Created
June 8, 2019 05:59
-
-
Save selmanj/4975670e31f36e9e5dee8cc078e23b06 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| export class Table<T> { | |
| private lastId = -1; | |
| private readonly data: Map<number, T> = new Map(); | |
| private readonly indexes: Map<keyof T, Map<T[keyof T], number[]>> = new Map(); | |
| constructor(...indexes: Array<keyof T>) { | |
| for (const idx of indexes) { | |
| this.indexes.set(idx, new Map()); | |
| } | |
| } | |
| insert(obj: T): number { | |
| this.data.set(++this.lastId, obj); | |
| for (const [idx, valMap] of this.indexes.entries()) { | |
| const val = obj[idx]; | |
| const ids = valMap.get(val); | |
| if (ids === undefined) { | |
| valMap.set(val, [this.lastId]); | |
| } else { | |
| ids.push(this.lastId); | |
| } | |
| } | |
| return this.lastId; | |
| } | |
| get(id: number): T | undefined { | |
| return this.data.get(id); | |
| } | |
| getByIndex<K extends keyof T>(idx: K, val: T[K]): T[] { | |
| const valMap = this.indexes.get(idx); | |
| if (valMap === undefined) { | |
| throw new Error(`No such index: ${idx}`); | |
| } | |
| const ids = valMap.get(val); | |
| if (ids === undefined) { | |
| return []; | |
| } | |
| return ids.map((id) => { | |
| const v = this.get(id); | |
| if (v === undefined) { | |
| throw new Error(`Runtime error while looking up index ${idx},` + | |
| ` had a mapping for object ${id} but none found`); | |
| } | |
| return v; | |
| }); | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment