Support result builder syntax for view spreading

Paralayout/UIView+Spreading.swift

@@ -1,5 +1,5 @@
 //
-// Copyright © 2021 Square, Inc.
+// Copyright © 2024 Block, Inc.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
@@ -70,6 +70,35 @@ extension UIView {
 
  // MARK: - Public Methods
 
+ #if swift(>=5.4)
+ /// Sizes and positions subviews to equally take up all horizontal space.
+ ///
+ /// - precondition: The available space on the horizontal axis of the receiver's bounds must be at least as large as
+ /// the space required for the specified `margin` between each subview. In other words, the `subviews` may each have
+ /// a size of zero along the horizontal axis, but their size may not be negative.
+ ///
+ /// - parameter margin: The space between each subview.
+ /// - parameter bounds: A custom area within which to layout the subviews in the receiver's coordinate space, or
+ /// `nil` to use the receiver's `bounds`. Defaults to `nil`.
+ /// - parameter orthogonalBehavior: Controls how the view should be sized and positioned along the vertical axis.
+ /// Defaults to filling the vertical space of the `bounds`.
+ /// - parameter subviews: The subviews to spread out, ordered from the leading edge to the trailing edge of the
+ /// receiver.
+ public func horizontallySpreadSubviews(
+ margin: CGFloat,
+ inRect bounds: CGRect? = nil,
+ orthogonalBehavior: VerticalSpreadingBehavior = .fill,
+ @ViewArrayBuilder _ subviews: () -> [UIView]
+ ) {
+ horizontallySpreadSubviews(
+ subviews(),
+ margin: margin,
+ inRect: bounds,
+ orthogonalBehavior: orthogonalBehavior
+ )
+ }
+ #endif
+
  /// Sizes and positions subviews to equally take up all horizontal space.
  ///
  /// - precondition: The available space on the horizontal axis of the receiver's bounds must be at least as large as
@@ -116,6 +145,34 @@ extension UIView {
  }
  }
 
+ #if swift(>=5.4)
+ /// Sizes and positions subviews to equally take up all vertical space.
+ ///
+ /// - precondition: The available space on the vertical axis of the receiver's bounds must be at least as large as
+ /// the space required for the specified `margin` between each subview. In other words, the `subviews` may each have
+ /// a size of zero along the vertical axis, but their size may not be negative.
+ ///
+ /// - parameter margin: The space between each subview.
+ /// - parameter bounds: A custom area within which to layout the subviews in the receiver's coordinate space, or
+ /// `nil` to use the receiver's `bounds`. Defaults to `nil`.
+ /// - parameter orthogonalBehavior: Controls how the view should be sized and positioned along the horizontal axis.
+ /// Defaults to filling the horizontal space of the `bounds`.
+ /// - parameter subviews: The subviews to spread out, ordered from the top edge to the bottom edge of the receiver.
+ public func verticallySpreadSubviews(
+ margin: CGFloat,
+ inRect bounds: CGRect? = nil,
+ orthogonalBehavior: HorizontalSpreadingBehavior = .fill,
+ @ViewArrayBuilder _ subviews: () -> [UIView]
+ ) {
+ verticallySpreadSubviews(
+ subviews(),
+ margin: margin,
+ inRect: bounds,
+ orthogonalBehavior: orthogonalBehavior
+ )
+ }
+ #endif
+
  /// Sizes and positions subviews to equally take up all vertical space.
  ///
  /// - precondition: The available space on the vertical axis of the receiver's bounds must be at least as large as

