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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift Collections open source project
//
// Copyright (c) 2021 - 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 !COLLECTIONS_SINGLE_MODULE
import InternalCollectionsUtilities
#endif
extension BitArray {
/// An unsafe-unowned bitarray view over `UInt` storage, providing bit array
/// primitives.
@usableFromInline
@frozen
internal struct _UnsafeHandle {
@usableFromInline
internal typealias _BitPosition = _UnsafeBitSet.Index
@usableFromInline
internal let _words: UnsafeBufferPointer<_Word>
@usableFromInline
internal var _count: UInt
#if DEBUG
/// True when this handle does not support table mutations.
/// (This is only checked in debug builds.)
@usableFromInline
internal let _mutable: Bool
#endif
@inline(__always)
internal func ensureMutable() {
#if DEBUG
assert(_mutable)
#endif
}
internal var _mutableWords: UnsafeMutableBufferPointer<_Word> {
ensureMutable()
return UnsafeMutableBufferPointer(mutating: _words)
}
@inlinable
@inline(__always)
internal init(
words: UnsafeBufferPointer<_Word>,
count: UInt,
mutable: Bool
) {
assert(count <= words.count * _Word.capacity)
assert(count > (words.count - 1) * _Word.capacity)
self._words = words
self._count = count
#if DEBUG
self._mutable = mutable
#endif
}
@inlinable
@inline(__always)
internal init(
words: UnsafeMutableBufferPointer<_Word>,
count: UInt,
mutable: Bool
) {
self.init(
words: UnsafeBufferPointer(words),
count: count,
mutable: mutable)
}
}
}
extension BitArray._UnsafeHandle {
internal var count: Int {
Int(_count)
}
internal var end: _BitPosition {
_BitPosition(_count)
}
internal func set(at position: Int) {
ensureMutable()
assert(position >= 0 && position < _count)
let (word, bit) = _BitPosition(UInt(position)).split
_mutableWords[word].insert(bit)
}
internal func clear(at position: Int) {
ensureMutable()
assert(position >= 0 && position < _count)
let (word, bit) = _BitPosition(UInt(position)).split
_mutableWords[word].remove(bit)
}
internal subscript(position: Int) -> Bool {
get {
assert(position >= 0 && position < _count)
let (word, bit) = _BitPosition(UInt(position)).split
return _words[word].contains(bit)
}
set {
ensureMutable()
assert(position >= 0 && position < _count)
let (word, bit) = _BitPosition(UInt(position)).split
if newValue {
_mutableWords[word].insert(bit)
} else {
_mutableWords[word].remove(bit)
}
}
}
}
extension BitArray._UnsafeHandle {
internal mutating func fill(in range: Range<Int>) {
ensureMutable()
precondition(
range.lowerBound >= 0 && range.upperBound <= count,
"Range out of bounds")
guard range.count > 0 else { return }
let (lw, lb) = _BitPosition(range.lowerBound).split
let (uw, ub) = _BitPosition(range.upperBound).endSplit
let words = _mutableWords
guard lw != uw else {
words[lw].formUnion(_Word(from: lb, to: ub))
return
}
words[lw].formUnion(_Word(upTo: lb).complement())
for w in lw + 1 ..< uw {
words[w] = _Word.allBits
}
words[uw].formUnion(_Word(upTo: ub))
}
internal mutating func clear(in range: Range<Int>) {
ensureMutable()
precondition(
range.lowerBound >= 0 && range.upperBound <= count,
"Range out of bounds")
guard range.count > 0 else { return }
let (lw, lb) = _BitPosition(range.lowerBound).split
let (uw, ub) = _BitPosition(range.upperBound).endSplit
let words = _mutableWords
guard lw != uw else {
words[lw].subtract(_Word(from: lb, to: ub))
return
}
words[lw].subtract(_Word(upTo: lb).complement())
for w in lw + 1 ..< uw {
words[w] = _Word.empty
}
words[uw].subtract(_Word(upTo: ub))
}
}
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