rbtree-ts/src/sorted-array.ts

A sorted list of key-value pairs in a fast, typed in-memory B+ tree with a powerful API.

import { IMap } from '../types/interfaces';

/** A super-inefficient sorted list for testing purposes */
export default class SortedArray<K=any, V=any> implements IMap<K,V>
{
  cmp: (a: K, b: K) => number;
  a: [K,V][];

  public constructor(compare?: (a: K, b: K) => number, entries?: [K,V][]) {
    this.cmp = compare || ((a: any, b: any) => a < b ? -1 : a > b ? 1 : a === b ? 0 : a - b);
    this.a = [];
    if (entries !== undefined)
      for (var e of entries)
        this.set(e[0], e[1]);
  }

  get size() { return this.a.length; }
  get(key: K, defaultValue?: V): V | undefined {
    var pair = this.a[this.indexOf(key, -1)];
    return pair === undefined ? defaultValue : pair[1];
  }
  set(key: K, value: V, overwrite?: boolean): boolean { 
    var i = this.indexOf(key, -1);
    if (i <= -1)
      this.a.splice(~i, 0, [key, value]);
    else
      this.a[i] = [key, value];
    return i <= -1;
  }
  has(key: K): boolean { 
    return this.indexOf(key, -1) >= 0;
  }
  delete(key: K): boolean {
    var i = this.indexOf(key, -1);
    if (i > -1)
      this.a.splice(i, 1);
    return i > -1;
  }
  clear() { this.a = []; }
  getArray() { return this.a; }
  minKey(): K | undefined { return this.a[0][0]; }
  maxKey(): K | undefined { return this.a[this.a.length-1][0]; }
  forEach(callbackFn: (v:V, k:K, list:SortedArray<K,V>) => void) {
    this.a.forEach(pair => callbackFn(pair[1], pair[0], this));
  }

  // a.values() used to implement IMap<K,V> but it's not actually available in Node v10.4
  [Symbol.iterator](): IterableIterator<[K,V]> { return this.a.values(); }
  entries(): IterableIterator<[K,V]> { return this.a.values(); }

  indexOf(key: K, failXor: number): number {
    var lo = 0, hi = this.a.length, mid = hi >> 1;
    while(lo < hi) {
      var c = this.cmp(this.a[mid][0], key);
      if (c < 0)
        lo = mid + 1;
      else if (c > 0) // keys[mid] > key
        hi = mid;
      else if (c === 0)
        return mid;
      else
        throw new Error("Problem: compare failed");
      mid = (lo + hi) >> 1;
    }
    return mid ^ failXor;
  }
}