Add static from method and tests

Author: chrismilson

src/__tests__/SortedSet.test.ts

@@ -1,9 +1,11 @@
 import { SortedSet } from '..'
 
 describe('SortedSet', () => {
+  const numberCompare = (a: number, b: number): number => a - b
+
   describe('get', () => {
     it('Should return undefined for invalid indicies', () => {
-      const arr = new SortedSet<number>((a, b) => a - b)
+      const arr = new SortedSet(numberCompare)
 
       arr.add(1)
       arr.add(5)
@@ -17,7 +19,7 @@ describe('SortedSet', () => {
 
   describe('size', () => {
     it('Should return the number of values in the tree', () => {
-      const arr = new SortedSet<number>((a, b) => a - b)
+      const arr = new SortedSet(numberCompare)
 
       expect(arr.size).toBe(0)
 
@@ -35,7 +37,7 @@ describe('SortedSet', () => {
 
   describe('iterator', () => {
     it('Should iterate the right values and in order', () => {
-      const arr = new SortedSet<number>((a, b) => a - b)
+      const arr = new SortedSet(numberCompare)
       arr.add(2)
       arr.add(3)
       arr.add(1)
@@ -50,7 +52,7 @@ describe('SortedSet', () => {
 
   describe('add', () => {
     it('Should insert values in order', () => {
-      const arr = new SortedSet<number>((a, b) => a - b)
+      const arr = new SortedSet(numberCompare)
 
       arr.add(1)
       arr.add(5)
@@ -65,7 +67,7 @@ describe('SortedSet', () => {
 
   describe('remove', () => {
     it('Should remove a value from a tree.', () => {
-      const s = new SortedSet<number>((a, b) => a - b)
+      const s = new SortedSet(numberCompare)
       const vals = []
       for (let i = 0; i < 10; i++) {
         s.add(i)
@@ -78,4 +80,23 @@ describe('SortedSet', () => {
       expect([...s]).toMatchObject(vals)
     })
   })
+
+  describe('from', () => {
+    const iterable = [1, 1, 2, 3, 6, -100]
+    const result = SortedSet.from(iterable, numberCompare)
+
+    it('Should contain the correct values', () => {
+      for (const value of iterable) {
+        expect(result.has(value)).toBe(true)
+      }
+    })
+
+    it('Should be the right size', () => {
+      expect(result.size).toBe(new Set(iterable).size)
+    })
+
+    it('Should be in-order', () => {
+      expect([...result]).toMatchObject([...result].sort())
+    })
+  })
 })

src/index.ts

@@ -191,4 +191,24 @@ export class SortedSet<T> implements Set<T> {
   values(): IterableIterator<T> {
     return this[Symbol.iterator]()
   }
+
+  /**
+   * Creates a sorted set from an iterable.
+   *
+   * @param iterable The itereable to turn into a sorted set.
+   * @param compare The compare method for the resulting Sorted Set
+   * @returns A new sorted set whose elements are from the passed iterable.
+   */
+  static from<T>(
+    iterable: Iterable<T>,
+    compare?: (a: T, b: T) => number
+  ): SortedSet<T> {
+    const result = new SortedSet<T>(compare)
+
+    for (const value of iterable) {
+      result.add(value)
+    }
+
+    return result
+  }
 }