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https://github.com/metabolist/metatext.git
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Refactoring
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parent
17506f5bd9
commit
6e0dcd6398
9 changed files with 122 additions and 49 deletions
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@ -8,11 +8,7 @@ struct BitArray {
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private var bytes: [UInt8]
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init(byteCount: Int) {
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self.bytes = [UInt8](repeating: 0, count: byteCount)
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}
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init(data: Data) {
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bytes = Array(data)
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bytes = [UInt8](repeating: 0, count: byteCount)
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}
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}
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@ -40,9 +36,7 @@ extension BitArray {
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extension BitArray: Codable {
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init(from decoder: Decoder) throws {
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let container = try decoder.singleValueContainer()
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bytes = Array(try container.decode(Data.self))
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bytes = Array(try decoder.singleValueContainer().decode(Data.self))
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}
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func encode(to encoder: Encoder) throws {
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@ -6,14 +6,19 @@ import Foundation
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// https://khanlou.com/2018/09/bloom-filters/
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// This implementation uses deterministic hashing functions so it can conform to Codable
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enum BloomFilterError: Error {
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case noHashesProvided
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}
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public struct BloomFilter<T: DeterministicallyHashable>: Codable {
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public let hashers: [DeterministicHasher]
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public let hashes: [Hash]
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private var data: BitArray
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public init(hashers: Set<DeterministicHasher>, byteCount: Int) {
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// Sort the hashers for consistent decoding output
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self.hashers = Array(hashers.sorted { $0.rawValue < $1.rawValue })
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public init(hashes: Set<Hash>, byteCount: Int) throws {
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guard !hashes.isEmpty else { throw BloomFilterError.noHashesProvided }
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// Sort the hashes for consistent decoding output
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self.hashes = Array(hashes.sorted { $0.rawValue < $1.rawValue })
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data = BitArray(byteCount: byteCount)
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}
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}
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@ -32,6 +37,6 @@ public extension BloomFilter {
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private extension BloomFilter {
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func indices(_ member: T) -> [Int] {
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hashers.map { abs($0.apply(member)) % data.bitCount }
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hashes.map { abs($0.apply(member)) % data.bitCount }
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}
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}
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@ -3,5 +3,5 @@
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import Foundation
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public protocol DeterministicallyHashable {
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var hashableData: Data { get }
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var dataForHashingDeterministically: Data { get }
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}
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@ -3,5 +3,5 @@
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import Foundation
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extension Data: DeterministicallyHashable {
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public var hashableData: Data { self }
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public var dataForHashingDeterministically: Data { self }
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}
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@ -3,5 +3,5 @@
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import Foundation
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extension String: DeterministicallyHashable {
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public var hashableData: Data { Data(utf8) }
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public var dataForHashingDeterministically: Data { Data(utf8) }
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}
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@ -2,17 +2,17 @@
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import Foundation
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public enum DeterministicHasher: String, Codable {
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case djb2
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case djb2a
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case sdbm
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case fnv1
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case fnv1a
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public enum Hash: String, Codable {
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case djb232
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case djb2a32
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case sdbm32
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case fnv132
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case fnv1a32
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}
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extension DeterministicHasher {
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extension Hash {
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func apply(_ hashable: DeterministicallyHashable) -> Int {
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Int(Array(hashable.hashableData)
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Int(Array(hashable.dataForHashingDeterministically)
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.map(UInt32.init)
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.reduce(offsetBasis, hash))
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}
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@ -21,28 +21,28 @@ extension DeterministicHasher {
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// http://www.cse.yorku.ca/~oz/hash.html
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// http://www.isthe.com/chongo/tech/comp/fnv/
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private extension DeterministicHasher {
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private extension Hash {
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static let fnvPrime: UInt32 = 16777619
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var offsetBasis: UInt32 {
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switch self {
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case .djb2, .djb2a: return 5381
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case .sdbm: return 0
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case .fnv1, .fnv1a: return 2166136261
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case .djb232, .djb2a32: return 5381
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case .sdbm32: return 0
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case .fnv132, .fnv1a32: return 2166136261
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}
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}
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func hash(result: UInt32, next: UInt32) -> UInt32 {
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switch self {
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case .djb2:
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case .djb232:
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return (result << 5) &+ result &+ next
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case .djb2a:
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case .djb2a32:
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return (result << 5) &+ result ^ next
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case .sdbm:
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case .sdbm32:
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return next &+ (result << 6) &+ (result << 16) &- result
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case .fnv1:
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case .fnv132:
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return (result &* Self.fnvPrime) ^ next
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case .fnv1a:
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case .fnv1a32:
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return (result ^ next) &* Self.fnvPrime
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}
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}
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@ -4,17 +4,26 @@
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import XCTest
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final class CodableBloomFilterTests: XCTestCase {
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func testHashers() {
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XCTAssertEqual(DeterministicHasher.djb2.apply("hash"), 2090320585)
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XCTAssertEqual(DeterministicHasher.djb2a.apply("hash"), 2087809207)
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XCTAssertEqual(DeterministicHasher.sdbm.apply("hash"), 385600046)
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XCTAssertEqual(DeterministicHasher.fnv1.apply("hash"), 3616638997)
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XCTAssertEqual(DeterministicHasher.fnv1a.apply("hash"), 3469047761)
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func testHashes() {
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XCTAssertEqual(Hash.djb232.apply("hash"), 2090320585)
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XCTAssertEqual(Hash.djb2a32.apply("hash"), 2087809207)
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XCTAssertEqual(Hash.sdbm32.apply("hash"), 385600046)
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XCTAssertEqual(Hash.fnv132.apply("hash"), 3616638997)
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XCTAssertEqual(Hash.fnv1a32.apply("hash"), 3469047761)
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}
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func testContains() {
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var sut = BloomFilter<String>(hashers: [.djb2, .sdbm, .fnv1, .fnv1a], byteCount: 128)
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func noHashesProvided() throws {
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XCTAssertThrowsError(try BloomFilter<String>(hashes: [], byteCount: 8)) {
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guard case BloomFilterError.noHashesProvided = $0 else {
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XCTFail("Expected no hashers provided error")
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return
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}
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}
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}
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func testContains() throws {
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var sut = try BloomFilter<String>(hashes: [.sdbm32, .djb232], byteCount: 8)
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sut.insert("lol")
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sut.insert("ok")
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@ -26,8 +35,8 @@ final class CodableBloomFilterTests: XCTestCase {
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}
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func testCoding() throws {
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var sut = BloomFilter<String>(hashers: [.sdbm, .djb2], byteCount: 8)
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let expectedSerialization = Data(#"{"data":"ABAAAAACAJA=","hashers":["djb2","sdbm"]}"#.utf8)
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var sut = try BloomFilter<String>(hashes: [.sdbm32, .djb232], byteCount: 8)
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let expectedData = Data(#"{"data":"ABAAAAACAJA=","hashes":["djb232","sdbm32"]}"#.utf8)
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sut.insert("lol")
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sut.insert("ok")
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@ -36,15 +45,80 @@ final class CodableBloomFilterTests: XCTestCase {
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encoder.outputFormatting = .sortedKeys
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let serialization = try encoder.encode(sut)
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let data = try encoder.encode(sut)
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XCTAssertEqual(serialization, expectedSerialization)
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XCTAssertEqual(data, expectedData)
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let decoded = try JSONDecoder().decode(BloomFilter<String>.self, from: serialization)
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let decoded = try JSONDecoder().decode(BloomFilter<String>.self, from: data)
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XCTAssert(decoded.contains("lol"))
