stress: utils like lodash / underscore , but smaller

README.md

@@ -2,18 +2,22 @@
 
 ---
 
-Common TypeScript code I used in multiple app.
+Simply and generic TypeScript utils.
 
 ![Check](https://github.com/jokester/ts-commonutil/workflows/Check/badge.svg)
 [![codecov](https://codecov.io/gh/jokester/ts-commonutil/graph/badge.svg?token=95f53H027x)](https://codecov.io/gh/jokester/ts-commonutil)
 [![npm version](https://badge.fury.io/js/%40jokester%2Fts-commonutil.svg)](https://badge.fury.io/js/%40jokester%2Fts-commonutil)
 
 ## How to Use
 
-```
-yarn add @jokester/ts-commonutil
+install `@jokester/ts-commonutil` from NPM.
 
-```
+## Not included but my go-to libraries
+
+- LRU: [lru-cache](https://www.npmjs.com/package/lru-cache)
+- fp: [fp-ts](https://www.npmjs.com/package/fp-ts)
+- React hooks
+  - [foxact](https://foxact.skk.moe/)
 
 ## Content
 

src/collection/default-map.ts

@@ -10,6 +10,22 @@
     if (!this.has(k)) {
       this.set(k, this.createDefault(k));
     }
     return this.get(k)!;
   }
 }
+
+export class WeakDefaultMap<K extends object, V> extends WeakMap<K, V> {
+  constructor(
+    private readonly createDefault: (k: K) => V,
+    entries?: readonly [K, V][],
+  ) {
+    super(entries);
+  }
+
+  getOrCreate(k: K): V {
+    if (!this.has(k)) {
+      this.set(k, this.createDefault(k));
+    }
+    return this.get(k)!;
+  }
+}

src/collection/iterables.ts

@@ -89,3 +89,11 @@
 
 type GeneralIterable<T> = Iterable<T> | AsyncIterable<T>;
 type MaybePromise<T> = T | PromiseLike<T>;
+
+export function toMap<T, K>(items: Iterable<T>, keyer: (t: T) => K): Map<K, T> {
+  const ret = new Map<K, T>();
+  for (const i of items) {
+    ret.set(keyer(i), i);
+  }
+  return ret;
+}

src/collection/min-heap.spec.ts

@@ -1,9 +1,9 @@
 import { MinHeap } from './min-heap';
-import { NumericOrder } from '../algebra/total-ordered';
+import * as fpts from 'fp-ts';
 
 describe('MinHeap', () => {
   it('insert elements', () => {
-    const testee = new MinHeap(NumericOrder);
+    const testee = new MinHeap(fpts.number.Ord);
     expect(testee.slice()).toEqual([]);
 
     expect(testee.insert(5).slice()).toEqual([5]);
@@ -16,7 +16,7 @@ describe('MinHeap', () => {
   });
 
   it('removes element', () => {
-    const testee = new MinHeap(NumericOrder).insertMany(5, 2, 1, 6, 0);
+    const testee = new MinHeap(fpts.number.Ord).insertMany(5, 2, 1, 6, 0);
 
     expect(testee.remove()).toEqual(0);
     expect(testee.slice()).toEqual([1, 5, 2, 6]);
@@ -30,15 +30,15 @@ describe('MinHeap', () => {
   });
 
   it('removes element - 2', () => {
-    const testee = new MinHeap(NumericOrder).insert(0).insert(2).insert(3).insert(100).insert(200).insert(4);
+    const testee = new MinHeap(fpts.number.Ord).insert(0).insert(2).insert(3).insert(100).insert(200).insert(4);
 
     expect(testee.slice()).toEqual([0, 2, 3, 100, 200, 4]);
     expect(testee.remove()).toEqual(0);
     expect(testee.slice()).toEqual([2, 4, 3, 100, 200]);
   });
 
   it('throws when remove from or peek an empty && strict heap', () => {
-    const testee = new MinHeap(NumericOrder, true);
+    const testee = new MinHeap(fpts.number.Ord, true);
     expect(testee.slice()).toEqual([]);
 
     expect(() => testee.remove()).toThrow(/nothing to remove/);
@@ -47,25 +47,25 @@ describe('MinHeap', () => {
   });
 
   it('can be initialized with initialTree', () => {
-    const testee = new MinHeap(NumericOrder, false, /* illegal tree */ [1, 0]);
+    const testee = new MinHeap(fpts.number.Ord, false, /* illegal tree */ [1, 0]);
 
