KeyPathReflectable

KeyPathReflectable.swift

// <https://github.com/tensorflow/swift-apis/blob/main/Sources/TensorFlow/Core/KeyPathIterable.swift>
// <https://github.com/apple/swift/blob/main/stdlib/public/core/ReflectionMirror.swift>
// <https://github.com/tensorflow/swift/blob/main/docs/DynamicPropertyIteration.md>

// <https://forums.swift.org/t/getting-keypaths-to-members-automatically-using-mirror/21207>
// <https://github.com/Azoy/Echo>

public protocol KeyPathReflectable {
    func reflect(allKeyPaths keyPaths: inout [PartialKeyPath<Self>])
    func reflect(allKeyPaths keyPaths: inout [String: PartialKeyPath<Self>])
}

extension KeyPathReflectable {
    @inlinable
    subscript(mirrorDescendant key: String) -> Any { Mirror(reflecting: self).descendant(key)! }
    
    public func reflect(allKeyPaths keyPaths: inout [PartialKeyPath<Self>]) {
        let mirror = Mirror(reflecting: self)
        for case let (label?, _) in mirror.children {
            keyPaths.append(\Self.[mirrorDescendant: label] as PartialKeyPath<Self>)
        }
    }
    
    public func reflect(allKeyPaths keyPaths: inout [String: PartialKeyPath<Self>]) {
        let mirror = Mirror(reflecting: self)
        for case let (label?, _) in mirror.children {
            keyPaths[label] = \Self.[mirrorDescendant: label] as PartialKeyPath<Self>
        }
    }
}