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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._Chunk {
func splitCounts(at i: String.Index) -> (left: Counts, right: Counts) {
precondition(i <= string.endIndex)
guard i < string.endIndex else {
return (self.counts, Counts())
}
guard i > string.startIndex else {
return (Counts(), self.counts)
}
let i = string.unicodeScalars._index(roundingDown: i)
let leftUTF16: Int
let leftScalars: Int
let rightUTF16: Int
let rightScalars: Int
if string._utf8Offset(of: i) <= utf8Count / 2 {
leftUTF16 = string.utf16.distance(from: string.startIndex, to: i)
rightUTF16 = self.utf16Count - leftUTF16
leftScalars = string.unicodeScalars.distance(from: string.startIndex, to: i)
rightScalars = self.unicodeScalarCount - leftScalars
} else {
rightUTF16 = string.utf16.distance(from: i, to: string.endIndex)
leftUTF16 = self.utf16Count - rightUTF16
rightScalars = string.unicodeScalars.distance(from: i, to: string.endIndex)
leftScalars = self.unicodeScalarCount - rightScalars
}
let left = _counts(upTo: i, utf16: leftUTF16, scalars: leftScalars)
let right = _counts(from: i, utf16: rightUTF16, scalars: rightScalars)
assert(left.utf8 + right.utf8 == self.counts.utf8)
assert(left.utf16 + right.utf16 == self.counts.utf16)
assert(left.unicodeScalars + right.unicodeScalars == self.counts.unicodeScalars)
assert(left.characters + right.characters == self.counts.characters)
return (left, right)
}
func counts(upTo i: String.Index) -> Counts {
precondition(i <= string.endIndex)
let i = string.unicodeScalars._index(roundingDown: i)
guard i > string.startIndex else { return Counts() }
guard i < string.endIndex else { return self.counts }
let utf16 = string.utf16.distance(from: string.startIndex, to: i)
let scalars = string.unicodeScalars.distance(from: string.startIndex, to: i)
return _counts(from: i, utf16: utf16, scalars: scalars)
}
func _counts(upTo i: String.Index, utf16: Int, scalars: Int) -> Counts {
assert(i > string.startIndex && i < string.endIndex)
let s = string[..<i]
var result = Counts(
utf8: s.utf8.count,
utf16: utf16,
unicodeScalars: scalars,
characters: 0,
prefix: 0,
suffix: 0)
let firstBreak = self.firstBreak
let lastBreak = self.lastBreak
if i <= firstBreak {
result.characters = 0
result._prefix = result.utf8
result._suffix = result.utf8
} else if i > lastBreak {
result._characters = self.counts._characters
result._prefix = self.counts._prefix
result._suffix = self.counts._suffix - (self.counts.utf8 - result.utf8)
} else { // i > firstBreak, i <= lastBreak
result._prefix = self.counts._prefix
let wholeChars = string[firstBreak ..< i]
assert(!wholeChars.isEmpty)
var state = _CharacterRecognizer()
let (characters, _, last) = state.consume(wholeChars)!
result.characters = characters
result.suffix = string.utf8.distance(from: last, to: i)
}
return result
}
func counts(from i: String.Index) -> Counts {
precondition(i <= string.endIndex)
let i = string.unicodeScalars._index(roundingDown: i)
guard i > string.startIndex else { return self.counts }
guard i < string.endIndex else { return Counts() }
let utf16 = string.utf16.distance(from: i, to: string.endIndex)
let scalars = string.unicodeScalars.distance(from: i, to: string.endIndex)
return _counts(from: i, utf16: utf16, scalars: scalars)
}
func _counts(from i: String.Index, utf16: Int, scalars: Int) -> Counts {
assert(i > string.startIndex && i < string.endIndex)
let s = string[i...]
var result = Counts(
utf8: s.utf8.count,
utf16: utf16,
unicodeScalars: scalars,
characters: 0,
prefix: 0,
suffix: 0)
let firstBreak = self.firstBreak
let lastBreak = self.lastBreak
if i > lastBreak {
result._characters = 0
result._prefix = result.utf8
result._suffix = result.utf8
} else if i <= firstBreak {
result._characters = self.counts._characters
result.prefix = self.counts.prefix - self.string._utf8Offset(of: i)
result._suffix = self.counts._suffix
} else { // i > firstBreak, i <= lastBreak
result._suffix = self.counts._suffix
let prevBreak = string[firstBreak..<lastBreak]._index(roundingDown: i)
var state = _CharacterRecognizer(partialCharacter: string[prevBreak ..< i])
if let (characters, first, _) = state.consume(string[i ..< lastBreak]) {
assert(first >= i)
result.characters = characters + 1
result.prefix = string.utf8.distance(from: i, to: first)
} else {
result.characters = 1
result.prefix = string.utf8.distance(from: i, to: lastBreak)
}
}
return result
}
}
#endif
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