How do you implement a wrapping flow layout using the SwiftUI `Layout` protocol?

struct FlowLayout: Layout {
    var horizontalSpacing: CGFloat = 12
    var verticalSpacing: CGFloat = 12

    func sizeThatFits(proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) -> CGSize {
        var width: CGFloat = 0
        var height: CGFloat = 0
        var rowHeight: CGFloat = 0
        let maxWidth = proposal.width ?? .infinity

        for subview in subviews {
            let size = subview.sizeThatFits(.unspecified)
            if width + size.width > maxWidth {
                width = 0
                height += rowHeight + verticalSpacing
                rowHeight = 0
            }
            width += size.width + horizontalSpacing
            rowHeight = max(rowHeight, size.height)
        }

        height += rowHeight
        return CGSize(width: maxWidth, height: height)
    }

    func placeSubviews(in bounds: CGRect, proposal: ProposedViewSize, subviews: Subviews, cache: inout ()) {
        var x: CGFloat = bounds.minX
        var y: CGFloat = bounds.minY
        var rowHeight: CGFloat = 0
        let maxWidth = bounds.width

        for subview in subviews {
            let size = subview.sizeThatFits(.unspecified)
            if x + size.width > maxWidth {
                x = bounds.minX
                y += rowHeight + verticalSpacing
                rowHeight = 0
            }
            subview.place(at: CGPoint(x: x, y: y), proposal: ProposedViewSize(size))
            x += size.width + horizontalSpacing
            rowHeight = max(rowHeight, size.height)
        }
    }
}