Add support for for loops in View.

Closes #20

Sources/Slipstream/Documentation.docc/Views/Fundamentals/ViewBuilder.md

@@ -6,6 +6,7 @@
 
 - ``ViewBuilder/buildBlock(_:)-eqvl``
 - ``ViewBuilder/buildBlock(_:)-2hz2p``
+- ``ViewBuilder/buildArray(_:)``
 
 ### Conditionally building content
 

Sources/Slipstream/Views/Fundamentals/ViewBuilder/ArrayView.swift

@@ -0,0 +1,19 @@
+import SwiftSoup
+
+/// A View created from a for loop of View values.
+@_documentation(visibility: private)
+public struct ArrayView: View {
+  public typealias Content = Never
+
+  init(array: [any View]) {
+    self.array = array
+  }
+
+  private var array: [any View]
+
+  public func render(_ container: Element, environment: EnvironmentValues) throws {
+    for view in array {
+      try view.render(container, environment: environment)
+    }
+  }
+}

Sources/Slipstream/Views/Fundamentals/ViewBuilder/ViewBuilder.swift

@@ -52,7 +52,6 @@ public struct ViewBuilder {
     return .init(condition: .isTrue(first))
   }
 
-
   /// An if/else statement, when the condition returns false.
   ///
   /// An example:
@@ -70,4 +69,20 @@ public struct ViewBuilder {
   where TrueContent: View, FalseContent: View {
     return .init(condition: .isFalse(second))
   }
+
+  /// Gathers the results of a loop into a single view.
+  ///
+  /// An example:
+  ///
+  /// ```swift
+  /// var body: some View {
+  ///    for i in 1...3 {
+  ///      Text("\(i)")
+  ///    }
+  /// }
+  /// ```
+  public static func buildArray<Content>(_ components: [Content]) -> ArrayView
+  where Content: View {
+    ArrayView(array: components)
+  }
 }

Tests/SlipstreamTests/ViewBuilderTests.swift

@@ -26,6 +26,14 @@ private struct ConditionalBlockView: View {
   }
 }
 
+private struct ArrayBlockView: View {
+  var body: some View {
+    for i in 1...3 {
+      Text("\(i)")
+    }
+  }
+}
+
 struct ViewBuilderTests {
   @Test func singleBlock() throws {
     try #expect(renderHTML(SingleBlockView()) == "Hello, world!")
@@ -39,4 +47,8 @@ struct ViewBuilderTests {
     try #expect(renderHTML(ConditionalBlockView(bool: true)) == "true")
     try #expect(renderHTML(ConditionalBlockView(bool: false)) == "false")
   }
+
+  @Test func arrayBlock() throws {
+    try #expect(renderHTML(ArrayBlockView()) == "123")
+  }
 }