UnsafeMutableRawBufferPointer
A mutable nonowning collection interface to the bytes in a region of memory.
@frozen struct UnsafeMutableRawBufferPointerYou can use an UnsafeMutableRawBufferPointer instance in low-level operations to eliminate uniqueness checks and release mode bounds checks. Bounds checks are always performed in debug mode.
An UnsafeMutableRawBufferPointer instance is a view of the raw bytes in a region of memory. Each byte in memory is viewed as a UInt8 value independent of the type of values held in that memory. Reading from and writing to memory through a raw buffer are untyped operations. Accessing this collection’s bytes does not bind the underlying memory to UInt8.
In addition to its collection interface, an UnsafeMutableRawBufferPointer instance also supports the following methods provided by UnsafeMutableRawPointer, including bounds checks in debug mode:
load(fromByteOffset:as:)loadUnaligned(fromByteOffset:as:)storeBytes(of:toByteOffset:as:)copyMemory(from:)
To access the underlying memory through typed operations, the memory must be bound to a trivial type.
UnsafeMutableRawBufferPointer Semantics
An UnsafeMutableRawBufferPointer instance is a view into memory and does not own the memory that it references. Copying a variable or constant of type UnsafeMutableRawBufferPointer does not copy the underlying memory. However, initializing another collection with an UnsafeMutableRawBufferPointer instance copies bytes out of the referenced memory and into the new collection.
The following example uses someBytes, an UnsafeMutableRawBufferPointer instance, to demonstrate the difference between assigning a buffer pointer and using a buffer pointer as the source for another collection’s elements. Here, the assignment to destBytes creates a new, nonowning buffer pointer covering the first n bytes of the memory that someBytes references—nothing is copied:
var destBytes = someBytes[0..<n]Next, the bytes referenced by destBytes are copied into byteArray, a new [UInt8] array, and then the remainder of someBytes is appended to byteArray:
var byteArray: [UInt8] = Array(destBytes)
byteArray += someBytes[n..<someBytes.count]Assigning into a ranged subscript of an UnsafeMutableRawBufferPointer instance copies bytes into the memory. The next n bytes of the memory that someBytes references are copied in this code:
destBytes[0..<n] = someBytes[n..<(n + n)]Citizens in Swift
Conformances
protocol BidirectionalCollectionA collection that supports backward as well as forward traversal.
protocol CollectionA sequence whose elements can be traversed multiple times, nondestructively, and accessed by an indexed subscript.
protocol CustomDebugStringConvertibleA type with a customized textual representation suitable for debugging purposes.
protocol MutableCollectionA collection that supports subscript assignment.
protocol RandomAccessCollectionA collection that supports efficient random-access index traversal.
protocol SendableA type whose values can safely be passed across concurrency domains by copying.
protocol SequenceA type that provides sequential, iterated access to its elements.
Members
init(UnsafeMutableRawBufferPointer) Creates a new buffer over the same memory as the given buffer.
init<T>(UnsafeMutableBufferPointer<T>) Creates a raw buffer over the contiguous bytes in the given typed buffer.
init(mutating: UnsafeRawBufferPointer) Creates a new mutable buffer over the same memory as the given buffer.
init(rebasing: Slice<UnsafeMutableRawBufferPointer>) Creates a raw buffer over the same memory as the given raw buffer slice, with the indices rebased to zero.
init(start: UnsafeMutableRawPointer?, count: Int) Creates a buffer over the specified number of contiguous bytes starting at the given pointer.
static func allocate(byteCount: Int, alignment: Int) -> UnsafeMutableRawBufferPointer Allocates uninitialized memory with the specified size and alignment.
var baseAddress: UnsafeMutableRawPointer?A pointer to the first byte of the buffer.
var count: IntThe number of bytes in the buffer.
var debugDescription: StringA textual representation of the buffer, suitable for debugging.
var endIndex: UnsafeMutableRawBufferPointer.IndexThe “past the end” position—that is, the position one greater than the last valid subscript argument.
