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fuchsia / third_party / swift / 34960788aa9e62e4c36d2cf5da08bd56a6635af5 / . / stdlib / public / core / KeyPath.swift
blob: 0ad7893fa83e03bbf1812adbb5a8340c8bc2ab68 [file] [log] [blame]
//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2017 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
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
import SwiftShims
internal func _abstract(
methodName: StaticString = #function,
file: StaticString = #file, line: UInt = #line
) -> Never {
#if INTERNAL_CHECKS_ENABLED
_fatalErrorMessage("abstract method", methodName, file: file, line: line,
flags: _fatalErrorFlags())
#else
_conditionallyUnreachable()
#endif
}
// MARK: Type-erased abstract base classes
// NOTE: older runtimes had Swift.AnyKeyPath as the ObjC name.
// The two must coexist, so it was renamed. The old name must not be
// used in the new runtime. _TtCs11_AnyKeyPath is the mangled name for
// Swift._AnyKeyPath.
@_objcRuntimeName(_TtCs11_AnyKeyPath)
/// A type-erased key path, from any root type to any resulting value
/// type.
public class AnyKeyPath: Hashable, _AppendKeyPath {
/// The root type for this key path.
@inlinable
public static var rootType: Any.Type {
return _rootAndValueType.root
}
/// The value type for this key path.
@inlinable
public static var valueType: Any.Type {
return _rootAndValueType.value
}
internal final var _kvcKeyPathStringPtr: UnsafePointer<CChar>?
/// The hash value.
final public var hashValue: Int {
return _hashValue(for: self)
}
/// Hashes the essential components of this value by feeding them into the
/// given hasher.
///
/// - Parameter hasher: The hasher to use when combining the components
/// of this instance.
@_effects(releasenone)
final public func hash(into hasher: inout Hasher) {
ObjectIdentifier(type(of: self)).hash(into: &hasher)
return withBuffer {
var buffer = $0
if buffer.data.isEmpty { return }
while true {
let (component, type) = buffer.next()
hasher.combine(component.value)
if let type = type {
hasher.combine(unsafeBitCast(type, to: Int.self))
} else {
break
}
}
}
}
public static func ==(a: AnyKeyPath, b: AnyKeyPath) -> Bool {
// Fast-path identical objects
if a === b {
return true
}
// Short-circuit differently-typed key paths
if type(of: a) != type(of: b) {
return false
}
return a.withBuffer {
var aBuffer = $0
return b.withBuffer {
var bBuffer = $0
// Two equivalent key paths should have the same reference prefix
if aBuffer.hasReferencePrefix != bBuffer.hasReferencePrefix {
return false
}
// Identity is equal to identity
if aBuffer.data.isEmpty {
return bBuffer.data.isEmpty
}
while true {
let (aComponent, aType) = aBuffer.next()
let (bComponent, bType) = bBuffer.next()
if aComponent.header.endOfReferencePrefix
!= bComponent.header.endOfReferencePrefix
|| aComponent.value != bComponent.value
|| aType != bType {
return false
}
if aType == nil {
return true
}
}
}
}
}
// SPI for the Foundation overlay to allow interop with KVC keypath-based
// APIs.
public var _kvcKeyPathString: String? {
guard let ptr = _kvcKeyPathStringPtr else { return nil }
return String(validatingUTF8: ptr)
}
// MARK: Implementation details
// Prevent normal initialization. We use tail allocation via
// allocWithTailElems().
internal init() {
_internalInvariantFailure("use _create(...)")
}
@usableFromInline
internal class var _rootAndValueType: (root: Any.Type, value: Any.Type) {
_abstract()
}
internal static func _create(
capacityInBytes bytes: Int,
initializedBy body: (UnsafeMutableRawBufferPointer) -> Void
) -> Self {
_internalInvariant(bytes > 0 && bytes % 4 == 0,
"capacity must be multiple of 4 bytes")
let result = Builtin.allocWithTailElems_1(self, (bytes/4)._builtinWordValue,
Int32.self)
result._kvcKeyPathStringPtr = nil
let base = UnsafeMutableRawPointer(Builtin.projectTailElems(result,
Int32.self))
body(UnsafeMutableRawBufferPointer(start: base, count: bytes))
return result
}
internal func withBuffer<T>(_ f: (KeyPathBuffer) throws -> T) rethrows -> T {
defer { _fixLifetime(self) }
let base = UnsafeRawPointer(Builtin.projectTailElems(self, Int32.self))
return try f(KeyPathBuffer(base: base))
}
@usableFromInline // Exposed as public API by MemoryLayout<Root>.offset(of:)
internal var _storedInlineOffset: Int? {
return withBuffer {
var buffer = $0
// The identity key path is effectively a stored keypath of type Self
// at offset zero
if buffer.data.isEmpty { return 0 }
var offset = 0
while true {
let (rawComponent, optNextType) = buffer.next()
switch rawComponent.header.kind {
case .struct:
offset += rawComponent._structOrClassOffset
case .class, .computed, .optionalChain, .optionalForce, .optionalWrap, .external:
return .none
}
if optNextType == nil { return .some(offset) }
}
}
}
}
/// A partially type-erased key path, from a concrete root type to any
/// resulting value type.
public class PartialKeyPath<Root>: AnyKeyPath { }
// MARK: Concrete implementations
internal enum KeyPathKind { case readOnly, value, reference }
/// A key path from a specific root type to a specific resulting value type.
public class KeyPath<Root, Value>: PartialKeyPath<Root> {
@usableFromInline
internal final override class var _rootAndValueType: (
root: Any.Type,
value: Any.Type
) {
return (Root.self, Value.self)
}
// MARK: Implementation
internal typealias Kind = KeyPathKind
internal class var kind: Kind { return .readOnly }
internal static func appendedType<AppendedValue>(
with t: KeyPath<Value, AppendedValue>.Type
) -> KeyPath<Root, AppendedValue>.Type {
let resultKind: Kind
switch (self.kind, t.kind) {
case (_, .reference):
resultKind = .reference
case (let x, .value):
resultKind = x
default:
resultKind = .readOnly
}
switch resultKind {
case .readOnly:
return KeyPath<Root, AppendedValue>.self
case .value:
return WritableKeyPath.self
case .reference:
return ReferenceWritableKeyPath.self
}
}
@usableFromInline
internal final func _projectReadOnly(from root: Root) -> Value {
// TODO: For perf, we could use a local growable buffer instead of Any
var curBase: Any = root
return withBuffer {
var buffer = $0
if buffer.data.isEmpty {
return unsafeBitCast(root, to: Value.self)
}
while true {
let (rawComponent, optNextType) = buffer.next()
let valueType = optNextType ?? Value.self
let isLast = optNextType == nil
func project<CurValue>(_ base: CurValue) -> Value? {
func project2<NewValue>(_: NewValue.Type) -> Value? {
switch rawComponent._projectReadOnly(base,
to: NewValue.self, endingWith: Value.self) {
case .continue(let newBase):
if isLast {
_internalInvariant(NewValue.self == Value.self,
"key path does not terminate in correct type")
return unsafeBitCast(newBase, to: Value.self)
} else {
curBase = newBase
return nil
}
case .break(let result):
return result
}
}
return _openExistential(valueType, do: project2)
}
if let result = _openExistential(curBase, do: project) {
return result
}
}
}
}
deinit {
withBuffer { $0.destroy() }
}
}
/// A key path that supports reading from and writing to the resulting value.
public class WritableKeyPath<Root, Value>: KeyPath<Root, Value> {
// MARK: Implementation detail
internal override class var kind: Kind { return .value }
// `base` is assumed to be undergoing a formal access for the duration of the
// call, so must not be mutated by an alias
@usableFromInline
internal func _projectMutableAddress(from base: UnsafePointer<Root>)
-> (pointer: UnsafeMutablePointer<Value>, owner: AnyObject?) {
var p = UnsafeRawPointer(base)
var type: Any.Type = Root.self
var keepAlive: AnyObject?
return withBuffer {
var buffer = $0
_internalInvariant(!buffer.hasReferencePrefix,
"WritableKeyPath should not have a reference prefix")
if buffer.data.isEmpty {
return (
UnsafeMutablePointer<Value>(
mutating: p.assumingMemoryBound(to: Value.self)),
nil)
}
while true {
let (rawComponent, optNextType) = buffer.next()
let nextType = optNextType ?? Value.self
func project<CurValue>(_: CurValue.Type) {
func project2<NewValue>(_: NewValue.Type) {
p = rawComponent._projectMutableAddress(p,
from: CurValue.self,
to: NewValue.self,
isRoot: p == UnsafeRawPointer(base),
keepAlive: &keepAlive)
}
_openExistential(nextType, do: project2)
}
_openExistential(type, do: project)
if optNextType == nil { break }
type = nextType
}
// TODO: With coroutines, it would be better to yield here, so that
// we don't need the hack of the keepAlive reference to manage closing
// accesses.
let typedPointer = p.assumingMemoryBound(to: Value.self)
return (pointer: UnsafeMutablePointer(mutating: typedPointer),
owner: keepAlive)
}
}
}
/// A key path that supports reading from and writing to the resulting value
/// with reference semantics.
public class ReferenceWritableKeyPath<
Root, Value
> : WritableKeyPath<Root, Value> {
// MARK: Implementation detail
internal final override class var kind: Kind { return .reference }
internal final override func _projectMutableAddress(
from base: UnsafePointer<Root>
) -> (pointer: UnsafeMutablePointer<Value>, owner: AnyObject?) {
// Since we're a ReferenceWritableKeyPath, we know we don't mutate the base
// in practice.
return _projectMutableAddress(from: base.pointee)
}
@usableFromInline
internal final func _projectMutableAddress(from origBase: Root)
-> (pointer: UnsafeMutablePointer<Value>, owner: AnyObject?) {
var keepAlive: AnyObject?
var address: UnsafeMutablePointer<Value> = withBuffer {
var buffer = $0
// Project out the reference prefix.
var base: Any = origBase
while buffer.hasReferencePrefix {
let (rawComponent, optNextType) = buffer.next()
_internalInvariant(optNextType != nil,
"reference prefix should not go to end of buffer")
let nextType = optNextType.unsafelyUnwrapped
func project<NewValue>(_: NewValue.Type) -> Any {
func project2<CurValue>(_ base: CurValue) -> Any {
return rawComponent._projectReadOnly(
base, to: NewValue.self, endingWith: Value.self)
.assumingContinue
}
return _openExistential(base, do: project2)
}
base = _openExistential(nextType, do: project)
}
// Start formal access to the mutable value, based on the final base
// value.
func formalMutation<MutationRoot>(_ base: MutationRoot)
-> UnsafeMutablePointer<Value> {
var base2 = base
return withUnsafeBytes(of: &base2) { baseBytes in
var p = baseBytes.baseAddress.unsafelyUnwrapped
var curType: Any.Type = MutationRoot.self
while true {
let (rawComponent, optNextType) = buffer.next()
let nextType = optNextType ?? Value.self
func project<CurValue>(_: CurValue.Type) {
func project2<NewValue>(_: NewValue.Type) {
p = rawComponent._projectMutableAddress(p,
from: CurValue.self,
to: NewValue.self,
isRoot: p == baseBytes.baseAddress,
keepAlive: &keepAlive)
}
_openExistential(nextType, do: project2)
}
_openExistential(curType, do: project)
if optNextType == nil { break }
curType = nextType
}
let typedPointer = p.assumingMemoryBound(to: Value.self)
return UnsafeMutablePointer(mutating: typedPointer)
}
}
return _openExistential(base, do: formalMutation)
}
return (address, keepAlive)
}
}
// MARK: Implementation details
internal enum KeyPathComponentKind {
/// The keypath references an externally-defined property or subscript whose
/// component describes how to interact with the key path.
case external
/// The keypath projects within the storage of the outer value, like a
/// stored property in a struct.
case `struct`
/// The keypath projects from the referenced pointer, like a
/// stored property in a class.
case `class`
/// The keypath projects using a getter/setter pair.
case computed
/// The keypath optional-chains, returning nil immediately if the input is
/// nil, or else proceeding by projecting the value inside.
case optionalChain
/// The keypath optional-forces, trapping if the input is
/// nil, or else proceeding by projecting the value inside.
case optionalForce
/// The keypath wraps a value in an optional.
case optionalWrap
}
internal struct ComputedPropertyID: Hashable {
internal var value: Int
internal var kind: KeyPathComputedIDKind
internal static func ==(
x: ComputedPropertyID, y: ComputedPropertyID
) -> Bool {
return x.value == y.value
&& x.kind == y.kind
}
internal func hash(into hasher: inout Hasher) {
hasher.combine(value)
hasher.combine(kind)
}
}
internal struct ComputedArgumentWitnesses {
internal typealias Destroy = @convention(thin)
(_ instanceArguments: UnsafeMutableRawPointer, _ size: Int) -> ()
internal typealias Copy = @convention(thin)
(_ srcInstanceArguments: UnsafeRawPointer,
_ destInstanceArguments: UnsafeMutableRawPointer,
_ size: Int) -> ()
internal typealias Equals = @convention(thin)
(_ xInstanceArguments: UnsafeRawPointer,
_ yInstanceArguments: UnsafeRawPointer,
_ size: Int) -> Bool
// FIXME(hasher) Combine to an inout Hasher instead
internal typealias Hash = @convention(thin)
(_ instanceArguments: UnsafeRawPointer,
_ size: Int) -> Int
internal let destroy: Destroy?
internal let copy: Copy
internal let equals: Equals
internal let hash: Hash
}
internal enum KeyPathComponent: Hashable {
internal struct ArgumentRef {
internal init(
data: UnsafeRawBufferPointer,
witnesses: UnsafePointer<ComputedArgumentWitnesses>,
witnessSizeAdjustment: Int
) {
self.data = data
self.witnesses = witnesses
self.witnessSizeAdjustment = witnessSizeAdjustment
}
internal var data: UnsafeRawBufferPointer
internal var witnesses: UnsafePointer<ComputedArgumentWitnesses>
internal var witnessSizeAdjustment: Int
}
/// The keypath projects within the storage of the outer value, like a
/// stored property in a struct.
case `struct`(offset: Int)
/// The keypath projects from the referenced pointer, like a
/// stored property in a class.
case `class`(offset: Int)
/// The keypath projects using a getter.
case get(id: ComputedPropertyID,
get: UnsafeRawPointer, argument: ArgumentRef?)
