Tree Filter

A stateful binary expression tree for set algebra. Nodes in the tree are Node.js EventEmitters, providing granular control of each part of the expression. Nodes representing an operation cache their result set, and re-cache their result when their child nodes change.

Install

$ npm install tree-filter

Use

var Filter = require('tree-filter');
 
var filter = new Filter();
var node = filter.add(['one', 'two', 'three']);
filter.add(['two', 'three', 'four']);
var resultSet = filter.results()
// returns the intersection by default: `['two', 'three']`
 
filter.remove(node);
filter.results();  // returns `['two', 'three', 'four']`

API

TreeFilter()

Construct an empty expression tree. The tree is an EvenEmitter and emits 'change' events if the expression changes.

add(array set [string operation])

Add the given set to the tree, using operation. Operations for now are only 'intersect'or 'union'. Operations can be referenced as properties on a filter instance: filterInstance.ops.intersect.

Returns LeafNode -- the tree node that was created for this set. This is a Node.js EvenEmitter, emitting a 'destroy' event.

removeNode(Node Node)

Remove the given Node from the tree. A Node is an instance of Node, returned by calling TreeFilter.add. Removing a node will update the results of the expression and emit a 'change' event on the tree instance.

results()

Returns the set that results from computing the expression, or false if the expression is empty.

Returns Array