grading/dist/cli/compareNumberAware.ts

Grading of student submissions, in particular programming tests.

function isNumber(str: string): boolean {
    return str >= '0' && str <= '9';
}

/**
 * Compare two strings which may contain numbers. The numbers are compared numerically, i.e. 01 an 1 is considered equal.
 * If two strings are equal, the shorter one is considered smaller.
 */
export function compareNumberAware(a: string, b: string): number {
    let ia = 0, ib = 0
    for (; ia < a.length && ib < b.length; ia++, ib++) {
        const aChar = a.charAt(ia);
        const bChar = b.charAt(ib);
        if (aChar == bChar) {
            continue;
        }
        if (isNumber(aChar) && isNumber(bChar)) {
            let endA = ia + 1;
            let endB = ib + 1;
            while (endA < a.length && isNumber(a.charAt(endA))) {
                endA++;
            }
            while (endB < b.length && isNumber(b.charAt(endB))) {
                endB++;
            }
            let aNum = parseInt(a.substring(ia, endA));
            let bNum = parseInt(b.substring(ib, endB));
            if (aNum != bNum) {
                return aNum - bNum;
            }
            ia = endA - 1;
            ib = endB - 1;
        } else {
            return aChar.localeCompare(bChar);
        }
    }
    if (ia < a.length) {
        return 1;
    } else if (ib < b.length) {
        return -1;
    }
    return a.length - b.length;
}