/// The keypath projects using a getter/setter pair. The setter can mutate
/// the base value in-place.
case mutatingGetSet(id: ComputedPropertyID,
get: UnsafeRawPointer, set: UnsafeRawPointer,
argument: ArgumentRef?)
/// The keypath projects using a getter/setter pair that does not mutate its
/// base.
case nonmutatingGetSet(id: ComputedPropertyID,
get: UnsafeRawPointer, set: UnsafeRawPointer,
argument: ArgumentRef?)
/// The keypath optional-chains, returning nil immediately if the input is
/// nil, or else proceeding by projecting the value inside.
case optionalChain
/// The keypath optional-forces, trapping if the input is
/// nil, or else proceeding by projecting the value inside.
case optionalForce
/// The keypath wraps a value in an optional.
case optionalWrap
internal static func ==(a: KeyPathComponent, b: KeyPathComponent) -> Bool {
switch (a, b) {
case (.struct(offset: let a), .struct(offset: let b)),
(.class (offset: let a), .class (offset: let b)):
return a == b
case (.optionalChain, .optionalChain),
(.optionalForce, .optionalForce),
(.optionalWrap, .optionalWrap):
return true
case (.get(id: let id1, get: _, argument: let argument1),
.get(id: let id2, get: _, argument: let argument2)),
(.mutatingGetSet(id: let id1, get: _, set: _, argument: let argument1),
.mutatingGetSet(id: let id2, get: _, set: _, argument: let argument2)),
(.nonmutatingGetSet(id: let id1, get: _, set: _, argument: let argument1),
.nonmutatingGetSet(id: let id2, get: _, set: _, argument: let argument2)):
if id1 != id2 {
return false
}
if let arg1 = argument1, let arg2 = argument2 {
return arg1.witnesses.pointee.equals(
arg1.data.baseAddress.unsafelyUnwrapped,
arg2.data.baseAddress.unsafelyUnwrapped,
arg1.data.count - arg1.witnessSizeAdjustment)
}
// If only one component has arguments, that should indicate that the
// only arguments in that component were generic captures and therefore
// not affecting equality.
return true
case (.struct, _),
(.class, _),
(.optionalChain, _),
(.optionalForce, _),
(.optionalWrap, _),
(.get, _),
(.mutatingGetSet, _),
(.nonmutatingGetSet, _):
return false
}
}
@_effects(releasenone)
internal func hash(into hasher: inout Hasher) {
func appendHashFromArgument(
_ argument: KeyPathComponent.ArgumentRef?
) {
if let argument = argument {
let hash = argument.witnesses.pointee.hash(
argument.data.baseAddress.unsafelyUnwrapped,
argument.data.count - argument.witnessSizeAdjustment)
// Returning 0 indicates that the arguments should not impact the
// hash value of the overall key path.
// FIXME(hasher): hash witness should just mutate hasher directly
if hash != 0 {
hasher.combine(hash)
}
}
}
switch self {
case .struct(offset: let a):
hasher.combine(0)
hasher.combine(a)
case .class(offset: let b):
hasher.combine(1)
hasher.combine(b)
case .optionalChain:
hasher.combine(2)
case .optionalForce:
hasher.combine(3)
case .optionalWrap:
hasher.combine(4)
case .get(id: let id, get: _, argument: let argument):
hasher.combine(5)
hasher.combine(id)
appendHashFromArgument(argument)
case .mutatingGetSet(id: let id, get: _, set: _, argument: let argument):
hasher.combine(6)
hasher.combine(id)
appendHashFromArgument(argument)
case .nonmutatingGetSet(id: let id, get: _, set: _, argument: let argument):
hasher.combine(7)
hasher.combine(id)
appendHashFromArgument(argument)
}
}
}
// A class that maintains ownership of another object while a mutable projection
// into it is underway. The lifetime of the instance of this class is also used
// to begin and end exclusive 'modify' access to the projected address.
internal final class ClassHolder<ProjectionType> {
/// The type of the scratch record passed to the runtime to record
/// accesses to guarantee exlcusive access.
internal typealias AccessRecord = Builtin.UnsafeValueBuffer
internal var previous: AnyObject?
internal var instance: AnyObject
internal init(previous: AnyObject?, instance: AnyObject) {
self.previous = previous
self.instance = instance
}
internal final class func _create(
previous: AnyObject?,
instance: AnyObject,
accessingAddress address: UnsafeRawPointer,
type: ProjectionType.Type
) -> ClassHolder {
// Tail allocate the UnsafeValueBuffer used as the AccessRecord.
// This avoids a second heap allocation since there is no source-level way to
// initialize a Builtin.UnsafeValueBuffer type and thus we cannot have a
// stored property of that type.
let holder: ClassHolder = Builtin.allocWithTailElems_1(self,
1._builtinWordValue,
AccessRecord.self)
// Initialize the ClassHolder's instance variables. This is done via
// withUnsafeMutablePointer(to:) because the instance was just allocated with
// allocWithTailElems_1 and so we need to make sure to use an initialization
// rather than an assignment.
withUnsafeMutablePointer(to: &holder.previous) {
$0.initialize(to: previous)
}
withUnsafeMutablePointer(to: &holder.instance) {
$0.initialize(to: instance)
}
let accessRecordPtr = Builtin.projectTailElems(holder, AccessRecord.self)
// Begin a 'modify' access to the address. This access is ended in
// ClassHolder's deinitializer.
Builtin.beginUnpairedModifyAccess(address._rawValue, accessRecordPtr, type)
return holder
}
deinit {
let accessRecordPtr = Builtin.projectTailElems(self, AccessRecord.self)
// Ends the access begun in _create().
Builtin.endUnpairedAccess(accessRecordPtr)
}
}
// A class that triggers writeback to a pointer when destroyed.
internal final class MutatingWritebackBuffer<CurValue, NewValue> {
internal let previous: AnyObject?
internal let base: UnsafeMutablePointer<CurValue>
internal let set: @convention(thin) (NewValue, inout CurValue, UnsafeRawPointer, Int) -> ()
internal let argument: UnsafeRawPointer
internal let argumentSize: Int
internal var value: NewValue
deinit {
set(value, &base.pointee, argument, argumentSize)
}
internal init(previous: AnyObject?,
base: UnsafeMutablePointer<CurValue>,
set: @escaping @convention(thin) (NewValue, inout CurValue, UnsafeRawPointer, Int) -> (),
argument: UnsafeRawPointer,
argumentSize: Int,
value: NewValue) {
self.previous = previous
self.base = base
self.set = set
self.argument = argument
self.argumentSize = argumentSize
self.value = value
}
}
// A class that triggers writeback to a non-mutated value when destroyed.
internal final class NonmutatingWritebackBuffer<CurValue, NewValue> {
internal let previous: AnyObject?
internal let base: CurValue
internal let set: @convention(thin) (NewValue, CurValue, UnsafeRawPointer, Int) -> ()
internal let argument: UnsafeRawPointer
internal let argumentSize: Int
internal var value: NewValue
deinit {
set(value, base, argument, argumentSize)
}
internal
init(previous: AnyObject?,
base: CurValue,
set: @escaping @convention(thin) (NewValue, CurValue, UnsafeRawPointer, Int) -> (),
argument: UnsafeRawPointer,
argumentSize: Int,
value: NewValue) {
self.previous = previous
self.base = base
self.set = set
self.argument = argument
self.argumentSize = argumentSize
self.value = value
}
}
internal typealias KeyPathComputedArgumentLayoutFn = @convention(thin)
(_ patternArguments: UnsafeRawPointer?) -> (size: Int, alignmentMask: Int)
internal typealias KeyPathComputedArgumentInitializerFn = @convention(thin)
(_ patternArguments: UnsafeRawPointer?,
_ instanceArguments: UnsafeMutableRawPointer) -> ()
internal enum KeyPathComputedIDKind {
case pointer
case storedPropertyIndex
case vtableOffset
}
internal enum KeyPathComputedIDResolution {
case resolved
case indirectPointer
case functionCall
}
internal struct RawKeyPathComponent {
internal init(header: Header, body: UnsafeRawBufferPointer) {
self.header = header
self.body = body
}
internal var header: Header
internal var body: UnsafeRawBufferPointer
internal struct Header {
internal static var payloadMask: UInt32 {
return _SwiftKeyPathComponentHeader_PayloadMask
}
internal static var discriminatorMask: UInt32 {
return _SwiftKeyPathComponentHeader_DiscriminatorMask
}
internal static var discriminatorShift: UInt32 {
return _SwiftKeyPathComponentHeader_DiscriminatorShift
}
internal static var externalTag: UInt32 {
return _SwiftKeyPathComponentHeader_ExternalTag
}
internal static var structTag: UInt32 {
return _SwiftKeyPathComponentHeader_StructTag
}
internal static var computedTag: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedTag
}
internal static var classTag: UInt32 {
return _SwiftKeyPathComponentHeader_ClassTag
}
internal static var optionalTag: UInt32 {
return _SwiftKeyPathComponentHeader_OptionalTag
}
internal static var optionalChainPayload: UInt32 {
return _SwiftKeyPathComponentHeader_OptionalChainPayload
}
internal static var optionalWrapPayload: UInt32 {
return _SwiftKeyPathComponentHeader_OptionalWrapPayload
}
internal static var optionalForcePayload: UInt32 {
return _SwiftKeyPathComponentHeader_OptionalForcePayload
}
internal static var endOfReferencePrefixFlag: UInt32 {
return _SwiftKeyPathComponentHeader_EndOfReferencePrefixFlag
}
internal static var storedMutableFlag: UInt32 {
return _SwiftKeyPathComponentHeader_StoredMutableFlag
}
internal static var storedOffsetPayloadMask: UInt32 {
return _SwiftKeyPathComponentHeader_StoredOffsetPayloadMask
}
internal static var outOfLineOffsetPayload: UInt32 {
return _SwiftKeyPathComponentHeader_OutOfLineOffsetPayload
}
internal static var unresolvedFieldOffsetPayload: UInt32 {
return _SwiftKeyPathComponentHeader_UnresolvedFieldOffsetPayload
}
internal static var unresolvedIndirectOffsetPayload: UInt32 {
return _SwiftKeyPathComponentHeader_UnresolvedIndirectOffsetPayload
}
internal static var maximumOffsetPayload: UInt32 {
return _SwiftKeyPathComponentHeader_MaximumOffsetPayload
}
internal var isStoredMutable: Bool {
_internalInvariant(kind == .struct || kind == .class)
return _value & Header.storedMutableFlag != 0
}
internal static var computedMutatingFlag: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedMutatingFlag
}
internal var isComputedMutating: Bool {
_internalInvariant(kind == .computed)
return _value & Header.computedMutatingFlag != 0
}
internal static var computedSettableFlag: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedSettableFlag
}
internal var isComputedSettable: Bool {
_internalInvariant(kind == .computed)
return _value & Header.computedSettableFlag != 0
}
internal static var computedIDByStoredPropertyFlag: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedIDByStoredPropertyFlag
}
internal static var computedIDByVTableOffsetFlag: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedIDByVTableOffsetFlag
}
internal var computedIDKind: KeyPathComputedIDKind {
let storedProperty = _value & Header.computedIDByStoredPropertyFlag != 0
let vtableOffset = _value & Header.computedIDByVTableOffsetFlag != 0
switch (storedProperty, vtableOffset) {
case (true, true):
_internalInvariantFailure("not allowed")
case (true, false):
return .storedPropertyIndex
case (false, true):
return .vtableOffset
case (false, false):
return .pointer
}
}
internal static var computedHasArgumentsFlag: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedHasArgumentsFlag
}
internal var hasComputedArguments: Bool {
_internalInvariant(kind == .computed)
return _value & Header.computedHasArgumentsFlag != 0
}
// If a computed component is instantiated from an external property
// descriptor, and both components carry arguments, we need to carry some
// extra matter to be able to map between the client and external generic
// contexts.
internal static var computedInstantiatedFromExternalWithArgumentsFlag: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedInstantiatedFromExternalWithArgumentsFlag
}
internal var isComputedInstantiatedFromExternalWithArguments: Bool {
get {
_internalInvariant(kind == .computed)
return
_value & Header.computedInstantiatedFromExternalWithArgumentsFlag != 0
}
set {
_internalInvariant(kind == .computed)
_value =
_value & ~Header.computedInstantiatedFromExternalWithArgumentsFlag
| (newValue ? Header.computedInstantiatedFromExternalWithArgumentsFlag
: 0)
}
}
internal static var externalWithArgumentsExtraSize: Int {
return MemoryLayout<Int>.size
}
internal static var computedIDResolutionMask: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedIDResolutionMask
}
internal static var computedIDResolved: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedIDResolved
}
internal static var computedIDUnresolvedIndirectPointer: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedIDUnresolvedIndirectPointer
}
internal static var computedIDUnresolvedFunctionCall: UInt32 {
return _SwiftKeyPathComponentHeader_ComputedIDUnresolvedFunctionCall
}
internal var computedIDResolution: KeyPathComputedIDResolution {
switch payload & Header.computedIDResolutionMask {
case Header.computedIDResolved:
return .resolved
case Header.computedIDUnresolvedIndirectPointer:
return .indirectPointer
case Header.computedIDUnresolvedFunctionCall:
return .functionCall
default:
_internalInvariantFailure("invalid key path resolution")
}
}
internal var _value: UInt32
internal var discriminator: UInt32 {
get {
return (_value & Header.discriminatorMask) >> Header.discriminatorShift
}
set {
let shifted = newValue << Header.discriminatorShift
_internalInvariant(shifted & Header.discriminatorMask == shifted,
"discriminator doesn't fit")
_value = _value & ~Header.discriminatorMask | shifted
}
}
internal var payload: UInt32 {
get {
return _value & Header.payloadMask
}
set {
_internalInvariant(newValue & Header.payloadMask == newValue,
"payload too big")
_value = _value & ~Header.payloadMask | newValue
}
}
internal var storedOffsetPayload: UInt32 {
get {
_internalInvariant(kind == .struct || kind == .class,
"not a stored component")
return _value & Header.storedOffsetPayloadMask
}
set {
_internalInvariant(kind == .struct || kind == .class,
"not a stored component")
_internalInvariant(newValue & Header.storedOffsetPayloadMask == newValue,
"payload too big")
_value = _value & ~Header.storedOffsetPayloadMask | newValue
}
}
internal var endOfReferencePrefix: Bool {
get {
return _value & Header.endOfReferencePrefixFlag != 0
}
set {
if newValue {
_value |= Header.endOfReferencePrefixFlag
} else {
_value &= ~Header.endOfReferencePrefixFlag
}
}
}
internal var kind: KeyPathComponentKind {
switch (discriminator, payload) {
case (Header.externalTag, _):
return .external
case (Header.structTag, _):
return .struct
case (Header.classTag, _):
return .class
case (Header.computedTag, _):
return .computed
case (Header.optionalTag, Header.optionalChainPayload):
return .optionalChain
case (Header.optionalTag, Header.optionalWrapPayload):
return .optionalWrap
case (Header.optionalTag, Header.optionalForcePayload):
return .optionalForce
default:
_internalInvariantFailure("invalid header")
}
}
// The component header is 4 bytes, but may be followed by an aligned
// pointer field for some kinds of component, forcing padding.
