Posted on 2007-01-07 14:37
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Flex 、
Flex2
这个函数只是一个示例函数，演示如何遍历一个Tree。
此函数严格说起来其实是两个函数：上半部分用于回溯父节点，下半部分递归遍历子节点
/**
* This method will traverse a Tree's model independent of it's
* type.
*
* <p>Note :: This method may look long and arduous but, rest assured
* it has all the checks to perform like a champ. Also, you 'could'
* refactor part of this method but, for the sake of explanation, I
* kept it all in one place.</p>
*
* <p>Remember, I had coupled the model to this method by tracing
* @label, obviously you do not need to do this. The intention of
* this example is to show you that the dataDescriptor seperates
* the models type and is awesome. It enables you to create a tight
* method like this without type checks on the model.</p>
*
* @param tree The Tree instance that will be examined by the method.
* @param item An item found in the dataProvider of the Tree passed in.
* @param startAtParent A boolean that determines if the method upon
* initialization will back up one leve3l to the item passed in and
* start it's recursion at the item's parent node.
*/
public
function walkTree
(tree:Tree, item:
Object, startAtParent:
Boolean =
false):
void{ // get the Tree's data descriptor var descriptor:ITreeDataDescriptor = tree.
dataDescriptor;
var cursor:IViewCursor;
var parentItem:
Object;
var childItem:
Object;
var childItems:
Object;
// if the item is null, stop if(item ==
null) return;
// do we back up one level to the item's parent if(startAtParent
) { // get the parent parentItem = tree.
getParentItem(item
);
// is the parent real if(parentItem
) { trace("|-- Parent Node ", parentItem
[tree.
labelField]);
// if the parent is a branch if(descriptor.
isBranch(parentItem
)) { // if the branch has children to run through if(descriptor.
hasChildren(parentItem
)) { // get the children of the branch // this part of the algorithm contains the item // passed childItems = descriptor.
getChildren(parentItem
);
} } // if the branch has valid child items if(childItems
) { // create our back step cursor cursor = childItems.
createCursor();
// loop through the items parent's children (item) while(!cursor.
afterLast) { // get the current child item childItem = cursor.
current;
var label:String = childItem[tree.labelField];
var branch:Boolean = descriptor.isBranch(childItem);
// good place for a custom method()
trace("Sibling Nodes :: ", label, "Is Branch :: ", branch);
// if the child item is a branch
if(descriptor.isBranch(childItem))
// traverse the childs branch all the way down
// before returning
walkTree(tree, childItem);
// do it again!
cursor.moveNext();
}
}
}
}
else// we don't want the parent OR this is the second iteration
{
// if we are a branch
if(descriptor.isBranch(item))
{
// if the branch has children to run through
if(descriptor.hasChildren(item))
{
// get the children of the branch
childItems = descriptor.getChildren(item);
}
// if the child items exist
if(childItems)
{
// create our cursor pointer
cursor = childItems.createCursor();
// loop through all of the children
// if one of these children are a branch we will recurse
while(!cursor.afterLast)
{
// get the current child item
childItem = cursor.current;
var label:String = childItem[tree.labelField];
var branch:Boolean = descriptor.isBranch(childItem);
// good place for a custom method()
trace("-- Sub Node :: ", label, "Is Branch :: ", branch);
// if the child item is a branch
if(descriptor.isBranch(childItem))
// traverse the childs branch all the way down
// before returning
walkTree(tree, childItem);
// check the next child
cursor.moveNext();
}
}
}
}
}