common.rs

//Counts the number of (non-overlapping) elements matching at the start and end of each slice
fn common_affix<E: TotalEq>(old: &[E], new: &[E]) -> (uint, uint) {
	let shorter = min(old.len(), new.len());

	let mut common_prefix = 0;
	for i in range(0, shorter) {
		if old.get(i) != new.get(i) {
			break;
		}
		common_prefix += 1;
	}

	let mut common_suffix = 0;
	for i in range(0, shorter - common_prefix) {
		if old.get((old.len() - 1) - i) != new.get((new.len() - 1) - i) {
			break;
		}
		common_suffix += 1;
	}

	return (common_prefix, common_suffix);
}