08-27-周三_17-09-29

node_modules/domutils/lib/helpers.js

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+// removeSubsets
+// Given an array of nodes, remove any member that is contained by another.
+exports.removeSubsets = function(nodes) {
+	var idx = nodes.length, node, ancestor, replace;
+
+	// Check if each node (or one of its ancestors) is already contained in the
+	// array.
+	while (--idx > -1) {
+		node = ancestor = nodes[idx];
+
+		// Temporarily remove the node under consideration
+		nodes[idx] = null;
+		replace = true;
+
+		while (ancestor) {
+			if (nodes.indexOf(ancestor) > -1) {
+				replace = false;
+				nodes.splice(idx, 1);
+				break;
+			}
+			ancestor = ancestor.parent;
+		}
+
+		// If the node has been found to be unique, re-insert it.
+		if (replace) {
+			nodes[idx] = node;
+		}
+	}
+
+	return nodes;
+};
+
+// Source: http://dom.spec.whatwg.org/#dom-node-comparedocumentposition
+var POSITION = {
+	DISCONNECTED: 1,
+	PRECEDING: 2,
+	FOLLOWING: 4,
+	CONTAINS: 8,
+	CONTAINED_BY: 16
+};
+
+// Compare the position of one node against another node in any other document.
+// The return value is a bitmask with the following values:
+//
+// document order:
+// > There is an ordering, document order, defined on all the nodes in the
+// > document corresponding to the order in which the first character of the
+// > XML representation of each node occurs in the XML representation of the
+// > document after expansion of general entities. Thus, the document element
+// > node will be the first node. Element nodes occur before their children.
+// > Thus, document order orders element nodes in order of the occurrence of
+// > their start-tag in the XML (after expansion of entities). The attribute
+// > nodes of an element occur after the element and before its children. The
+// > relative order of attribute nodes is implementation-dependent./
+// Source:
+// http://www.w3.org/TR/DOM-Level-3-Core/glossary.html#dt-document-order
+//
+// @argument {Node} nodaA The first node to use in the comparison
+// @argument {Node} nodeB The second node to use in the comparison
+//
+// @return {Number} A bitmask describing the input nodes' relative position.
+//         See http://dom.spec.whatwg.org/#dom-node-comparedocumentposition for
+//         a description of these values.
+var comparePos = exports.compareDocumentPosition = function(nodeA, nodeB) {
+	var aParents = [];
+	var bParents = [];
+	var current, sharedParent, siblings, aSibling, bSibling, idx;
+
+	if (nodeA === nodeB) {
+		return 0;
+	}
+
+	current = nodeA;
+	while (current) {
+		aParents.unshift(current);
+		current = current.parent;
+	}
+	current = nodeB;
+	while (current) {
+		bParents.unshift(current);
+		current = current.parent;
+	}
+
+	idx = 0;
+	while (aParents[idx] === bParents[idx]) {
+		idx++;
+	}
+
+	if (idx === 0) {
+		return POSITION.DISCONNECTED;
+	}
+
+	sharedParent = aParents[idx - 1];
+	siblings = sharedParent.children;
+	aSibling = aParents[idx];
+	bSibling = bParents[idx];
+
+	if (siblings.indexOf(aSibling) > siblings.indexOf(bSibling)) {
+		if (sharedParent === nodeB) {
+			return POSITION.FOLLOWING | POSITION.CONTAINED_BY;
+		}
+		return POSITION.FOLLOWING;
+	} else {
+		if (sharedParent === nodeA) {
+			return POSITION.PRECEDING | POSITION.CONTAINS;
+		}
+		return POSITION.PRECEDING;
+	}
+};
+
+// Sort an array of nodes based on their relative position in the document and
+// remove any duplicate nodes. If the array contains nodes that do not belong
+// to the same document, sort order is unspecified.
+//
+// @argument {Array} nodes Array of DOM nodes
+//
+// @returns {Array} collection of unique nodes, sorted in document order
+exports.uniqueSort = function(nodes) {
+	var idx = nodes.length, node, position;
+
+	nodes = nodes.slice();
+
+	while (--idx > -1) {
+		node = nodes[idx];
+		position = nodes.indexOf(node);
+		if (position > -1 && position < idx) {
+			nodes.splice(idx, 1);
+		}
+	}
+	nodes.sort(function(a, b) {
+		var relative = comparePos(a, b);
+		if (relative & POSITION.PRECEDING) {
+			return -1;
+		} else if (relative & POSITION.FOLLOWING) {
+			return 1;
+		}
+		return 0;
+	});
+
+	return nodes;
+};