internal static var pointerAlignmentSkew: Int {
return MemoryLayout<Int>.size - MemoryLayout<Int32>.size
}
internal var isTrivialPropertyDescriptor: Bool {
return _value ==
_SwiftKeyPathComponentHeader_TrivialPropertyDescriptorMarker
}
/// If this is the header for a component in a key path pattern, return
/// the size of the body of the component.
internal var patternComponentBodySize: Int {
return _componentBodySize(forPropertyDescriptor: false)
}
/// If this is the header for a property descriptor, return
/// the size of the body of the component.
internal var propertyDescriptorBodySize: Int {
if isTrivialPropertyDescriptor { return 0 }
return _componentBodySize(forPropertyDescriptor: true)
}
internal func _componentBodySize(forPropertyDescriptor: Bool) -> Int {
switch kind {
case .struct, .class:
if storedOffsetPayload == Header.unresolvedFieldOffsetPayload
|| storedOffsetPayload == Header.outOfLineOffsetPayload
|| storedOffsetPayload == Header.unresolvedIndirectOffsetPayload {
// A 32-bit offset is stored in the body.
return MemoryLayout<UInt32>.size
}
// Otherwise, there's no body.
return 0
case .external:
// The body holds a pointer to the external property descriptor,
// and some number of substitution arguments, the count of which is
// in the payload.
return 4 * (1 + Int(payload))
case .computed:
// The body holds at minimum the id and getter.
var size = 8
// If settable, it also holds the setter.
if isComputedSettable {
size += 4
}
// If there are arguments, there's also a layout function,
// witness table, and initializer function.
// Property descriptors never carry argument information, though.
if !forPropertyDescriptor && hasComputedArguments {
size += 12
}
return size
case .optionalForce, .optionalChain, .optionalWrap:
// Otherwise, there's no body.
return 0
}
}
init(discriminator: UInt32, payload: UInt32) {
_value = 0
self.discriminator = discriminator
self.payload = payload
}
init(optionalForce: ()) {
self.init(discriminator: Header.optionalTag,
payload: Header.optionalForcePayload)
}
init(optionalWrap: ()) {
self.init(discriminator: Header.optionalTag,
payload: Header.optionalWrapPayload)
}
init(optionalChain: ()) {
self.init(discriminator: Header.optionalTag,
payload: Header.optionalChainPayload)
}
init(stored kind: KeyPathStructOrClass,
mutable: Bool,
inlineOffset: UInt32) {
let discriminator: UInt32
switch kind {
case .struct: discriminator = Header.structTag
case .class: discriminator = Header.classTag
}
_internalInvariant(inlineOffset <= Header.maximumOffsetPayload)
let payload = inlineOffset
| (mutable ? Header.storedMutableFlag : 0)
self.init(discriminator: discriminator,
payload: payload)
}
init(storedWithOutOfLineOffset kind: KeyPathStructOrClass,
mutable: Bool) {
let discriminator: UInt32
switch kind {
case .struct: discriminator = Header.structTag
case .class: discriminator = Header.classTag
}
let payload = Header.outOfLineOffsetPayload
| (mutable ? Header.storedMutableFlag : 0)
self.init(discriminator: discriminator,
payload: payload)
}
init(computedWithIDKind kind: KeyPathComputedIDKind,
mutating: Bool,
settable: Bool,
hasArguments: Bool,
instantiatedFromExternalWithArguments: Bool) {
let discriminator = Header.computedTag
var payload =
(mutating ? Header.computedMutatingFlag : 0)
| (settable ? Header.computedSettableFlag : 0)
| (hasArguments ? Header.computedHasArgumentsFlag : 0)
| (instantiatedFromExternalWithArguments
? Header.computedInstantiatedFromExternalWithArgumentsFlag : 0)
switch kind {
case .pointer:
break
case .storedPropertyIndex:
payload |= Header.computedIDByStoredPropertyFlag
case .vtableOffset:
payload |= Header.computedIDByVTableOffsetFlag
}
self.init(discriminator: discriminator,
payload: payload)
}
}
internal var bodySize: Int {
let ptrSize = MemoryLayout<Int>.size
switch header.kind {
case .struct, .class:
if header.storedOffsetPayload == Header.outOfLineOffsetPayload {
return 4 // overflowed
}
return 0
case .external:
_internalInvariantFailure("should be instantiated away")
case .optionalChain, .optionalForce, .optionalWrap:
return 0
case .computed:
// align to pointer, minimum two pointers for id and get
var total = Header.pointerAlignmentSkew + ptrSize * 2
// additional word for a setter
if header.isComputedSettable {
total += ptrSize
}
// include the argument size
if header.hasComputedArguments {
// two words for argument header: size, witnesses
total += ptrSize * 2
// size of argument area
total += _computedArgumentSize
if header.isComputedInstantiatedFromExternalWithArguments {
total += Header.externalWithArgumentsExtraSize
}
}
return total
}
}
internal var _structOrClassOffset: Int {
_internalInvariant(header.kind == .struct || header.kind == .class,
"no offset for this kind")
// An offset too large to fit inline is represented by a signal and stored
// in the body.
if header.storedOffsetPayload == Header.outOfLineOffsetPayload {
// Offset overflowed into body
_internalInvariant(body.count >= MemoryLayout<UInt32>.size,
"component not big enough")
return Int(body.load(as: UInt32.self))
}
return Int(header.storedOffsetPayload)
}
internal var _computedIDValue: Int {
_internalInvariant(header.kind == .computed,
"not a computed property")
return body.load(fromByteOffset: Header.pointerAlignmentSkew,
as: Int.self)
}
internal var _computedID: ComputedPropertyID {
_internalInvariant(header.kind == .computed,
"not a computed property")
return ComputedPropertyID(
value: _computedIDValue,
kind: header.computedIDKind)
}
internal var _computedGetter: UnsafeRawPointer {
_internalInvariant(header.kind == .computed,
"not a computed property")
return body.load(
fromByteOffset: Header.pointerAlignmentSkew + MemoryLayout<Int>.size,
as: UnsafeRawPointer.self)
}
internal var _computedSetter: UnsafeRawPointer {
_internalInvariant(header.isComputedSettable,
"not a settable property")
return body.load(
fromByteOffset: Header.pointerAlignmentSkew + MemoryLayout<Int>.size * 2,
as: UnsafeRawPointer.self)
}
internal var _computedArgumentHeaderPointer: UnsafeRawPointer {
_internalInvariant(header.hasComputedArguments, "no arguments")
return body.baseAddress.unsafelyUnwrapped
+ Header.pointerAlignmentSkew
+ MemoryLayout<Int>.size *
(header.isComputedSettable ? 3 : 2)
}
internal var _computedArgumentSize: Int {
return _computedArgumentHeaderPointer.load(as: Int.self)
}
internal
var _computedArgumentWitnesses: UnsafePointer<ComputedArgumentWitnesses> {
return _computedArgumentHeaderPointer.load(
fromByteOffset: MemoryLayout<Int>.size,
as: UnsafePointer<ComputedArgumentWitnesses>.self)
}
internal var _computedArguments: UnsafeRawPointer {
var base = _computedArgumentHeaderPointer + MemoryLayout<Int>.size * 2
// If the component was instantiated from an external property descriptor
// with its own arguments, we include some additional capture info to
// be able to map to the original argument context by adjusting the size
// passed to the witness operations.
if header.isComputedInstantiatedFromExternalWithArguments {
base += Header.externalWithArgumentsExtraSize
}
return base
}
internal var _computedMutableArguments: UnsafeMutableRawPointer {
return UnsafeMutableRawPointer(mutating: _computedArguments)
}
internal var _computedArgumentWitnessSizeAdjustment: Int {
if header.isComputedInstantiatedFromExternalWithArguments {
return _computedArguments.load(
fromByteOffset: -Header.externalWithArgumentsExtraSize,
as: Int.self)
}
return 0
}
internal var value: KeyPathComponent {
switch header.kind {
case .struct:
return .struct(offset: _structOrClassOffset)
case .class:
return .class(offset: _structOrClassOffset)
case .optionalChain:
return .optionalChain
case .optionalForce:
return .optionalForce
case .optionalWrap:
return .optionalWrap
case .computed:
let isSettable = header.isComputedSettable
let isMutating = header.isComputedMutating
let id = _computedID
let get = _computedGetter
// Argument value is unused if there are no arguments.
let argument: KeyPathComponent.ArgumentRef?
if header.hasComputedArguments {
argument = KeyPathComponent.ArgumentRef(
data: UnsafeRawBufferPointer(start: _computedArguments,
count: _computedArgumentSize),
witnesses: _computedArgumentWitnesses,
witnessSizeAdjustment: _computedArgumentWitnessSizeAdjustment)
} else {
argument = nil
}
switch (isSettable, isMutating) {
case (false, false):
return .get(id: id, get: get, argument: argument)
case (true, false):
return .nonmutatingGetSet(id: id,
get: get,
set: _computedSetter,
argument: argument)
case (true, true):
return .mutatingGetSet(id: id,
get: get,
set: _computedSetter,
argument: argument)
case (false, true):
_internalInvariantFailure("impossible")
}
case .external:
_internalInvariantFailure("should have been instantiated away")
}
}
internal func destroy() {
switch header.kind {
case .struct,
.class,
.optionalChain,
.optionalForce,
.optionalWrap:
// trivial
break
case .computed:
// Run destructor, if any
if header.hasComputedArguments,
let destructor = _computedArgumentWitnesses.pointee.destroy {
destructor(_computedMutableArguments,
_computedArgumentSize - _computedArgumentWitnessSizeAdjustment)
}
case .external:
_internalInvariantFailure("should have been instantiated away")
}
}
internal func clone(into buffer: inout UnsafeMutableRawBufferPointer,
endOfReferencePrefix: Bool) {
var newHeader = header
newHeader.endOfReferencePrefix = endOfReferencePrefix
var componentSize = MemoryLayout<Header>.size
buffer.storeBytes(of: newHeader, as: Header.self)
switch header.kind {
case .struct,
.class:
if header.storedOffsetPayload == Header.outOfLineOffsetPayload {
let overflowOffset = body.load(as: UInt32.self)
buffer.storeBytes(of: overflowOffset, toByteOffset: 4,
as: UInt32.self)
componentSize += 4
}
case .optionalChain,
.optionalForce,
.optionalWrap:
break
case .computed:
// Fields are pointer-aligned after the header
componentSize += Header.pointerAlignmentSkew
buffer.storeBytes(of: _computedIDValue,
toByteOffset: componentSize,
as: Int.self)
componentSize += MemoryLayout<Int>.size
buffer.storeBytes(of: _computedGetter,
toByteOffset: componentSize,
as: UnsafeRawPointer.self)
componentSize += MemoryLayout<Int>.size
if header.isComputedSettable {
buffer.storeBytes(of: _computedSetter,
toByteOffset: MemoryLayout<Int>.size * 3,
as: UnsafeRawPointer.self)
componentSize += MemoryLayout<Int>.size
}
if header.hasComputedArguments {
let arguments = _computedArguments
let argumentSize = _computedArgumentSize
buffer.storeBytes(of: argumentSize,
toByteOffset: componentSize,
as: Int.self)
componentSize += MemoryLayout<Int>.size
buffer.storeBytes(of: _computedArgumentWitnesses,
toByteOffset: componentSize,
as: UnsafePointer<ComputedArgumentWitnesses>.self)
componentSize += MemoryLayout<Int>.size
if header.isComputedInstantiatedFromExternalWithArguments {
// Include the extra matter for components instantiated from
// external property descriptors with arguments.
buffer.storeBytes(of: _computedArgumentWitnessSizeAdjustment,
toByteOffset: componentSize,
as: Int.self)
componentSize += MemoryLayout<Int>.size
}
let adjustedSize = argumentSize - _computedArgumentWitnessSizeAdjustment
let argumentDest =
buffer.baseAddress.unsafelyUnwrapped + componentSize
_computedArgumentWitnesses.pointee.copy(
arguments,
argumentDest,
adjustedSize)
if header.isComputedInstantiatedFromExternalWithArguments {
// The extra information for external property descriptor arguments
// can always be memcpy'd.
_memcpy(dest: argumentDest + adjustedSize,
src: arguments + adjustedSize,
size: UInt(_computedArgumentWitnessSizeAdjustment))
}
componentSize += argumentSize
}
case .external:
_internalInvariantFailure("should have been instantiated away")
}
buffer = UnsafeMutableRawBufferPointer(
start: buffer.baseAddress.unsafelyUnwrapped + componentSize,
count: buffer.count - componentSize)
}
internal enum ProjectionResult<NewValue, LeafValue> {
/// Continue projecting the key path with the given new value.
case `continue`(NewValue)
/// Stop projecting the key path and use the given value as the final
/// result of the projection.
case `break`(LeafValue)
internal var assumingContinue: NewValue {
switch self {
case .continue(let x):
return x
case .break:
_internalInvariantFailure("should not have stopped key path projection")
}
}
}
internal func _projectReadOnly<CurValue, NewValue, LeafValue>(
_ base: CurValue,
to: NewValue.Type,
endingWith: LeafValue.Type
) -> ProjectionResult<NewValue, LeafValue> {
switch value {
case .struct(let offset):
var base2 = base
return .continue(withUnsafeBytes(of: &base2) {
let p = $0.baseAddress.unsafelyUnwrapped.advanced(by: offset)
// The contents of the struct should be well-typed, so we can assume
// typed memory here.
return p.assumingMemoryBound(to: NewValue.self).pointee
})
case .class(let offset):
_internalInvariant(CurValue.self is AnyObject.Type,
"base is not a class")
let baseObj = unsafeBitCast(base, to: AnyObject.self)
let basePtr = UnsafeRawPointer(Builtin.bridgeToRawPointer(baseObj))
defer { _fixLifetime(baseObj) }
let offsetAddress = basePtr.advanced(by: offset)
// Perform an instaneous record access on the address in order to
// ensure that the read will not conflict with an already in-progress
// 'modify' access.
