@packages/parse-function/README.md
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# parse-function [![npm version][npmv-img]][npmv-url] [![License][license-img]][license-url] [![Libera Manifesto][libera-manifesto-img]][libera-manifesto-url]
> Parse a function into an object using espree, acorn or babylon parsers.
> Extensible through Smart Plugins
Please consider following this project's author,
[Charlike Mike Reagent](https://github.com/tunnckoCore), and :star: the project
to show your :heart: and support.
<div id="readme"></div>
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If you have any _how-to_ kind of questions, please read the [Contributing
Guide][contributing-url] and [Code of Conduct][code_of_conduct-url] documents.
For bugs reports and feature requests, [please create an issue][open-issue-url]
or ping [@tunnckoCore](https://twitter.com/tunnckoCore) at Twitter.
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Project is [semantically](https://semver.org) versioned & automatically released
from [GitHub Actions](https://github.com/features/actions) with
[Lerna](https://github.com/lerna/lerna).
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| Topic | Contact |
| :--------------------------------------------------------------- | ------------------------------------------------: |
| Any legal or licensing questions, like private or commerical use | ![tunnckocore_legal][tunnckocore_legal] |
| For any critical problems and security reports | ![tunnckocore_security][tunnckocore_security] |
| Consulting, professional support, personal or team training | ![tunnckocore_consulting][tunnckocore_consulting] |
| For any questions about Open Source, partnerships and sponsoring | ![tunnckocore_opensource][tunnckocore_opensource] |
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## Features
- **Always up-to-date:** auto-publish new version when new version of dependency
is out, [Renovate](https://renovateapp.com)
- **Standard:** using StandardJS, Prettier, SemVer, Semantic Release and
conventional commits
- **Smart Plugins:** for extending the core API or the end [Result](#result),
see [.use](#use) method and [Plugins Architecture](#plugins-architecture)
- **Extensible:** using plugins for working directly on AST nodes, see the
[Plugins Architecture](#plugins-architecture)
- **ES2020+ Ready:** by using `.parseExpression` method of the Babel `v7.x`
parser
- **Customization:** allows switching the parser, through `options.parse`
- **Support for:** arrow functions, default parameters, generators and
async/await functions
- **Stable:** battle-tested in production and against all parsers - [espree][],
[acorn][], [@babel/parser](https://npmjs.com/packages/@babel/parser)
- **Tested:** with [450+ tests](./test/index.js) for _200%_ coverage
## Table of Contents
- [Install](#install)
- [Which version to use?](#which-version-to-use)
- [Notes](#notes)
- [Throws in one specific case](#throws-in-one-specific-case)
- [Function named _"anonymous"_](#function-named-_anonymous_)
- [Real anonymous function](#real-anonymous-function)
- [Plugins Architecture](#plugins-architecture)
- [API](#api)
- [parseFunction](#parsefunction)
- [.parse](#parse)
- [.use](#use)
- [.define](#define)
- [Contributing](#contributing)
- [Guides and Community](#guides-and-community)
- [Support the project](#support-the-project)
- [Contributors](#contributors)
- [License](#license)
_(TOC generated by [verb](https://github.com/verbose/verb) using
[markdown-toc](https://github.com/jonschlinkert/markdown-toc))_
## Install
This project requires [**Node.js**](https://nodejs.org) **>=8.11** _(see
[Support & Release Policy](https://github.com/tunnckoCoreLabs/support-release-policy))_.
Install it using [**yarn**](https://yarnpkg.com) or
[**npm**](https://npmjs.com).<br> _We highly recommend to use Yarn when you
think to contribute to this project._
```bash
$ yarn add parse-function
```
## Which version to use?
There's no breaking changes between the `v2.x` version. The only breaking is
`v2.1` which also is not working properly, so no use it.
**Use v2.0.x**
When you don't need support for `arrow functions` and `es6 default params`. This
version uses a RegExp expression to work.
**Use v2.2.x**
Only when you need a _basic_ support for `es6 features` like arrow functions.
This version uses a RegExp expression to work.
**Use v2.3.x**
When you want _full\*_ support for `arrow functions` and `es6 default params`.
Where this "full", means "almost full", because it has bugs. This version also
uses (`acorn.parse`) real parser to do the parsing.
**Use v3.x**
When you want to use different parser instead of the default `babylon.parse`, by
passing custom parse function to the `options.parse` option. **From this version
we require `node >= 4`**.
**Use v4.x**
When you want full customization and most stable support for old and modern
features. This version uses `babylon.parseExpression` for parsing and provides a
[Plugins API](#plugins-architecture). See the [Features](#features) section for
more info.
**Use v5.x**
It is basically the same as `v4`, but requires Node 6 & npm 5. Another is
boilerplate stuff.
**[back to top](#readme)**
## Notes
### Throws in one specific case
> _see: [issue #3](https://github.com/tunnckoCore/parse-function/issues/3) and
> [test/index.js#L229-L235](https://github.com/tunnckoCore/parse-function/blob/master/test/index.js#L229-L235)_
It may throw in one specific case, otherwise it won't throw, so you should relay
on the `result.isValid` for sure.
### Function named _"anonymous"_
> _see:
> [test/index.js#L319-L324](https://github.com/tunnckoCore/parse-function/blob/master/test/index.js#L319-L324)
> and [Result](#result) section_
If you pass a function which is named _"anonymous"_ the `result.name` will be
`'anonymous'`, but the `result.isAnonymous` will be `false` and `result.isNamed`
will be `true`, because in fact it's a named function.
### Real anonymous function
> _see:
> [test/index.js#L326-L331](https://github.com/tunnckoCore/parse-function/blob/master/test/index.js#L326-L331)
> and [Result](#result) section_
Only if you pass really an anonymous function you will get `result.name` equal
to `null`, `result.isAnonymous` equal to `true` and `result.isNamed` equal to
`false`.
**[back to top](#readme)**
### Plugins Architecture
> _see: the [.use](#use) method,
> [test/index.js#L305-L317](https://github.com/tunnckoCore/parse-function/blob/master/test/index.js#L305-L317)
> and
> [test/index.js#L396-L414](https://github.com/tunnckoCore/parse-function/blob/master/test/index.js#L396-L414)_
A more human description of the plugin mechanism. Plugins are **synchronous** -
no support and no need for **async** plugins here, but notice that you can do
that manually, because that exact architecture.
The first function that is passed to the [.use](#use) method is used for
extending the core API, for example adding a new method to the `app` instance.
That function is immediately invoked.
```js
const parseFunction = require('parse-function');
const app = parseFunction();
app.use((self) => {
// self is same as `app`
console.log(self.use);
console.log(self.parse);
console.log(self.define);
self.define(self, 'foo', (bar) => bar + 1);
});
console.log(app.foo(2)); // => 3
```
On the other side, if you want to access the AST of the parser, you should
return a function from that plugin, which function is passed with
`(node, result)` signature.
This function is lazy plugin, it is called only when the [.parse](#parse) method
is called.
```js
const parseFunction = require('parse-function');
const app = parseFunction();
app.use((self) => {
console.log('immediately called');
return (node, result) => {
console.log('called only when .parse is invoked');
console.log(node);
console.log(result);
};
});
```
Where **1)** the `node` argument is an object - actual and real AST Node coming
from the parser and **2)** the `result` is an object too - the end
[Result](#result), on which you can add more properties if you want.
**[back to top](#readme)**
## API
<!-- docks-start -->
_Generated using [jest-runner-docs](https://ghub.now.sh/jest-runner-docs)._
### [parseFunction](./src/index.js#L52)
> Initializes with optional `opts` object which is passed directly to the
> desired parser and returns an object with `.use` and `.parse` methods. The
> default parse which is used is [babylon][]'s `.parseExpression` method from
> `v7`.
<span id="parsefunction-signature"></span>
#### Signature
```ts
function(opts = {})
```
<span id="parsefunction-params"></span>
#### Params
- `opts` **{object}** - optional, merged with options passed to `.parse` method
- `returns` **{object}** - app object with `.use` and `.parse` methods
<span id="parsefunction-examples"></span>
#### Examples
```js
const parseFunction = require('parse-function');
const app = parseFunction({
ecmaVersion: 2017,
});
const fixtureFn = (a, b, c) => {
a = b + c;
return a + 2;
};
const result = app.parse(fixtureFn);
console.log(result);
// see more
console.log(result.name); // => null
console.log(result.isNamed); // => false
console.log(result.isArrow); // => true
console.log(result.isAnonymous); // => true
// array of names of the arguments
console.log(result.args); // => ['a', 'b', 'c']
// comma-separated names of the arguments
console.log(result.params); // => 'a, b, c'
```
### [.parse](./src/index.js#L117)
> Parse a given `code` and returns a `result` object with useful properties -
> such as `name`, `body` and `args`. By default it uses Babylon parser, but you
> can switch it by passing `options.parse` - for example
> `options.parse: acorn.parse`. In the below example will show how to use
> `acorn` parser, instead of the default one.
<span id="parse-params"></span>
#### Params
- `code` **{Function|string}** - any kind of function or string to be parsed
- `options` **{object}** - directly passed to the parser babylon, acorn, espree
- `options.parse` **{Function}** - by default `babylon.parseExpression`, all
`options` are passed as second argument
- `returns` **{object}** - result see [result section](#result) for more info
<span id="parse-examples"></span>
#### Examples
```js
const acorn = require('acorn');
const parseFn = require('parse-function');
const app = parseFn();
const fn = function foo(bar, baz) {
return bar * baz;
};
const result = app.parse(fn, {
parse: acorn.parse,
ecmaVersion: 2017,
});
console.log(result.name); // => 'foo'
console.log(result.args); // => ['bar', 'baz']
console.log(result.body); // => ' return bar * baz '
console.log(result.isNamed); // => true
console.log(result.isArrow); // => false
console.log(result.isAnonymous); // => false
console.log(result.isGenerator); // => false
```
### [.use](./src/index.js#L170)
> Add a plugin `fn` function for extending the API or working on the AST nodes.
> The `fn` is immediately invoked and passed with `app` argument which is
> instance of `parseFunction()` call. That `fn` may return another function that
> accepts `(node, result)` signature, where `node` is an AST node and `result`
> is an object which will be returned [result](#result) from the `.parse`
> method. This retuned function is called on each node only when `.parse` method
> is called.
<span id="use-params"></span>
#### Params
- `fn` **{Function}** - plugin to be called
- `returns` **{object}** - app instance for chaining
_See [Plugins Architecture](#plugins-architecture) section._
<span id="use-examples"></span>
#### Examples
```js
// plugin extending the `app`
app.use((app) => {
app.define(app, 'hello', (place) => `Hello ${place}!`);
});
const hi = app.hello('World');
console.log(hi); // => 'Hello World!'
// or plugin that works on AST nodes
app.use((app) => (node, result) => {
if (node.type === 'ArrowFunctionExpression') {
result.thatIsArrow = true;
}
return result;
});
const result = app.parse((a, b) => a + b + 123);
console.log(result.name); // => null
console.log(result.isArrow); // => true
console.log(result.thatIsArrow); // => true
const result = app.parse(function foo() {
return 123;
});
console.log(result.name); // => 'foo'
console.log(result.isArrow); // => false
console.log(result.thatIsArrow); // => undefined
```
### [.define](./src/index.js#L228)
> Define a non-enumerable property on an object. Just a convenience mirror of
> the [define-property][] library, so check out its docs. Useful to be used in
> plugins.
<span id="define-params"></span>
#### Params
- `obj` **{object}** - the object on which to define the property
- `prop` **{string}** - the name of the property to be defined or modified
- `val` **{any}** - the descriptor for the property being defined or modified
- `returns` **{object}** - obj the passed object, but modified
<span id="define-examples"></span>
#### Examples
```js
const parseFunction = require('parse-function');
const app = parseFunction();
// use it like `define-property` lib
const obj = {};
app.define(obj, 'hi', 'world');
console.log(obj); // => { hi: 'world' }
// or define a custom plugin that adds `.foo` property
// to the end result, returned from `app.parse`
app.use((app) => {
return (node, result) => {
// this function is called
// only when `.parse` is called
app.define(result, 'foo', 123);
return result;
};
});
// fixture function to be parsed
const asyncFn = async (qux) => {
const bar = await Promise.resolve(qux);
return bar;
};
const result = app.parse(asyncFn);
console.log(result.name); // => null
console.log(result.foo); // => 123
console.log(result.args); // => ['qux']
console.log(result.isAsync); // => true
console.log(result.isArrow); // => true
console.log(result.isNamed); // => false
console.log(result.isAnonymous); // => true
```
<!-- docks-end -->
**[back to top](#readme)**
## Contributing
### Guides and Community
Please read the [Contributing Guide][contributing-url] and [Code of
Conduct][code_of_conduct-url] documents for advices.
