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8851bac1be
Add inlinability annotations to restore performance parity with 4.2 String. Take advantage of known NFC as a fast-path for comparison, and overhaul comparison dispatch. RRC improvements and optmizations.
62 lines
1.9 KiB
Swift
62 lines
1.9 KiB
Swift
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SwiftShims
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extension String : Hashable {
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/// Hashes the essential components of this value by feeding them into the
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/// given hasher.
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///
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/// - Parameter hasher: The hasher to use when combining the components
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/// of this instance.
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@inlinable // For pre-normal fast paths
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public func hash(into hasher: inout Hasher) {
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// TODO(UTF8 perf): pre-normal checks, fast-paths, etc.
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_guts._normalizedHash(into: &hasher)
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}
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}
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extension StringProtocol {
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/// Hashes the essential components of this value by feeding them into the
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/// given hasher.
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///
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/// - Parameter hasher: The hasher to use when combining the components
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/// of this instance.
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@inlinable
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public func hash(into hasher: inout Hasher) {
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// TODO(UTF8 perf): skip extra copy
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_ephemeralString.hash(into: &hasher)
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}
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}
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extension _StringGuts {
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@usableFromInline // @opaque
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@inline(never) // slow-path
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internal func _normalizedHash(into hasher: inout Hasher) {
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if self.isNFC && self.isFastUTF8 {
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self.withFastUTF8 {
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hasher.combine(bytes: UnsafeRawBufferPointer($0))
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}
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} else {
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// TODO(UTF8 perf): Other fast-paths, incremental (non-allocating)
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// normalization, etc.
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String(self)._normalize().withUnsafeBytes {
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hasher.combine(bytes: $0)
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}
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}
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hasher.combine(0xFF as UInt8) // terminator
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}
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}
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