Paralayout/ViewArrayBuilder.swift

@@ -0,0 +1,90 @@
+//
+// Copyright © 2024 Block, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import UIKit
+
+#if swift(>=5.4)
+@resultBuilder
+public struct ViewArrayBuilder {
+
+ // Build expressions, which are turned into partial results.
+
+ public static func buildExpression(_ component: UIView) -> [UIView] {
+ return [component]
+ }
+ public static func buildExpression(_ component: [UIView?]) -> [UIView] {
+ return component.compactMap { $0 }
+ }
+ public static func buildExpression(_ component: [UIView]) -> [UIView] {
+ return component
+ }
+ public static func buildExpression(_ component: UIView?) -> [UIView] {
+ return [component].compactMap { $0 }
+ }
+
+ // Build partial results, which accumulate.
+
+ public static func buildPartialBlock(first: UIView) -> [UIView] {
+ return [first]
+ }
+ public static func buildPartialBlock(first: [UIView]) -> [UIView] {
+ return first
+ }
+ public static func buildPartialBlock(accumulated: UIView, next: UIView) -> [UIView] {
+ return [accumulated, next]
+ }
+ public static func buildPartialBlock(accumulated: UIView, next: [UIView]) -> [UIView] {
+ return [accumulated] + next
+ }
+ public static func buildPartialBlock(accumulated: [UIView], next: UIView) -> [UIView] {
+ return accumulated + [next]
+ }
+ public static func buildPartialBlock(accumulated: [UIView], next: [UIView]) -> [UIView] {
+ return accumulated + next
+ }
+
+ // Build if statements
+
+ public static func buildOptional(_ component: [UIView]?) -> [UIView] {
+ return component ?? []
+ }
+ public static func buildOptional(_ component: [UIView]) -> [UIView] {
+ return component
+ }
+
+ // Build if-else and switch statements
+
+ public static func buildEither(first component: [UIView]) -> [UIView] {
+ return component
+ }
+ public static func buildEither(second component: [UIView]) -> [UIView] {
+ return component
+ }
+
+ // Build for-loop statements
+
+ public static func buildArray(_ components: [[UIView]]) -> [UIView] {
+ return components.flatMap { $0 }
+ }
+
+ // Build the blocks that turn into results.
+
+ public static func buildBlock(_ components: [UIView]...) -> [UIView] {
+ return components.flatMap { $0 }
+ }
+
+}
+#endif

ParalayoutTests/ViewArrayBuilderTests.swift

@@ -0,0 +1,194 @@
+//
+// Copyright © 2024 Block, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Paralayout
+import XCTest
+
+#if swift(>=5.4)
+final class ViewArrayBuilderTests: XCTestCase {
+
+ // MARK: - Tests
+
+ func testSimpleResultBuilder() throws {
+ let view1 = UIView()
+ let view2 = UIView()
+ XCTAssertEqual(
+ viewArray {
+ view1
+ view2
+ },
+ [
+ view1,
+ view2,
+ ]
+ )
+ }
+
+ func testIfTrueResultBuilder() throws {
+ let view1 = UIView()
+ let view2 = UIView()
+ let view3 = UIView()
+ let condition = true
+ XCTAssertEqual(
+ viewArray {
+ view1
+ if condition {
+ view2
+ }
+ view3
+ },
+ [
+ view1,
+ view2,
+ view3,
+ ]
+ )
+ }
+
+ func testIfFalseResultBuilder() throws {
+ let view1 = UIView()
+ let view2 = UIView()
+ let view3 = UIView()
+ let condition = false
+ XCTAssertEqual(
+ viewArray {
+ view1
+ if condition {
+ view2
+ }
+ view3
+ },
+ [
+ view1,
+ view3,
+ ]
+ )
+ }
+
+ func testIfElseFirstBranchResultBuilder() throws {
+ let view1 = UIView()
+ let view2 = UIView()
+ let view3 = UIView()
+ let view4 = UIView()
+ let condition = true
+ XCTAssertEqual(
+ viewArray {
+ view1
+ if condition {
+ view2
+ } else {
+ view3
+ }
+ view4
+ },
+ [
+ view1,
+ view2,
+ view4,
+ ]
+ )
+ }
+
+ func testIfElseSecondBranchResultBuilder() throws {
+ let view1 = UIView()
+ let view2 = UIView()
+ let view3 = UIView()
+ let view4 = UIView()
+ let condition = false
+ XCTAssertEqual(
+ viewArray {
+ view1
+ if condition {
+ view2
+ } else {
+ view3
+ }
+ view4
+ },
+ [
+ view1,
+ view3,
+ view4,
+ ]
+ )
+ }
+
+ func testSwitchCaseResultBuilder() throws {
+ let view1 = UIView()
+ let view2 = UIView()
+ let view3 = UIView()
+ let value = 1
+ XCTAssertEqual(
+ viewArray {
+ view1
+ switch value {
+ case 1:
+ view2
+ default:
+ nil
+ }
+ view3
+ },
+ [
+ view1,
+ view2,
+ view3,
+ ]
+ )
+ }
+
+ func testSwitchDefaultResultBuilder() throws {
+ let view1 = UIView()
+ let view2 = UIView()
+ let view3 = UIView()
+ let value = 2
+ XCTAssertEqual(
+ viewArray {
+ view1
+ switch value {
+ case 1:
+ view2
+ default:
+ nil
+ }
+ view3
+ },
+ [
+ view1,
+ view3,
+ ]
+ )
+ }
+
+ func testForLoopResultBuilder() throws {
+ let views = [UIView(), UIView(), UIView()]
+ XCTAssertEqual(
+ viewArray {
+ for view in views {
+ view
+ }
+ },
+ views
+ )
+ }
+
+ // MARK: - Private Methods
+
+ private func viewArray(@ViewArrayBuilder _ builder: () -> [UIView]) -> [UIView] {
+ builder()
+ }
+}
+#endif