snapdragon-node

Class for creating AST nodes.

Please consider following this project's author, Jon Schlinkert, and consider starring the project to show your :heart: and support.

Install

Install with npm:

1$ npm install --save snapdragon-node

Usage

1const Node = require('snapdragon-node');
2// either pass on object with "type" and (optional) "val"
3const node1 = new Node({type: 'star', val: '*'});
4// or pass "val" (first) and "type" (second) as string
5const node2 = new Node('*', 'star');
6// both result in => Node { type: 'star', val: '*' }

Snapdragon usage

With snapdragon v0.9.0 and higher, it's recommended that you use this.node() to create a new Node inside parser handlers (instead of doing new Node()).

Snapdragon ^1.0.0

Example usage inside a snapdragon parser handler function.

1const Node = require('snapdragon-node');
2const Token = require('snapdragon-token');
3
4// create a new AST node
5const node = new Node({ type: 'star', value: '*' });
6
7// convert a Lexer Token into an AST Node
8const token = new Token({ type: 'star', value: '*' });
9const node = new Node(token);

Node objects

AST Nodes are represented as Node objects that implement the following interface:

1interface Node {
2  type: string;
3  value: string | undefined
4  nodes: array | undefined
5}

• type {string} - A string representing the node variant type. This property is often used for classifying the purpose or nature of the node, so that parsers or compilers can determine what to do with it.
• value {string|undefined} (optional) - In general, value should only be a string when node.nodes is undefined. This is not reinforced, but is considered good practice. Use a different property name to store arbitrary strings on the node when node.nodes is an array.
• nodes {array|undefined} (optional) - array of child nodes

A number of useful methods and non-enumerable properties are also exposed for adding, finding and removing child nodes, etc.

Continue reading the API documentation for more details.

Node API

Node

Create a new AST Node with the given type and value, or an object to initialize with.

Params

• type {object|string}: Either an object to initialize with, or a string to be used as the node.type.
• value {string|boolean}: If the first argument is a string, the second argument may be a string value to set on node.value.
• clone {boolean}: When an object is passed as the first argument, pass true as the last argument to deep clone values before assigning them to the new node.
• returns {Object}: node instance

Example

1console.log(new Node({ type: 'star', value: '*' }));
2console.log(new Node('star', '*'));
3// both result in => Node { type: 'star', value: '*' }

.clone

Return a clone of the node. Values that are arrays or plain objects are deeply cloned.

• returns {Object}: returns a clone of the node

Example

1const node = new Node({type: 'star', value: '*'});
2consle.log(node.clone() !== node);
3//=> true

.stringify

Return a string created from node.value and/or recursively visiting over node.nodes.

• returns {String}

Example

1const node = new Node({type: 'star', value: '*'});
2consle.log(node.stringify());
3//=> '*'

.push

Push a child node onto the node.nodes array.

Params

• node {Object}
• returns {Number}: Returns the length of node.nodes, like Array.push

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3foo.push(bar);

.unshift

Unshift a child node onto node.nodes, and set node as the parent on child.parent.

Params

• node {Object}
• returns {Number}: Returns the length of node.nodes

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3foo.unshift(bar);

.pop

Pop a node from node.nodes.

• returns {Number}: Returns the popped node

Example

1const node = new Node({type: 'foo'});
2node.push(new Node({type: 'a'}));
3node.push(new Node({type: 'b'}));
4node.push(new Node({type: 'c'}));
5node.push(new Node({type: 'd'}));
6console.log(node.nodes.length);
7//=> 4
8node.pop();
9console.log(node.nodes.length);
10//=> 3

.shift

Shift a node from node.nodes.

• returns {Object}: Returns the shifted node

Example

1const node = new Node({type: 'foo'});
2node.push(new Node({type: 'a'}));
3node.push(new Node({type: 'b'}));
4node.push(new Node({type: 'c'}));
5node.push(new Node({type: 'd'}));
6console.log(node.nodes.length);
7//=> 4
8node.shift();
9console.log(node.nodes.length);
10//=> 3

.remove

Remove node from node.nodes.

Params

• node {Object}
• returns {Object}: Returns the removed node.

Example

1node.remove(childNode);

.find

Get the first child node from node.nodes that matches the given type. If type is a number, the child node at that index is returned.

Params

• type {String}
• returns {Object}: Returns a child node or undefined.

Example

1const child = node.find(1); //<= index of the node to get
2const child = node.find('foo'); //<= node.type of a child node
3const child = node.find(/^(foo|bar)$/); //<= regex to match node.type
4const child = node.find(['foo', 'bar']); //<= array of node.type(s)

.has

Returns true if node.nodes array contains the given node.

Params

• type {String}
• returns {Boolean}

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3cosole.log(foo.has(bar)); // false
4foo.push(bar);
5cosole.log(foo.has(bar)); // true

.hasType

Return true if the node.nodes has the given type.

Params

• type {String}
• returns {Boolean}

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3foo.push(bar);
4
5cosole.log(foo.hasType('qux'));          // false
6cosole.log(foo.hasType(/^(qux|bar)$/));  // true
7cosole.log(foo.hasType(['qux', 'bar'])); // true

.isType

Return true if the node is the given type.

