137 lines
3 KiB
Markdown
137 lines
3 KiB
Markdown
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# Multimap - Map which Allow Multiple Values for the same Key
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[](http://badge.fury.io/js/multimap)
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[](https://travis-ci.org/villadora/multi-map)
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## Install
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```bash
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npm install multimap --save
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```
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## Usage
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If you'd like to use native version when it exists and fallback to polyfill if it doesn't, but without implementing `Map` on global scope, do:
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```javascript
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var Multimap = require('multimap');
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var m = new Multimap();
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```
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If the global es6 `Map` exists or `Multimap.Map` is set, `Multimap` will use the `Map` as inner store, that means Object can be used as key.
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```javascript
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var Multimap = require('multimap');
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// if harmony is on
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/* nothing need to do */
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// or if you are using es6-shim
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Multimap.Map = ShimMap;
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var m = new Multimap();
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var key = {};
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m.set(key, 'one');
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```
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Otherwise, an object will be used, all the keys will be transformed into string.
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### In Modern Browser
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Just download the `index.js` as `Multimap.js`.
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```
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<script src=Multimap.js"></script>
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<script>
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var map = new Multimap([['a', 1], ['b', 2], ['c', 3]]);
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map = map.set('b', 20);
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map.get('b'); // [2, 20]
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</script>
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```
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Or use as an AMD loader:
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```
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require(['./Multimap.js'], function (Multimap) {
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var map = new Multimap([['a', 1], ['b', 2], ['c', 3]]);
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map = map.set('b', 20);
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map.get('b'); // [2, 20]
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});
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```
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* Browsers should support `Object.defineProperty` and `Array.prototype.forEach`.
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## API
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Following shows how to use `Multimap`:
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```javascript
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var Multimap = require('multimap');
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var map = new Multimap([['a', 'one'], ['b', 1], ['a', 'two'], ['b', 2]]);
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map.size; // 4
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map.count; // 2
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map.get('a'); // ['one', 'two']
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map.get('b'); // [1, 2]
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map.has('a'); // true
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map.has('foo'); // false
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map.has('a', 'one'); // true
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map.has('b', 3); // false
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map.set('a', 'three');
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map.size; // 5
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map.count; // 2
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map.get('a'); // ['one', 'two', 'three']
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map.set('b', 3, 4);
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map.size; // 7
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map.count; // 2
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map.delete('a', 'three'); // true
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map.delete('x'); // false
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map.delete('a', 'four'); // false
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map.delete('b'); // true
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map.size; // 2
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map.count; // 1
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map.set('b', 1, 2);
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map.size; // 4
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map.count; // 2
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map.forEach(function (value, key) {
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// iterates { 'one', 'a' }, { 'two', 'a' }, { 1, b }, { 2, 'b' }
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});
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map.forEachEntry(function (entry, key) {
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// iterates {['one', 'two'], 'a' }, {[1, 2], 'b' }
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});
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var keys = map.keys(); // iterator with ['a', 'b']
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keys.next().value; // 'a'
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var values = map.values(); // iterator ['one', 'two', 1, 2]
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map.clear(); // undefined
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map.size; // 0
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map.count; // 0
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```
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## License
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(The MIT License)
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Copyright (c) 2013, Villa.Gao <jky239@gmail.com>;
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All rights reserved.
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