For bug reports and feature requests, please join our [community][community-url]
forum and open a thread there with prefixing the title of the thread with the
name of the project if there's no separate channel for it.
Consider reading the
[Support and Release Policy](https://github.com/tunnckoCoreLabs/support-release-policy)
guide if you are interested in what are the supported Node.js versions and how
we proceed. In short, we support latest two even-numbered Node.js release lines.
### Support the project
[Become a Partner or Sponsor?][kofi-url] :dollar: Check the **OpenSource**
Commision (tier). :tada: You can get your company logo, link & name on this
file. It's also rendered on package's page in [npmjs.com][npmv-url] and
[yarnpkg.com](https://yarnpkg.com/en/package/parse-function) sites too! :rocket:
Not financial support? Okey!
[Pull requests](https://github.com/tunnckoCoreLabs/contributing#opening-a-pull-request),
stars and all kind of
[contributions](https://opensource.guide/how-to-contribute/#what-it-means-to-contribute)
are always welcome. :sparkles:
## Contributors
This project follows the
[all-contributors](https://github.com/all-contributors/all-contributors)
specification. Contributions of any kind are welcome!
Thanks goes to these wonderful people
([emoji key](https://allcontributors.org/docs/en/emoji-key)), consider showing
your [support](#support-the-project) to them:
<!-- ALL-CONTRIBUTORS-LIST:START -->
<!-- prettier-ignore-start -->
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<table>
<tr>
<td align="center"><a href="https://tunnckoCore.com"><img src="https://avatars3.githubusercontent.com/u/5038030?v=4" width="100px;" alt=""/><br /><sub><b>Charlike Mike Reagent</b></sub></a><br /><a href="#infra-tunnckoCore" title="Infrastructure (Hosting, Build-Tools, etc)">🚇</a> <a href="https://github.com/node-formidable/node-formidable/commits?author=tunnckoCore" title="Code">💻</a> <a href="https://github.com/node-formidable/node-formidable/commits?author=tunnckoCore" title="Documentation">📖</a> <a href="#ideas-tunnckoCore" title="Ideas, Planning, & Feedback">🤔</a> <a href="#maintenance-tunnckoCore" title="Maintenance">🚧</a> <a href="https://github.com/node-formidable/node-formidable/commits?author=tunnckoCore" title="Tests">⚠️</a></td>
</tr>
</table>
<!-- markdownlint-enable -->
<!-- prettier-ignore-end -->
<!-- ALL-CONTRIBUTORS-LIST:END -->
**[back to top](#readme)**
## License
Copyright (c) 2016-present, [Charlike Mike Reagent](https://tunnckocore.com)
`<opensource@tunnckocore.com>` & [contributors](#wonderful-contributors).<br>
Released under the [MPL-2.0 License][license-url].
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[contributing-url]: https://github.com/tunnckoCore/opensource/blob/master/CONTRIBUTING.md
[code_of_conduct-url]: https://github.com/tunnckoCore/opensource/blob/master/CODE_OF_CONDUCT.md
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<!-- prettier-ignore-end -->
[acorn]: https://github.com/acornjs/acorn
[babylon]: https://babeljs.io/
[cacache]: https://github.com/npm/cacache
[collect-mentions]: https://github.com/olstenlarck/collect-mentions
[define-property]: https://github.com/jonschlinkert/define-property
[espree]: https://github.com/eslint/espree
[execa]: https://github.com/sindresorhus/execa
[fast-glob]: https://github.com/mrmlnc/fast-glob
[glob]: https://github.com/isaacs/node-glob
[globby]: https://github.com/sindresorhus/globby
[koa-convert]: https://github.com/gyson/koa-convert
[koa]: https://github.com/koajs/koa
[tiny-glob]: https://github.com/terkelg/tiny-glob