From 59b5f647200b61dd996a6c4aec21b11ea517b6d2 Mon Sep 17 00:00:00 2001
From: Justin Mazzocchi <2831158+jzzocc@users.noreply.github.com>
Date: Sun, 13 Sep 2020 02:06:52 -0700
Subject: [PATCH] Simplify bit array

---
 .../Sources/CodableBloomFilter/BitArray.swift | 23 +++----------------
 1 file changed, 3 insertions(+), 20 deletions(-)

diff --git a/CodableBloomFilter/Sources/CodableBloomFilter/BitArray.swift b/CodableBloomFilter/Sources/CodableBloomFilter/BitArray.swift
index f0cc651..736b160 100644
--- a/CodableBloomFilter/Sources/CodableBloomFilter/BitArray.swift
+++ b/CodableBloomFilter/Sources/CodableBloomFilter/BitArray.swift
@@ -1,7 +1,5 @@
 // Copyright © 2020 Metabolist. All rights reserved.
 
-// Adapted from https://github.com/dduan/BitArray
-
 import Foundation
 
 struct BitArray {
@@ -19,13 +17,13 @@ extension BitArray {
 
     subscript(index: Int) -> Bool {
         get {
-            let (byteIndex, bitIndex) = Self.byteAndBitIndices(index: index)
+            let (byteIndex, bitIndex) = index.quotientAndRemainder(dividingBy: Self.bitsInByte)
 
             return bytes[byteIndex] & Self.mask(bitIndex: bitIndex) > 0
         }
 
         set {
-            let (byteIndex, bitIndex) = Self.byteAndBitIndices(index: index)
+            let (byteIndex, bitIndex) = index.quotientAndRemainder(dividingBy: Self.bitsInByte)
 
             if newValue {
                 bytes[byteIndex] |= Self.mask(bitIndex: bitIndex)
@@ -51,22 +49,7 @@ extension BitArray: Codable {
 private extension BitArray {
     static let bitsInByte = 8
 
-    static func byteAndBitIndices(index: Int) -> (Int, Int) {
-        index.quotientAndRemainder(dividingBy: bitsInByte)
-    }
-
     static func mask(bitIndex: Int) -> UInt8 {
-        switch bitIndex {
-        case 0: return 0b00000001
-        case 1: return 0b00000010
-        case 2: return 0b00000100
-        case 3: return 0b00001000
-        case 4: return 0b00010000
-        case 5: return 0b00100000
-        case 6: return 0b01000000
-        case 7: return 0b10000000
-        default:
-            fatalError("Invalid bit index: \(bitIndex)")
-        }
+        UInt8(2 << (bitIndex - 1))
     }
 }