-    expect(() => new MinHeap(NumericOrder, true, [1, 0])).toThrow(/assertInvariants/);
+    expect(() => new MinHeap(fpts.number.Ord, true, [1, 0])).toThrow(/assertInvariants/);
   });
 
   it('can be cloned', () => {
-    const testee = new MinHeap(NumericOrder, false, /* illegal tree */ [1, 0]);
+    const testee = new MinHeap(fpts.number.Ord, false, /* illegal tree */ [1, 0]);
 
     expect(testee.clone().slice()).toEqual([1, 0]);
   });
 
   it('can be shrinked', () => {
-    const testee = new MinHeap(NumericOrder).insertMany(5, 4, 3, 2, 1, -1);
+    const testee = new MinHeap(fpts.number.Ord).insertMany(5, 4, 3, 2, 1, -1);
 
     expect(testee.shrink(3).removeMany(3)).toEqual([-1, 1, 2]);
   });
 
   it('can shrink to a given upperlimit', () => {
-    const testee = new MinHeap(NumericOrder).insertMany(5, 4, 3, 2, 1, -1);
+    const testee = new MinHeap(fpts.number.Ord).insertMany(5, 4, 3, 2, 1, -1);
 
     expect(testee.clone().shrinkUntil(4).removeMany(100)).toEqual([-1, 1, 2, 3]);
 

src/collection/min-heap.ts

@@ -1,12 +1,16 @@
-import { TotalOrdered } from '../algebra/total-ordered';
 import { positions } from './btree';
+import { Ord } from 'fp-ts/Ord';
+
+function isBefore<T>(ord: Ord<T>, a: T, b: T): boolean {
+  return ord.compare(a, b) < 0;
+}
 
 export class MinHeap<T> {
   private readonly tree: T[] = [];
   slice = this.tree.slice.bind(this.tree);
 
   constructor(
-    private readonly order: TotalOrdered<T>,
+    private readonly order: Ord<T>,
     private readonly strict = false,
     initialTree?: T[],
   ) {
@@ -27,7 +31,8 @@
       j = positions.parent(i);
     this.tree[i] = value;
 
-    while (i && this.order.before(value /* i.e. this.tree[i] */, this.tree[j])) {
+    while (i && isBefore(this.order, value /* i.e. this.tree[i] */, this.tree[j])) {
+      // pop up new value
       this.tree[i] = this.tree[j];
       this.tree[j] = value;
 
@@ -47,7 +52,7 @@
     } else {
       const ret = this.tree[0];
 
       const v = (this.tree[0] = this.tree.pop()!);
 
       for (let i = 0; i < this.tree.length; ) {
         const l = positions.leftChild(i),
@@ -61,20 +66,20 @@
          */
         if (r < this.tree.length) {
           // when it has 2 children
-          if (this.order.before(this.tree[l], this.tree[r]) && this.order.before(this.tree[l], v)) {
+          if (isBefore(this.order, this.tree[l], this.tree[r]) && isBefore(this.order, this.tree[l], v)) {
             // swap [i] and [l] and continue
             this.tree[i] = this.tree[l];
             this.tree[l] = v;
             i = l;
-          } else if (this.order.before(this.tree[r], this.tree[l]) && this.order.before(this.tree[r], v)) {
+          } else if (isBefore(this.order, this.tree[r], this.tree[l]) && isBefore(this.order, this.tree[r], v)) {
             // swap [i] and [l] and continue
             this.tree[i] = this.tree[r];
             this.tree[r] = v;
             i = r;
           } else {
             break; // v is already before all children
           }
-        } else if (l < this.tree.length && this.order.before(this.tree[l], v)) {
+        } else if (l < this.tree.length && isBefore(this.order, this.tree[l], v)) {
           this.tree[i] = this.tree[l];
           this.tree[l] = v;
           break; // there cannot be next level
@@ -94,7 +99,7 @@
   removeMany(count: number): T[] {
     const ret: T[] = [];
     for (let i = 0; i < count && (this.strict /* to let remove() throw */ || this.tree.length); i++) {
       ret[i] = this.remove()!;
     }
 