var indices: UnsafeMutableRawBufferPointer.Indicesvar startIndex: UnsafeMutableRawBufferPointer.IndexAlways zero, which is the index of the first byte in a nonempty buffer.
subscript(Range<Int>) -> UnsafeMutableRawBufferPointer.SubSequence Accesses the bytes in the specified memory region.
subscript(Int) -> UnsafeMutableRawBufferPointer.Element Accesses the byte at the given offset in the memory region as a
UInt8value.func assumingMemoryBound<T>(to: T.Type) -> UnsafeMutableBufferPointer<T> Returns a typed buffer to the memory referenced by this buffer, assuming that the memory is already bound to the specified type.
func bindMemory<T>(to: T.Type) -> UnsafeMutableBufferPointer<T> Binds this buffer’s memory to the specified type and returns a typed buffer of the bound memory.
func copyBytes<C>(from: C) Copies from a collection of
UInt8into this buffer’s memory.func copyMemory(from: UnsafeRawBufferPointer) Copies the bytes from the given buffer to this buffer’s memory.
func deallocate() Deallocates the memory block previously allocated at this buffer pointer’s base address.
func initializeMemory<S>(as: S.Element.Type, from: S) -> (unwritten: S.Iterator, initialized: UnsafeMutableBufferPointer<S.Element>) Initializes the buffer’s memory with the given elements, binding the initialized memory to the elements’ type.
func initializeMemory<C>(as: C.Element.Type, fromContentsOf: C) -> UnsafeMutableBufferPointer<C.Element> Initializes the buffer’s memory with every element of the source, binding the initialized memory to the elements’ type.
func initializeMemory<T>(as: T.Type, repeating: T) -> UnsafeMutableBufferPointer<T> Initializes the memory referenced by this buffer with the given value, binds the memory to the value’s type, and returns a typed buffer of the initialized memory.
func load<T>(fromByteOffset: Int, as: T.Type) -> T Returns a new instance of the given type, read from the buffer pointer’s raw memory at the specified byte offset.
func loadUnaligned<T>(fromByteOffset: Int, as: T.Type) -> T Returns a new instance of the given type, constructed from the raw memory at the specified offset.
func makeIterator() -> UnsafeMutableRawBufferPointer.Iterator Returns an iterator over the bytes of this sequence.
func moveInitializeMemory<T>(as: T.Type, fromContentsOf: UnsafeMutableBufferPointer<T>) -> UnsafeMutableBufferPointer<T> Moves every element of an initialized source buffer into the uninitialized memory referenced by this buffer, leaving the source memory uninitialized and this buffer’s memory initialized.
func moveInitializeMemory<T>(as: T.Type, fromContentsOf: Slice<UnsafeMutableBufferPointer<T>>) -> UnsafeMutableBufferPointer<T> Moves every element of an initialized source buffer slice into the uninitialized memory referenced by this buffer, leaving the source memory uninitialized and this buffer’s memory initialized.
func storeBytes<T>(of: T, toByteOffset: Int, as: T.Type) Stores a value’s bytes into the buffer pointer’s raw memory at the specified byte offset.
func swapAt(Int, Int) Exchanges the byte values at the specified indices in this buffer’s memory.
func withContiguousMutableStorageIfAvailable<R>((inout UnsafeMutableBufferPointer<UnsafeMutableRawBufferPointer.Element>) throws -> R) rethrows -> R? func withContiguousStorageIfAvailable<R>((UnsafeBufferPointer<UnsafeMutableRawBufferPointer.Element>) throws -> R) rethrows -> R? func withMemoryRebound<T, Result>(to: T.Type, (UnsafeMutableBufferPointer<T>) throws -> Result) rethrows -> Result Executes the given closure while temporarily binding the buffer to instances of type
T.typealias Elementtypealias Indextypealias Indicestypealias Iteratortypealias SubSequencestatic func allocate(count: Int) -> UnsafeMutableRawBufferPointer func copyBytes(from: UnsafeRawBufferPointer)
Features
var first: Self.Element?The first element of the collection.
var last: Self.Element?The last element of the collection.
