snapdragon-node

What is snapdragon-node?

The snapdragon-node npm package is a utility for creating, visiting, and manipulating AST (Abstract Syntax Tree) nodes. It is commonly used in conjunction with other libraries to parse and transform code or data structures.

What are snapdragon-node's main functionalities?

Creating Nodes

This feature allows you to create new AST nodes. In this example, a new node of type 'text' with the value 'Hello, world!' is created.

const Node = require('snapdragon-node');
const node = new Node({ type: 'text', value: 'Hello, world!' });
console.log(node);

Visiting Nodes

This feature allows you to visit nodes of a specific type within an AST. In this example, all 'text' nodes within the root node are visited, and their values are logged.

const Node = require('snapdragon-node');
const visit = require('snapdragon-visit');
const node = new Node({ type: 'root', nodes: [new Node({ type: 'text', value: 'Hello' }), new Node({ type: 'text', value: 'World' })] });
visit(node, 'text', (node) => console.log(node.value));

Manipulating Nodes

This feature allows you to manipulate existing nodes. In this example, the value of a 'text' node is changed from 'Hello' to 'Hello, world!'.

const Node = require('snapdragon-node');
const node = new Node({ type: 'text', value: 'Hello' });
node.value = 'Hello, world!';
console.log(node);

Other packages similar to snapdragon-node

unist

Unist (Universal Syntax Tree) is a project that provides a set of specifications for syntax trees. It is similar to snapdragon-node in that it deals with ASTs, but it is more focused on providing a universal format for different types of syntax trees.

babel-types

Babel-types is a utility library for AST nodes used by Babel. It provides methods for building, validating, and converting AST nodes. It is similar to snapdragon-node but is more specialized for use with Babel's ecosystem.

README

snapdragon-node

Snapdragon utility for creating a new AST node in custom code, such as plugins.

Install

Install with npm:

$ npm install --save snapdragon-node

Usage

With snapdragon v0.9.0 and higher you can use this.node() to create a new Node, whenever it makes sense.

var Node = require('snapdragon-node');
var Snapdragon = require('snapdragon');
var snapdragon = new Snapdragon();

// example usage inside a parser visitor function
snapdragon.parser.set('foo', function() {
  // get the current "start" position
  var pos = this.position();

  // returns the match if regex matches the substring 
  // at the current position on `parser.input`
  var match = this.match(/foo/);
  if (match) {
    // call "pos" on the node, to set the start and end 
    // positions, and return the node to push it onto the AST
    // (snapdragon will push the node onto the correct
    // nodes array, based on the stack)
    return pos(new Node({type: 'bar', val: match[0]}));
  }
});

API

Node

Create a new AST Node with the given val and type.

Params

• val {String|Object}: Pass a matched substring, or an object to merge onto the node.
• type {String}: The node type to use when val is a string.
• returns {Object}: node instance

Example

var node = new Node('*', 'Star');
var node = new Node({type: 'star', val: '*'});

.isNode

Returns true if the given value is a node.

Params

• node {Object}
• returns {Boolean}

Example

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

.define

Define a non-enumberable property on the node instance. Useful for adding properties that shouldn't be extended or visible during debugging.

Params

• name {String}
• val {any}
• returns {Object}: returns the node instance

Example

var node = new Node();
node.define('foo', 'something non-enumerable');

.isEmpty

Returns true if node.val 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

var node = new Node({type: 'text'});
node.isEmpty(); //=> true
node.val = 'foo';
node.isEmpty(); //=> false

.push

Given node foo and node bar, push node bar onto foo.nodes, and set foo as bar.parent.

Params

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

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
foo.push(bar);

.unshift

Given node foo and node bar, unshift node bar onto foo.nodes, and set foo as bar.parent.

Params

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

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
foo.unshift(bar);

.pop

Pop a node from node.nodes.

• returns {Number}: Returns the popped node

Example

var node = new Node({type: 'foo'});
node.push(new Node({type: 'a'}));
node.push(new Node({type: 'b'}));
node.push(new Node({type: 'c'}));
node.push(new Node({type: 'd'}));
console.log(node.nodes.length);
//=> 4
node.pop();
console.log(node.nodes.length);
//=> 3

.shift

Shift a node from node.nodes.

• returns {Object}: Returns the shifted node

Example

var node = new Node({type: 'foo'});
node.push(new Node({type: 'a'}));
node.push(new Node({type: 'b'}));
node.push(new Node({type: 'c'}));
node.push(new Node({type: 'd'}));
console.log(node.nodes.length);
//=> 4
node.shift();
console.log(node.nodes.length);
//=> 3

.remove

Remove node from node.nodes.

Params

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

Example

node.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

var child = node.find(1); //<= index of the node to get
var child = node.find('foo');
var child = node.find(/^(foo|bar)$/);
var child = node.find(['foo', 'bar']);

.isType

Return true if the node is the given type.

Params

• type {String}
• returns {Boolean}

Example

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

.hasType

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

Params

• type {String}
• returns {Boolean}

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
foo.push(bar);

cosole.log(foo.hasType('qux'));          // false
cosole.log(foo.hasType(/^(qux|bar)$/));  // true
cosole.log(foo.hasType(['qux', 'bar'])); // true

• returns {Array}

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
var baz = new Node({type: 'baz'});
foo.push(bar);
foo.push(baz);

console.log(bar.siblings.length) // 2
console.log(baz.siblings.length) // 2

• returns {Number}

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
var baz = new Node({type: 'baz'});
var qux = new Node({type: 'qux'});
foo.push(bar);
foo.push(baz);
foo.unshift(qux);

console.log(bar.index) // 1
console.log(baz.index) // 2
console.log(qux.index) // 0

• returns {Object}

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
var baz = new Node({type: 'baz'});
foo.push(bar);
foo.push(baz);

console.log(baz.prev.type) // 'bar'

• returns {Object}

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
var baz = new Node({type: 'baz'});
foo.push(bar);
foo.push(baz);

console.log(bar.siblings.length) // 2
console.log(baz.siblings.length) // 2

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

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
var baz = new Node({type: 'baz'});
var qux = new Node({type: 'qux'});
foo.push(bar);
foo.push(baz);
foo.push(qux);

console.log(foo.first.type) // 'bar'

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

Example

var foo = new Node({type: 'foo'});
var bar = new Node({type: 'bar'});
var baz = new Node({type: 'baz'});
var qux = new Node({type: 'qux'});
foo.push(bar);
foo.push(baz);
foo.push(qux);

console.log(foo.last.type) // 'qux'

Release history

Changelog entries are classified using the following labels from keep-a-changelog:

• added: for new features
• changed: for changes in existing functionality
• deprecated: for once-stable features removed in upcoming releases
• removed: for deprecated features removed in this release
• fixed: for any bug fixes

Custom labels used in this changelog:

• dependencies: bumps dependencies
• housekeeping: code re-organization, minor edits, or other changes that don't fit in one of the other categories.

[2.0.0] - 2017-05-01

Changed

• .unshiftNode was renamed to .unshift
• .pushNode was renamed to .push
• .getNode was renamed to .find

Added

• .isNode
• .isEmpty
• .pop
• .shift
• .remove

[0.1.0]

First release.

About

Related 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

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Please read the contributing guide for advice on opening issues, pull requests, and coding standards.

Building docs

(This project's readme.md is generated by verb, please don't edit the readme directly. Any changes to the readme must be made in the .verb.md readme template.)

To generate the readme, run the following command:

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

Running tests

Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:

$ npm install && npm test

Author

Jon Schlinkert

• github/jonschlinkert
• twitter/jonschlinkert

License

Copyright © 2017, Jon Schlinkert. Released under the MIT License.

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This file was generated by verb-generate-readme, v0.6.0, on May 01, 2017.