     return ret;
@@ -119,9 +124,9 @@
     const afterShrink: T[] = [];
     while (
       this.tree.length &&
-      (this.order.before(this.tree[0], v) || (inclusive && this.order.equal(this.tree[0], v)))
+      (isBefore(this.order, this.tree[0], v) || (inclusive && !this.order.compare(this.tree[0], v)))
     ) {
       afterShrink.push(this.remove()!);
     }
     this.tree.splice(0, this.tree.length, ...afterShrink);
     return this;
@@ -130,7 +135,7 @@
   private assertInvariants() {
     for (let i = 1; i < this.tree.length; i++) {
       const p = positions.parent(i);
-      if (!this.order.before(this.tree[p], this.tree[i])) {
+      if (!isBefore(this.order, this.tree[p], this.tree[i])) {
         throw new Error(`MinHeap#assertInvariants(): expected this.tree[${p} to be ordered before this.tree[${i}]`);
       }
     }

src/collection/multiset.spec.ts

@@ -16,8 +16,8 @@ describe(Multiset, () => {
     testee.setCount('abc', 0);
     testee.setCount('abc', 1);
     testee.setCount('abc', 1);
-    testee.setCount('abc', 0, false);
-    expect(testee.maxCount()).toEqual(1);
+    testee.setCount('abc', 0);
+    expect(testee.maxCount()).toBe(1);
     expect(testee.getCount('abc')).toEqual(0);
     expect(testee.getCount('abd')).toEqual(1);
     expect(testee.findByCount(0)).toEqual(['abc']);

src/collection/multiset.ts

@@ -4,7 +4,7 @@
   private map = new DefaultMap</* count */ number, /* objects */ Set<T>>((k) => new Set());
   private countMap = new Map</* object*/ T, /* count */ number>();
 
-  setCount(obj: T, count: number, removeOnZeroFreq = true): void {
+  setCount(obj: T, count: number): void {
     const existedCount = this.countMap.get(obj);
 
     if (existedCount === count) {
@@ -14,9 +14,9 @@
       this.countMap.set(obj, count);
       this.map.getOrCreate(count).add(obj);
 
       const existedSet = this.map.get(existedCount)!;
       existedSet.delete(obj);
-      if (!existedSet.size && removeOnZeroFreq) {
+      if (!existedSet.size) {
         this.map.delete(existedCount);
       }
     } else {
@@ -39,7 +39,7 @@
     const count = this.countMap.get(obj);
     if (count !== undefined) {
       this.countMap.delete(obj);
       const s = this.map.get(count)!;
       s.delete(obj);
       if (!s.size) this.map.delete(count);
     }

src/collection/segment-tree.ts

@@ -1,4 +1,4 @@
-import { Monoid } from '../algebra/monoid';
+import { Monoid } from 'fp-ts/lib/Monoid';
 import { positions, powOf2 } from './btree';
 
 /**
@@ -35,7 +35,7 @@
     const sums: T[] = (this.sums = []);
 
     for (let i = 0; i < lenSums; i++) {
-      sums[i] = this.monoid.id;
+      sums[i] = this.monoid.empty;
     }
 
