Function xmlXPathSubstringFunction

ThirdParty/libxml2/vtklibxml2/xpath.c:8050–8123

* xmlXPathSubstringFunction: * @ctxt: the XPath Parser context * @nargs: the number of arguments * * Implement the substring() XPath function * string substring(string, number, number?) * The substring function returns the substring of the first argument * starting at the position specified in the second argument with * length specified in the third argument. For example, * substring

 *  - substring("12345", -1 div 0, 1 div 0) returns ""
 */
void
xmlXPathSubstringFunction(xmlXPathParserContextPtr ctxt, int nargs) {
    xmlXPathObjectPtr str, start, len;
    double le=0, in;
    int i = 1, j = INT_MAX;

    if (nargs < 2) {
	CHECK_ARITY(2);
    }
    if (nargs > 3) {
	CHECK_ARITY(3);
    }
    /*
     * take care of possible last (position) argument
    */
    if (nargs == 3) {
	CAST_TO_NUMBER;
	CHECK_TYPE(XPATH_NUMBER);
	len = valuePop(ctxt);
	le = len->floatval;
	xmlXPathReleaseObject(ctxt->context, len);
    }

    CAST_TO_NUMBER;
    CHECK_TYPE(XPATH_NUMBER);
    start = valuePop(ctxt);
    in = start->floatval;
    xmlXPathReleaseObject(ctxt->context, start);
    CAST_TO_STRING;
    CHECK_TYPE(XPATH_STRING);
    str = valuePop(ctxt);

    if (!(in < INT_MAX)) { /* Logical NOT to handle NaNs */
        i = INT_MAX;
    } else if (in >= 1.0) {
        i = (int)in;
        if (in - floor(in) >= 0.5)
            i += 1;
    }

    if (nargs == 3) {
        double rin, rle, end;

        rin = floor(in);
        if (in - rin >= 0.5)
            rin += 1.0;

        rle = floor(le);
        if (le - rle >= 0.5)
            rle += 1.0;

        end = rin + rle;
        if (!(end >= 1.0)) { /* Logical NOT to handle NaNs */
            j = 1;
        } else if (end < INT_MAX) {
            j = (int)end;
        }
    }