can-queues/element-sort.js

A light weight JavaScript task queue

// Taken from jQuery
var hasDuplicate,
	sortInput,
	sortStable = true,
	indexOf = Array.prototype.indexOf;

function sortOrder( a, b ) {

	// Flag for duplicate removal
	if ( a === b ) {
		hasDuplicate = true;
		return 0;
	}

	// Sort on method existence if only one input has compareDocumentPosition
	var compare = !a.compareDocumentPosition - !b.compareDocumentPosition;
	if ( compare ) {
		return compare;
	}

	// Calculate position if both inputs belong to the same document
	compare = ( a.ownerDocument || a ) === ( b.ownerDocument || b ) ?
		a.compareDocumentPosition( b ) :

		// Otherwise we know they are disconnected
		1;

	// Disconnected nodes
	if ( compare & 1 ) {

		// Choose the first element that is related to our preferred document
		if ( a === document || a.ownerDocument === document &&
			document.documentElement.contains(a) ) {
			return -1;
		}
		if ( b === document || b.ownerDocument === document &&
			document.documentElement.contains(b) ) {
			return 1;
		}

		// Maintain original order
		return sortInput ?
			( indexOf.call( sortInput, a ) - indexOf.call( sortInput, b ) ) :
			0;
	}

	return compare & 4 ? -1 : 1;
}

function uniqueSort( results ) {
	var elem,
		duplicates = [],
		j = 0,
		i = 0;

	hasDuplicate = false;
	sortInput = !sortStable && results.slice( 0 );
	results.sort( sortOrder );

	if ( hasDuplicate ) {
		while ( ( elem = results[ i++ ] ) ) {
			if ( elem === results[ i ] ) {
				j = duplicates.push( i );
			}
		}
		while ( j-- ) {
			results.splice( duplicates[ j ], 1 );
		}
	}

	// Clear input after sorting to release objects
	// See https://github.com/jquery/sizzle/pull/225
	sortInput = null;

	return results;
}

module.exports = {
	uniqueSort: uniqueSort,
	sortOrder: sortOrder
};