https://github.com/mikolalysenko/ancestor-of

Checks if a node is an ancestor of another node in a JSON object
https://github.com/mikolalysenko/ancestor-of

Last synced: 6 days ago
JSON representation

Checks if a node is an ancestor of another node in a JSON object

• Host: GitHub
• URL: https://github.com/mikolalysenko/ancestor-of
• Owner: mikolalysenko
• License: mit
• Created: 2014-03-28T00:26:35.000Z (over 10 years ago)
• Default Branch: master
• Last Pushed: 2014-04-02T14:49:55.000Z (over 10 years ago)
• Last Synced: 2024-12-16T22:34:40.514Z (9 days ago)
• Language: JavaScript
• Size: 145 KB
• Stars: 3
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
ancestor-of

===========

Preprocess a tree (encoded as a JSON object) so that given any two nodes in the tree it is possible to determine whether one is the ancestor of the other. Ancestor queries take O(1) time, and the data structure requres O(n) space and preprocessing time.

# Example

```javascript

var preprocess = require("ancestor-of")

//Construct some tree

var tree = {

  a: {

    x: {},

    y: {}

  },

  b: [ [], [[]] ]

}

//Construct ancestorOf data structure

var ancestorOf = preprocess(tree)

//Now we can check ancestor relations on elements of tree:

var assert = require("assert")

assert.ok(ancestorOf(tree.a, tree.a.x))

assert.ok(!ancestorOf(tree.a.ax, tree.a))

assert.ok(!ancestorOf(tree.b, tree.a))

assert.ok(ancestorOf(tree.b, tree.b[1][0]))

```

# Install

```

npm install ancestor-of

```

# API

### `var ancestorOf = require("ancestor-of")(tree[,childrenOf(node)])`

Preprocesses `tree` to answer ancestor queries.

* `tree` is the root of a JSON object tree

* `childrenOf(node)` is an optional function which returns an array of children of `node`

    + `node` is the subtree node

    `childrenOf` should return an array of all possible children of node

**Returns** A query which answers ancestor queries

### `ancestorOf(a,b)`

Determine if `b` is an ancestor of `a`

* `a` is the first node

* `b` is the node which is tested to be ancestor of `a`

**Returns** `true` if `b` is an ancestor of `a`, otherwise `false`

### `ancestorOf.rebuild()`

Rebuild the data structure if some of the children of `tree` have changed.

# Credits

(c) 2014 Mikola Lysenko. MIT License