HStack 2

Sources/TerminalUI/Layouts/HStack.swift

@@ -0,0 +1,68 @@
+
+struct HStack {
+  private let children: [any View]
+  @Mutable private var sizes: [Size] = []
+}
+
+extension HStack: Builtin, View {
+
+  func size(
+    for proposal: ProposedSize,
+    environment: EnvironmentValues
+  ) -> Size {
+
+    let flexibility = children.map { child in
+      let min = ProposedSize(width: 0, height: proposal.height)
+      let max = ProposedSize(width: .max, height: proposal.height)
+      let smallest = child._size(for: min)
+      let largest = child._size(for: max)
+      return largest.width - smallest.width
+    }
+
+    var indices = children.indices
+      .sorted { flexibility[$0] < flexibility[$1] }
+
+    sizes = Array(repeating: .zero, count: children.count)
+    var remaining = proposal.width
+
+    while !indices.isEmpty {
+
+      let proposal = ProposedSize(
+        width: remaining / indices.count,
+        height: proposal.height)
+
+      let index = indices.removeFirst()
+
+      let child = children[index]
+      let size = child._size(for: proposal, environment: environment)
+      sizes[index] = size
+      remaining -= size.width
+      if remaining < 0 { remaining = 0 }
+    }
+
+    let width = sizes.map(\.width).reduce(0, +)
+    let height = sizes.map(\.height).reduce(0, +)
+    return Size(width: width, height: height)
+  }
+
+  func render(
+    in canvas: any Canvas,
+    size: Size,
+    environment: EnvironmentValues
+  ) {
+    var x: Horizontal = 0
+    for (child, childSize) in zip(children, sizes) {
+      let canvas = canvas.translateBy(x: x, y: 0)
+      child._render(in: canvas, size: childSize, environment: environment)
+      x += childSize.width
+    }
+  }
+}
+
+extension Horizontal {
+  fileprivate static var max: Self { Self(Int.max) }
+}
+
+extension Size {
+  fileprivate static var zero: Size { Size(width: 0, height: 0) }
+}

Sources/TerminalUI/Primitives/Dimensions.swift

@@ -56,6 +56,12 @@ extension Horizontal {
   }
 }
 
+extension Horizontal {
+  static func / (lhs: Horizontal, rhs: Int) -> Horizontal {
+    Horizontal(lhs.value / rhs)
+  }
+}
+
 // MARK: - Vertical
 
 /// A measurement of the vertical dimension.