composite-map

composite-map

A module for mapping between multi-part keys and values

Install

npm install composite-map

Usage

const { CompositeMap } = require("composite-map");
const map = new CompositeMap();
map.set(["one", 2, true], "test-value");
map.get(["one", 2, true]);
//=> 'test-value'

API

new CompositeMap([entries, [options]])

entries

Type: CompositeMap Array

Elements to populate the map with. Array inputs must be in the same form as those created by the CompositeMap.prototype.toJSON() method.

const map1 = new CompositeMap();
const map2 = new CompositeMap(map1);
const map3 = new CompositeMap([["one", "test-value"], ["two", "test-value-2"]], { keyLength: 1 });
const map4 = new CompositeMap([["one", [[2, "test-value"]]]], { keyLength: 2 });
const map5 = new CompositeMap([["one", [[2, [[true, "test-value"]]]]]], { keyLength: 3 });

options

Type: Object

copy

Type: "on-write" "keys"
Default: "keys"

Determines when the keys for the provided CompositeMap are copied.

"on-write"

Copy keys as changes are made.

"keys"

Copy all keys immediately.

keyLength

Type: number

Manually specify the length of keys. Only used when constructing using an array of elements.

CompositeMap.prototype.clear()

Removes all key/value pairs from the CompositeMap object.

CompositeMap.prototype.delete(key)

Returns true if an element in the CompositeMap object existed and has been removed, or false if the element does not exist.

key

Type: Array

The key of the element to be deleted. Shorter keys will delete all elements with matching keys.

CompositeMap.prototype.entries()

Returns a new Iterator object that contains an array of [key, value] for each element in the CompositeMap object.

CompositeMap.prototype.forEach(callbackFn)

Calls callbackFn once for each key-value pair present in the CompositeMap object.

CompositeMap.prototype.get(key)

Returns the value associated to the key, or undefined if there is none.

key

Type: Array

The key of the element to be returned. Shorter keys will return the Map object associated to the key if one exists.

CompositeMap.prototype.has(key)

Returns a boolean asserting whether a value has been associated to the key in the CompositeMap object or not.

key

Type: Array

The key of the element to be found. Shorter keys will find any elements with matching keys.

CompositeMap.prototype.keys()

Returns a new Iterator object that contains the keys for each element in the CompositeMap object.

CompositeMap.prototype.set(key, value)

Sets the value of the key in the CompositeMap object. Returns the CompositeMap object.

key

Type: Array

The key to set the value for. All keys must have the same Array length.

value

Type: any

The value to store.

CompositeMap.prototype.toJSON()

Returns a tree-like Array structure containing all elements in the CompositeMap object.

const map = new CompositeMap();
map.set(["one", 2, true], "test-value");
const json = JSON.stringify(map);
console.log(json);
//=>[["one", [[2, [[true, "test-value"]]]]]]
const map2 = new CompositeMap(JSON.parse(json), { keyLength: 3 });

CompositeMap.prototype.values()

Returns a new Iterator object that contains the values for each element in the CompositeMap object.

CompositeMap.prototype[@@iterator]()

Returns a new Iterator object that contains an array of [key, value] for each element in the CompositeMap object.

TypeScript

To provide better typing support, you can import copies of the CompositeMap class typed for the length of key being used.

import { CompositeMap3 } from "composite-map";
const map = new CompositeMap3<string, number, boolean, string>();
map.set(["one", 2, true], "test-value");
const value: string = map.get(["one", 2, true]);
const subMap: Map<boolean, string> = map.get(["one", 2]);

Related

• composite-object - A module for mapping between multi-part string keys and values.
• json-key-map - A module for mapping between JSON keys and values.

License

MIT

Sources

Some text from this readme was sourced from developer.mozilla.org.

Changelog

1.1.0 (2019-02-03)

• bugfix: Removed copy "reference" option.
• bugfix: Clear method when using copy-on-write should not affect the original data.
• bugfix: Copy-on-write object are garbage collected when deleted directly.