Builtin.performInstantaneousReadAccess(offsetAddress._rawValue,
NewValue.self)
return .continue(offsetAddress
.assumingMemoryBound(to: NewValue.self)
.pointee)
case .get(id: _, get: let rawGet, argument: let argument),
.mutatingGetSet(id: _, get: let rawGet, set: _, argument: let argument),
.nonmutatingGetSet(id: _, get: let rawGet, set: _, argument: let argument):
typealias Getter
= @convention(thin) (CurValue, UnsafeRawPointer, Int) -> NewValue
let get = unsafeBitCast(rawGet, to: Getter.self)
return .continue(get(base,
argument?.data.baseAddress ?? rawGet,
argument?.data.count ?? 0))
case .optionalChain:
_internalInvariant(CurValue.self == Optional<NewValue>.self,
"should be unwrapping optional value")
_internalInvariant(_isOptional(LeafValue.self),
"leaf result should be optional")
if let baseValue = unsafeBitCast(base, to: Optional<NewValue>.self) {
return .continue(baseValue)
} else {
// TODO: A more efficient way of getting the `none` representation
// of a dynamically-optional type...
return .break((Optional<()>.none as Any) as! LeafValue)
}
case .optionalForce:
_internalInvariant(CurValue.self == Optional<NewValue>.self,
"should be unwrapping optional value")
return .continue(unsafeBitCast(base, to: Optional<NewValue>.self)!)
case .optionalWrap:
_internalInvariant(NewValue.self == Optional<CurValue>.self,
"should be wrapping optional value")
return .continue(
unsafeBitCast(base as Optional<CurValue>, to: NewValue.self))
}
}
internal func _projectMutableAddress<CurValue, NewValue>(
_ base: UnsafeRawPointer,
from _: CurValue.Type,
to _: NewValue.Type,
isRoot: Bool,
keepAlive: inout AnyObject?
) -> UnsafeRawPointer {
switch value {
case .struct(let offset):
return base.advanced(by: offset)
case .class(let offset):
// A class dereference should only occur at the root of a mutation,
// since otherwise it would be part of the reference prefix.
_internalInvariant(isRoot,
"class component should not appear in the middle of mutation")
// AnyObject memory can alias any class reference memory, so we can
// assume type here
let object = base.assumingMemoryBound(to: AnyObject.self).pointee
let offsetAddress = UnsafeRawPointer(Builtin.bridgeToRawPointer(object))
.advanced(by: offset)
// Keep the base alive for the duration of the derived access and also
// enforce exclusive access to the address.
keepAlive = ClassHolder._create(previous: keepAlive, instance: object,
accessingAddress: offsetAddress,
type: NewValue.self)
return offsetAddress
case .mutatingGetSet(id: _, get: let rawGet, set: let rawSet,
argument: let argument):
typealias Getter
= @convention(thin) (CurValue, UnsafeRawPointer, Int) -> NewValue
typealias Setter
= @convention(thin) (NewValue, inout CurValue, UnsafeRawPointer, Int) -> ()
let get = unsafeBitCast(rawGet, to: Getter.self)
let set = unsafeBitCast(rawSet, to: Setter.self)
let baseTyped = UnsafeMutablePointer(
mutating: base.assumingMemoryBound(to: CurValue.self))
let argValue = argument?.data.baseAddress ?? rawGet
let argSize = argument?.data.count ?? 0
let writeback = MutatingWritebackBuffer(previous: keepAlive,
base: baseTyped,
set: set,
argument: argValue,
argumentSize: argSize,
value: get(baseTyped.pointee, argValue, argSize))
keepAlive = writeback
// A maximally-abstracted, final, stored class property should have
// a stable address.
return UnsafeRawPointer(Builtin.addressof(&writeback.value))
case .nonmutatingGetSet(id: _, get: let rawGet, set: let rawSet,
argument: let argument):
// A nonmutating property should only occur at the root of a mutation,
// since otherwise it would be part of the reference prefix.
_internalInvariant(isRoot,
"nonmutating component should not appear in the middle of mutation")
typealias Getter
= @convention(thin) (CurValue, UnsafeRawPointer, Int) -> NewValue
typealias Setter
= @convention(thin) (NewValue, CurValue, UnsafeRawPointer, Int) -> ()
let get = unsafeBitCast(rawGet, to: Getter.self)
let set = unsafeBitCast(rawSet, to: Setter.self)
let baseValue = base.assumingMemoryBound(to: CurValue.self).pointee
let argValue = argument?.data.baseAddress ?? rawGet
let argSize = argument?.data.count ?? 0
let writeback = NonmutatingWritebackBuffer(previous: keepAlive,
base: baseValue,
set: set,
argument: argValue,
argumentSize: argSize,
value: get(baseValue, argValue, argSize))
keepAlive = writeback
// A maximally-abstracted, final, stored class property should have
// a stable address.
return UnsafeRawPointer(Builtin.addressof(&writeback.value))
case .optionalForce:
_internalInvariant(CurValue.self == Optional<NewValue>.self,
"should be unwrapping an optional value")
// Optional's layout happens to always put the payload at the start
// address of the Optional value itself, if a value is present at all.
let baseOptionalPointer
= base.assumingMemoryBound(to: Optional<NewValue>.self)
// Assert that a value exists
_ = baseOptionalPointer.pointee!
return base
case .optionalChain, .optionalWrap, .get:
_internalInvariantFailure("not a mutable key path component")
}
}
}
internal func _pop<T>(from: inout UnsafeRawBufferPointer,
as type: T.Type) -> T {
let buffer = _pop(from: &from, as: type, count: 1)
return buffer.baseAddress.unsafelyUnwrapped.pointee
}
internal func _pop<T>(from: inout UnsafeRawBufferPointer,
as: T.Type,
count: Int) -> UnsafeBufferPointer<T> {
_internalInvariant(_isPOD(T.self), "should be POD")
from = MemoryLayout<T>._roundingUpBaseToAlignment(from)
let byteCount = MemoryLayout<T>.stride * count
let result = UnsafeBufferPointer(
start: from.baseAddress.unsafelyUnwrapped.assumingMemoryBound(to: T.self),
count: count)
from = UnsafeRawBufferPointer(
start: from.baseAddress.unsafelyUnwrapped + byteCount,
count: from.count - byteCount)
return result
}
internal struct KeyPathBuffer {
internal var data: UnsafeRawBufferPointer
internal var trivial: Bool
internal var hasReferencePrefix: Bool
internal var mutableData: UnsafeMutableRawBufferPointer {
return UnsafeMutableRawBufferPointer(mutating: data)
}
internal struct Header {
internal var _value: UInt32
internal static var sizeMask: UInt32 {
return _SwiftKeyPathBufferHeader_SizeMask
}
internal static var reservedMask: UInt32 {
return _SwiftKeyPathBufferHeader_ReservedMask
}
internal static var trivialFlag: UInt32 {
return _SwiftKeyPathBufferHeader_TrivialFlag
}
internal static var hasReferencePrefixFlag: UInt32 {
return _SwiftKeyPathBufferHeader_HasReferencePrefixFlag
}
internal init(size: Int, trivial: Bool, hasReferencePrefix: Bool) {
_internalInvariant(size <= Int(Header.sizeMask), "key path too big")
_value = UInt32(size)
| (trivial ? Header.trivialFlag : 0)
| (hasReferencePrefix ? Header.hasReferencePrefixFlag : 0)
}
internal var size: Int { return Int(_value & Header.sizeMask) }
internal var trivial: Bool { return _value & Header.trivialFlag != 0 }
internal var hasReferencePrefix: Bool {
get {
return _value & Header.hasReferencePrefixFlag != 0
}
set {
if newValue {
_value |= Header.hasReferencePrefixFlag
} else {
_value &= ~Header.hasReferencePrefixFlag
}
}
}
// In a key path pattern, the "trivial" flag is used to indicate
// "instantiable in-line"
internal var instantiableInLine: Bool {
return trivial
}
internal func validateReservedBits() {
_precondition(_value & Header.reservedMask == 0,
"Reserved bits set to an unexpected bit pattern")
}
}
internal init(base: UnsafeRawPointer) {
let header = base.load(as: Header.self)
data = UnsafeRawBufferPointer(
start: base + MemoryLayout<Int>.size,
count: header.size)
trivial = header.trivial
hasReferencePrefix = header.hasReferencePrefix
}
internal init(partialData: UnsafeRawBufferPointer,
trivial: Bool = false,
hasReferencePrefix: Bool = false) {
self.data = partialData
self.trivial = trivial
self.hasReferencePrefix = hasReferencePrefix
}
internal func destroy() {
// Short-circuit if nothing in the object requires destruction.
if trivial { return }
var bufferToDestroy = self
while true {
let (component, type) = bufferToDestroy.next()
component.destroy()
guard let _ = type else { break }
}
}
internal mutating func next() -> (RawKeyPathComponent, Any.Type?) {
let header = _pop(from: &data, as: RawKeyPathComponent.Header.self)
// Track if this is the last component of the reference prefix.
if header.endOfReferencePrefix {
_internalInvariant(self.hasReferencePrefix,
"beginMutation marker in non-reference-writable key path?")
self.hasReferencePrefix = false
}
var component = RawKeyPathComponent(header: header, body: data)
// Shrinkwrap the component buffer size.
let size = component.bodySize
component.body = UnsafeRawBufferPointer(start: component.body.baseAddress,
count: size)
_ = _pop(from: &data, as: Int8.self, count: size)
// fetch type, which is in the buffer unless it's the final component
let nextType: Any.Type?
if data.count == 0 {
nextType = nil
} else {
nextType = _pop(from: &data, as: Any.Type.self)
}
return (component, nextType)
}
}
// MARK: Library intrinsics for projecting key paths.
@_silgen_name("swift_getAtPartialKeyPath")
public // COMPILER_INTRINSIC
func _getAtPartialKeyPath<Root>(
root: Root,
keyPath: PartialKeyPath<Root>
) -> Any {
func open<Value>(_: Value.Type) -> Any {
return _getAtKeyPath(root: root,
keyPath: unsafeDowncast(keyPath, to: KeyPath<Root, Value>.self))
}
return _openExistential(type(of: keyPath).valueType, do: open)
}
@_silgen_name("swift_getAtAnyKeyPath")
public // COMPILER_INTRINSIC
func _getAtAnyKeyPath<RootValue>(
root: RootValue,
keyPath: AnyKeyPath
) -> Any? {
let (keyPathRoot, keyPathValue) = type(of: keyPath)._rootAndValueType
func openRoot<KeyPathRoot>(_: KeyPathRoot.Type) -> Any? {
guard let rootForKeyPath = root as? KeyPathRoot else {
return nil
}
func openValue<Value>(_: Value.Type) -> Any {
return _getAtKeyPath(root: rootForKeyPath,
keyPath: unsafeDowncast(keyPath, to: KeyPath<KeyPathRoot, Value>.self))
}
return _openExistential(keyPathValue, do: openValue)
}
return _openExistential(keyPathRoot, do: openRoot)
}
@_silgen_name("swift_getAtKeyPath")
public // COMPILER_INTRINSIC
func _getAtKeyPath<Root, Value>(
root: Root,
keyPath: KeyPath<Root, Value>
) -> Value {
return keyPath._projectReadOnly(from: root)
}
// The release that ends the access scope is guaranteed to happen
// immediately at the end_apply call because the continuation is a
// runtime call with a manual release (access scopes cannot be extended).
@_silgen_name("_swift_modifyAtWritableKeyPath_impl")
public // runtime entrypoint
func _modifyAtWritableKeyPath_impl<Root, Value>(
root: inout Root,
keyPath: WritableKeyPath<Root, Value>
) -> (UnsafeMutablePointer<Value>, AnyObject?) {
return keyPath._projectMutableAddress(from: &root)
}
// The release that ends the access scope is guaranteed to happen
// immediately at the end_apply call because the continuation is a
// runtime call with a manual release (access scopes cannot be extended).
@_silgen_name("_swift_modifyAtReferenceWritableKeyPath_impl")
public // runtime entrypoint
func _modifyAtReferenceWritableKeyPath_impl<Root, Value>(
root: Root,
keyPath: ReferenceWritableKeyPath<Root, Value>
) -> (UnsafeMutablePointer<Value>, AnyObject?) {
return keyPath._projectMutableAddress(from: root)
}
@_silgen_name("swift_setAtWritableKeyPath")
public // COMPILER_INTRINSIC
func _setAtWritableKeyPath<Root, Value>(
root: inout Root,
keyPath: WritableKeyPath<Root, Value>,
value: __owned Value
) {
// TODO: we should be able to do this more efficiently than projecting.
let (addr, owner) = keyPath._projectMutableAddress(from: &root)
addr.pointee = value
_fixLifetime(owner)
// FIXME: this needs a deallocation barrier to ensure that the
// release isn't extended, along with the access scope.
}
@_silgen_name("swift_setAtReferenceWritableKeyPath")
public // COMPILER_INTRINSIC
func _setAtReferenceWritableKeyPath<Root, Value>(
root: Root,
keyPath: ReferenceWritableKeyPath<Root, Value>,
value: __owned Value
) {
// TODO: we should be able to do this more efficiently than projecting.
let (addr, owner) = keyPath._projectMutableAddress(from: root)
addr.pointee = value
_fixLifetime(owner)
// FIXME: this needs a deallocation barrier to ensure that the
// release isn't extended, along with the access scope.
}
// MARK: Appending type system
// FIXME(ABI): The type relationships between KeyPath append operands are tricky
// and don't interact well with our overriding rules. Hack things by injecting
// a bunch of `appending` overloads as protocol extensions so they aren't
// constrained by being overrides, and so that we can use exact-type constraints
// on `Self` to prevent dynamically-typed methods from being inherited by
// statically-typed key paths.
/// An implementation detail of key path expressions; do not use this protocol
/// directly.
@_show_in_interface
public protocol _AppendKeyPath {}
extension _AppendKeyPath where Self == AnyKeyPath {
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Appending the key path passed as `path` is successful only if the
/// root type for `path` matches this key path's value type. This example
/// creates key paths from `Array<Int>` to `String` and from `String` to
/// `Int`, and then tries appending each to the other:
///
/// let arrayDescription: AnyKeyPath = \Array<Int>.description
/// let stringLength: AnyKeyPath = \String.count
///
/// // Creates a key path from `Array<Int>` to `Int`
/// let arrayDescriptionLength = arrayDescription.appending(path: stringLength)
///
/// let invalidKeyPath = stringLength.appending(path: arrayDescription)
/// // invalidKeyPath == nil
///
/// The second call to `appending(path:)` returns `nil`
/// because the root type of `arrayDescription`, `Array<Int>`, does not
/// match the value type of `stringLength`, `Int`.
