feat(variable): Allow Swift type introspection

CHANGELOG.md

@@ -17,6 +17,9 @@
 
 ### Enhancements
 
+- Variable lookup now supports introspection of Swift types. You can now lookup
+  values of Swift structures and classes inside a Context.
+
 - If tags can now use prefix and infix operators such as `not`, `and` and `or`.
 
     ```html+django

README.md

@@ -11,21 +11,28 @@ feel right at home with Stencil.
 ```html+django
 There are {{ articles.count }} articles.
 
-{% for article in articles %}
-  - {{ article.title }} by {{ article.author }}.
-{% endfor %}
+<ul>
+  {% for article in articles %}
+    <li>{{ article.title }} by {{ article.author }}</li>
+  {% endfor %}
+</ul>
 ```
 
 ```swift
+struct Article {
+  let title: String
+  let author: String
+}
+
 let context = Context(dictionary: [
   "articles": [
-    [ "title": "Migrating from OCUnit to XCTest", "author": "Kyle Fuller" ],
-    [ "title": "Memory Management with ARC", "author": "Kyle Fuller" ],
+    Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
+    Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
   ]
 ])
 
 do {
-  let template = try Template(named: "template.stencil")
+  let template = try Template(named: "template.html")
   let rendered = try template.render(context)
   print(rendered)
 } catch {

Sources/Variable.swift

@@ -87,6 +87,13 @@ public struct Variable : Equatable, Resolvable {
 #else
         current = object.value(forKey: bit)
 #endif
+      } else if let value = current {
+        let mirror = Mirror(reflecting: value)
+        current = mirror.descendant(bit)
+
+        if current == nil {
+          return nil
+        }
       } else {
         return nil
       }

Tests/StencilTests/StencilSpec.swift

@@ -2,16 +2,23 @@ import Spectre
 import Stencil
 
 
-class CustomNode : NodeType {
+fileprivate class CustomNode : NodeType {
   func render(_ context:Context) throws -> String {
     return "Hello World"
   }
 }
 
 
+fileprivate struct Article {
+  let title: String
+  let author: String
+}
+
+
 func testStencil() {
   describe("Stencil") {
     $0.it("can render the README example") {
+
       let templateString = "There are {{ articles.count }} articles.\n" +
         "\n" +
         "{% for article in articles %}" +
@@ -20,8 +27,8 @@ func testStencil() {
 
       let context = Context(dictionary: [
         "articles": [
-          [ "title": "Migrating from OCUnit to XCTest", "author": "Kyle Fuller" ],
-          [ "title": "Memory Management with ARC", "author": "Kyle Fuller" ],
+          Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
+          Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
         ]
       ])
 

Tests/StencilTests/VariableSpec.swift

@@ -9,6 +9,14 @@ import Stencil
 }
 #endif
 
+fileprivate struct Person {
+  let name: String
+}
+
+fileprivate struct Article {
+  let author: Person
+}
+
 
 func testVariable() {
   describe("Variable") {
@@ -18,6 +26,7 @@ func testVariable() {
       "profiles": [
         "github": "kylef",
       ],
+      "article": Article(author: Person(name: "Kyle"))
     ])
 
 #if os(OSX)
@@ -80,6 +89,12 @@ func testVariable() {
       try expect(result) == "Carlton"
     }
 
+    $0.it("can resolve a property with reflection") {
+      let variable = Variable("article.author.name")
+      let result = try variable.resolve(context) as? String
+      try expect(result) == "Kyle"
+    }
+
 #if os(OSX)
     $0.it("can resolve a value via KVO") {
       let variable = Variable("object.title")

docs/index.rst

@@ -17,15 +17,20 @@ feel right at home with Stencil.
 
 .. code-block:: swift
 
+   struct Article {
+     let title: String
+     let author: String
+   }
+
     let context = Context(dictionary: [
       "articles": [
-        [ "title": "Migrating from OCUnit to XCTest", "author": "Kyle Fuller" ],
-        [ "title": "Memory Management with ARC", "author": "Kyle Fuller" ],
+        Article(title: "Migrating from OCUnit to XCTest", author: "Kyle Fuller"),
+        Article(title: "Memory Management with ARC", author: "Kyle Fuller"),
       ]
     ])
 
     do {
-      let template = try Template(named: "template.stencil")
+      let template = try Template(named: "template.html")
       let rendered = try template.render(context)
       print(rendered)
     } catch {

docs/templates.rst

@@ -22,6 +22,7 @@ following lookup:
 - Dictionary lookup
 - Array lookup (first, last, count, index)
 - Key value coding lookup
+- Type introspection
 
 For example, if `people` was an array: