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# snapdragon-util [![NPM version](https://img.shields.io/npm/v/snapdragon-util.svg?style=flat)](https://www.npmjs.com/package/snapdragon-util) [![NPM monthly downloads](https://img.shields.io/npm/dm/snapdragon-util.svg?style=flat)](https://npmjs.org/package/snapdragon-util) [![NPM total downloads](https://img.shields.io/npm/dt/snapdragon-util.svg?style=flat)](https://npmjs.org/package/snapdragon-util) [![Linux Build Status](https://img.shields.io/travis/jonschlinkert/snapdragon-util.svg?style=flat&label=Travis)](https://travis-ci.org/jonschlinkert/snapdragon-util)

> Utilities for the snapdragon parser/compiler.

<details>
<summary><strong>Table of Contents</strong></summary>

- [Install](#install)
- [Usage](#usage)
- [API](#api)
- [Release history](#release-history)
  * [[3.0.0] - 2017-05-01](#300---2017-05-01)
  * [[0.1.0]](#010)
- [About](#about)

</details>

## Install

Install with [npm](https://www.npmjs.com/):

```sh
$ npm install --save snapdragon-util
```

Install with [yarn](https://yarnpkg.com):

```sh
$ yarn add snapdragon-util
```

## Usage

```js
var util = require('snapdragon-util');
```

## API

### [.isNode](index.js#L21)

Returns true if the given value is a node.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**

**Example**

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

### [.noop](index.js#L37)

Emit an empty string for the given `node`.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{undefined}**

**Example**

```js
// do nothing for beginning-of-string
snapdragon.compiler.set('bos', utils.noop);
```

### [.identity](index.js#L53)

Appdend `node.val` to `compiler.output`, exactly as it was created by the parser.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{undefined}**

**Example**

```js
snapdragon.compiler.set('text', utils.identity);
```

### [.append](index.js#L76)

Previously named `.emit`, this method appends the given `val` to `compiler.output` for the given node. Useful when you know what value should be appended advance, regardless of the actual value of `node.val`.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Function}**: Returns a compiler middleware function.

**Example**

```js
snapdragon.compiler
  .set('i', function(node) {
    this.mapVisit(node);
  })
  .set('i.open', utils.append('<i>'))
  .set('i.close', utils.append('</i>'))
```

### [.toNoop](index.js#L99)

Used in compiler middleware, this onverts an AST node into an empty `text` node and deletes `node.nodes` if it exists. The advantage of this method is that, as opposed to completely removing the node, indices will not need to be re-calculated in sibling nodes, and nothing is appended to the output.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `nodes` **{Array}**: Optionally pass a new `nodes` value, to replace the existing `node.nodes` array.

**Example**

```js
utils.toNoop(node);
// convert `node.nodes` to the given value instead of deleting it
utils.toNoop(node, []);
```

### [.visit](index.js#L128)

Visit `node` with the given `fn`. The built-in `.visit` method in snapdragon automatically calls registered compilers, this allows you to pass a visitor function.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `fn` **{Function}**
* `returns` **{Object}**: returns the node after recursively visiting all child nodes.

**Example**

```js
snapdragon.compiler.set('i', function(node) {
  utils.visit(node, function(childNode) {
    // do stuff with "childNode"
    return childNode;
  });
});
```

### [.mapVisit](index.js#L155)

Map [visit](#visit) the given `fn` over `node.nodes`. This is called by [visit](#visit), use this method if you do not want `fn` to be called on the first node.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `options` **{Object}**
* `fn` **{Function}**
* `returns` **{Object}**: returns the node

**Example**

```js
snapdragon.compiler.set('i', function(node) {
  utils.mapVisit(node, function(childNode) {
    // do stuff with "childNode"
    return childNode;
  });
});
```

### [.addOpen](index.js#L194)

Unshift an `*.open` node onto `node.nodes`.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `Node` **{Function}**: (required) Node constructor function from [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node).
* `filter` **{Function}**: Optionaly specify a filter function to exclude the node.
* `returns` **{Object}**: Returns the created opening node.

**Example**

```js
var Node = require('snapdragon-node');
snapdragon.parser.set('brace', function(node) {
  var match = this.match(/^{/);
  if (match) {
    var parent = new Node({type: 'brace'});
    utils.addOpen(parent, Node);
    console.log(parent.nodes[0]):
    // { type: 'brace.open', val: '' };

    // push the parent "brace" node onto the stack
    this.push(parent);

    // return the parent node, so it's also added to the AST
    return brace;
  }
});
```

### [.addClose](index.js#L244)

Push a `*.close` node onto `node.nodes`.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `Node` **{Function}**: (required) Node constructor function from [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node).
* `filter` **{Function}**: Optionaly specify a filter function to exclude the node.
* `returns` **{Object}**: Returns the created closing node.

**Example**

```js
var Node = require('snapdragon-node');
snapdragon.parser.set('brace', function(node) {
  var match = this.match(/^}/);
  if (match) {
    var parent = this.parent();
    if (parent.type !== 'brace') {
      throw new Error('missing opening: ' + '}');
    }

    utils.addClose(parent, Node);
    console.log(parent.nodes[parent.nodes.length - 1]):
    // { type: 'brace.close', val: '' };

    // no need to return a node, since the parent
    // was already added to the AST
    return;
  }
});
```

### [.wrapNodes](index.js#L274)

Wraps the given `node` with `*.open` and `*.close` nodes.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `Node` **{Function}**: (required) Node constructor function from [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node).
* `filter` **{Function}**: Optionaly specify a filter function to exclude the node.
* `returns` **{Object}**: Returns the node

### [.pushNode](index.js#L299)

Push the given `node` onto `parent.nodes`, and set `parent` as `node.parent.

**Params**

* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Object}**: Returns the child node

**Example**

```js
var parent = new Node({type: 'foo'});
var node = new Node({type: 'bar'});
utils.pushNode(parent, node);
console.log(parent.nodes[0].type) // 'bar'
console.log(node.parent.type) // 'foo'
```

### [.unshiftNode](index.js#L325)

Unshift `node` onto `parent.nodes`, and set `parent` as `node.parent.

**Params**

* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{undefined}**

**Example**

```js
var parent = new Node({type: 'foo'});
var node = new Node({type: 'bar'});
utils.unshiftNode(parent, node);
console.log(parent.nodes[0].type) // 'bar'
console.log(node.parent.type) // 'foo'
```

### [.popNode](index.js#L354)

Pop the last `node` off of `parent.nodes`. The advantage of using this method is that it checks for `node.nodes` and works with any version of `snapdragon-node`.

**Params**

* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Number|Undefined}**: Returns the length of `node.nodes` or undefined.

**Example**

```js
var parent = new Node({type: 'foo'});
utils.pushNode(parent, new Node({type: 'foo'}));
utils.pushNode(parent, new Node({type: 'bar'}));
utils.pushNode(parent, new Node({type: 'baz'}));
console.log(parent.nodes.length); //=> 3
utils.popNode(parent);
console.log(parent.nodes.length); //=> 2
```

### [.shiftNode](index.js#L382)

Shift the first `node` off of `parent.nodes`. The advantage of using this method is that it checks for `node.nodes` and works with any version of `snapdragon-node`.

**Params**

* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Number|Undefined}**: Returns the length of `node.nodes` or undefined.

**Example**

```js
var parent = new Node({type: 'foo'});
utils.pushNode(parent, new Node({type: 'foo'}));
utils.pushNode(parent, new Node({type: 'bar'}));
utils.pushNode(parent, new Node({type: 'baz'}));
console.log(parent.nodes.length); //=> 3
utils.shiftNode(parent);
console.log(parent.nodes.length); //=> 2
```

### [.removeNode](index.js#L409)

Remove the specified `node` from `parent.nodes`.

**Params**

* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Object|undefined}**: Returns the removed node, if successful, or undefined if it does not exist on `parent.nodes`.

**Example**

```js
var parent = new Node({type: 'abc'});
var foo = new Node({type: 'foo'});
utils.pushNode(parent, foo);
utils.pushNode(parent, new Node({type: 'bar'}));
utils.pushNode(parent, new Node({type: 'baz'}));
console.log(parent.nodes.length); //=> 3
utils.removeNode(parent, foo);
console.log(parent.nodes.length); //=> 2
```

### [.isType](index.js#L443)

Returns true if `node.type` matches the given `type`. Throws a `TypeError` if `node` is not an instance of `Node`.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `type` **{String}**
* `returns` **{Boolean}**

**Example**

```js
var Node = require('snapdragon-node');
var node = new Node({type: 'foo'});
console.log(utils.isType(node, 'foo')); // false
console.log(utils.isType(node, 'bar')); // true
```

