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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Collections open source project
//
// Copyright (c) 2023 - 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
//
//===----------------------------------------------------------------------===//
#if swift(>=5.8)
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString {
internal struct _Chunk {
typealias Slice = (string: Substring, characters: Int, prefix: Int, suffix: Int)
var string: String
var counts: Counts
init() {
self.string = ""
self.counts = Counts()
}
init(_ string: String, _ counts: Counts) {
self.string = string
self.string.makeContiguousUTF8()
self.counts = counts
invariantCheck()
}
init(_ string: Substring, _ counts: Counts) {
self.string = String(string)
self.counts = counts
invariantCheck()
}
init(_ slice: Slice) {
self.string = String(slice.string)
self.string.makeContiguousUTF8()
self.counts = Counts((self.string[...], slice.characters, slice.prefix, slice.suffix))
invariantCheck()
}
}
}
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString._Chunk {
@inline(__always)
static var maxUTF8Count: Int { 255 }
@inline(__always)
static var minUTF8Count: Int { maxUTF8Count / 2 - maxSlicingError }
@inline(__always)
static var maxSlicingError: Int { 3 }
}
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString._Chunk {
@inline(__always)
mutating func take() -> Self {
let r = self
self = Self()
return r
}
@inline(__always)
mutating func modify<R>(
_ body: (inout Self) -> R
) -> R {
body(&self)
}
}
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString._Chunk {
@inline(__always)
var characterCount: Int { counts.characters }
@inline(__always)
var unicodeScalarCount: Int { Int(counts.unicodeScalars) }
@inline(__always)
var utf16Count: Int { Int(counts.utf16) }
@inline(__always)
var utf8Count: Int { Int(counts.utf8) }
@inline(__always)
var prefixCount: Int { counts.prefix }
@inline(__always)
var suffixCount: Int { counts.suffix }
var firstScalar: UnicodeScalar { string.unicodeScalars.first! }
var lastScalar: UnicodeScalar { string.unicodeScalars.last! }
}
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString._Chunk {
var availableSpace: Int { Swift.max(0, Self.maxUTF8Count - utf8Count) }
mutating func clear() {
string = ""
counts = Counts()
}
}
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString._Chunk {
func hasSpaceToMerge(_ other: some StringProtocol) -> Bool {
utf8Count + other.utf8.count <= Self.maxUTF8Count
}
func hasSpaceToMerge(_ other: Self) -> Bool {
utf8Count + other.utf8Count <= Self.maxUTF8Count
}
}
#endif
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