Result builder fixes (#137)

* Link elements are valid in HTML body if they use an itemprop attribute that is body-ok

https://html.spec.whatwg.org/multipage/links.html#body-ok

* Update ContentBuilder DSL to support partial blocks

* Add new statement tests

* Restore the comments

* Remove unused methods from the result builder

---------

Co-authored-by: Mattes Mohr <mail@mattesmohr.de>

Sources/HTMLKit/Abstraction/Elements/HeadElements.swift

@@ -711,7 +711,7 @@ extension Style: GlobalAttributes, GlobalEventAttributes, TypeAttribute, MediaAt
 /// ```html
 /// <link>
 /// ```
-public struct Link: EmptyNode, HeadElement {
+public struct Link: EmptyNode, HeadElement, BodyElement {
 
     internal var name: String { "link" }
 

Sources/HTMLKit/Framework/Builders/ContentBuilder.swift

@@ -1,18 +1,20 @@
-/*
- Abstract:
- The file contains the builder to build up the result from a sequence of elements.
- */
+// Abstract:
+// The file contains the builder to build up the result from a sequence of elements.
 
 /// The builder builds up a result value from a sequence of elements.
-@resultBuilder public class ContentBuilder<T> {
+@resultBuilder public enum ContentBuilder<T> {
 
+    public typealias Component = [T]
+
+    public typealias Expression = T
+
     /// Builds an empty block
     ///
     /// ```swift
     /// Tag {
     /// }
     /// ```
-    public static func buildBlock() -> [T] {
+    public static func buildBlock() -> Component {
         return []
     }
 
@@ -24,8 +26,8 @@
     ///    }
     /// }
     /// ```
-    public static func buildBlock(_ component: T) -> [T] {
-        return [component]
+    public static func buildPartialBlock(first: Component) -> Component {
+        return first
     }
 
     /// Builds a block with more than one element.
@@ -38,10 +40,40 @@
     ///    }
     /// }
     /// ```
-    public static func buildBlock(_ components: T...) -> [T] {
-        return components.compactMap { $0 }
+    public static func buildPartialBlock(accumulated: Component, next: Component) -> Component {
+        return accumulated + next
+    }
+
+    /// Builds a block
+    ///
+    /// ```swift
+    /// let content = "Content"
+    ///
+    /// Tag {
+    ///    content
+    /// }
+    /// ```
+    public static func buildExpression(_ element: Expression?) -> Component {
+
+        guard let element else {
+            return []
+        }
+        return [element]
     }
 
+    /// Builds a block
+    ///
+    /// ```swift
+    /// let content: [Type]
+    ///
+    /// Tag {
+    ///    content
+    /// }
+    /// ```
+    public static func buildExpression(_ element: Component) -> Component {
+        return element
+    }
+
     /// Builds a block with one element.
     ///
     /// ```swift
@@ -53,13 +85,12 @@
     ///    }
     /// }
     /// ```
-    public static func buildOptional(_ component: T?) -> [T] {
-        
-        if let component = component {
-            return [component]
+    public static func buildOptional(_ component: Component?) -> Component {
+
+        guard let component else {
+            return []
         }
-
-        return []
+        return component
     }
 
     /// Builds a block, if the condition is true.
@@ -72,8 +103,8 @@
     ///    }
     /// }
     /// ```
-    public static func buildEither(first component: T) -> [T] {
-        return [component]
+    public static func buildEither(first: Component) -> Component {
+        return first
     }
 
     /// Builds a block, if the condition is false.
@@ -90,10 +121,10 @@
     ///    }
     /// }
     /// ```
-    public static func buildEither(second component: T) -> [T] {
-        return [component]
+    public static func buildEither(second: Component) -> Component {
+        return second
     }
-    
+
     /// Builds blocks by running through a sequence of elements.
     ///
     /// ```swift
@@ -105,20 +136,7 @@
     ///    }
     /// }
     /// ```
-    public static func buildArray(_ components: [[T]]) -> [T] {
+    public static func buildArray(_ components: [Component]) -> Component {
         return components.flatMap { $0 }
     }
-
-    /// Builds a block with embeded content.
-    ///
-    /// ```swift
-    /// Tag {
-    ///    content
-    ///    Tag {
-    ///    }
-    /// }
-    /// ```
-    public static func buildBlock(_ content: [T], _ components: T...) -> [T] {
-        return content + components.compactMap { $0 }
-    }
 }

Tests/HTMLKitTests/StatementTests.swift

@@ -96,4 +96,71 @@ final class StatementTests: XCTestCase {
                        """
         )
     }
+
+    func testOptionalBeforeElement() throws {
+
+        let name: String? = "Tony"
+
+        let view = TestView {
+            if let name = name {
+                Paragraph {
+                    name
+                }
+            }
+            Division {
+            }
+        }
+
+        XCTAssertEqual(try renderer.render(view: view),
+                       """
+                       <p>Tony</p>\
+                       <div></div>
+                       """
+        )
+    }
+
+    func testOptionalAfterElement() throws {
+
+        let name: String? = "Tony"
+
+        let view = TestView {
+            Division {
+            }
+            if let name = name {
+                Paragraph {
+                    name
+                }
+            }
+        }
+
+        XCTAssertEqual(try renderer.render(view: view),
+                       """
+                       <div></div>\
+                       <p>Tony</p>
+                       """
+        )
+    }
+
+    func testOptionalWithExpectedResult() throws {
+
+        let name: String? = "Tony"
+
+        let view = TestView {
+            Body {
+                if let name = name {
+                    Paragraph {
+                        name
+                    }
+                }
+            }
+        }
+
+        XCTAssertEqual(try renderer.render(view: view),
+                       """
+                       <body>\
+                       <p>Tony</p>\
+                       </body>
+                       """
+        )
+    }
 }