Refactoring

CodableBloomFilter/Sources/CodableBloomFilter/BloomFilter.swift

@@ -7,24 +7,19 @@ import Foundation
 // This implementation uses deterministic hashing functions so it can be serialized / deserialized
 
 public struct BloomFilter<T: DeterministicallyHashable> {
-    public let hashes: [Hash]
+    public let hashers: [DeterministicHasher]
     public let bits: Int
 
     private var data: BitArray
 
-    public init(hashes: [Hash], bits: Int) {
-        self.hashes = hashes
+    public init(hashes: [DeterministicHasher], bits: Int) {
+        self.hashers = hashes
         self.bits = bits
         data = BitArray(count: bits)
     }
 }
 
 public extension BloomFilter {
-    enum Hash: String, Codable {
-        case djb2
-        case sdbm
-    }
-
     mutating func insert(_ newMember: T) {
         for index in indices(newMember) {
             data[index] = true
@@ -38,7 +33,7 @@ public extension BloomFilter {
 
 extension BloomFilter: Codable {
     private enum CodingKeys: String, CodingKey {
-        case hashes
+        case hashers
         case bits
         case data
     }
@@ -46,7 +41,7 @@ extension BloomFilter: Codable {
     public init(from decoder: Decoder) throws {
         let container = try decoder.container(keyedBy: CodingKeys.self)
 
-        hashes = try container.decode([Hash].self, forKey: .hashes)
+        hashers = try container.decode([DeterministicHasher].self, forKey: .hashers)
         bits = try container.decode(Int.self, forKey: .bits)
         data = BitArray(data: try container.decode(Data.self, forKey: .data), count: bits)
     }
@@ -54,7 +49,7 @@ extension BloomFilter: Codable {
     public func encode(to encoder: Encoder) throws {
         var container = encoder.container(keyedBy: CodingKeys.self)
 
-        try container.encode(hashes, forKey: .hashes)
+        try container.encode(hashers, forKey: .hashers)
         try container.encode(bits, forKey: .bits)
         try container.encode(data.data, forKey: .data)
     }
@@ -62,32 +57,6 @@ extension BloomFilter: Codable {
 
 private extension BloomFilter {
     func indices(_ member: T) -> [Int] {
-        hashes.map { abs($0.apply(member)) % bits }
-    }
-}
-
-// https://gist.github.com/kharrison/2355182ac03b481921073c5cf6d77a73
-
-private extension BloomFilter.Hash {
-    func apply(_ member: T) -> Int {
-        Array(member.deterministicallyHashableData)
-            .map(Int.init)
-            .reduce(initial, then)
-    }
-
-    var initial: Int {
-        switch self {
-        case .djb2: return 5381
-        case .sdbm: return 0
-        }
-    }
-
-    func then(result: Int, next: Int) -> Int {
-        switch self {
-        case .djb2:
-            return (result << 5) &+ result &+ next
-        case .sdbm:
-            return next &+ (result << 6) &+ (result << 16) - result
-        }
+        hashers.map { abs($0.apply(member)) % bits }
     }
 }

CodableBloomFilter/Sources/CodableBloomFilter/DeterministicHasher.swift

@@ -0,0 +1,36 @@
+// Copyright © 2020 Metabolist. All rights reserved.
+
+import Foundation
+
+public enum DeterministicHasher: String, Codable {
+    case djb2
+    case sdbm
+}
+
+extension DeterministicHasher {
+    func apply(_ hashable: DeterministicallyHashable) -> Int {
+        Array(hashable.hashableData)
+            .map(Int.init)
+            .reduce(initial, then)
+    }
+}
+
+// https://gist.github.com/kharrison/2355182ac03b481921073c5cf6d77a73
+
+private extension DeterministicHasher {
+    var initial: Int {
+        switch self {
+        case .djb2: return 5381
+        case .sdbm: return 0
+        }
+    }
+
+    func then(result: Int, next: Int) -> Int {
+        switch self {
+        case .djb2:
+            return (result << 5) &+ result &+ next
+        case .sdbm:
+            return next &+ (result << 6) &+ (result << 16) - result
+        }
+    }
+}

CodableBloomFilter/Sources/CodableBloomFilter/DeterministicallyHashable.swift

@@ -3,5 +3,5 @@
 import Foundation
 
 public protocol DeterministicallyHashable {
-    var deterministicallyHashableData: Data { get }
+    var hashableData: Data { get }
 }

CodableBloomFilter/Sources/CodableBloomFilter/Extensions/Data+DeterministicallyHashable.swift

@@ -3,5 +3,5 @@
 import Foundation
 
 extension Data: DeterministicallyHashable {
-    public var deterministicallyHashableData: Data { self }
+    public var hashableData: Data { self }
 }

CodableBloomFilter/Sources/CodableBloomFilter/Extensions/String+DeterministicallyHashable.swift

@@ -3,5 +3,5 @@
 import Foundation
 
 extension String: DeterministicallyHashable {
-    public var deterministicallyHashableData: Data { Data(utf8) }
+    public var hashableData: Data { Data(utf8) }
 }

CodableBloomFilter/Tests/CodableBloomFilterTests/CodableBloomFilterTests.swift

@@ -16,7 +16,7 @@ final class CodableBloomFilterTests: XCTestCase {
 
     func testCoding() throws {
         var sut = BloomFilter<String>(hashes: [.djb2, .sdbm], bits: 64)
-        let expectedSerialization = Data(#"{"bits":64,"data":"ABAAAAACAJA=","hashes":["djb2","sdbm"]}"#.utf8)
+        let expectedSerialization = Data(#"{"bits":64,"data":"ABAAAAACAJA=","hashers":["djb2","sdbm"]}"#.utf8)
 
         sut.insert("lol")
         sut.insert("ok")