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https://github.com/s-leroux/mmoize
Simple cache/single argument memoization library.
https://github.com/s-leroux/mmoize
Last synced: about 1 month ago
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Simple cache/single argument memoization library.
- Host: GitHub
- URL: https://github.com/s-leroux/mmoize
- Owner: s-leroux
- Created: 2018-03-08T12:13:36.000Z (almost 7 years ago)
- Default Branch: master
- Last Pushed: 2022-02-11T00:31:34.000Z (almost 3 years ago)
- Last Synced: 2024-11-20T09:16:56.489Z (about 2 months ago)
- Language: JavaScript
- Size: 47.9 KB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 2
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
mmoize
======
A simple cache/single-argument memoization library.
[](https://travis-ci.org/s-leroux/mmoize)
## Installation
npm install --save mmoize
## API
### const mm = mmoize(fn, [options])
Create a new cache instance.
The first argument is a function used to create missing value from
a key.
* `option.size` is the maximum cache size
* `options.valid({key, value})` a user-defined function invoked after a value has been retrieved from
the cache. If this function returns `true` the cached value is assumed to be still valid. Otherwise, a
new value will be obtained by calling `fn(key)`.
Each invocation of the returned function will produce a _promise_ that will
be fulfilled either by the value in cache _or_ by the value returned by `fn(key)`.
Newly created values are always stored in the cache. If there isn't enough room left,
the least recently used values is discarded.
## Example
### Basic usage
```
const Promise = require('bluebird');
const mmoize = require('mmoize');
const assert = require('assert');
const readFile = Promise.promisify(require("fs").readFile);
let n = 0;
const read = mmoize((key) => { n += 1; return readFile(key, "utf8"); });
// Will actually read the file only once
read("./test/data/a")
.then(console.log)
.then(() => assert.equal(n, 1));
read("./test/data/a")
.then(console.log)
.then(() => assert.equal(n, 1));
read("./test/data/a")
.then(console.log)
.then(() => assert.equal(n, 1));
```
### Concurent access (typically used with promise-returning functions)
```
const Promise = require('bluebird');
const mmoize = require('mmoize');
const readFile = Promise.promisify(require("fs").readFile);
const read = mmoize((key) => readFile(key, "utf8"), {size: 3 });
Promise.all([
read("./test/data/a"),
read("./test/data/a"),
read("./test/data/b"),
read("./test/data/c"),
read("./test/data/d"),
read("./test/data/d"),
read("./test/data/c"),
read("./test/data/b"),
read("./test/data/a"),
]).then(console.log);
```
## Node version
Require NodeJS >= v10.0
Tested with v10.0 and v14.15
## License
(The MIT License)
Copyright (c) 2018 [Sylvain Leroux](mailto:[email protected])
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.