Function xmlXPathCompOpEvalFilterFirst

ThirdParty/libxml2/vtklibxml2/xpath.c:11692–11782

#ifdef XP_OPTIMIZED_FILTER_FIRST
static int
xmlXPathCompOpEvalFilterFirst(xmlXPathParserContextPtr ctxt,
			      xmlXPathStepOpPtr op, xmlNodePtr * first)
{
    int total = 0;
    xmlXPathCompExprPtr comp;
    xmlXPathObjectPtr obj;
    xmlNodeSetPtr set;

    CHECK_ERROR0;
    comp = ctxt->comp;
    /*
    * Optimization for ()[last()] selection i.e. the last elem
    */
    if ((op->ch1 != -1) && (op->ch2 != -1) &&
	(comp->steps[op->ch1].op == XPATH_OP_SORT) &&
	(comp->steps[op->ch2].op == XPATH_OP_SORT)) {
	int f = comp->steps[op->ch2].ch1;

	if ((f != -1) &&
	    (comp->steps[f].op == XPATH_OP_FUNCTION) &&
	    (comp->steps[f].value5 == NULL) &&
	    (comp->steps[f].value == 0) &&
	    (comp->steps[f].value4 != NULL) &&
	    (xmlStrEqual
	    (comp->steps[f].value4, BAD_CAST "last"))) {
	    xmlNodePtr last = NULL;

	    total +=
		xmlXPathCompOpEvalLast(ctxt,
		    &comp->steps[op->ch1],
		    &last);
	    CHECK_ERROR0;
	    /*
	    * The nodeset should be in document order,
	    * Keep only the last value
	    */
	    if ((ctxt->value != NULL) &&
		(ctxt->value->type == XPATH_NODESET) &&
		(ctxt->value->nodesetval != NULL) &&
		(ctxt->value->nodesetval->nodeTab != NULL) &&
		(ctxt->value->nodesetval->nodeNr > 1)) {
                xmlXPathNodeSetKeepLast(ctxt->value->nodesetval);
		*first = *(ctxt->value->nodesetval->nodeTab);
	    }
	    return (total);
	}
    }

    if (op->ch1 != -1)
	total += xmlXPathCompOpEval(ctxt, &comp->steps[op->ch1]);
    CHECK_ERROR0;
    if (op->ch2 == -1)
	return (total);
    if (ctxt->value == NULL)
	return (total);

#ifdef LIBXML_XPTR_LOCS_ENABLED