var lazy: LazySequence<Self>A sequence containing the same elements as this sequence, but on which some operations, such as
mapandfilter, are implemented lazily.func allSatisfy((Self.Element) throws -> Bool) rethrows -> Bool Returns a Boolean value indicating whether every element of a sequence satisfies a given predicate.
func compactMap<ElementOfResult>((Self.Element) throws -> ElementOfResult?) rethrows -> [ElementOfResult] Returns an array containing the non-
nilresults of calling the given transformation with each element of this sequence.func contains(Self.Element) -> Bool Returns a Boolean value indicating whether the sequence contains the given element.
func contains(where: (Self.Element) throws -> Bool) rethrows -> Bool Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.
func difference<C>(from: C) -> CollectionDifference<Self.Element> Returns the difference needed to produce this collection’s ordered elements from the given collection.
func difference<C>(from: C, by: (C.Element, Self.Element) -> Bool) -> CollectionDifference<Self.Element> Returns the difference needed to produce this collection’s ordered elements from the given collection, using the given predicate as an equivalence test.
func drop(while: (Self.Element) throws -> Bool) rethrows -> Self.SubSequence Returns a subsequence by skipping elements while
predicatereturnstrueand returning the remaining elements.func dropFirst(Int) -> Self.SubSequence Returns a subsequence containing all but the given number of initial elements.
func dropLast(Int) -> Self.SubSequence Returns a subsequence containing all but the specified number of final elements.
func elementsEqual<OtherSequence>(OtherSequence) -> Bool Returns a Boolean value indicating whether this sequence and another sequence contain the same elements in the same order.
func elementsEqual<OtherSequence>(OtherSequence, by: (Self.Element, OtherSequence.Element) throws -> Bool) rethrows -> Bool Returns a Boolean value indicating whether this sequence and another sequence contain equivalent elements in the same order, using the given predicate as the equivalence test.
func enumerated() -> EnumeratedSequence<Self> Returns a sequence of pairs (n, x), where n represents a consecutive integer starting at zero and x represents an element of the sequence.
func filter((Self.Element) throws -> Bool) rethrows -> [Self.Element] Returns an array containing, in order, the elements of the sequence that satisfy the given predicate.
func first(where: (Self.Element) throws -> Bool) rethrows -> Self.Element? Returns the first element of the sequence that satisfies the given predicate.
func firstIndex(of: Self.Element) -> Self.Index? Returns the first index where the specified value appears in the collection.
func firstIndex(where: (Self.Element) throws -> Bool) rethrows -> Self.Index? Returns the first index in which an element of the collection satisfies the given predicate.
func flatMap<SegmentOfResult>((Self.Element) throws -> SegmentOfResult) rethrows -> [SegmentOfResult.Element] Returns an array containing the concatenated results of calling the given transformation with each element of this sequence.
func forEach((Self.Element) throws -> Void) rethrows Calls the given closure on each element in the sequence in the same order as a
for-inloop.func formIndex(inout Self.Index, offsetBy: Int) Offsets the given index by the specified distance.
func formIndex(inout Self.Index, offsetBy: Int, limitedBy: Self.Index) -> Bool Offsets the given index by the specified distance, or so that it equals the given limiting index.
func last(where: (Self.Element) throws -> Bool) rethrows -> Self.Element? Returns the last element of the sequence that satisfies the given predicate.
func lastIndex(of: Self.Element) -> Self.Index? Returns the last index where the specified value appears in the collection.
func lastIndex(where: (Self.Element) throws -> Bool) rethrows -> Self.Index? Returns the index of the last element in the collection that matches the given predicate.
func lexicographicallyPrecedes<OtherSequence>(OtherSequence) -> Bool Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the less-than operator (
<) to compare elements.func lexicographicallyPrecedes<OtherSequence>(OtherSequence, by: (Self.Element, Self.Element) throws -> Bool) rethrows -> Bool Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.
func map<T>((Self.Element) throws -> T) rethrows -> [T] Returns an array containing the results of mapping the given closure over the sequence’s elements.