     // FIXME: set

src/concurrency/resource-pool.spec.ts

@@ -37,7 +37,7 @@ describe(ResourcePool.name, () => {
         testee.use(() => wait(0.5e3));
         const becameEmpty = await testee.wait({ freeCount: 2 });
         expect(becameEmpty).toBeTruthy();
-        expect(Date.now() - start).toBeGreaterThan(0.5e3);
+        expect(Date.now() - start).toBeGreaterThanOrEqual(0.5e3);
       });
 
       it('returns false when other tasks running', async () => {

src/stress/chunk.ts

@@ -0,0 +1,23 @@
+export function* chunk<T>(elements: Iterable<T>, chunkSize: number): Iterable<T[]> {
+  let currentChunk: T[] = [];
+  for (const e of elements) {
+    currentChunk.push(e);
+    if (currentChunk.length >= chunkSize) {
+      yield currentChunk;
+      currentChunk = [];
+    }
+  }
+  if (currentChunk.length) {
+    yield currentChunk;
+  }
+}
+
+export function* chunkArray<T>(elements: readonly T[], chunkSize: number): Iterable<T[]> {
+  for (let s = 0; ; s += chunkSize) {
+    const chunk = elements.slice(s, s + chunkSize);
+    if (!chunk.length) {
+      break;
+    }
+    yield chunk;
+  }
+}

src/stress/groupBy.spec.ts

@@ -0,0 +1,11 @@
+import { groupBy } from './groupBy';
+
+describe(groupBy, () => {
+  it('groups value with provided keyer()', () => {
+    expect(groupBy([], () => 0)).toEqual({});
+    expect(groupBy(new Set([1, 2, 4]), (v) => v % 2)).toEqual({
+      1: [1],
+      0: [2, 4],
+    });
+  });
+});

src/stress/groupBy.ts

@@ -0,0 +1,16 @@
+import { DefaultMap } from '../collection/default-map';
+
+export function groupBy<T, K extends string | number | symbol>(
+  values: Iterable<T>,
+  keyer: (value: T) => K,
+): Record<K, T[]> {
+  return Object.fromEntries(groupByAsMap(values, keyer)) as Record<K, T[]>;
+}
+
+export function groupByAsMap<T, K>(values: Iterable<T>, keyer: (value: T) => K): ReadonlyMap<K, T[]> {
+  const map = new DefaultMap<K, T[]>(() => []);
+  for (const v of values) {
+    map.getOrCreate(keyer(v)).push(v);
+  }
+  return map;
+}

src/stress/sortBy.spec.ts

@@ -0,0 +1,12 @@
+import { sortBy } from './sortBy';
+
+describe('orderBy', () => {
+  it('sorts value DESC by "natural" JS ordering', () => {
+    expect(sortBy([2, 3, 1], (v) => v, false)).toEqual([3, 2, 1]);
+    expect(sortBy([1, 1, 2], (v) => v, false)).toEqual([2, 1, 1]);
+  });
+  it('sorts value ASC by "natural" JS ordering', () => {
+    expect(sortBy([2, 3, 1], (v) => v)).toEqual([1, 2, 3]);
+    expect(sortBy([1, 1, 2], (v) => v)).toEqual([1, 1, 2]);
+  });
+});

src/stress/sortBy.ts

@@ -0,0 +1,18 @@
+/**
+ * (for more complicated case, consider fp-ts Ord<T> typeclass)
+ * @param values
+ * @param key (if it should be cached, caller should use a cached impl)
+ * @param asc
+ */
+export function sortBy<T, O>(values: T[], key: (v: T) => O, asc = true): T[] {
+  const indexes = values.map((v, i) => ({ v, i }));
+  return indexes.sort((a, b) => (asc ? compare(a.v, b.v) : -compare(a.v, b.v))).map((_) => _.v);
+}
+
+function compare(a: any, b: any): number {
+  if (a < b) {
+    return -1;
+  } else if (a > b) {
+    return 1;
+  } else return 0;
+}