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Squire/source/TreeWalker.js

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/*jshint strict:false */
/*
Native TreeWalker is buggy in IE and Opera:
* IE9/10 sometimes throw errors when calling TreeWalker#nextNode or
TreeWalker#previousNode. No way to feature detect this.
* Some versions of Opera have a bug in TreeWalker#previousNode which makes
it skip to the wrong node.
Rather than risk further bugs, it's easiest just to implement our own
(subset) of the spec in all browsers.
*/
var typeToBitArray = {
// ELEMENT_NODE
1: 1,
// ATTRIBUTE_NODE
2: 2,
// TEXT_NODE
3: 4,
// COMMENT_NODE
8: 128,
// DOCUMENT_NODE
9: 256,
// DOCUMENT_FRAGMENT_NODE
11: 1024
};
var always = function () {
return true;
};
function TreeWalker ( root, nodeType, filter ) {
this.root = this.currentNode = root;
this.nodeType = nodeType;
this.filter = filter || always;
}
TreeWalker.prototype.nextNode = function () {
var current = this.currentNode,
root = this.root,
nodeType = this.nodeType,
filter = this.filter,
node;
while ( true ) {
node = current.firstChild;
while ( !node && current ) {
if ( current === root ) {
break;
}
node = current.nextSibling;
if ( !node ) { current = current.parentNode; }
}
if ( !node ) {
return null;
}
if ( ( typeToBitArray[ node.nodeType ] & nodeType ) &&
filter( node ) ) {
this.currentNode = node;
return node;
}
current = node;
}
};
TreeWalker.prototype.previousNode = function () {
var current = this.currentNode,
root = this.root,
nodeType = this.nodeType,
filter = this.filter,
node;
while ( true ) {
if ( current === root ) {
return null;
}
node = current.previousSibling;
if ( node ) {
while ( current = node.lastChild ) {
node = current;
}
} else {
node = current.parentNode;
}
if ( !node ) {
return null;
}
if ( ( typeToBitArray[ node.nodeType ] & nodeType ) &&
filter( node ) ) {
this.currentNode = node;
return node;
}
current = node;
}
};
// Previous node in post-order.
TreeWalker.prototype.previousPONode = function () {
var current = this.currentNode,
root = this.root,
nodeType = this.nodeType,
filter = this.filter,
node;
while ( true ) {
node = current.lastChild;
while ( !node && current ) {
if ( current === root ) {
break;
}
node = current.previousSibling;
if ( !node ) { current = current.parentNode; }
}
if ( !node ) {
return null;
}
if ( ( typeToBitArray[ node.nodeType ] & nodeType ) &&
filter( node ) ) {
this.currentNode = node;
return node;
}
current = node;
}
};