func map<T>((Self.Element) throws -> T) rethrows -> [T] Returns an array containing the results of mapping the given closure over the sequence’s elements.
func max() -> Self.Element? Returns the maximum element in the sequence.
func max(by: (Self.Element, Self.Element) throws -> Bool) rethrows -> Self.Element? Returns the maximum element in the sequence, using the given predicate as the comparison between elements.
func min() -> Self.Element? Returns the minimum element in the sequence.
func min(by: (Self.Element, Self.Element) throws -> Bool) rethrows -> Self.Element? Returns the minimum element in the sequence, using the given predicate as the comparison between elements.
func prefix(Int) -> Self.SubSequence Returns a subsequence, up to the specified maximum length, containing the initial elements of the collection.
func prefix(through: Self.Index) -> Self.SubSequence Returns a subsequence from the start of the collection through the specified position.
func prefix(upTo: Self.Index) -> Self.SubSequence Returns a subsequence from the start of the collection up to, but not including, the specified position.
func prefix(while: (Self.Element) throws -> Bool) rethrows -> Self.SubSequence Returns a subsequence containing the initial elements until
predicatereturnsfalseand skipping the remaining elements.func randomElement() -> Self.Element? Returns a random element of the collection.
func randomElement<T>(using: inout T) -> Self.Element? Returns a random element of the collection, using the given generator as a source for randomness.
func reduce<Result>(Result, (Result, Self.Element) throws -> Result) rethrows -> Result Returns the result of combining the elements of the sequence using the given closure.
func reduce<Result>(into: Result, (inout Result, Self.Element) throws -> ()) rethrows -> Result Returns the result of combining the elements of the sequence using the given closure.
func reverse() Reverses the elements of the collection in place.
func reversed() -> ReversedCollection<Self> Returns a view presenting the elements of the collection in reverse order.
func shuffle() Shuffles the collection in place.
func shuffle<T>(using: inout T) Shuffles the collection in place, using the given generator as a source for randomness.
func shuffled() -> [Self.Element] Returns the elements of the sequence, shuffled.
func shuffled<T>(using: inout T) -> [Self.Element] Returns the elements of the sequence, shuffled using the given generator as a source for randomness.
func sort() Sorts the collection in place.
func sort(by: (Self.Element, Self.Element) throws -> Bool) rethrows Sorts the collection in place, using the given predicate as the comparison between elements.
func sorted() -> [Self.Element] Returns the elements of the sequence, sorted.
func sorted(by: (Self.Element, Self.Element) throws -> Bool) rethrows -> [Self.Element] Returns the elements of the sequence, sorted using the given predicate as the comparison between elements.
func split(maxSplits: Int, omittingEmptySubsequences: Bool, whereSeparator: (Self.Element) throws -> Bool) rethrows -> [Self.SubSequence] Returns the longest possible subsequences of the collection, in order, that don’t contain elements satisfying the given predicate.
func split(separator: Self.Element, maxSplits: Int, omittingEmptySubsequences: Bool) -> [Self.SubSequence] Returns the longest possible subsequences of the collection, in order, around elements equal to the given element.
func starts<PossiblePrefix>(with: PossiblePrefix) -> Bool Returns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.
func starts<PossiblePrefix>(with: PossiblePrefix, by: (Self.Element, PossiblePrefix.Element) throws -> Bool) rethrows -> Bool Returns a Boolean value indicating whether the initial elements of the sequence are equivalent to the elements in another sequence, using the given predicate as the equivalence test.
func suffix(Int) -> Self.SubSequence Returns a subsequence, up to the given maximum length, containing the final elements of the collection.
func suffix(from: Self.Index) -> Self.SubSequence Returns a subsequence from the specified position to the end of the collection.
func flatMap<ElementOfResult>((Self.Element) throws -> ElementOfResult?) rethrows -> [ElementOfResult] func index(of: Self.Element) -> Self.Index? Returns the first index where the specified value appears in the collection.
Available in Foundation
Conformances
protocol ContiguousBytesIndicates that the conforming type is a contiguous collection of raw bytes whose underlying storage is directly accessible by withUnsafeBytes.