Supports multiple describing layout blocks and layout containers in one place. #59

Author: muukii

Demo_MondrianLayout/Book.Overlay.swift

@@ -5,6 +5,30 @@ import UIKit
 var _book_overlay: BookView {
   BookNavigationLink(title: "Overlay") {
 
+    BookPreview {
+      ExampleView(width: nil, height: nil) { (view: UIView) in
+
+        view.mondrian.buildSubviews {
+          UIView.mock(
+            backgroundColor: .mondrianYellow,
+            preferredSize: .init(width: 100, height: 100)
+          )
+            .viewBlock
+            .overlay(
+              UIView.mock(backgroundColor: .layeringColor)
+                .viewBlock
+                .overlay(
+                  UIView.mock(backgroundColor: .layeringColor)
+                    .viewBlock
+                    .padding(10)
+                )
+                .padding(10)
+            )
+        }
+      }
+    }
+
+
     BookPreview {
       ExampleView(width: nil, height: nil) { (view: UIView) in
         view.mondrian.buildSubviews {

MondrianLayout/Extensions/UIView+Mondrian.swift

@@ -1,39 +1,81 @@
 import UIKit
 
-extension MondrianNamespace where Base : UIView {
+@resultBuilder
+public enum EntrypointBuilder {
 
-  /**
-   Applies the layout constraints
-   Adding subviews included in layout
+  public enum Either {
+    case block(_LayoutBlockType)
+    case container(LayoutContainer)
+  }
 
-   You might use ``LayoutContainer`` from describe beginning in order to support safe-area.
-   */
-  @discardableResult
-  public func buildSubviews<Block: _LayoutBlockType>(
-    build: () -> Block
-  ) -> LayoutBuilderContext {
+  public static func buildBlock(_ components: [Either]...) -> [Either] {
+    return components.flatMap { $0 }
+  }
 
-    let context = LayoutBuilderContext(targetView: base)
-    let container = build()
-    container.setupConstraints(parent: .init(view: base), in: context)
-    context.prepareViewHierarchy()
-    context.activate()
+  public static func buildExpression<Block: _LayoutBlockType>(_ components: Block...) -> [Either] {
+    return components.map { .block($0) }
+  }
 
-    return context
+  public static func buildExpression(_ components: LayoutContainer...) -> [EntrypointBuilder.Either] {
+    return components.map { .container($0) }
   }
 
+}
+
+extension MondrianNamespace where Base : UIView {
+
   /**
-   Applies the layout constraints
-   Adding subviews included in layout
+   Builds subviews of this view.
+   - activating layout-constraints
+   - adding layout-guides
+   - applying content-hugging, content-compression-resistance
+
+   You can start to describe like followings:
+
+   ```swift
+   view.mondrian.buildSubviews {
+     ZStackBlock {
+       ...
+     }
+   }
+   ```
+
+   ```swift
+   view.mondrian.buildSubviews {
+     LayoutContainer(attachedSafeAreaEdges: .vertical) {
+       ...
+     }
+   }
+   ```
+
+
+   ```swift
+   view.mondrian.buildSubviews {
+     LayoutContainer(attachedSafeAreaEdges: .vertical) {
+       ...
+     }
+     ZStackBlock {
+       ...
+     }
+   }
+   ```
    */
   @discardableResult
-  public func buildSubviews(
-    build: () -> LayoutContainer
-  ) -> LayoutBuilderContext {
+  public func buildSubviews(@EntrypointBuilder _ build: () -> [EntrypointBuilder.Either]) -> LayoutBuilderContext {
+
+    let entrypoints = build()
 
     let context = LayoutBuilderContext(targetView: base)
-    let container = build()
-    container.setupConstraints(parent: base, in: context)
+
+    for entrypoint in entrypoints {
+      switch entrypoint {
+      case .block(let block):
+        block.setupConstraints(parent: .init(view: base), in: context)
+      case .container(let container):
+        container.setupConstraints(parent: base, in: context)
+      }
+    }
+
     context.prepareViewHierarchy()
     context.activate()