return {
	make: make,
	getRow: getRow,
	getColumn: getColumn,
	vertical: vertical,
	horizontal: horizontal,
	diagonal: diagonal,
	zero: zero,
	plus: plus,
	opposite: opposite,
	isSmaller: isSmaller,
	toKey: toKey,
	ofKey: ofKey,
};

function make(row, column) {
	return {row: parseInt(row), column: parseInt(column)};
}

function getRow(v) {
	return v.row;
}

function getColumn(v) {
	return v.column;
}

function zero() {
	return make(0, 0);
}

function vertical(length) {
	return make(length, 0);
}

function horizontal(length) {
	return make(0, length);
}

function diagonal(length) {
	return make(length, length);
}

function plus(v0, v1) {
	return make(v0.row + v1.row, v0.column + v1.column);
}

function opposite(v) {
	return make(-v.row, -v.column);
}

function isSmaller(v0, v1) {
	return v0.row <= v1.row && v0.column <= v1.column;
}

function toKey(v) {
	return v.row + ':' + v.column;
	//return 8*v.row + v.column;
}

function ofKey(k) {
	return make.apply(null, k.split(':'));
	//return make.call(null, Math.floor(k / 8), k % 8);
}