///
/// - Parameter path: The key path to append.
/// - Returns: A key path from the root of this key path and the value type
/// of `path`, if `path` can be appended. If `path` can't be appended,
/// returns `nil`.
@inlinable
public func appending(path: AnyKeyPath) -> AnyKeyPath? {
return _tryToAppendKeyPaths(root: self, leaf: path)
}
}
extension _AppendKeyPath /* where Self == PartialKeyPath<T> */ {
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Appending the key path passed as `path` is successful only if the
/// root type for `path` matches this key path's value type. This example
/// creates key paths from `Array<Int>` to `String` and from `String` to
/// `Int`, and then tries appending each to the other:
///
/// let arrayDescription: PartialKeyPath<Array<Int>> = \.description
/// let stringLength: PartialKeyPath<String> = \.count
///
/// // Creates a key path from `Array<Int>` to `Int`
/// let arrayDescriptionLength = arrayDescription.appending(path: stringLength)
///
/// let invalidKeyPath = stringLength.appending(path: arrayDescription)
/// // invalidKeyPath == nil
///
/// The second call to `appending(path:)` returns `nil`
/// because the root type of `arrayDescription`, `Array<Int>`, does not
/// match the value type of `stringLength`, `Int`.
///
/// - Parameter path: The key path to append.
/// - Returns: A key path from the root of this key path and the value type
/// of `path`, if `path` can be appended. If `path` can't be appended,
/// returns `nil`.
@inlinable
public func appending<Root>(path: AnyKeyPath) -> PartialKeyPath<Root>?
where Self == PartialKeyPath<Root> {
return _tryToAppendKeyPaths(root: self, leaf: path)
}
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Appending the key path passed as `path` is successful only if the
/// root type for `path` matches this key path's value type. This example
/// creates a key path from `Array<Int>` to `String`, and then tries
/// appending compatible and incompatible key paths:
///
/// let arrayDescription: PartialKeyPath<Array<Int>> = \.description
///
/// // Creates a key path from `Array<Int>` to `Int`
/// let arrayDescriptionLength = arrayDescription.appending(path: \String.count)
///
/// let invalidKeyPath = arrayDescription.appending(path: \Double.isZero)
/// // invalidKeyPath == nil
///
/// The second call to `appending(path:)` returns `nil` because the root type
/// of the `path` parameter, `Double`, does not match the value type of
/// `arrayDescription`, `String`.
///
/// - Parameter path: The key path to append.
/// - Returns: A key path from the root of this key path to the value type
/// of `path`, if `path` can be appended. If `path` can't be appended,
/// returns `nil`.
@inlinable
public func appending<Root, AppendedRoot, AppendedValue>(
path: KeyPath<AppendedRoot, AppendedValue>
) -> KeyPath<Root, AppendedValue>?
where Self == PartialKeyPath<Root> {
return _tryToAppendKeyPaths(root: self, leaf: path)
}
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Appending the key path passed as `path` is successful only if the
/// root type for `path` matches this key path's value type.
///
/// - Parameter path: The reference writeable key path to append.
/// - Returns: A key path from the root of this key path to the value type
/// of `path`, if `path` can be appended. If `path` can't be appended,
/// returns `nil`.
@inlinable
public func appending<Root, AppendedRoot, AppendedValue>(
path: ReferenceWritableKeyPath<AppendedRoot, AppendedValue>
) -> ReferenceWritableKeyPath<Root, AppendedValue>?
where Self == PartialKeyPath<Root> {
return _tryToAppendKeyPaths(root: self, leaf: path)
}
}
extension _AppendKeyPath /* where Self == KeyPath<T,U> */ {
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Calling `appending(path:)` results in the same key path as if the
/// given key path had been specified using dot notation. In the following
/// example, `keyPath1` and `keyPath2` are equivalent:
///
/// let arrayDescription = \Array<Int>.description
/// let keyPath1 = arrayDescription.appending(path: \String.count)
///
/// let keyPath2 = \Array<Int>.description.count
///
/// - Parameter path: The key path to append.
/// - Returns: A key path from the root of this key path to the value type of
/// `path`.
@inlinable
public func appending<Root, Value, AppendedValue>(
path: KeyPath<Value, AppendedValue>
) -> KeyPath<Root, AppendedValue>
where Self: KeyPath<Root, Value> {
return _appendingKeyPaths(root: self, leaf: path)
}
/* TODO
public func appending<Root, Value, Leaf>(
path: Leaf,
// FIXME: Satisfy "Value generic param not used in signature" constraint
_: Value.Type = Value.self
) -> PartialKeyPath<Root>?
where Self: KeyPath<Root, Value>, Leaf == AnyKeyPath {
return _tryToAppendKeyPaths(root: self, leaf: path)
}
*/
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Calling `appending(path:)` results in the same key path as if the
/// given key path had been specified using dot notation.
///
/// - Parameter path: The key path to append.
/// - Returns: A key path from the root of this key path to the value type of
/// `path`.
@inlinable
public func appending<Root, Value, AppendedValue>(
path: ReferenceWritableKeyPath<Value, AppendedValue>
) -> ReferenceWritableKeyPath<Root, AppendedValue>
where Self == KeyPath<Root, Value> {
return _appendingKeyPaths(root: self, leaf: path)
}
}
extension _AppendKeyPath /* where Self == WritableKeyPath<T,U> */ {
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Calling `appending(path:)` results in the same key path as if the
/// given key path had been specified using dot notation.
///
/// - Parameter path: The key path to append.
/// - Returns: A key path from the root of this key path to the value type of
/// `path`.
@inlinable
public func appending<Root, Value, AppendedValue>(
path: WritableKeyPath<Value, AppendedValue>
) -> WritableKeyPath<Root, AppendedValue>
where Self == WritableKeyPath<Root, Value> {
return _appendingKeyPaths(root: self, leaf: path)
}
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Calling `appending(path:)` results in the same key path as if the
/// given key path had been specified using dot notation.
///
/// - Parameter path: The key path to append.
/// - Returns: A key path from the root of this key path to the value type of
/// `path`.
@inlinable
public func appending<Root, Value, AppendedValue>(
path: ReferenceWritableKeyPath<Value, AppendedValue>
) -> ReferenceWritableKeyPath<Root, AppendedValue>
where Self == WritableKeyPath<Root, Value> {
return _appendingKeyPaths(root: self, leaf: path)
}
}
extension _AppendKeyPath /* where Self == ReferenceWritableKeyPath<T,U> */ {
/// Returns a new key path created by appending the given key path to this
/// one.
///
/// Use this method to extend this key path to the value type of another key
/// path. Calling `appending(path:)` results in the same key path as if the
/// given key path had been specified using dot notation.
///
/// - Parameter path: The key path to append.
/// - Returns: A key path from the root of this key path to the value type of
/// `path`.
@inlinable
public func appending<Root, Value, AppendedValue>(
path: WritableKeyPath<Value, AppendedValue>
) -> ReferenceWritableKeyPath<Root, AppendedValue>
where Self == ReferenceWritableKeyPath<Root, Value> {
return _appendingKeyPaths(root: self, leaf: path)
}
}
@usableFromInline
internal func _tryToAppendKeyPaths<Result: AnyKeyPath>(
root: AnyKeyPath,
leaf: AnyKeyPath
) -> Result? {
let (rootRoot, rootValue) = type(of: root)._rootAndValueType
let (leafRoot, leafValue) = type(of: leaf)._rootAndValueType
if rootValue != leafRoot {
return nil
}
func open<Root>(_: Root.Type) -> Result {
func open2<Value>(_: Value.Type) -> Result {
func open3<AppendedValue>(_: AppendedValue.Type) -> Result {
let typedRoot = unsafeDowncast(root, to: KeyPath<Root, Value>.self)
let typedLeaf = unsafeDowncast(leaf,
to: KeyPath<Value, AppendedValue>.self)
let result = _appendingKeyPaths(root: typedRoot, leaf: typedLeaf)
return unsafeDowncast(result, to: Result.self)
}
return _openExistential(leafValue, do: open3)
}
return _openExistential(rootValue, do: open2)
}
return _openExistential(rootRoot, do: open)
}
@usableFromInline
internal func _appendingKeyPaths<
Root, Value, AppendedValue,
Result: KeyPath<Root, AppendedValue>
>(
root: KeyPath<Root, Value>,
leaf: KeyPath<Value, AppendedValue>
) -> Result {
let resultTy = type(of: root).appendedType(with: type(of: leaf))
return root.withBuffer {
var rootBuffer = $0
return leaf.withBuffer {
var leafBuffer = $0
// If either operand is the identity key path, then we should return
// the other operand back untouched.
if leafBuffer.data.isEmpty {
return unsafeDowncast(root, to: Result.self)
}
if rootBuffer.data.isEmpty {
return unsafeDowncast(leaf, to: Result.self)
}
// Reserve room for the appended KVC string, if both key paths are
// KVC-compatible.
let appendedKVCLength: Int, rootKVCLength: Int, leafKVCLength: Int
if let rootPtr = root._kvcKeyPathStringPtr,
let leafPtr = leaf._kvcKeyPathStringPtr {
rootKVCLength = Int(_swift_stdlib_strlen(rootPtr))
leafKVCLength = Int(_swift_stdlib_strlen(leafPtr))
// root + "." + leaf
appendedKVCLength = rootKVCLength + 1 + leafKVCLength + 1
} else {
rootKVCLength = 0
leafKVCLength = 0
appendedKVCLength = 0
}
// Result buffer has room for both key paths' components, plus the
// header, plus space for the middle type.
// Align up the root so that we can put the component type after it.
let rootSize = MemoryLayout<Int>._roundingUpToAlignment(rootBuffer.data.count)
let resultSize = rootSize + leafBuffer.data.count
+ 2 * MemoryLayout<Int>.size
// Tail-allocate space for the KVC string.
let totalResultSize = MemoryLayout<Int32>
._roundingUpToAlignment(resultSize + appendedKVCLength)
var kvcStringBuffer: UnsafeMutableRawPointer? = nil
let result = resultTy._create(capacityInBytes: totalResultSize) {
var destBuffer = $0
// Remember where the tail-allocated KVC string buffer begins.
if appendedKVCLength > 0 {
kvcStringBuffer = destBuffer.baseAddress.unsafelyUnwrapped
.advanced(by: resultSize)
destBuffer = .init(start: destBuffer.baseAddress,
count: resultSize)
}
func pushRaw(size: Int, alignment: Int)
-> UnsafeMutableRawBufferPointer {
var baseAddress = destBuffer.baseAddress.unsafelyUnwrapped
var misalign = Int(bitPattern: baseAddress) % alignment
if misalign != 0 {
misalign = alignment - misalign
baseAddress = baseAddress.advanced(by: misalign)
}
let result = UnsafeMutableRawBufferPointer(
start: baseAddress,
count: size)
destBuffer = UnsafeMutableRawBufferPointer(
start: baseAddress + size,
count: destBuffer.count - size - misalign)
return result
}
func push<T>(_ value: T) {
let buf = pushRaw(size: MemoryLayout<T>.size,
alignment: MemoryLayout<T>.alignment)
buf.storeBytes(of: value, as: T.self)
}
// Save space for the header.
let leafIsReferenceWritable = type(of: leaf).kind == .reference
let header = KeyPathBuffer.Header(
size: resultSize - MemoryLayout<Int>.size,
trivial: rootBuffer.trivial && leafBuffer.trivial,
hasReferencePrefix: rootBuffer.hasReferencePrefix
|| leafIsReferenceWritable
)
push(header)
// Start the components at pointer alignment
_ = pushRaw(size: RawKeyPathComponent.Header.pointerAlignmentSkew,
alignment: 4)
let leafHasReferencePrefix = leafBuffer.hasReferencePrefix
// Clone the root components into the buffer.
while true {
let (component, type) = rootBuffer.next()
let isLast = type == nil
// If the leaf appended path has a reference prefix, then the
// entire root is part of the reference prefix.
let endOfReferencePrefix: Bool
if leafHasReferencePrefix {
endOfReferencePrefix = false
} else if isLast && leafIsReferenceWritable {
endOfReferencePrefix = true
} else {
endOfReferencePrefix = component.header.endOfReferencePrefix
}
component.clone(
into: &destBuffer,
endOfReferencePrefix: endOfReferencePrefix)
if let type = type {
push(type)
} else {
// Insert our endpoint type between the root and leaf components.
push(Value.self as Any.Type)
break
}
}
// Clone the leaf components into the buffer.
while true {
let (component, type) = leafBuffer.next()
component.clone(
into: &destBuffer,
endOfReferencePrefix: component.header.endOfReferencePrefix)
if let type = type {
push(type)
} else {
break
}
}
_internalInvariant(destBuffer.count == 0,
"did not fill entire result buffer")
}
// Build the KVC string if there is one.
if let kvcStringBuffer = kvcStringBuffer {
let rootPtr = root._kvcKeyPathStringPtr.unsafelyUnwrapped
let leafPtr = leaf._kvcKeyPathStringPtr.unsafelyUnwrapped
_memcpy(dest: kvcStringBuffer,
src: rootPtr,
size: UInt(rootKVCLength))
kvcStringBuffer.advanced(by: rootKVCLength)
.storeBytes(of: 0x2E /* '.' */, as: CChar.self)
_memcpy(dest: kvcStringBuffer.advanced(by: rootKVCLength + 1),
src: leafPtr,
size: UInt(leafKVCLength))
result._kvcKeyPathStringPtr =
UnsafePointer(kvcStringBuffer.assumingMemoryBound(to: CChar.self))
kvcStringBuffer.advanced(by: rootKVCLength + leafKVCLength + 1)
.storeBytes(of: 0 /* '\0' */, as: CChar.self)
}
return unsafeDowncast(result, to: Result.self)
}
}
}
// The distance in bytes from the address point of a KeyPath object to its
// buffer header. Includes the size of the Swift heap object header and the
// pointer to the KVC string.
internal var keyPathObjectHeaderSize: Int {
return MemoryLayout<HeapObject>.size + MemoryLayout<Int>.size
}
internal var keyPathPatternHeaderSize: Int {
return 16
}
// Runtime entry point to instantiate a key path object.
// Note that this has a compatibility override shim in the runtime so that
// future compilers can backward-deploy support for instantiating new key path
// pattern features.
