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321 lines
8.7 KiB
321 lines
8.7 KiB
# snapdragon [](https://www.npmjs.com/package/snapdragon) [](https://npmjs.org/package/snapdragon) [](https://travis-ci.org/jonschlinkert/snapdragon)
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> Fast, pluggable and easy-to-use parser-renderer factory.
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## Install
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Install with [npm](https://www.npmjs.com/):
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```sh
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$ npm install --save snapdragon
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```
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Created by [jonschlinkert](https://github.com/jonschlinkert) and [doowb](https://github.com/doowb).
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**Features**
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* Bootstrap your own parser, get sourcemap support for free
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* All parsing and compiling is handled by simple, reusable middleware functions
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* Inspired by the parsers in [pug](http://jade-lang.com) and [css](https://github.com/reworkcss/css).
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## History
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### v0.5.0
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**Breaking changes**
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Substantial breaking changes were made in v0.5.0! Most of these changes are part of a larger refactor that will be finished in 0.6.0, including the introduction of a `Lexer` class.
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* Renderer was renamed to `Compiler`
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* the `.render` method was renamed to `.compile`
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* Many other smaller changes. A more detailed overview will be provided in 0.6.0. If you don't have to time review code, I recommend you wait for the 0.6.0 release.
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## Usage examples
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```js
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var Snapdragon = require('snapdragon');
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var snapdragon = new Snapdragon();
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```
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**Parse**
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```js
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var ast = snapdragon.parser('some string', options)
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// parser middleware that can be called by other middleware
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.set('foo', function () {})
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// parser middleware, runs immediately in the order defined
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.use(bar())
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.use(baz())
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```
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**Render**
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```js
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// pass the `ast` from the parse method
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var res = snapdragon.compiler(ast)
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// compiler middleware, called when the name of the middleware
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// matches the `node.type` (defined in a parser middleware)
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.set('bar', function () {})
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.set('baz', function () {})
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.compile()
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```
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See the [examples](./examples/).
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## Getting started
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**Parsers**
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Parsers are middleware functions used for parsing a string into an ast node.
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```js
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var ast = snapdragon.parser(str, options)
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.use(function() {
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var pos = this.position();
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var m = this.match(/^\./);
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if (!m) return;
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return pos({
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// `type` specifies the compiler to use
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type: 'dot',
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val: m[0]
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});
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})
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```
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**AST node**
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When the parser finds a match, `pos()` is called, pushing a token for that node onto the ast that looks something like:
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```js
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{ type: 'dot',
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val: '.',
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position:
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{ start: { lineno: 1, column: 1 },
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end: { lineno: 1, column: 2 } }}
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```
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**Renderers**
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Renderers are _named_ middleware functions that visit over an array of ast nodes to compile a string.
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```js
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var res = snapdragon.compiler(ast)
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.set('dot', function (node) {
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console.log(node.val)
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//=> '.'
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return this.emit(node.val);
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})
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```
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**Source maps**
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If you want source map support, make sure to emit the position as well.
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```js
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var res = snapdragon.compiler(ast)
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.set('dot', function (node) {
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return this.emit(node.val, node.position);
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})
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```
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## Docs
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### Parser middleware
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A parser middleware is a function that returns an abject called a `token`. This token is pushed onto the AST as a node.
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**Example token**
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```js
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{ type: 'dot',
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val: '.',
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position:
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{ start: { lineno: 1, column: 1 },
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end: { lineno: 1, column: 2 } }}
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```
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**Example parser middleware**
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Match a single `.` in a string:
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1. Get the starting position by calling `this.position()`
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2. pass a regex for matching a single dot to the `.match` method
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3. if **no match** is found, return `undefined`
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4. if a **match** is found, `pos()` is called, which returns a token with:
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- `type`: the name of the [compiler] to use
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- `val`: The actual value captured by the regex. In this case, a `.`. Note that you can capture and return whatever will be needed by the corresponding [compiler].
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- The ending position: automatically calculated by adding the length of the first capture group to the starting position.
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## Renderer middleware
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Renderers are run when the name of the compiler middleware matches the `type` defined on an ast `node` (which is defined in a parser).
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**Example**
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Exercise: Parse a dot, then compile it as an escaped dot.
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```js
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var ast = snapdragon.parser('.')
