TreeRBXS.c Iter_next method

TreeRBXS.c

XS_EUPXS(XS_Tree__RB__XS__Iter_next); /* prototype to pass -Wmissing-prototypes */
XS_EUPXS(XS_Tree__RB__XS__Iter_next)
{
    dVAR; dXSARGS;
    dXSI32;
    if (items < 1 || items > 2)
       croak_xs_usage(cv,  "iter, count_sv= NULL");
    PERL_UNUSED_VAR(ax); /* -Wall */
    SP -= items;
    {
	struct TreeRBXS_iter *	iter;
	SV*	count_sv;

	iter= TreeRBXS_get_magic_iter(ST(0), OR_DIE)
;

	if (items < 2)
	    count_sv = NULL;
	else {
	    count_sv = ST(1)
;
	}
#line 1857 "TreeRBXS.xs"
		size_t pos, n, i, tree_count= TreeRBXS_get_count(iter->tree);
		IV request;
		rbtree_node_t *node;
		rbtree_node_t *(*step)(rbtree_node_t *)= iter->reverse? &rbtree_node_prev : rbtree_node_next;
#line 2761 "TreeRBXS.c"
#line 1862 "TreeRBXS.xs"
		if (iter->item) {
			request= !count_sv? 1
				: SvPOK(count_sv) && *SvPV_nolen(count_sv) == '*'? tree_count
				: SvIV(count_sv);
			if (request < 1) {
				n= i= 0;
			}
			// A request for 1 is simpler because there is no need to count how many will be returned.
			// iter->item wasn't NULL so it is guaranteed to be 1.
			else if (GIMME_V == G_VOID) {
				// skip all the busywork if called in void context
				// (but still advance the iterator below)
				n= request;
				i= 0;
			}
			else if (request == 1) {
				n= i= 1;
				ST(0)= ix == 0? sv_2mortal(TreeRBXS_wrap_item(iter->item))
					: ix == 2? iter->item->value
					: sv_2mortal(TreeRBXS_item_wrap_key(iter->item));
				if (ix == 3) {
					warn("EXTEND(SP, %d)", 2);
					EXTEND(SP, 2);
					ST(1)= iter->item->value;
				}
			}
			else {
				pos= rbtree_node_index(&iter->item->rbnode);
				// calculate how many nodes will be returned
				n= iter->reverse? 1 + pos : tree_count - pos;
				if (n > request) n= request;
				node= &iter->item->rbnode;
				warn("EXTEND(SP, %ld", ix == 3? 2*n : n);
				EXTEND(SP, ix == 3? 2*n : n);
				if (ix == 0) {
					for (i= 0; i < n && node; i++, node= step(node)) {
						warn("Accessing ST(%ld)", i);
						ST(i)= sv_2mortal(TreeRBXS_wrap_item(GET_TreeRBXS_item_FROM_rbnode(node)));
					}
				}
				else if (ix == 1) {
					for (i= 0; i < n && node; i++, node= step(node)) {
						warn("Accessing ST(%ld)", i);
						ST(i)= sv_2mortal(TreeRBXS_item_wrap_key(GET_TreeRBXS_item_FROM_rbnode(node)));
					}
				}
				else if (ix == 2) {
					for (i= 0; i < n && node; i++, node= step(node)) {
						warn("Accessing ST(%ld)", i);
						ST(i)= GET_TreeRBXS_item_FROM_rbnode(node)->value;
					}
				}
				else {
					for (i= 0; i < n && node; i++, node= step(node)) {
						warn("Accessing ST(%ld), ST(%ld)", i*2, i*2+1);
						ST(i*2)= sv_2mortal(TreeRBXS_item_wrap_key(GET_TreeRBXS_item_FROM_rbnode(node)));
						ST(i*2+1)= GET_TreeRBXS_item_FROM_rbnode(node)->value;
					}
				}
				if (i != n)
					croak("BUG: expected %ld nodes but found %ld", (long) n, (long) i);
			}
			TreeRBXS_iter_advance(iter, n);
			warn("XSRETURN(%ld)", ix == 3? 2*i : i);
			XSRETURN(ix == 3? 2*i : i);
		} else {
			// end of iteration, nothing to do
			ST(0)= &PL_sv_undef;
			// return the undef only if the user didn't specify a count
			warn("XSRETURN(%d)", count_sv? 0 : 1);
			XSRETURN(count_sv? 0 : 1);
		}
#line 2835 "TreeRBXS.c"
	PUTBACK;
	return;
    }
}