@_cdecl("swift_getKeyPathImpl")
public func _swift_getKeyPath(pattern: UnsafeMutableRawPointer,
arguments: UnsafeRawPointer)
-> UnsafeRawPointer {
// The key path pattern is laid out like a key path object, with a few
// modifications:
// - Pointers in the instantiated object are compressed into 32-bit
// relative offsets in the pattern.
// - The pattern begins with a field that's either zero, for a pattern that
// depends on instantiation arguments, or that's a relative reference to
// a global mutable pointer variable, which can be initialized to a single
// shared instantiation of this pattern.
// - Instead of the two-word object header with isa and refcount, two
// pointers to metadata accessors are provided for the root and leaf
// value types of the key path.
// - Components may have unresolved forms that require instantiation.
// - Type metadata and protocol conformance pointers are replaced with
// relative-referenced accessor functions that instantiate the
// needed generic argument when called.
//
// The pattern never precomputes the capabilities of the key path (readonly/
// writable/reference-writable), nor does it encode the reference prefix.
// These are resolved dynamically, so that they always reflect the dynamic
// capability of the properties involved.
let oncePtrPtr = pattern
let patternPtr = pattern.advanced(by: 4)
let bufferHeader = patternPtr.load(fromByteOffset: keyPathPatternHeaderSize,
as: KeyPathBuffer.Header.self)
bufferHeader.validateReservedBits()
// If the first word is nonzero, it relative-references a cache variable
// we can use to reference a single shared instantiation of this key path.
let oncePtrOffset = oncePtrPtr.load(as: Int32.self)
let oncePtr: UnsafeRawPointer?
if oncePtrOffset != 0 {
let theOncePtr = _resolveRelativeAddress(oncePtrPtr, oncePtrOffset)
oncePtr = theOncePtr
// See whether we already instantiated this key path.
// This is a non-atomic load because the instantiated pointer will be
// written with a release barrier, and loads of the instantiated key path
// ought to carry a dependency through this loaded pointer.
let existingInstance = theOncePtr.load(as: UnsafeRawPointer?.self)
if let existingInstance = existingInstance {
// Return the instantiated object at +1.
let object = Unmanaged<AnyKeyPath>.fromOpaque(existingInstance)
// TODO: This retain will be unnecessary once we support global objects
// with inert refcounting.
_ = object.retain()
return existingInstance
}
} else {
oncePtr = nil
}
// Instantiate a new key path object modeled on the pattern.
// Do a pass to determine the class of the key path we'll be instantiating
// and how much space we'll need for it.
let (keyPathClass, rootType, size, _)
= _getKeyPathClassAndInstanceSizeFromPattern(patternPtr, arguments)
// Allocate the instance.
let instance = keyPathClass._create(capacityInBytes: size) { instanceData in
// Instantiate the pattern into the instance.
_instantiateKeyPathBuffer(patternPtr, instanceData, rootType, arguments)
}
// Adopt the KVC string from the pattern.
let kvcStringBase = patternPtr.advanced(by: 12)
let kvcStringOffset = kvcStringBase.load(as: Int32.self)
if kvcStringOffset == 0 {
// Null pointer.
instance._kvcKeyPathStringPtr = nil
} else {
let kvcStringPtr = _resolveRelativeAddress(kvcStringBase, kvcStringOffset)
instance._kvcKeyPathStringPtr =
kvcStringPtr.assumingMemoryBound(to: CChar.self)
}
// If we can cache this instance as a shared instance, do so.
if let oncePtr = oncePtr {
// Try to replace a null pointer in the cache variable with the instance
// pointer.
let instancePtr = Unmanaged.passRetained(instance)
while true {
let (oldValue, won) = Builtin.cmpxchg_seqcst_seqcst_Word(
oncePtr._rawValue,
0._builtinWordValue,
UInt(bitPattern: instancePtr.toOpaque())._builtinWordValue)
// If the exchange succeeds, then the instance we formed is the canonical
// one.
if Bool(won) {
break
}
// Otherwise, someone raced with us to instantiate the key path pattern
// and won. Their instance should be just as good as ours, so we can take
// that one and let ours get deallocated.
if let existingInstance = UnsafeRawPointer(bitPattern: Int(oldValue)) {
// Return the instantiated object at +1.
let object = Unmanaged<AnyKeyPath>.fromOpaque(existingInstance)
// TODO: This retain will be unnecessary once we support global objects
// with inert refcounting.
_ = object.retain()
// Release the instance we created.
instancePtr.release()
return existingInstance
} else {
// Try the cmpxchg again if it spuriously failed.
continue
}
}
}
return UnsafeRawPointer(Unmanaged.passRetained(instance).toOpaque())
}
// A reference to metadata, which is a pointer to a mangled name.
internal typealias MetadataReference = UnsafeRawPointer
// Determine the length of the given mangled name.
internal func _getSymbolicMangledNameLength(_ base: UnsafeRawPointer) -> Int {
var end = base
while let current = Optional(end.load(as: UInt8.self)), current != 0 {
// Skip the current character
end = end + 1
// Skip over a symbolic reference
if current >= 0x1 && current <= 0x17 {
end += 4
} else if current >= 0x18 && current <= 0x1F {
end += MemoryLayout<Int>.size
}
}
return end - base
}
// Resolve a mangled name in a generic environment, described by either a
// flat GenericEnvironment * (if the bottom tag bit is 0) or possibly-nested
// ContextDescriptor * (if the bottom tag bit is 1)
internal func _getTypeByMangledNameInEnvironmentOrContext(
_ name: UnsafePointer<UInt8>,
_ nameLength: UInt,
genericEnvironmentOrContext: UnsafeRawPointer?,
genericArguments: UnsafeRawPointer?)
-> Any.Type? {
let taggedPointer = UInt(bitPattern: genericEnvironmentOrContext)
if taggedPointer & 1 == 0 {
return _getTypeByMangledNameInEnvironment(name, nameLength,
genericEnvironment: genericEnvironmentOrContext,
genericArguments: genericArguments)
} else {
let context = UnsafeRawPointer(bitPattern: taggedPointer & ~1)
return _getTypeByMangledNameInContext(name, nameLength,
genericContext: context,
genericArguments: genericArguments)
}
}
// Resolve the given generic argument reference to a generic argument.
internal func _resolveKeyPathGenericArgReference(
_ reference: UnsafeRawPointer,
genericEnvironment: UnsafeRawPointer?,
arguments: UnsafeRawPointer?)
-> UnsafeRawPointer {
// If the low bit is clear, it's a direct reference to the argument.
if (UInt(bitPattern: reference) & 0x01 == 0) {
return reference;
}
// Adjust the reference.
let referenceStart = reference - 1
// If we have a symbolic reference to an accessor, call it.
let first = referenceStart.load(as: UInt8.self)
if first == 255 && reference.load(as: UInt8.self) == 9 {
typealias MetadataAccessor =
@convention(c) (UnsafeRawPointer?) -> UnsafeRawPointer
// Unaligned load of the offset.
let pointerReference = reference + 1
var offset: Int32 = 0
_memcpy(dest: &offset, src: pointerReference, size: 4)
let accessorPtr = _resolveRelativeAddress(pointerReference, offset)
let accessor = unsafeBitCast(accessorPtr, to: MetadataAccessor.self)
return accessor(arguments)
}
let nameLength = _getSymbolicMangledNameLength(referenceStart)
let namePtr = referenceStart.bindMemory(to: UInt8.self,
capacity: nameLength + 1)
// FIXME: Could extract this information from the mangled name.
guard let result =
_getTypeByMangledNameInEnvironmentOrContext(namePtr, UInt(nameLength),
genericEnvironmentOrContext: genericEnvironment,
genericArguments: arguments)
else {
let nameStr = String._fromUTF8Repairing(
UnsafeBufferPointer(start: namePtr, count: nameLength)
).0
fatalError("could not demangle keypath type from '\(nameStr)'")
}
return unsafeBitCast(result, to: UnsafeRawPointer.self)
}
// Resolve the given metadata reference to (type) metadata.
internal func _resolveKeyPathMetadataReference(
_ reference: UnsafeRawPointer,
genericEnvironment: UnsafeRawPointer?,
arguments: UnsafeRawPointer?)
-> Any.Type {
return unsafeBitCast(
_resolveKeyPathGenericArgReference(
reference,
genericEnvironment: genericEnvironment,
arguments: arguments),
to: Any.Type.self)
}
internal enum KeyPathStructOrClass {
case `struct`, `class`
}
internal enum KeyPathPatternStoredOffset {
case inline(UInt32)
case outOfLine(UInt32)
case unresolvedFieldOffset(UInt32)
case unresolvedIndirectOffset(UnsafePointer<UInt32>)
}
internal struct KeyPathPatternComputedArguments {
var getLayout: KeyPathComputedArgumentLayoutFn
var witnesses: UnsafePointer<ComputedArgumentWitnesses>
var initializer: KeyPathComputedArgumentInitializerFn
}
internal protocol KeyPathPatternVisitor {
mutating func visitHeader(genericEnvironment: UnsafeRawPointer?,
rootMetadataRef: MetadataReference,
leafMetadataRef: MetadataReference,
kvcCompatibilityString: UnsafeRawPointer?)
mutating func visitStoredComponent(kind: KeyPathStructOrClass,
mutable: Bool,
offset: KeyPathPatternStoredOffset)
mutating func visitComputedComponent(mutating: Bool,
idKind: KeyPathComputedIDKind,
idResolution: KeyPathComputedIDResolution,
idValueBase: UnsafeRawPointer,
idValue: Int32,
getter: UnsafeRawPointer,
setter: UnsafeRawPointer?,
arguments: KeyPathPatternComputedArguments?,
externalArgs: UnsafeBufferPointer<Int32>?)
mutating func visitOptionalChainComponent()
mutating func visitOptionalForceComponent()
mutating func visitOptionalWrapComponent()
mutating func visitIntermediateComponentType(metadataRef: MetadataReference)
mutating func finish()
}
internal func _resolveRelativeAddress(_ base: UnsafeRawPointer,
_ offset: Int32) -> UnsafeRawPointer {
// Sign-extend the offset to pointer width and add with wrap on overflow.
return UnsafeRawPointer(bitPattern: Int(bitPattern: base) &+ Int(offset))
.unsafelyUnwrapped
}
internal func _resolveRelativeIndirectableAddress(_ base: UnsafeRawPointer,
_ offset: Int32)
-> UnsafeRawPointer {
// Low bit indicates whether the reference is indirected or not.
if offset & 1 != 0 {
let ptrToPtr = _resolveRelativeAddress(base, offset - 1)
return ptrToPtr.load(as: UnsafeRawPointer.self)
}
return _resolveRelativeAddress(base, offset)
}
internal func _loadRelativeAddress<T>(at: UnsafeRawPointer,
fromByteOffset: Int = 0,
as: T.Type) -> T {
let offset = at.load(fromByteOffset: fromByteOffset, as: Int32.self)
return unsafeBitCast(_resolveRelativeAddress(at + fromByteOffset, offset),
to: T.self)
}
internal func _walkKeyPathPattern<W: KeyPathPatternVisitor>(
_ pattern: UnsafeRawPointer,
walker: inout W) {
// Visit the header.
let genericEnvironment = _loadRelativeAddress(at: pattern,
as: UnsafeRawPointer.self)
let rootMetadataRef = _loadRelativeAddress(at: pattern, fromByteOffset: 4,
as: MetadataReference.self)
let leafMetadataRef = _loadRelativeAddress(at: pattern, fromByteOffset: 8,
as: MetadataReference.self)
let kvcString = _loadRelativeAddress(at: pattern, fromByteOffset: 12,
as: UnsafeRawPointer.self)
walker.visitHeader(genericEnvironment: genericEnvironment,
rootMetadataRef: rootMetadataRef,
leafMetadataRef: leafMetadataRef,
kvcCompatibilityString: kvcString)
func visitStored(header: RawKeyPathComponent.Header,
componentBuffer: inout UnsafeRawBufferPointer) {
// Decode a stored property. A small offset may be stored inline in the
// header word, or else be stored out-of-line, or need instantiation of some
// kind.
let offset: KeyPathPatternStoredOffset
switch header.storedOffsetPayload {
case RawKeyPathComponent.Header.outOfLineOffsetPayload:
offset = .outOfLine(_pop(from: &componentBuffer,
as: UInt32.self))
case RawKeyPathComponent.Header.unresolvedFieldOffsetPayload:
offset = .unresolvedFieldOffset(_pop(from: &componentBuffer,
as: UInt32.self))
case RawKeyPathComponent.Header.unresolvedIndirectOffsetPayload:
let base = componentBuffer.baseAddress.unsafelyUnwrapped
let relativeOffset = _pop(from: &componentBuffer,
as: Int32.self)
let ptr = _resolveRelativeIndirectableAddress(base, relativeOffset)
offset = .unresolvedIndirectOffset(
ptr.assumingMemoryBound(to: UInt32.self))
default:
offset = .inline(header.storedOffsetPayload)
}
let kind: KeyPathStructOrClass = header.kind == .struct
? .struct : .class
walker.visitStoredComponent(kind: kind,
mutable: header.isStoredMutable,
offset: offset)
}
func popComputedAccessors(header: RawKeyPathComponent.Header,
componentBuffer: inout UnsafeRawBufferPointer)
-> (idValueBase: UnsafeRawPointer,
idValue: Int32,
getter: UnsafeRawPointer,
setter: UnsafeRawPointer?) {
let idValueBase = componentBuffer.baseAddress.unsafelyUnwrapped
let idValue = _pop(from: &componentBuffer, as: Int32.self)
let getterBase = componentBuffer.baseAddress.unsafelyUnwrapped
let getterRef = _pop(from: &componentBuffer, as: Int32.self)
let getter = _resolveRelativeAddress(getterBase, getterRef)
let setter: UnsafeRawPointer?
