/*
** check whether, in an assignment to a local variable, the local variable
** is needed in a previous assignment (to a table). If so, save original
** local value in a safe place and use this safe copy in the previous
** assignment.
*/
private static void check_conflict(LexState ls, LHS_assign lh, expdesc v)
{
FuncState fs = ls.fs;
int extra = fs.freereg; /* eventual position to save local variable */
int conflict = 0;
for (; lh!=null; lh = lh.prev) {
if (lh.v.k == expkind.VINDEXED) {
if (lh.v.u.s.info == v.u.s.info) { /* conflict? */
conflict = 1;
lh.v.u.s.info = extra; /* previous assignment will use safe copy */
}
if (lh.v.u.s.aux == v.u.s.info) { /* conflict? */
conflict = 1;
lh.v.u.s.aux = extra; /* previous assignment will use safe copy */
}
}
}
if (conflict != 0) {
LuaKCodeABC(fs, OpCode.OP_MOVE, fs.freereg, v.u.s.info, 0); /* make copy */
LuaKReserveRegs(fs, 1);
}
}
private static void exprstat(LexState ls)
{
/* stat . func | assignment */
FuncState fs = ls.fs;
LHS_assign v = new LHS_assign();
primaryexp(ls, v.v);
if (v.v.k == expkind.VCALL) /* stat . func */
SETARG_C(GetCode(fs, v.v), 1); /* call statement uses no results */
else { /* stat . assignment */
v.prev = null;
assignment(ls, v, 1);
}
}
private static void assignment(LexState ls, LHS_assign lh, int nvars)
{
expdesc e = new expdesc();
check_condition(ls, expkind.VLOCAL <= lh.v.k && lh.v.k <= expkind.VINDEXED,
"syntax error");
if (testnext(ls, ',') != 0) { /* assignment . `,' primaryexp assignment */
LHS_assign nv = new LHS_assign();
nv.prev = lh;
primaryexp(ls, nv.v);
if (nv.v.k == expkind.VLOCAL)
check_conflict(ls, lh, nv.v);
luaY_checklimit(ls.fs, nvars, LUAI_MAXCCALLS - ls.L.nCcalls,
"variables in assignment");
assignment(ls, nv, nvars+1);
}
else { /* assignment . `=' explist1 */
int nexps;
checknext(ls, '=');
nexps = explist1(ls, e);
if (nexps != nvars) {
adjust_assign(ls, nvars, nexps, e);
if (nexps > nvars)
ls.fs.freereg -= nexps - nvars; /* remove extra values */
}
else {
LuaKSetOneRet(ls.fs, e); /* close last expression */
LuaKStoreVar(ls.fs, lh.v, e);
return; /* avoid default */
}
}
init_exp(e, expkind.VNONRELOC, ls.fs.freereg - 1); /* default assignment */
LuaKStoreVar(ls.fs, lh.v, e);
}