static int lp_argcapture (lua_State *L) {
int n = (int)luaL_checkinteger(L, 1);
TTree *tree = newemptycap(L, Carg);
tree->key = n;
luaL_argcheck(L, 0 < n && n <= SHRT_MAX, 1, "invalid argument index");
return 1;
}
/*
** Constant capture
*/
static int lp_constcapture (lua_State *L) {
int i;
int n = lua_gettop(L); /* number of values */
if (n == 0) /* no values? */
newleaf(L, TTrue); /* no capture */
else if (n == 1)
newemptycap(L, Cconst, 1); /* single constant capture */
else { /* create a group capture with all values */
TTree *tree = newtree(L, 1 + 3 * (n - 1) + 2);
tree->tag = TCapture;
tree->cap = Cgroup;
tree->key = 0;
tree = sib1(tree);
for (i = 1; i <= n - 1; i++) {
tree->tag = TSeq;
tree->u.ps = 3; /* skip TCapture and its sibling */
auxemptycap(L, sib1(tree), Cconst, i);
tree = sib2(tree);
}
auxemptycap(L, tree, Cconst, i);
}
return 1;
}
static int lp_poscapture (lua_State *L) {
newemptycap(L, Cposition);
return 1;
}
static int lp_backref (lua_State *L) {
luaL_checkstring(L, 1);
newemptycap(L, Cbackref, 1);
return 1;
}