if header.isComputedSettable {
let setterBase = componentBuffer.baseAddress.unsafelyUnwrapped
let setterRef = _pop(from: &componentBuffer, as: Int32.self)
setter = _resolveRelativeAddress(setterBase, setterRef)
} else {
setter = nil
}
return (idValueBase: idValueBase, idValue: idValue,
getter: getter, setter: setter)
}
func popComputedArguments(header: RawKeyPathComponent.Header,
componentBuffer: inout UnsafeRawBufferPointer)
-> KeyPathPatternComputedArguments? {
if header.hasComputedArguments {
let getLayoutBase = componentBuffer.baseAddress.unsafelyUnwrapped
let getLayoutRef = _pop(from: &componentBuffer, as: Int32.self)
let getLayoutRaw = _resolveRelativeAddress(getLayoutBase, getLayoutRef)
let getLayout = unsafeBitCast(getLayoutRaw,
to: KeyPathComputedArgumentLayoutFn.self)
let witnessesBase = componentBuffer.baseAddress.unsafelyUnwrapped
let witnessesRef = _pop(from: &componentBuffer, as: Int32.self)
let witnesses: UnsafeRawPointer
if witnessesRef == 0 {
witnesses = __swift_keyPathGenericWitnessTable_addr()
} else {
witnesses = _resolveRelativeAddress(witnessesBase, witnessesRef)
}
let initializerBase = componentBuffer.baseAddress.unsafelyUnwrapped
let initializerRef = _pop(from: &componentBuffer, as: Int32.self)
let initializerRaw = _resolveRelativeAddress(initializerBase,
initializerRef)
let initializer = unsafeBitCast(initializerRaw,
to: KeyPathComputedArgumentInitializerFn.self)
return KeyPathPatternComputedArguments(getLayout: getLayout,
witnesses:
witnesses.assumingMemoryBound(to: ComputedArgumentWitnesses.self),
initializer: initializer)
} else {
return nil
}
}
// We declare this down here to avoid the temptation to use it within
// the functions above.
let bufferPtr = pattern.advanced(by: keyPathPatternHeaderSize)
let bufferHeader = bufferPtr.load(as: KeyPathBuffer.Header.self)
var buffer = UnsafeRawBufferPointer(start: bufferPtr + 4,
count: bufferHeader.size)
while !buffer.isEmpty {
let header = _pop(from: &buffer,
as: RawKeyPathComponent.Header.self)
// Ensure that we pop an amount of data consistent with what
// RawKeyPathComponent.Header.patternComponentBodySize computes.
var bufferSizeBefore = 0
var expectedPop = 0
_internalInvariant({
bufferSizeBefore = buffer.count
expectedPop = header.patternComponentBodySize
return true
}())
switch header.kind {
case .class, .struct:
visitStored(header: header, componentBuffer: &buffer)
case .computed:
let (idValueBase, idValue, getter, setter)
= popComputedAccessors(header: header,
componentBuffer: &buffer)
// If there are arguments, gather those too.
let arguments = popComputedArguments(header: header,
componentBuffer: &buffer)
walker.visitComputedComponent(mutating: header.isComputedMutating,
idKind: header.computedIDKind,
idResolution: header.computedIDResolution,
idValueBase: idValueBase,
idValue: idValue,
getter: getter,
setter: setter,
arguments: arguments,
externalArgs: nil)
case .optionalChain:
walker.visitOptionalChainComponent()
case .optionalWrap:
walker.visitOptionalWrapComponent()
case .optionalForce:
walker.visitOptionalForceComponent()
case .external:
// Look at the external property descriptor to see if we should take it
// over the component given in the pattern.
let genericParamCount = Int(header.payload)
let descriptorBase = buffer.baseAddress.unsafelyUnwrapped
let descriptorOffset = _pop(from: &buffer,
as: Int32.self)
let descriptor =
_resolveRelativeIndirectableAddress(descriptorBase, descriptorOffset)
let descriptorHeader =
descriptor.load(as: RawKeyPathComponent.Header.self)
if descriptorHeader.isTrivialPropertyDescriptor {
// If the descriptor is trivial, then use the local candidate.
// Skip the external generic parameter accessors to get to it.
_ = _pop(from: &buffer, as: Int32.self, count: genericParamCount)
continue
}
// Grab the generic parameter accessors to pass to the external component.
let externalArgs = _pop(from: &buffer, as: Int32.self,
count: genericParamCount)
// Grab the header for the local candidate in case we need it for
// a computed property.
let localCandidateHeader = _pop(from: &buffer,
as: RawKeyPathComponent.Header.self)
let localCandidateSize = localCandidateHeader.patternComponentBodySize
_internalInvariant({
expectedPop += localCandidateSize + 4
return true
}())
let descriptorSize = descriptorHeader.propertyDescriptorBodySize
var descriptorBuffer = UnsafeRawBufferPointer(start: descriptor + 4,
count: descriptorSize)
// Look at what kind of component the external property has.
switch descriptorHeader.kind {
case .struct, .class:
// A stored component. We can instantiate it
// without help from the local candidate.
_ = _pop(from: &buffer, as: UInt8.self, count: localCandidateSize)
visitStored(header: descriptorHeader,
componentBuffer: &descriptorBuffer)
case .computed:
// A computed component. The accessors come from the descriptor.
let (idValueBase, idValue, getter, setter)
= popComputedAccessors(header: descriptorHeader,
componentBuffer: &descriptorBuffer)
// Get the arguments from the external descriptor and/or local candidate
// component.
let arguments: KeyPathPatternComputedArguments?
if localCandidateHeader.kind == .computed
&& localCandidateHeader.hasComputedArguments {
// If both have arguments, then we have to build a bit of a chimera.
// The canonical identity and accessors come from the descriptor,
// but the argument equality/hash handling is still as described
// in the local candidate.
// We don't need the local candidate's accessors.
_ = popComputedAccessors(header: localCandidateHeader,
componentBuffer: &buffer)
// We do need the local arguments.
arguments = popComputedArguments(header: localCandidateHeader,
componentBuffer: &buffer)
} else {
// If the local candidate doesn't have arguments, we don't need
// anything from it at all.
_ = _pop(from: &buffer, as: UInt8.self, count: localCandidateSize)
arguments = nil
}
walker.visitComputedComponent(
mutating: descriptorHeader.isComputedMutating,
idKind: descriptorHeader.computedIDKind,
idResolution: descriptorHeader.computedIDResolution,
idValueBase: idValueBase,
idValue: idValue,
getter: getter,
setter: setter,
arguments: arguments,
externalArgs: genericParamCount > 0 ? externalArgs : nil)
case .optionalChain, .optionalWrap, .optionalForce, .external:
_internalInvariantFailure("not possible for property descriptor")
}
}
// Check that we consumed the expected amount of data from the pattern.
_internalInvariant(
{
// Round the amount of data we read up to alignment.
let popped = MemoryLayout<Int32>._roundingUpToAlignment(
bufferSizeBefore - buffer.count)
return expectedPop == popped
}(),
"""
component size consumed during pattern walk does not match \
component size returned by patternComponentBodySize
""")
// Break if this is the last component.
if buffer.isEmpty { break }
// Otherwise, pop the intermediate component type accessor and
// go around again.
let componentTypeBase = buffer.baseAddress.unsafelyUnwrapped
let componentTypeOffset = _pop(from: &buffer, as: Int32.self)
let componentTypeRef = _resolveRelativeAddress(componentTypeBase,
componentTypeOffset)
walker.visitIntermediateComponentType(metadataRef: componentTypeRef)
_internalInvariant(!buffer.isEmpty)
}
// We should have walked the entire pattern.
_internalInvariant(buffer.isEmpty, "did not walk entire pattern buffer")
walker.finish()
}
internal struct GetKeyPathClassAndInstanceSizeFromPattern
: KeyPathPatternVisitor {
var size: Int = MemoryLayout<Int>.size // start with one word for the header
var capability: KeyPathKind = .value
var didChain: Bool = false
var root: Any.Type!
var leaf: Any.Type!
var genericEnvironment: UnsafeRawPointer?
let patternArgs: UnsafeRawPointer?
init(patternArgs: UnsafeRawPointer?) {
self.patternArgs = patternArgs
}
mutating func roundUpToPointerAlignment() {
size = MemoryLayout<Int>._roundingUpToAlignment(size)
}
mutating func visitHeader(genericEnvironment: UnsafeRawPointer?,
rootMetadataRef: MetadataReference,
leafMetadataRef: MetadataReference,
kvcCompatibilityString: UnsafeRawPointer?) {
self.genericEnvironment = genericEnvironment
// Get the root and leaf type metadata so we can form the class type
// for the entire key path.
root = _resolveKeyPathMetadataReference(
rootMetadataRef,
genericEnvironment: genericEnvironment,
arguments: patternArgs)
leaf = _resolveKeyPathMetadataReference(
leafMetadataRef,
genericEnvironment: genericEnvironment,
arguments: patternArgs)
}
mutating func visitStoredComponent(kind: KeyPathStructOrClass,
mutable: Bool,
offset: KeyPathPatternStoredOffset) {
// Mutable class properties can be the root of a reference mutation.
// Mutable struct properties pass through the existing capability.
if mutable {
switch kind {
case .class:
capability = .reference
case .struct:
break
}
} else {
// Immutable properties can only be read.
capability = .readOnly
}
// The size of the instantiated component depends on whether we can fit
// the offset inline.
switch offset {
case .inline:
size += 4
case .outOfLine, .unresolvedFieldOffset, .unresolvedIndirectOffset:
size += 8
}
}
mutating func visitComputedComponent(mutating: Bool,
idKind: KeyPathComputedIDKind,
idResolution: KeyPathComputedIDResolution,
idValueBase: UnsafeRawPointer,
idValue: Int32,
getter: UnsafeRawPointer,
setter: UnsafeRawPointer?,
arguments: KeyPathPatternComputedArguments?,
externalArgs: UnsafeBufferPointer<Int32>?) {
let settable = setter != nil
switch (settable, mutating) {
case (false, false):
// If the property is get-only, the capability becomes read-only, unless
// we get another reference-writable component.
capability = .readOnly
case (true, false):
capability = .reference
case (true, true):
// Writable if the base is. No effect.
break
case (false, true):
_internalInvariantFailure("unpossible")
}
// Save space for the header...
size += 4
roundUpToPointerAlignment()
// ...id, getter, and maybe setter...
size += MemoryLayout<Int>.size * 2
if settable {
size += MemoryLayout<Int>.size
}
// ...and the arguments, if any.
let argumentHeaderSize = MemoryLayout<Int>.size * 2
switch (arguments, externalArgs) {
case (nil, nil):
break
case (let arguments?, nil):
size += argumentHeaderSize
// If we have arguments, calculate how much space they need by invoking
// the layout function.
let (addedSize, addedAlignmentMask) = arguments.getLayout(patternArgs)
// TODO: Handle over-aligned values
_internalInvariant(addedAlignmentMask < MemoryLayout<Int>.alignment,
"overaligned computed property element not supported")
size += addedSize
case (let arguments?, let externalArgs?):
// If we're referencing an external declaration, and it takes captured
// arguments, then we have to build a bit of a chimera. The canonical
// identity and accessors come from the descriptor, but the argument
// handling is still as described in the local candidate.
size += argumentHeaderSize
let (addedSize, addedAlignmentMask) = arguments.getLayout(patternArgs)
// TODO: Handle over-aligned values
_internalInvariant(addedAlignmentMask < MemoryLayout<Int>.alignment,
"overaligned computed property element not supported")
size += addedSize
// We also need to store the size of the local arguments so we can
// find the external component arguments.
roundUpToPointerAlignment()
size += RawKeyPathComponent.Header.externalWithArgumentsExtraSize
size += MemoryLayout<Int>.size * externalArgs.count
case (nil, let externalArgs?):
// If we're instantiating an external property with a local
// candidate that has no arguments, then things are a little
// easier. We only need to instantiate the generic
// arguments for the external component's accessors.
size += argumentHeaderSize
size += MemoryLayout<Int>.size * externalArgs.count
}
}
mutating func visitOptionalChainComponent() {
// Optional chaining forces the entire keypath to be read-only, even if
// there are further reference-writable components.
didChain = true
capability = .readOnly
size += 4
}
mutating func visitOptionalWrapComponent() {
// Optional chaining forces the entire keypath to be read-only, even if
// there are further reference-writable components.
didChain = true
capability = .readOnly
size += 4
}
mutating func visitOptionalForceComponent() {
// Force-unwrapping passes through the mutability of the preceding keypath.
size += 4
}
mutating
func visitIntermediateComponentType(metadataRef _: MetadataReference) {
// The instantiated component type will be stored in the instantiated
// object.
roundUpToPointerAlignment()
size += MemoryLayout<Int>.size
}
mutating func finish() {
}
}
internal func _getKeyPathClassAndInstanceSizeFromPattern(
_ pattern: UnsafeRawPointer,
_ arguments: UnsafeRawPointer
) -> (
keyPathClass: AnyKeyPath.Type,
rootType: Any.Type,
size: Int,
alignmentMask: Int
) {
var walker = GetKeyPathClassAndInstanceSizeFromPattern(patternArgs: arguments)
_walkKeyPathPattern(pattern, walker: &walker)
// Chaining always renders the whole key path read-only.
if walker.didChain {
walker.capability = .readOnly
}
// Grab the class object for the key path type we'll end up with.
func openRoot<Root>(_: Root.Type) -> AnyKeyPath.Type {
func openLeaf<Leaf>(_: Leaf.Type) -> AnyKeyPath.Type {
switch walker.capability {
case .readOnly:
return KeyPath<Root, Leaf>.self
case .value:
return WritableKeyPath<Root, Leaf>.self
case .reference:
return ReferenceWritableKeyPath<Root, Leaf>.self
}
}
return _openExistential(walker.leaf!, do: openLeaf)
}
let classTy = _openExistential(walker.root!, do: openRoot)
return (keyPathClass: classTy,
rootType: walker.root!,
size: walker.size,
// FIXME: Handle overalignment
alignmentMask: MemoryLayout<Int>._alignmentMask)
}
internal struct InstantiateKeyPathBuffer : KeyPathPatternVisitor {
var destData: UnsafeMutableRawBufferPointer
var genericEnvironment: UnsafeRawPointer?
let patternArgs: UnsafeRawPointer?
var base: Any.Type
init(destData: UnsafeMutableRawBufferPointer,
patternArgs: UnsafeRawPointer?,
root: Any.Type) {
self.destData = destData
self.patternArgs = patternArgs
self.base = root
}
// Track the triviality of the resulting object data.
var isTrivial: Bool = true
// Track where the reference prefix begins.
