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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: Sequence {
public typealias Element = Character
public func makeIterator() -> Iterator {
Iterator(self)
}
}
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString {
public struct Iterator {
internal let _base: BigString
internal var _utf8BaseOffset: Int
internal var _ropeIndex: _Rope.Index
internal var _chunkIndex: String.Index
internal var _next: String.Index
internal init(_ string: BigString) {
self._base = string
self._ropeIndex = string._rope.startIndex
string._rope.grease(&_ropeIndex)
self._utf8BaseOffset = 0
guard _ropeIndex < string._rope.endIndex else {
_chunkIndex = "".startIndex
_next = "".endIndex
return
}
let chunk = _base._rope[_ropeIndex]
assert(chunk.firstBreak == chunk.string.startIndex)
self._chunkIndex = chunk.firstBreak
self._next = chunk.string[_chunkIndex...].index(after: _chunkIndex)
}
internal init(
_ string: BigString,
from start: Index
) {
self._base = string
self._utf8BaseOffset = start.utf8Offset
if start == string.endIndex {
self._ropeIndex = string._rope.endIndex
self._chunkIndex = "".startIndex
self._next = "".endIndex
return
}
let i = string.resolve(start, preferEnd: false)
self._ropeIndex = i._rope!
self._utf8BaseOffset = i._utf8BaseOffset
self._chunkIndex = i._chunkIndex
self._next = _base._rope[_ropeIndex].wholeCharacters.index(after: _chunkIndex)
}
}
}
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString.Iterator: IteratorProtocol {
public typealias Element = Character
internal var isAtEnd: Bool {
_chunkIndex == _next
}
internal var isAtStart: Bool {
_ropeIndex == _base._rope.startIndex && _chunkIndex._utf8Offset == 0
}
internal var current: Element {
assert(!isAtEnd)
let chunk = _base._rope[_ropeIndex]
var str = String(chunk.string[_chunkIndex ..< _next])
if _next < chunk.string.endIndex { return Character(str) }
var i = _base._rope.index(after: _ropeIndex)
while i < _base._rope.endIndex {
let chunk = _base._rope[i]
let b = chunk.firstBreak
str += chunk.string[..<b]
if b < chunk.string.endIndex { break }
_base._rope.formIndex(after: &i)
}
return Character(str)
}
mutating func stepForward() -> Bool {
guard !isAtEnd else { return false }
let chunk = _base._rope[_ropeIndex]
if _next < chunk.string.endIndex {
_chunkIndex = _next
_next = chunk.wholeCharacters.index(after: _next)
return true
}
var baseOffset = _utf8BaseOffset + chunk.utf8Count
var i = _base._rope.index(after: _ropeIndex)
while i < _base._rope.endIndex {
let chunk = _base._rope[i]
let b = chunk.firstBreak
if b < chunk.string.endIndex {
_ropeIndex = i
_utf8BaseOffset = baseOffset
_chunkIndex = b
_next = chunk.string[b...].index(after: b)
return true
}
baseOffset += chunk.utf8Count
_base._rope.formIndex(after: &i)
}
return false
}
mutating func stepBackward() -> Bool {
if !isAtEnd {
let chunk = _base._rope[_ropeIndex]
let i = chunk.firstBreak
if _chunkIndex > i {
_next = _chunkIndex
_chunkIndex = chunk.string[i...].index(before: _chunkIndex)
return true
}
}
var i = _ropeIndex
var baseOffset = _utf8BaseOffset
while i > _base._rope.startIndex {
_base._rope.formIndex(before: &i)
let chunk = _base._rope[i]
baseOffset -= chunk.utf8Count
if chunk.hasBreaks {
_ropeIndex = i
_utf8BaseOffset = baseOffset
_next = chunk.string.endIndex
_chunkIndex = chunk.lastBreak
return true
}
}
return false
}
public mutating func next() -> Character? {
guard !isAtEnd else { return nil }
let item = self.current
if !stepForward() {
_chunkIndex = _next
}
return item
}
}
@available(macOS 13.3, iOS 16.4, watchOS 9.4, tvOS 16.4, *)
extension BigString.Iterator {
// The UTF-8 offset of the current position, from the start of the string.
var utf8Offset: Int {
_utf8BaseOffset + _chunkIndex._utf8Offset
}
var index: BigString.Index {
BigString.Index(baseUTF8Offset: _utf8BaseOffset, _rope: _ropeIndex, chunk: _chunkIndex)
}
internal var nextIndex: BigString.Index {
assert(!isAtEnd)
let chunk = _base._rope[_ropeIndex]
if _next < chunk.string.endIndex {
return BigString.Index(baseUTF8Offset: _utf8BaseOffset, _rope: _ropeIndex, chunk: _next)
}
var i = _base._rope.index(after: _ropeIndex)
var base = _utf8BaseOffset
while i < _base._rope.endIndex {
let chunk = _base._rope[i]
let b = chunk.firstBreak
if b < chunk.string.endIndex {
return BigString.Index(baseUTF8Offset: base, _rope: i, chunk: b)
}
base += chunk.utf8Count
_base._rope.formIndex(after: &i)
}
return _base.endIndex
}
/// The UTF-8 offset range of the current character, measured from the start of the string.
var utf8Range: Range<Int> {
assert(!isAtEnd)
let start = utf8Offset
var end = _utf8BaseOffset
var chunk = _base._rope[_ropeIndex]
if _next < chunk.string.endIndex {
end += _next._utf8Offset
return Range(uncheckedBounds: (start, end))
}
end += chunk.utf8Count
var i = _base._rope.index(after: _ropeIndex)
while i < _base._rope.endIndex {
chunk = _base._rope[i]
let b = chunk.firstBreak
if b < chunk.string.endIndex {
end += b._utf8Offset
break
}
end += chunk.utf8Count
_base._rope.formIndex(after: &i)
}
return Range(uncheckedBounds: (start, end))
}
func isAbove(_ index: BigString.Index) -> Bool {
self.utf8Offset > index.utf8Offset
}
func isBelow(_ index: BigString.Index) -> Bool {
self.utf8Offset < index.utf8Offset
}
}
#endif
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