Add typed shorthand markdown commands

Sources/Generator/Generators/MarkdownProcessor.swift

@@ -72,6 +72,7 @@ struct PageContentGenerator {
 
     private func processMarkdownImage(markdown: Substring, html: String, page: Element) -> String {
         // Split the markdown ![alt](file title)
+        // There are several known shorthand commands
         // For images: ![left_title](file right_title)
         // For videos: ![option1,option2,...](file)
         // For svg with custom area: ![x,y,width,height](file.svg)
@@ -80,17 +81,8 @@ struct PageContentGenerator {
         // External pages: ![external](url1, text1; url2, text2, ...)
         let fileAndTitle = markdown.between("(", and: ")")
         let alt = markdown.between("[", and: "]").nonEmpty
-        switch alt {
-        case "download":
-            return handleDownloadButtons(page: page, content: fileAndTitle)
-        case "external":
-            return handleExternalButtons(page: page, content: fileAndTitle)
-        case "html":
-            return handleExternalHTML(page: page, file: fileAndTitle)
-        case "box":
-            return handleSimpleBox(page: page, content: fileAndTitle)
-        default:
-            break
+        if let alt = alt, let command = ShorthandMarkdownKey(rawValue: alt) {
+            return handleShortHandCommand(command, page: page, content: fileAndTitle)
         }
 
         let file = fileAndTitle.dropAfterFirst(" ")
@@ -109,6 +101,19 @@ struct PageContentGenerator {
         return handleFile(page: page, file: file, fileExtension: fileExtension)
     }
 
+    private func handleShortHandCommand(_ command: ShorthandMarkdownKey, page: Element, content: String) -> String {
+        switch command {
+        case .downloadButtons:
+            return handleDownloadButtons(page: page, content: content)
+        case .externalLink:
+            return handleExternalButtons(page: page, content: content)
+        case .includedHtml:
+            return handleExternalHTML(page: page, file: content)
+        case .box:
+            return handleSimpleBox(page: page, content: content)
+        }
+    }
+
     private func handleImage(page: Element, file: String, rightTitle: String?, leftTitle: String?) -> String {
         let imagePath = page.pathRelativeToRootForContainedInputFile(file)
 

Sources/Generator/Generators/ShorthandMarkdownKey.swift

@@ -0,0 +1,24 @@
+import Foundation
+
+enum ShorthandMarkdownKey: String {
+
+    /**
+     A variable number of download buttons for file downloads
+     */
+    case downloadButtons = "download"
+
+    /**
+     A large button to an external page.
+     */
+    case externalLink = "external"
+
+    /**
+     Additional HTML code include verbatim into the page.
+     */
+    case includedHtml = "html"
+
+    /**
+     A box with a heading and a text description
+     */
+    case box = "box"
+}