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XCTAssert(decoded.contains("ok"))
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XCTAssertFalse(decoded.contains("wtf"))
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XCTAssertFalse(decoded.contains("no"))
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}
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func testInvalidHash() throws {
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let invalidData = Data(#"{"data":"ABAAAAACAJA=","hashes":["djb232","invalid"]}"#.utf8)
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XCTAssertThrowsError(try JSONDecoder().decode(BloomFilter<String>.self, from: invalidData)) {
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guard case DecodingError.dataCorrupted = $0 else {
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XCTFail("Expected data corrupted error")
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return
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}
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}
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}
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func testDataEncodingStrategy() throws {
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var sut = try BloomFilter<String>(hashes: [.sdbm32, .djb232], byteCount: 8)
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let expectedData = Data(#"{"data":"0010000000020090","hashes":["djb232","sdbm32"]}"#.utf8)
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sut.insert("lol")
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sut.insert("ok")
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let encoder = JSONEncoder()
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encoder.outputFormatting = .sortedKeys
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encoder.dataEncodingStrategy = .custom { data, encoder in
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var container = encoder.singleValueContainer()
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try container.encode(data.map { String(format: "%02.2hhx", $0) }.joined())
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}
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let data = try encoder.encode(sut)
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XCTAssertEqual(data, expectedData)
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}
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func testDataDecodingStrategy() throws {
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let data = Data(#"{"data":"0010000000020090","hashes":["djb232","sdbm32"]}"#.utf8)
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let decoder = JSONDecoder()
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decoder.dataDecodingStrategy = .custom { decoder in
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let container = try decoder.singleValueContainer()
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let string = try container.decode(String.self)
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var bytes = [UInt8]()
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var i = string.startIndex
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while i != string.endIndex {
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let j = string.index(i, offsetBy: 2)
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guard let byte = UInt8(string[i..<j], radix: 16) else {
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throw DecodingError.dataCorruptedError(in: container, debugDescription: "Invalid byte")
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}
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bytes.append(byte)
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i = j
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}
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return Data(bytes)
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}
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let sut = try decoder.decode(BloomFilter<String>.self, from: data)
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XCTAssert(sut.contains("lol"))
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XCTAssert(sut.contains("ok"))
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XCTAssertFalse(sut.contains("wtf"))
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XCTAssertFalse(sut.contains("no"))
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}
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}
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@ -62,7 +62,7 @@ private extension InstanceFilterService {
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static let updatedFilterUserDefaultsKey = "updatedFilter"
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// Ugly, but baking this into the compiled app instead of loading the data from the bundle is more secure
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// swiftlint:disable line_length
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static let defaultFilterData = #"{"hashers":["djb2","djb2a","fnv1","fnv1a","sdbm"],"data":"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAgAIAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAgAAAAAQAAAAAABAAACAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAABAAAEAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAIAAAAAABAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAIAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAIAAAQAAAAAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAAAAAAQAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAADAAAAAAAAAAAAA=="}"#
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static let defaultFilterData = #"{"hashes":["djb232","djb2a32","fnv132","fnv1a32","sdbm32"],"data":"AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAgAIAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAgAAAAAQAAAAAABAAACAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAABAAAEAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAIAAAAAABAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAEAAAIAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAACAAAAAAAAAAAAAAAAAAAAAQAAAAAAAAAAAAAAAAAAAAAAAIAAAQAAAAAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAIAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAQAAAAAAAQAAAAAAAAAAAEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAADAAAAAAAAAAAAA=="}"#
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.data(using: .utf8)!
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// swiftlint:enable line_length
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// swiftlint:disable force_try
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@ -29,7 +29,7 @@ class InstanceFilterServiceTests: XCTestCase {
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XCTAssertTrue(sut.isFiltered(url: previouslyFilteredInstanceURL))
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XCTAssertFalse(sut.isFiltered(url: newlyFilteredInstanceURL))
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var updatedFilter = BloomFilter<String>(hashers: [.djb2, .sdbm], byteCount: 16)
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var updatedFilter = try BloomFilter<String>(hashes: [.djb232, .sdbm32], byteCount: 16)
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updatedFilter.insert("instance.filtered")
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