feat: Allow iterating over tuple, struct and class properties

Closes #173

CHANGELOG.md

@@ -5,6 +5,8 @@
 ### Enhancements
 
 - Added support for resolving superclass properties for not-NSObject subclasses
+- The `{% for %}` tag can now iterate over tuples, structures and classes via
+  their stored properties.
 
 ### Bug Fixes
 

Sources/ForTag.swift

@@ -94,6 +94,22 @@ class ForNode : NodeType {
       values = Array(range)
     } else if let range = resolved as? CountableRange<Int> {
       values = Array(range)
+    } else if let resolved = resolved {
+      let mirror = Mirror(reflecting: resolved)
+      switch mirror.displayStyle {
+      case .struct?, .tuple?:
+        values = Array(mirror.children)
+      case .class?:
+        var children = Array(mirror.children)
+        var currentMirror: Mirror? = mirror
+        while let superclassMirror = currentMirror?.superclassMirror {
+          children.append(contentsOf: superclassMirror.children)
+          currentMirror = superclassMirror
+        }
+        values = Array(children)
+      default:
+        values = []
+      }
     } else {
       values = []
     }

Tests/StencilTests/ForNodeSpec.swift

@@ -176,7 +176,84 @@ func testForNode() {
       let error = TemplateSyntaxError("'for' statements should use the following 'for x in y where condition' `for i`.")
       try expect(try parser.parse()).toThrow(error)
     }
+
+    $0.it("can iterate over struct properties") {
+      struct MyStruct {
+        let string: String
+        let number: Int
+      }
+
+      let context = Context(dictionary: [
+        "struct": MyStruct(string: "abc", number: 123)
+      ])
+
+      let nodes: [NodeType] = [
+        VariableNode(variable: "property"),
+        TextNode(text: "="),
+        VariableNode(variable: "value"),
+        TextNode(text: "\n"),
+      ]
+      let node = ForNode(resolvable: Variable("struct"), loopVariables: ["property", "value"], nodes: nodes, emptyNodes: [])
+      let result = try node.render(context)
+
+      try expect(result) == "string=abc\nnumber=123\n"
+    }
+
+    $0.it("can iterate tuple items") {
+      let context = Context(dictionary: [
+        "tuple": (one: 1, two: "dva"),
+      ])
+
+      let nodes: [NodeType] = [
+        VariableNode(variable: "label"),
+        TextNode(text: "="),
+        VariableNode(variable: "value"),
+        TextNode(text: "\n"),
+      ]
+
+      let node = ForNode(resolvable: Variable("tuple"), loopVariables: ["label", "value"], nodes: nodes, emptyNodes: [])
+      let result = try node.render(context)
+
+      try expect(result) == "one=1\ntwo=dva\n"
+    }
+
+    $0.it("can iterate over class properties") {
+      class MyClass {
+        var baseString: String
+        var baseInt: Int
+        init(_ string: String, _ int: Int) {
+          baseString = string
+          baseInt = int
+        }
+      }
+
+      class MySubclass: MyClass {
+        var childString: String
+        init(_ childString: String, _ string: String, _ int: Int) {
+          self.childString = childString
+          super.init(string, int)
+        }
+      }
+
+      let context = Context(dictionary: [
+        "class": MySubclass("child", "base", 1)
+      ])
+
+      let nodes: [NodeType] = [
+        VariableNode(variable: "label"),
+        TextNode(text: "="),
+        VariableNode(variable: "value"),
+        TextNode(text: "\n"),
+      ]
+
+      let node = ForNode(resolvable: Variable("class"), loopVariables: ["label", "value"], nodes: nodes, emptyNodes: [])
+      let result = try node.render(context)
+
+      try expect(result) == "childString=child\nbaseString=base\nbaseInt=1\n"
+    }
+
   }
+
 }