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.use(function () {
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var pos = this.position();
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var m = this.match(/^\./);
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if (!m) return;
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return pos({
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// define the `type` of compiler to use
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type: 'dot',
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val: m[0]
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})
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})
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var result = snapdragon.compiler(ast)
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.set('dot', function (node) {
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return this.emit('\\' + node.val);
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})
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.compile()
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console.log(result.output);
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//=> '\.'
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```
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## API
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### [Parser](lib/parser.js#L19)
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Create a new `Parser` with the given `input` and `options`.
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**Params**
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* `input` **{String}**
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* `options` **{Object}**
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### [.define](lib/parser.js#L103)
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Define a non-enumberable property on the `Parser` instance.
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**Example**
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```js
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parser.define('foo', 'bar');
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```
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**Params**
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* `key` **{String}**: propery name
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* `val` **{any}**: property value
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* `returns` **{Object}**: Returns the Parser instance for chaining.
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Set parser `name` with the given `fn`
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**Params**
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* `name` **{String}**
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* `fn` **{Function}**
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Get parser `name`
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**Params**
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* `name` **{String}**
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Push a `token` onto the `type` stack.
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**Params**
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* `type` **{String}**
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* `returns` **{Object}** `token`
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Pop a token off of the `type` stack
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**Params**
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* `type` **{String}**
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* `returns` **{Object}**: Returns a token
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Return true if inside a `stack` node. Types are `braces`, `parens` or `brackets`.
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**Params**
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* `type` **{String}**
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* `returns` **{Boolean}**
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**Example**
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```js
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parser.isType(node, 'brace');
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```
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**Params**
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* `node` **{Object}**
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* `type` **{String}**
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* `returns` **{Boolean}**
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### [.define](lib/compiler.js#L71)
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Define a non-enumberable property on the `Compiler` instance.
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**Example**
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```js
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compiler.define('foo', 'bar');
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```
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**Params**
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* `key` **{String}**: propery name
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* `val` **{any}**: property value
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* `returns` **{Object}**: Returns the Compiler instance for chaining.
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## About
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### Related projects
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* [braces](https://www.npmjs.com/package/braces): Fastest brace expansion for node.js, with the most complete support for the Bash 4.3 braces… [more](https://github.com/jonschlinkert/braces) | [homepage](https://github.com/jonschlinkert/braces "Fastest brace expansion for node.js, with the most complete support for the Bash 4.3 braces specification.")
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* [expand-brackets](https://www.npmjs.com/package/expand-brackets): Expand POSIX bracket expressions (character classes) in glob patterns. | [homepage](https://github.com/jonschlinkert/expand-brackets "Expand POSIX bracket expressions (character classes) in glob patterns.")
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* [extglob](https://www.npmjs.com/package/extglob): Convert extended globs to regex-compatible strings. Add (almost) the expressive power of regular expressions to… [more](https://github.com/jonschlinkert/extglob) | [homepage](https://github.com/jonschlinkert/extglob "Convert extended globs to regex-compatible strings. Add (almost) the expressive power of regular expressions to glob patterns.")
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* [micromatch](https://www.npmjs.com/package/micromatch): Glob matching for javascript/node.js. A drop-in replacement and faster alternative to minimatch and multimatch. | [homepage](https://github.com/jonschlinkert/micromatch "Glob matching for javascript/node.js. A drop-in replacement and faster alternative to minimatch and multimatch.")
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### Contributing
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Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
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### Contributors
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| **Commits** | **Contributor**<br/> |
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| --- | --- |
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| 106 | [jonschlinkert](https://github.com/jonschlinkert) |
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| 2 | [doowb](https://github.com/doowb) |
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### Building docs
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_(This document was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme) (a [verb](https://github.com/verbose/verb) generator), please don't edit the readme directly. Any changes to the readme must be made in [.verb.md](.verb.md).)_
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To generate the readme and API documentation with [verb](https://github.com/verbose/verb):
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```sh
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$ npm install -g verb verb-generate-readme && verb
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```
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### Running tests
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Install dev dependencies:
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```sh
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$ npm install -d && npm test
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```
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### Author
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**Jon Schlinkert**
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* [github/jonschlinkert](https://github.com/jonschlinkert)
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* [twitter/jonschlinkert](http://twitter.com/jonschlinkert)
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### License
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Copyright © 2016, [Jon Schlinkert](https://github.com/jonschlinkert).
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Released under the [MIT license](https://github.com/jonschlinkert/snapdragon/blob/master/LICENSE).
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***
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_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.1.31, on October 10, 2016._ |