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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2023 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
//
//===----------------------------------------------------------------------===//
extension UInt32 {
private static var KEYPATH_HEADER_BUFFER_SIZE_MASK: UInt32 { 0x00FF_FFFF }
private static var COMPONENT_HEADER_KIND_MASK: UInt32 { 0x7F00_0000 }
private static var COMPONENT_HEADER_PAYLOAD_MASK: UInt32 { 0x00FF_FFFF }
private static var COMPUTED_COMPONENT_PAYLOAD_ARGUMENTS_MASK: UInt32 { 0x0008_0000 }
private static var COMPUTED_COMPONENT_PAYLOAD_SETTABLE_MASK: UInt32 { 0x0040_0000 }
fileprivate var _keyPathHeader_bufferSize: Int {
Int(self & Self.KEYPATH_HEADER_BUFFER_SIZE_MASK)
}
fileprivate var _keyPathComponentHeader_kind: Int {
Int((self & Self.COMPONENT_HEADER_KIND_MASK) >> 24)
}
fileprivate var _keyPathComponentHeader_payload: UInt32 {
self & Self.COMPONENT_HEADER_PAYLOAD_MASK
}
fileprivate var _keyPathComponentHeader_computedHasArguments: Bool {
(_keyPathComponentHeader_payload & Self.COMPUTED_COMPONENT_PAYLOAD_ARGUMENTS_MASK) != 0
}
fileprivate var _keyPathComponentHeader_computedIsSettable: Bool {
(_keyPathComponentHeader_payload & Self.COMPUTED_COMPONENT_PAYLOAD_SETTABLE_MASK) != 0
}
}
private func _keyPathOffset<T>(_ root: T.Type, _ keyPath: AnyKeyPath) -> Int? {
MemoryLayout<T>.offset(of: keyPath as! PartialKeyPath<T>)
}
extension AnyKeyPath {
private static var WORD_SIZE: Int { MemoryLayout<Int>.size }
func _validateForPredicateUsage(restrictArguments: Bool = false) {
var ptr = unsafeBitCast(self, to: UnsafeRawPointer.self)
ptr = ptr.advanced(by: Self.WORD_SIZE * 3) // skip isa, type metadata, and KVC string pointers
let header = ptr.load(as: UInt32.self)
ptr = ptr.advanced(by: Self.WORD_SIZE)
let firstComponentHeader = ptr.load(as: UInt32.self)
switch firstComponentHeader._keyPathComponentHeader_kind {
case 1: // struct/tuple/self stored property
fallthrough
case 3: // class stored property
// Key paths to stored properties are only single-component if MemoryLayout.offset(of:) returns an offset
func project<T>(_: T.Type) -> Bool {
_keyPathOffset(T.self, self) == nil
}
if _openExistential(Self.rootType, do: project) {
fatalError("Predicate does not support keypaths with multiple components")
}
case 2: // computed
var componentWords = 3
if firstComponentHeader._keyPathComponentHeader_computedIsSettable {
componentWords += 1
}
if firstComponentHeader._keyPathComponentHeader_computedHasArguments {
if restrictArguments {
fatalError("Predicate does not support keypaths with arguments")
}
let capturesSize = ptr.advanced(by: Self.WORD_SIZE * componentWords).load(as: UInt.self)
componentWords += 2 + (Int(capturesSize) / Self.WORD_SIZE)
}
if header._keyPathHeader_bufferSize > (Self.WORD_SIZE * componentWords) {
fatalError("Predicate does not support keypaths with multiple components")
}
case 4: // optional chain
fatalError("Predicate does not support keypaths with optional chaining/unwrapping")
default: // unknown keypath component
fatalError("Predicate does not support this type of keypath (\(firstComponentHeader._keyPathComponentHeader_kind))")
}
}
}
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