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new semantics for "for" local variables

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This commit is contained in:
Roberto Ierusalimschy
2003-05-13 17:15:59 -03:00
parent c767747191
commit 6d268b0b00
5 changed files with 61 additions and 52 deletions
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56
lvm.c
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@@ -1,5 +1,5 @@
/*
** $Id: lvm.c,v 1.284 2003/04/03 13:35:34 roberto Exp roberto $
** $Id: lvm.c,v 1.285 2003/05/05 18:39:57 roberto Exp roberto $
** Lua virtual machine
** See Copyright Notice in lua.h
*/
@@ -639,43 +639,45 @@ StkId luaV_execute (lua_State *L) {
}
}
case OP_FORLOOP: {
lua_Number step, idx, limit;
const TObject *plimit = ra+1;
const TObject *pstep = ra+2;
if (!ttisnumber(ra))
luaG_runerror(L, "`for' initial value must be a number");
if (!tonumber(plimit, ra+1))
luaG_runerror(L, "`for' limit must be a number");
if (!tonumber(pstep, ra+2))
luaG_runerror(L, "`for' step must be a number");
step = nvalue(pstep);
idx = nvalue(ra) + step; /* increment index */
limit = nvalue(plimit);
lua_Number step = nvalue(ra+2);
lua_Number idx = nvalue(ra) + step; /* increment index */
lua_Number limit = nvalue(ra+1);
if (step > 0 ? idx <= limit : idx >= limit) {
dojump(pc, GETARG_sBx(i)); /* jump back */
chgnvalue(ra, idx); /* update index */
setnvalue(ra, idx); /* update internal index... */
setnvalue(ra+3, idx); /* ...and external index */
}
break;
}
case OP_FORPREP: {
const TObject *init = ra;
const TObject *plimit = ra+1;
const TObject *pstep = ra+2;
if (!tonumber(init, ra))
luaG_runerror(L, "`for' initial value must be a number");
else if (!tonumber(plimit, ra+1))
luaG_runerror(L, "`for' limit must be a number");
else if (!tonumber(pstep, ra+2))
luaG_runerror(L, "`for' step must be a number");
setnvalue(ra, nvalue(ra) - nvalue(pstep));
dojump(pc, GETARG_sBx(i));
break;
}
case OP_TFORLOOP: {
int nvar = GETARG_C(i) + 1;
StkId cb = ra + nvar + 2; /* call base */
setobjs2s(cb, ra);
setobjs2s(cb+1, ra+1);
StkId cb = ra + 3; /* call base */
setobjs2s(cb+2, ra+2);
setobjs2s(cb+1, ra+1);
setobjs2s(cb, ra);
L->top = cb+3; /* func. + 2 args (state and index) */
luaD_call(L, cb, nvar);
luaD_call(L, cb, GETARG_C(i));
L->top = L->ci->top;
ra = XRA(i) + 2; /* final position of first result */
cb = ra + nvar;
do { /* move results to proper positions */
nvar--;
setobjs2s(ra+nvar, cb+nvar);
} while (nvar > 0);
if (ttisnil(ra)) /* break loop? */
cb = XRA(i) + 3; /* previous call may change the stack */
if (ttisnil(cb)) /* break loop? */
pc++; /* skip jump (break loop) */
else
else {
setobjs2s(cb-1, cb); /* save control variable */
dojump(pc, GETARG_sBx(*pc) + 1); /* jump back */
}
break;
}
case OP_TFORPREP: { /* for compatibility only */