66 lines
1.7 KiB
Markdown
66 lines
1.7 KiB
Markdown
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# lru-queue
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## Size limited queue based on [LRU](http://en.wikipedia.org/wiki/Least_Recently_Used#LRU) algorithm
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_Originally derived from [memoizee](https://github.com/medikoo/memoize) package._
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It's low-level utility meant to be used internally within cache algorithms. It backs up [`max`](https://github.com/medikoo/memoize#limiting-cache-size) functionality in [memoizee](https://github.com/medikoo/memoize) project.
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### Installation
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$ npm install lru-queue
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To port it to Browser or any other (non CJS) environment, use your favorite CJS bundler. No favorite yet? Try: [Browserify](http://browserify.org/), [Webmake](https://github.com/medikoo/modules-webmake) or [Webpack](http://webpack.github.io/)
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### Usage
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Create queue, and provide a limit
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```javascript
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var lruQueue = require('lru-queue');
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var queue = lruQueue(3); // limit size to 3
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```
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Each queue exposes three methods:
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#### queue.hit(id)
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Registers hit for given _id_ (must be plain string).
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```javascript
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queue.hit('raz'); // size: 1
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```
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If hit doesn't remove any old item from list it returns `undefined`, otherwise it returns removed _id_.
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```javascript
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queue.hit('dwa'); // undefined, size: 2
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queue.hit('trzy'); // undefined, size: 3 (at max)
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queue.hit('raz'); // undefined, size: 3 (at max)
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queue.hit('dwa'); // undefined, size: 3 (at max)
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queue.hit('cztery'); // 'trzy', size: 3 (at max)
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```
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#### queue.delete(id);
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_id's_ can be cleared from queue externally
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```javascript
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queue.delete('raz'); // size: 2
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queue.delete('cztery'); // size: 1
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```
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#### queue.clear();
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Resets queue
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```javascript
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queue.clear(); // size: 0
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```
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### Tests [](https://travis-ci.org/medikoo/lru-queue)
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$ npm test
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