microsoft/typespec
Publicmirrored from https://github.com/microsoft/typespecAvailable
packages/asset-emitter/src/custom-key-map.ts
53lines · modecode
| 1 | /** |
| 2 | * This is a map type that allows providing a custom keyer function. The keyer |
| 3 | * function returns a string that is used to look up in the map. This is useful |
| 4 | * for implementing maps that look up based on an arbitrary number of keys. |
| 5 | * |
| 6 | * For example, to look up in a map with a [ObjA, ObjB)] tuple, such that tuples |
| 7 | * with identical values (but not necessarily identical tuples!) create an |
| 8 | * object keyer for each of the objects: |
| 9 | * |
| 10 | * const aKeyer = CustomKeyMap.objectKeyer(); |
| 11 | * const bKeyer = CUstomKeyMap.objectKeyer(); |
| 12 | * |
| 13 | * And compose these into a tuple keyer to use when instantiating the custom key |
| 14 | * map: |
| 15 | * |
| 16 | * const tupleKeyer = ([a, b]) => `${aKeyer.getKey(a)}-${bKeyer.getKey(b)}`; |
| 17 | * const map = new CustomKeyMap(tupleKeyer); |
| 18 | * |
| 19 | */ |
| 20 | export class CustomKeyMap<K extends readonly any[], V> { |
| 21 | #items = new Map<string, V>(); |
| 22 | #keyer; |
| 23 | |
| 24 | constructor(keyer: (args: K) => string) { |
| 25 | this.#keyer = keyer; |
| 26 | } |
| 27 | |
| 28 | get(items: K): V | undefined { |
| 29 | return this.#items.get(this.#keyer(items)); |
| 30 | } |
| 31 | |
| 32 | set(items: K, value: V): void { |
| 33 | const key = this.#keyer(items); |
| 34 | this.#items.set(key, value); |
| 35 | } |
| 36 | |
| 37 | static objectKeyer() { |
| 38 | const knownKeys = new WeakMap<object, number>(); |
| 39 | let count = 0; |
| 40 | return { |
| 41 | getKey(o: object) { |
| 42 | if (knownKeys.has(o)) { |
| 43 | return knownKeys.get(o); |
| 44 | } |
| 45 | |
| 46 | const key = count; |
| 47 | count++; |
| 48 | knownKeys.set(o, key); |
| 49 | return key; |
| 50 | }, |
| 51 | }; |
| 52 | } |
| 53 | } |
| 54 | |