else { /* no table */
lua_assert(p->flag & PF_VAHID);
buildhiddenargs(L, ci, p, totalargs, nfixparams, nextra);
/* set vararg parameter to nil */
setnilvalue(s2v(ci->func.p + nfixparams + 1));
lua_assert(L->top.p <= ci->top.p && ci->top.p <= L->stack_last.p);
}
}
void luaT_getvararg (CallInfo *ci, StkId ra, TValue *rc) {
int nextra = ci->u.l.nextraargs;
lua_Integer n;
if (tointegerns(rc, &n)) { /* integral value? */
if (l_castS2U(n) - 1 < cast_uint(nextra)) {
StkId slot = ci->func.p - nextra + cast_int(n) - 1;
setobjs2s(((lua_State*)NULL), ra, slot);
return;
}
}
else if (ttisstring(rc)) { /* string value? */
size_t len;
const char *s = getlstr(tsvalue(rc), len);
if (len == 1 && s[0] == 'n') { /* key is "n"? */
setivalue(s2v(ra), nextra);
return;
}
}
setnilvalue(s2v(ra)); /* else produce nil */
}
/*
** Get the number of extra arguments in a vararg function. If vararg
** table has been optimized away, that number is in the call info.
** Otherwise, get the field 'n' from the vararg table and check that it
** has a proper value (non-negative integer not larger than the stack
** limit).
*/
static int getnumargs (lua_State *L, CallInfo *ci, Table *h) {
if (h == NULL) /* no vararg table? */
return ci->u.l.nextraargs;
else {
TValue res;
if (luaH_getshortstr(h, luaS_new(L, "n"), &res) != LUA_VNUMINT ||
l_castS2U(ivalue(&res)) > cast_uint(INT_MAX/2))
luaG_runerror(L, "vararg table has no proper 'n'");
return cast_int(ivalue(&res));
}
}
/*
** Get 'wanted' vararg arguments and put them in 'where'. 'vatab' is
** the register of the vararg table or -1 if there is no vararg table.
*/
void luaT_getvarargs (lua_State *L, CallInfo *ci, StkId where, int wanted,
int vatab) {
Table *h = (vatab < 0) ? NULL : hvalue(s2v(ci->func.p + vatab + 1));
int nargs = getnumargs(L, ci, h); /* number of available vararg args. */
int i, touse; /* 'touse' is minimum between 'wanted' and 'nargs' */
if (wanted < 0) {
touse = wanted = nargs; /* get all extra arguments available */
checkstackp(L, nargs, where); /* ensure stack space */
L->top.p = where + nargs; /* next instruction will need top */
}
else
touse = (nargs > wanted) ? wanted : nargs;
if (h == NULL) { /* no vararg table? */
for (i = 0; i < touse; i++) /* get vararg values from the stack */
setobjs2s(L, where + i, ci->func.p - nargs + i);
}
else { /* get vararg values from vararg table */
for (i = 0; i < touse; i++) {
lu_byte tag = luaH_getint(h, i + 1, s2v(where + i));
if (tagisempty(tag))
setnilvalue(s2v(where + i));
}
}
for (; i < wanted; i++) /* complete required results with nil */
setnilvalue(s2v(where + i));
}