### [.hasType](index.js#L486)

Returns true if the given `node` has the given `type` in `node.nodes`. Throws a `TypeError` if `node` is not an instance of `Node`.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `type` **{String}**
* `returns` **{Boolean}**

**Example**

```js
var Node = require('snapdragon-node');
var node = new Node({
  type: 'foo',
  nodes: [
    new Node({type: 'bar'}),
    new Node({type: 'baz'})
  ]
});
console.log(utils.hasType(node, 'xyz')); // false
console.log(utils.hasType(node, 'baz')); // true
```

### [.firstOfType](index.js#L519)

Returns the first node from `node.nodes` of the given `type`

**Params**

* `nodes` **{Array}**
* `type` **{String}**
* `returns` **{Object|undefined}**: Returns the first matching node or undefined.

**Example**

```js
var node = new Node({
  type: 'foo',
  nodes: [
    new Node({type: 'text', val: 'abc'}),
    new Node({type: 'text', val: 'xyz'})
  ]
});

var textNode = utils.firstOfType(node.nodes, 'text');
console.log(textNode.val);
//=> 'abc'
```

### [.findNode](index.js#L556)

Returns the node at the specified index, or the first node of the given `type` from `node.nodes`.

**Params**

* `nodes` **{Array}**
* `type` **{String|Number}**: Node type or index.
* `returns` **{Object}**: Returns a node or undefined.

**Example**

```js
var node = new Node({
  type: 'foo',
  nodes: [
    new Node({type: 'text', val: 'abc'}),
    new Node({type: 'text', val: 'xyz'})
  ]
});

var nodeOne = utils.findNode(node.nodes, 'text');
console.log(nodeOne.val);
//=> 'abc'

var nodeTwo = utils.findNode(node.nodes, 1);
console.log(nodeTwo.val);
//=> 'xyz'
```

### [.isOpen](index.js#L584)

Returns true if the given node is an "*.open" node.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**

**Example**

```js
var Node = require('snapdragon-node');
var brace = new Node({type: 'brace'});
var open = new Node({type: 'brace.open'});
var close = new Node({type: 'brace.close'});

console.log(utils.isOpen(brace)); // false
console.log(utils.isOpen(open)); // true
console.log(utils.isOpen(close)); // false
```

### [.isClose](index.js#L607)

Returns true if the given node is a "*.close" node.

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**

**Example**

```js
var Node = require('snapdragon-node');
var brace = new Node({type: 'brace'});
var open = new Node({type: 'brace.open'});
var close = new Node({type: 'brace.close'});

console.log(utils.isClose(brace)); // false
console.log(utils.isClose(open)); // false
console.log(utils.isClose(close)); // true
```

### [.hasOpen](index.js#L633)

Returns true if `node.nodes` **has** an `.open` node

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**

**Example**

```js
var Node = require('snapdragon-node');
var brace = new Node({
  type: 'brace',
  nodes: []
});

var open = new Node({type: 'brace.open'});
console.log(utils.hasOpen(brace)); // false

brace.pushNode(open);
console.log(utils.hasOpen(brace)); // true
```

### [.hasClose](index.js#L663)

Returns true if `node.nodes` **has** a `.close` node

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**

**Example**

```js
var Node = require('snapdragon-node');
var brace = new Node({
  type: 'brace',
  nodes: []
});

var close = new Node({type: 'brace.close'});
console.log(utils.hasClose(brace)); // false

brace.pushNode(close);
console.log(utils.hasClose(brace)); // true
```

### [.hasOpenAndClose](index.js#L697)

Returns true if `node.nodes` has both `.open` and `.close` nodes

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**

**Example**

```js
var Node = require('snapdragon-node');
var brace = new Node({
  type: 'brace',
  nodes: []
});

var open = new Node({type: 'brace.open'});
var close = new Node({type: 'brace.close'});
console.log(utils.hasOpen(brace)); // false
console.log(utils.hasClose(brace)); // false

brace.pushNode(open);
brace.pushNode(close);
console.log(utils.hasOpen(brace)); // true
console.log(utils.hasClose(brace)); // true
```

### [.addType](index.js#L719)

Push the given `node` onto the `state.inside` array for the given type. This array is used as a specialized "stack" for only the given `node.type`.

**Params**

* `state` **{Object}**: The `compiler.state` object or custom state object.
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Array}**: Returns the `state.inside` stack for the given type.

