binarySearch and improve insertEventInto___List() to use that and .splice()

utils.test.ts

@@ -1,6 +1,6 @@
 import { describe, test, expect } from 'bun:test'
 import { buildEvent } from './test-helpers.ts'
-import { Queue, insertEventIntoAscendingList, insertEventIntoDescendingList } from './utils.ts'
+import { Queue, insertEventIntoAscendingList, insertEventIntoDescendingList, binarySearch } from './utils.ts'
 
 import type { Event } from './event.ts'
 
@@ -214,13 +214,13 @@ describe('inserting into a asc sorted list of events', () => {
   })
 })
 
-describe('enque a message into MessageQueue', () => {
-  test('enque into an empty queue', () => {
+describe('enqueue a message into MessageQueue', () => {
+  test('enqueue into an empty queue', () => {
     const queue = new Queue()
     queue.enqueue('node1')
     expect(queue.first!.value).toBe('node1')
   })
-  test('enque into a non-empty queue', () => {
+  test('enqueue into a non-empty queue', () => {
     const queue = new Queue()
     queue.enqueue('node1')
     queue.enqueue('node3')
@@ -255,3 +255,11 @@ describe('enque a message into MessageQueue', () => {
     expect(item3).toBe(null)
   })
 })
+
+test('binary search', () => {
+  expect(binarySearch(['a', 'b', 'd', 'e'], 'e', (a, b) => (a < b ? -1 : a === b ? 0 : 1))).toEqual([3, true])
+  expect(binarySearch(['a', 'b', 'd', 'e'], 'x', (a, b) => (a < b ? -1 : a === b ? 0 : 1))).toEqual([4, false])
+  expect(binarySearch(['a', 'b', 'd', 'e'], 'c', (a, b) => (a < b ? -1 : a === b ? 0 : 1))).toEqual([2, false])
+  expect(binarySearch(['a', 'b', 'd', 'e'], 'a', (a, b) => (a < b ? -1 : a === b ? 0 : 1))).toEqual([0, true])
+  expect(binarySearch(['a', 'b', 'd', 'e'], '[', (a, b) => (a < b ? -1 : a === b ? 0 : 1))).toEqual([0, false])
+})

utils.ts

@@ -13,85 +13,52 @@ export function normalizeURL(url: string): string {
   return p.toString()
 }
 
-//
-// fast insert-into-sorted-array functions adapted from https://github.com/terrymorse58/fast-sorted-array
-//
 export function insertEventIntoDescendingList(sortedArray: Event[], event: Event) {
-  let start = 0
-  let end = sortedArray.length - 1
-  let midPoint
-  let position = start
-
-  if (end < 0) {
-    position = 0
-  } else if (event.created_at < sortedArray[end].created_at) {
-    position = end + 1
-  } else if (event.created_at >= sortedArray[start].created_at) {
-    position = start
-  } else
-    while (true) {
-      if (end <= start + 1) {
-        position = end
-        break
+  const [idx, found] = binarySearch(sortedArray, event, (a, b) => {
+    if (a.id === b.id) return 0
+    if (a.created_at === b.created_at) return -1
+    return b.created_at - a.created_at
+  })
+  if (!found) {
+    sortedArray.splice(idx, 0, event)
   }
-      midPoint = Math.floor(start + (end - start) / 2)
-      if (sortedArray[midPoint].created_at > event.created_at) {
-        start = midPoint
-      } else if (sortedArray[midPoint].created_at < event.created_at) {
-        end = midPoint
-      } else {
-        // aMidPoint === num
-        position = midPoint
-        break
-      }
-    }
-
-  // insert when num is NOT already in (no duplicates)
-  if (sortedArray[position]?.id !== event.id) {
-    return [...sortedArray.slice(0, position), event, ...sortedArray.slice(position)]
-  }
-
   return sortedArray
 }
 
 export function insertEventIntoAscendingList(sortedArray: Event[], event: Event) {
-  let start = 0
-  let end = sortedArray.length - 1
-  let midPoint
-  let position = start
-
-  if (end < 0) {
-    position = 0
-  } else if (event.created_at > sortedArray[end].created_at) {
-    position = end + 1
-  } else if (event.created_at <= sortedArray[start].created_at) {
-    position = start
-  } else
-    while (true) {
-      if (end <= start + 1) {
-        position = end
-        break
+  const [idx, found] = binarySearch(sortedArray, event, (a, b) => {
+    if (a.id === b.id) return 0
+    if (a.created_at === b.created_at) return -1
+    return a.created_at - b.created_at
+  })
+  if (!found) {
+    sortedArray.splice(idx, 0, event)
   }
-      midPoint = Math.floor(start + (end - start) / 2)
-      if (sortedArray[midPoint].created_at < event.created_at) {
-        start = midPoint
-      } else if (sortedArray[midPoint].created_at > event.created_at) {
-        end = midPoint
-      } else {
-        // aMidPoint === num
-        position = midPoint
-        break
-      }
-    }
-
-  // insert when num is NOT already in (no duplicates)
-  if (sortedArray[position]?.id !== event.id) {
-    return [...sortedArray.slice(0, position), event, ...sortedArray.slice(position)]
-  }
-
   return sortedArray
 }
 
+export function binarySearch<T>(arr: T[], val: T, compare: (a: T, b: T) => number): [number, boolean] {
+  let start = 0
+  let end = arr.length - 1
+
+  while (start <= end) {
+    const mid = Math.floor((start + end) / 2)
+    const cmp = compare(val, arr[mid])
+
+    if (cmp === 0) {
+      return [mid, true]
+    }
+
+    if (cmp < 0) {
+      end = mid - 1
+    } else {
+      start = mid + 1
+    }
+  }
+
+  return [start, false]
+}
+
 export class QueueNode<V> {
   public value: V
   public next: QueueNode<V> | null = null