var endOfReferencePrefixComponent: UnsafeMutableRawPointer? = nil
var previousComponentAddr: UnsafeMutableRawPointer? = nil
mutating func pushDest<T>(_ value: T) {
_internalInvariant(_isPOD(T.self))
let size = MemoryLayout<T>.size
let alignment = MemoryLayout<T>.alignment
var baseAddress = destData.baseAddress.unsafelyUnwrapped
var misalign = Int(bitPattern: baseAddress) % alignment
if misalign != 0 {
misalign = alignment - misalign
baseAddress = baseAddress.advanced(by: misalign)
}
withUnsafeBytes(of: value) {
_memcpy(dest: baseAddress, src: $0.baseAddress.unsafelyUnwrapped,
size: UInt(size))
}
destData = UnsafeMutableRawBufferPointer(
start: baseAddress + size,
count: destData.count - size - misalign)
}
mutating func updatePreviousComponentAddr() -> UnsafeMutableRawPointer? {
let oldValue = previousComponentAddr
previousComponentAddr = destData.baseAddress.unsafelyUnwrapped
return oldValue
}
mutating func visitHeader(genericEnvironment: UnsafeRawPointer?,
rootMetadataRef: MetadataReference,
leafMetadataRef: MetadataReference,
kvcCompatibilityString: UnsafeRawPointer?) {
self.genericEnvironment = genericEnvironment
}
mutating func visitStoredComponent(kind: KeyPathStructOrClass,
mutable: Bool,
offset: KeyPathPatternStoredOffset) {
let previous = updatePreviousComponentAddr()
switch kind {
case .class:
// A mutable class property can end the reference prefix.
if mutable {
endOfReferencePrefixComponent = previous
}
fallthrough
case .struct:
// Resolve the offset.
switch offset {
case .inline(let value):
let header = RawKeyPathComponent.Header(stored: kind,
mutable: mutable,
inlineOffset: value)
pushDest(header)
case .outOfLine(let offset):
let header = RawKeyPathComponent.Header(storedWithOutOfLineOffset: kind,
mutable: mutable)
pushDest(header)
pushDest(offset)
case .unresolvedFieldOffset(let offsetOfOffset):
// Look up offset in the type metadata. The value in the pattern is
// the offset within the metadata object.
let metadataPtr = unsafeBitCast(base, to: UnsafeRawPointer.self)
let offset: UInt32
switch kind {
case .class:
offset = UInt32(metadataPtr.load(fromByteOffset: Int(offsetOfOffset),
as: UInt.self))
case .struct:
offset = UInt32(metadataPtr.load(fromByteOffset: Int(offsetOfOffset),
as: UInt32.self))
}
let header = RawKeyPathComponent.Header(storedWithOutOfLineOffset: kind,
mutable: mutable)
pushDest(header)
pushDest(offset)
case .unresolvedIndirectOffset(let pointerToOffset):
// Look up offset in the indirectly-referenced variable we have a
// pointer.
let offset = UInt32(pointerToOffset.pointee)
let header = RawKeyPathComponent.Header(storedWithOutOfLineOffset: kind,
mutable: mutable)
pushDest(header)
pushDest(offset)
}
}
}
mutating func visitComputedComponent(mutating: Bool,
idKind: KeyPathComputedIDKind,
idResolution: KeyPathComputedIDResolution,
idValueBase: UnsafeRawPointer,
idValue: Int32,
getter: UnsafeRawPointer,
setter: UnsafeRawPointer?,
arguments: KeyPathPatternComputedArguments?,
externalArgs: UnsafeBufferPointer<Int32>?) {
let previous = updatePreviousComponentAddr()
let settable = setter != nil
// A nonmutating settable property can end the reference prefix.
if settable && !mutating {
endOfReferencePrefixComponent = previous
}
// Resolve the ID.
let resolvedID: UnsafeRawPointer?
switch idKind {
case .storedPropertyIndex, .vtableOffset:
_internalInvariant(idResolution == .resolved)
// Zero-extend the integer value to get the instantiated id.
let value = UInt(UInt32(bitPattern: idValue))
resolvedID = UnsafeRawPointer(bitPattern: value)
case .pointer:
// Resolve the sign-extended relative reference.
var absoluteID: UnsafeRawPointer? = idValueBase + Int(idValue)
// If the pointer ID is unresolved, then it needs work to get to
// the final value.
switch idResolution {
case .resolved:
break
case .indirectPointer:
// The pointer in the pattern is an indirect pointer to the real
// identifier pointer.
absoluteID = absoluteID.unsafelyUnwrapped
.load(as: UnsafeRawPointer?.self)
case .functionCall:
// The pointer in the pattern is to a function that generates the
// identifier pointer.
typealias Resolver = @convention(c) (UnsafeRawPointer?) -> UnsafeRawPointer?
let resolverFn = unsafeBitCast(absoluteID.unsafelyUnwrapped,
to: Resolver.self)
absoluteID = resolverFn(patternArgs)
}
resolvedID = absoluteID
}
// Bring over the header, getter, and setter.
let header = RawKeyPathComponent.Header(computedWithIDKind: idKind,
mutating: mutating,
settable: settable,
hasArguments: arguments != nil || externalArgs != nil,
instantiatedFromExternalWithArguments:
arguments != nil && externalArgs != nil)
pushDest(header)
pushDest(resolvedID)
pushDest(getter)
if let setter = setter {
pushDest(setter)
}
if let arguments = arguments {
// Instantiate the arguments.
let (baseSize, alignmentMask) = arguments.getLayout(patternArgs)
_internalInvariant(alignmentMask < MemoryLayout<Int>.alignment,
"overaligned computed arguments not implemented yet")
// The real buffer stride will be rounded up to alignment.
var totalSize = (baseSize + alignmentMask) & ~alignmentMask
// If an external property descriptor also has arguments, they'll be
// added to the end with pointer alignment.
if let externalArgs = externalArgs {
totalSize = MemoryLayout<Int>._roundingUpToAlignment(totalSize)
totalSize += MemoryLayout<Int>.size * externalArgs.count
}
pushDest(totalSize)
pushDest(arguments.witnesses)
// A nonnull destructor in the witnesses file indicates the instantiated
// payload is nontrivial.
if let _ = arguments.witnesses.pointee.destroy {
isTrivial = false
}
// If the descriptor has arguments, store the size of its specific
// arguments here, so we can drop them when trying to invoke
// the component's witnesses.
if let externalArgs = externalArgs {
pushDest(externalArgs.count * MemoryLayout<Int>.size)
}
// Initialize the local candidate arguments here.
_internalInvariant(Int(bitPattern: destData.baseAddress) & alignmentMask == 0,
"argument destination not aligned")
arguments.initializer(patternArgs,
destData.baseAddress.unsafelyUnwrapped)
destData = UnsafeMutableRawBufferPointer(
start: destData.baseAddress.unsafelyUnwrapped + baseSize,
count: destData.count - baseSize)
}
if let externalArgs = externalArgs {
if arguments == nil {
// If we're instantiating an external property without any local
// arguments, then we only need to instantiate the arguments to the
// property descriptor.
let stride = MemoryLayout<Int>.size * externalArgs.count
pushDest(stride)
pushDest(__swift_keyPathGenericWitnessTable_addr())
}
// Write the descriptor's generic arguments, which should all be relative
// references to metadata accessor functions.
for i in externalArgs.indices {
let base = externalArgs.baseAddress.unsafelyUnwrapped + i
let offset = base.pointee
let metadataRef = UnsafeRawPointer(base) + Int(offset)
let result = _resolveKeyPathGenericArgReference(
metadataRef,
genericEnvironment: genericEnvironment,
arguments: patternArgs)
pushDest(result)
}
}
}
mutating func visitOptionalChainComponent() {
let _ = updatePreviousComponentAddr()
let header = RawKeyPathComponent.Header(optionalChain: ())
pushDest(header)
}
mutating func visitOptionalWrapComponent() {
let _ = updatePreviousComponentAddr()
let header = RawKeyPathComponent.Header(optionalWrap: ())
pushDest(header)
}
mutating func visitOptionalForceComponent() {
let _ = updatePreviousComponentAddr()
let header = RawKeyPathComponent.Header(optionalForce: ())
pushDest(header)
}
mutating func visitIntermediateComponentType(metadataRef: MetadataReference) {
// Get the metadata for the intermediate type.
let metadata = _resolveKeyPathMetadataReference(
metadataRef,
genericEnvironment: genericEnvironment,
arguments: patternArgs)
pushDest(metadata)
base = metadata
}
mutating func finish() {
// Should have filled the entire buffer by the time we reach the end of the
// pattern.
_internalInvariant(destData.isEmpty,
"should have filled entire destination buffer")
}
}
#if INTERNAL_CHECKS_ENABLED
// In debug builds of the standard library, check that instantiation produces
// components whose sizes are consistent with the sizing visitor pass.
internal struct ValidatingInstantiateKeyPathBuffer: KeyPathPatternVisitor {
var sizeVisitor: GetKeyPathClassAndInstanceSizeFromPattern
var instantiateVisitor: InstantiateKeyPathBuffer
let origDest: UnsafeMutableRawPointer
init(sizeVisitor: GetKeyPathClassAndInstanceSizeFromPattern,
instantiateVisitor: InstantiateKeyPathBuffer) {
self.sizeVisitor = sizeVisitor
self.instantiateVisitor = instantiateVisitor
origDest = self.instantiateVisitor.destData.baseAddress.unsafelyUnwrapped
}
mutating func visitHeader(genericEnvironment: UnsafeRawPointer?,
rootMetadataRef: MetadataReference,
leafMetadataRef: MetadataReference,
kvcCompatibilityString: UnsafeRawPointer?) {
sizeVisitor.visitHeader(genericEnvironment: genericEnvironment,
rootMetadataRef: rootMetadataRef,
leafMetadataRef: leafMetadataRef,
kvcCompatibilityString: kvcCompatibilityString)
instantiateVisitor.visitHeader(genericEnvironment: genericEnvironment,
rootMetadataRef: rootMetadataRef,
leafMetadataRef: leafMetadataRef,
kvcCompatibilityString: kvcCompatibilityString)
}
mutating func visitStoredComponent(kind: KeyPathStructOrClass,
mutable: Bool,
offset: KeyPathPatternStoredOffset) {
sizeVisitor.visitStoredComponent(kind: kind, mutable: mutable,
offset: offset)
instantiateVisitor.visitStoredComponent(kind: kind, mutable: mutable,
offset: offset)
checkSizeConsistency()
}
mutating func visitComputedComponent(mutating: Bool,
idKind: KeyPathComputedIDKind,
idResolution: KeyPathComputedIDResolution,
idValueBase: UnsafeRawPointer,
idValue: Int32,
getter: UnsafeRawPointer,
setter: UnsafeRawPointer?,
arguments: KeyPathPatternComputedArguments?,
externalArgs: UnsafeBufferPointer<Int32>?) {
sizeVisitor.visitComputedComponent(mutating: mutating,
idKind: idKind,
idResolution: idResolution,
idValueBase: idValueBase,
idValue: idValue,
getter: getter,
setter: setter,
arguments: arguments,
externalArgs: externalArgs)
instantiateVisitor.visitComputedComponent(mutating: mutating,
idKind: idKind,
idResolution: idResolution,
idValueBase: idValueBase,
idValue: idValue,
getter: getter,
setter: setter,
arguments: arguments,
externalArgs: externalArgs)
checkSizeConsistency()
}
mutating func visitOptionalChainComponent() {
sizeVisitor.visitOptionalChainComponent()
instantiateVisitor.visitOptionalChainComponent()
checkSizeConsistency()
}
mutating func visitOptionalWrapComponent() {
sizeVisitor.visitOptionalWrapComponent()
instantiateVisitor.visitOptionalWrapComponent()
checkSizeConsistency()
}
mutating func visitOptionalForceComponent() {
sizeVisitor.visitOptionalForceComponent()
instantiateVisitor.visitOptionalForceComponent()
checkSizeConsistency()
}
mutating func visitIntermediateComponentType(metadataRef: MetadataReference) {
sizeVisitor.visitIntermediateComponentType(metadataRef: metadataRef)
instantiateVisitor.visitIntermediateComponentType(metadataRef: metadataRef)
checkSizeConsistency()
}
mutating func finish() {
sizeVisitor.finish()
instantiateVisitor.finish()
checkSizeConsistency()
}
func checkSizeConsistency() {
let nextDest = instantiateVisitor.destData.baseAddress.unsafelyUnwrapped
let curSize = nextDest - origDest + MemoryLayout<Int>.size
_internalInvariant(curSize == sizeVisitor.size,
"size and instantiation visitors out of sync")
}
}
#endif // INTERNAL_CHECKS_ENABLED
internal func _instantiateKeyPathBuffer(
_ pattern: UnsafeRawPointer,
_ origDestData: UnsafeMutableRawBufferPointer,
_ rootType: Any.Type,
_ arguments: UnsafeRawPointer
) {
let destHeaderPtr = origDestData.baseAddress.unsafelyUnwrapped
var destData = UnsafeMutableRawBufferPointer(
start: destHeaderPtr.advanced(by: MemoryLayout<Int>.size),
count: origDestData.count - MemoryLayout<Int>.size)
#if INTERNAL_CHECKS_ENABLED
// If checks are enabled, use a validating walker that ensures that the
// size pre-walk and instantiation walk are in sync.
let sizeWalker = GetKeyPathClassAndInstanceSizeFromPattern(
patternArgs: arguments)
let instantiateWalker = InstantiateKeyPathBuffer(
destData: destData,
patternArgs: arguments,
root: rootType)
var walker = ValidatingInstantiateKeyPathBuffer(sizeVisitor: sizeWalker,
instantiateVisitor: instantiateWalker)
#else
var walker = InstantiateKeyPathBuffer(
destData: destData,
patternArgs: arguments,
root: rootType)
#endif
_walkKeyPathPattern(pattern, walker: &walker)
#if INTERNAL_CHECKS_ENABLED
let isTrivial = walker.instantiateVisitor.isTrivial
let endOfReferencePrefixComponent =
walker.instantiateVisitor.endOfReferencePrefixComponent
#else
let isTrivial = walker.isTrivial
let endOfReferencePrefixComponent = walker.endOfReferencePrefixComponent
#endif
// Write out the header.
let destHeader = KeyPathBuffer.Header(
size: origDestData.count - MemoryLayout<Int>.size,
trivial: isTrivial,
hasReferencePrefix: endOfReferencePrefixComponent != nil)
destHeaderPtr.storeBytes(of: destHeader, as: KeyPathBuffer.Header.self)
// Mark the reference prefix if there is one.
if let endOfReferencePrefixComponent = endOfReferencePrefixComponent {
var componentHeader = endOfReferencePrefixComponent
.load(as: RawKeyPathComponent.Header.self)
componentHeader.endOfReferencePrefix = true
endOfReferencePrefixComponent.storeBytes(of: componentHeader,
as: RawKeyPathComponent.Header.self)
}
}