# gulp-cache

[![NPM version][npm]][npm-url]
[![Node version][node]][node-url]
[![Dependency status][deps]][deps-url]
[![Build status][build]][build-url]
[![Coverage status][coverage]][coverage-url]

[npm]: https://img.shields.io/npm/v/gulp-cache.svg
[npm-url]: https://www.npmjs.com/package/gulp-cache

[node]: https://img.shields.io/node/v/gulp-cache.svg
[node-url]: https://nodejs.org

[deps]: https://img.shields.io/david/jgable/gulp-cache.svg
[deps-url]: https://david-dm.org/jgable/gulp-cache

[build]: https://travis-ci.org/jgable/gulp-cache.svg?branch=master
[build-url]: https://travis-ci.org/jgable/gulp-cache

[coverage]: https://img.shields.io/coveralls/jgable/gulp-cache.svg
[coverage-url]: https://coveralls.io/r/jgable/gulp-cache

A temp file based caching proxy task for [gulp](http://gulpjs.com/).

## Install

```bash
npm i -D gulp-cache
# or
yarn add -D gulp-cache
```

## API

### `gulpCachePlugin(gulpPluginToCache, options?)`

#### `gulpPluginToCache`

Target plugin, the output of which will be cached.

#### `options`

Options for `gulp-cache` plugin.

##### `options.fileCache`

> [Optional] Where to store the cache objects

- Defaults to `new Cache({ cacheDirName: 'gulp-cache' })`

- Create your own with [`new cache.Cache({ cacheDirName: 'custom-cache' })`](https://github.com/jgable/cache-swap)

##### `options.name`

> [Optional] The name of the bucket which stores the cached objects

- Defaults to `default`

##### `options.key`

> [Optional] What to use to determine the uniqueness of an input file for this task.

- Can return a string or a `Promise` that resolves to a string.  

- The result of this method is converted to a unique MD5 hash automatically; no need to do this yourself.

- Defaults to `file.contents` if a Buffer, or `undefined` if a Stream.

##### `options.success`

> [Optional] How to determine if the resulting file was successful.

- Must return a truthy value that is used to determine whether to cache the result of the task. `Promise` is supported.

- Defaults to true, so any task results will be cached.

##### `options.value`

> [Optional] What to store as the cached result of the task.

- Can be a function that returns an Object or a `Promise` that resolves to an Object.

- Can also be set to a string that will be picked of the task result file.

- The result of this method is run through `JSON.stringify` and stored in a temp file for later retrieval.

- Defaults to `'contents'` which will grab the resulting file.contents and store them as a string.

## Usage examples

### Simple

```js
import gulp from 'gulp';
import favicons from 'gulp-favicons';
import srcset from 'gulp-srcset';
import cache from 'gulp-cache';

gulp.task('favicon', () =>
    gulp.src('src/favicon.svg')
        .pipe(cache(
            // Target plugin, the output of which will be cached.
            favicons(faviconsConfig),
            // Options for `gulp-cache` plugin.
            {
                // Bucket to store favicons in cache.
                name: 'favicons'
            }
        ))
        .pipe(gulp.dest('./favicons'))
);

gulp.task('images', () =>
    gulp.src('src/**/*.{jpg,png,svg}')
        .pipe(cache(
            // Target plugin, the output of which will be cached.
            srcset(srcsetRules),
            // Options for `gulp-cache` plugin.
            {
                // Bucket to store images in cache.
                name: 'images'
            }
        ))
        .pipe(gulp.dest('./images'))
);
```

### Complex

```js
import fs from 'fs';
import gulp from 'gulp';
import jshint from 'gulp-jshint';
import cache from 'gulp-cache';

const jsHintVersion = '2.4.1';
const jshintOptions = fs.readFileSync('.jshintrc');

function makeHashKey(file) {
    // Key off the file contents, jshint version and options
    return `${file.contents.toString('utf8')}${jshintVersion}${jshintOptions}`;
}

gulp.task('lint', () =>
    gulp.src('src/**/*.js')
        .pipe(cache(
            // Target plugin, the output of which will be cached.
            jshint('.jshintrc'),
            // Options for `gulp-cache` plugin.
            {
                key: makeHashKey,
                // What on the result indicates it was successful
                success(jshintedFile) {
                    return jshintedFile.jshint.success;
                },
                // What to store as the result of the successful action
                value(jshintedFile) {
                    // Will be extended onto the file object on a cache hit next time task is ran
                    return {
                        jshint: jshintedFile.jshint
                    };
                }
            }
        ))
        .pipe(jshint.reporter('default'))
});
```

## Clearing the cache

If you find yourself needing to clear the cache, there is a handy dandy `cache.clearAll()` method:

```js
import cache from 'gulp-cache';

gulp.task('clear', () =>
    cache.clearAll()
);
```

You can then run it with `gulp clear`.

## One-to-many caching

To support one-to-many caching in Your Gulp-plugin, you should:

* Use `clone` method, to save `_cachedKey` property:
```js
const outputFile1 = inputFile.clone({ contents: false });
const outputFile2 = inputFile.clone({ contents: false });

outputFile1.contents = new Buffer(...);
outputFile2.contents = new Buffer(...);

const outputFiles = [
    outputFile1,
    outputFile2,
    ...
];
```
* Or, do it manually:
```js
const outputFiles = [
    new Vinyl({..., _cachedKey: inputFile._cachedKey}),
    new Vinyl({..., _cachedKey: inputFile._cachedKey}),
    ...
];
```

## License

[The MIT License (MIT)](./LICENSE)

Copyright (c) 2014 - 2017 [Jacob Gable](http://jacobgable.com)