Params

• type {String}
• returns {Boolean}

Example

1const node = new Node({type: 'bar'});
2cosole.log(node.isType('foo'));          // false
3cosole.log(node.isType(/^(foo|bar)$/));  // true
4cosole.log(node.isType(['foo', 'bar'])); // true

.isEmpty

Returns true if node.value is an empty string, or node.nodes does not contain any non-empty text nodes.

Params

• fn {Function}: (optional) Filter function that is called on node and/or child nodes. isEmpty will return false immediately when the filter function returns false on any nodes.
• returns {Boolean}

Example

1const node = new Node({type: 'text'});
2node.isEmpty(); //=> true
3node.value = 'foo';
4node.isEmpty(); //=> false

.isInside

Returns true if the node has an ancestor node of the given type

Params

• type {String}
• returns {Boolean}

Example

1const box = new Node({type: 'box'});
2const marble = new Node({type: 'marble'});
3box.push(marble);
4marble.isInside('box'); //=> true

.siblings

Get the siblings array, or null if it doesn't exist.

• returns {Array}

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3const baz = new Node({type: 'baz'});
4foo.push(bar);
5foo.push(baz);
6
7console.log(bar.siblings.length) // 2
8console.log(baz.siblings.length) // 2

.index

Calculate the node's current index on node.parent.nodes, or -1 if the node does not have a parent, or is not on node.parent.nodes.

• returns {Number}

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3const baz = new Node({type: 'baz'});
4const qux = new Node({type: 'qux'});
5foo.push(bar);
6foo.push(baz);
7foo.unshift(qux);
8
9console.log(bar.index) // 1
10console.log(baz.index) // 2
11console.log(qux.index) // 0

.prev

Get the previous node from the siblings array or null.

• returns {Object}

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3const baz = new Node({type: 'baz'});
4foo.push(bar);
5foo.push(baz);
6
7console.log(baz.prev.type) // 'bar'

.next

Get the next element from the siblings array, or null if a next node does not exist.

• returns {Object}

Example

1const parent = new Node({type: 'root'});
2const foo = new Node({type: 'foo'});
3const bar = new Node({type: 'bar'});
4const baz = new Node({type: 'baz'});
5parent.push(foo);
6parent.push(bar);
7parent.push(baz);
8
9console.log(foo.next.type) // 'bar'
10console.log(bar.next.type) // 'baz'

.first

Get the first child node from node.nodes.

• returns {Object}: The first node, or undefiend

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3const baz = new Node({type: 'baz'});
4const qux = new Node({type: 'qux'});
5foo.push(bar);
6foo.push(baz);
7foo.push(qux);
8
9console.log(foo.first.type) // 'bar'

.last

Get the last child node from node.nodes.

• returns {Object}: The last node, or undefiend

Example

1const foo = new Node({type: 'foo'});
2const bar = new Node({type: 'bar'});
3const baz = new Node({type: 'baz'});
4const qux = new Node({type: 'qux'});
5foo.push(bar);
6foo.push(baz);
7foo.push(qux);
8
9console.log(foo.last.type) // 'qux'

.depth

Get the node.depth. The root node has a depth of 0. Add 1 to child nodes for each level of nesting.

• returns {Object}: The last node, or undefiend

Example

1const foo = new Node({type: 'foo'});
2foo.push(bar);
3
4console.log(foo.depth) // 1
5console.log(bar.depth) // 2

Node#isNode

Static method that returns true if the given value is a node.

Params

• node {Object}
• returns {Boolean}

Example

1const Node = require('snapdragon-node');
2const node = new Node({type: 'foo'});
3console.log(Node.isNode(node)); //=> true
4console.log(Node.isNode({})); //=> false

Non-enumerable properties

• node.isNode {boolean} - this value is set to true when a node is created. This can be useful in situationas as a fast alternative to using instanceof Node if you need to determine if a value is a node object.
• node.size {number} - the number of child nodes that have been pushed or unshifted onto node.nodes using the node's API. This is useful for determining if nodes were added to node.nodes without using node.push() or node.unshift() (for example: if (node.nodes && node.size !== node.nodes.length))
• node.parent {object} (instance of Node)

Release history

See the changelog.

About

1$ npm install && npm test

1$ npm install -g verbose/verb#dev verb-generate-readme && verb

Related projects

You might also be interested in these projects:

• breakdance: Breakdance is a node.js library for converting HTML to markdown. Highly pluggable, flexible and easy… more | homepage
• snapdragon-capture: Snapdragon plugin that adds a capture method to the parser instance. | homepage
• snapdragon-cheerio: Snapdragon plugin for converting a cheerio AST to a snapdragon AST. | homepage
• snapdragon-util: Utilities for the snapdragon parser/compiler. | homepage
• snapdragon: Easy-to-use plugin system for creating powerful, fast and versatile parsers and compilers, with built-in source-map… more | homepage

Author

Jon Schlinkert

• GitHub Profile
• Twitter Profile
• LinkedIn Profile

License

Copyright © 2018, Jon Schlinkert. Released under the MIT License.

This file was generated by verb-generate-readme, v0.8.0, on November 24, 2018.