**Example**

```js
var state = { inside: {}};
var node = new Node({type: 'brace'});
utils.addType(state, node);
console.log(state.inside);
//=> { brace: [{type: 'brace'}] }
```

### [.removeType](index.js#L759)

Remove the given `node` from the `state.inside` array for the given type. This array is used as a specialized "stack" for only the given `node.type`.

**Params**

* `state` **{Object}**: The `compiler.state` object or custom state object.
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Array}**: Returns the `state.inside` stack for the given type.

**Example**

```js
var state = { inside: {}};
var node = new Node({type: 'brace'});
utils.addType(state, node);
console.log(state.inside);
//=> { brace: [{type: 'brace'}] }
utils.removeType(state, node);
//=> { brace: [] }
```

### [.isEmpty](index.js#L788)

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

**Params**

* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `fn` **{Function}**
* `returns` **{Boolean}**

**Example**

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

### [.isInsideType](index.js#L833)

Returns true if the `state.inside` stack for the given type exists and has one or more nodes on it.

**Params**

* `state` **{Object}**
* `type` **{String}**
* `returns` **{Boolean}**

**Example**

```js
var state = { inside: {}};
var node = new Node({type: 'brace'});
console.log(utils.isInsideType(state, 'brace')); //=> false
utils.addType(state, node);
console.log(utils.isInsideType(state, 'brace')); //=> true
utils.removeType(state, node);
console.log(utils.isInsideType(state, 'brace')); //=> false
```

### [.isInside](index.js#L867)

Returns true if `node` is either a child or grand-child of the given `type`, or `state.inside[type]` is a non-empty array.

**Params**

* `state` **{Object}**: Either the `compiler.state` object, if it exists, or a user-supplied state object.
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `type` **{String}**: The `node.type` to check for.
* `returns` **{Boolean}**

**Example**

```js
var state = { inside: {}};
var node = new Node({type: 'brace'});
var open = new Node({type: 'brace.open'});
console.log(utils.isInside(state, open, 'brace')); //=> false
utils.pushNode(node, open);
console.log(utils.isInside(state, open, 'brace')); //=> true
```

### [.last](index.js#L915)

Get the last `n` element from the given `array`. Used for getting
a node from `node.nodes.`

**Params**

* `array` **{Array}**
* `n` **{Number}**
* `returns` **{undefined}**

### [.arrayify](index.js#L935)

Cast the given `val` to an array.

**Params**

* `val` **{any}**
* `returns` **{Array}**

**Example**

```js
console.log(utils.arraify(''));
//=> []
console.log(utils.arraify('foo'));
//=> ['foo']
console.log(utils.arraify(['foo']));
//=> ['foo']
```

### [.stringify](index.js#L948)

Convert the given `val` to a string by joining with `,`. Useful
for creating a cheerio/CSS/DOM-style selector from a list of strings.

**Params**

* `val` **{any}**
* `returns` **{Array}**

### [.trim](index.js#L961)

Ensure that the given value is a string and call `.trim()` on it,
or return an empty string.

**Params**

* `str` **{String}**
* `returns` **{String}**

## Release history

Changelog entries are classified using the following labels from [keep-a-changelog](https://github.com/olivierlacan/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.

### [3.0.0] - 2017-05-01

**Changed**

* `.emit` was renamed to [.append](#append)
* `.addNode` was renamed to [.pushNode](#pushNode)
* `.getNode` was renamed to [.findNode](#findNode)
* `.isEmptyNodes` was renamed to [.isEmpty](#isEmpty): also now works with `node.nodes` and/or `node.val`

**Added**

* [.identity](#identity)
* [.removeNode](#removeNode)
* [.shiftNode](#shiftNode)
* [.popNode](#popNode)

### [0.1.0]

First release.

## About

### Contributing

Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).

Please read the [contributing guide](.github/contributing.md) for advice on opening issues, pull requests, and coding standards.

### Building docs

_(This project's readme.md is generated by [verb](https://github.com/verbose/verb-generate-readme), please don't edit the readme directly. Any changes to the readme must be made in the [.verb.md](.verb.md) readme template.)_

To generate the readme, run the following command:

```sh
$ 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:

```sh
$ npm install && npm test
```

### Author

**Jon Schlinkert**

* [github/jonschlinkert](https://github.com/jonschlinkert)
* [twitter/jonschlinkert](https://twitter.com/jonschlinkert)

### License

Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
Released under the [MIT License](LICENSE).

***

_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on May 01, 2017._