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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Collections open source project
//
// Copyright (c) 2022 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
//
//===----------------------------------------------------------------------===//
/// An abstract representation of a hash value.
struct Hash {
var value: Int
init(_ value: Int) {
self.value = value
}
init(_ value: UInt) {
self.value = Int(bitPattern: value)
}
}
extension Hash {
static var bucketBitWidth: Int { 5 }
static var bucketCount: Int { 1 << bucketBitWidth }
static var bitWidth: Int { UInt.bitWidth }
}
extension Hash: Equatable {
static func ==(left: Self, right: Self) -> Bool {
left.value == right.value
}
}
extension Hash: Hashable {
func hash(into hasher: inout Hasher) {
hasher.combine(value)
}
}
extension Hash: CustomStringConvertible {
var description: String {
// Print hash values in radix 32 & reversed, so that the path in the hash
// tree is readily visible.
let p = String(
UInt(bitPattern: value),
radix: Self.bucketCount,
uppercase: true)
#if false // The zeroes look overwhelmingly long in this context
let c = (Self.bitWidth + Self.bucketBitWidth - 1) / Self.bucketBitWidth
let path = String(repeating: "0", count: Swift.max(0, c - p.count)) + p
return String(path.reversed())
#else
return String(p.reversed())
#endif
}
}
extension Hash: LosslessStringConvertible {
init?(_ description: String) {
let s = String(description.reversed())
guard let hash = UInt(s, radix: 32) else { return nil }
self.init(Int(bitPattern: hash))
}
}
extension Hash: ExpressibleByIntegerLiteral {
init(integerLiteral value: UInt) {
self.init(value)
}
}
extension Hash: ExpressibleByStringLiteral {
init(stringLiteral value: String) {
self.init(value)!
}
}
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