minor code refactoring

Sources/Errors.swift

@@ -44,6 +44,17 @@ public struct TemplateSyntaxError : Error, Equatable, CustomStringConvertible {
 
 }
 
+extension Error {
+  func withToken(_ token: Token?) -> Error {
+    if var error = self as? TemplateSyntaxError {
+      error.token = error.token ?? token
+      return error
+    } else {
+      return TemplateSyntaxError(reason: "\(self)", token: token)
+    }
+  }
+}
+
 public protocol ErrorReporter: class {
   func renderError(_ error: Error) -> String
 }

Sources/ForTag.swift

@@ -24,10 +24,6 @@ class ForNode : NodeType {
     let variable = components[3]
     let filter = try parser.compileFilter(variable, containedIn: token)
 
-    var emptyNodes = [NodeType]()
-
-    let forNodes = try parser.parse(until(["endfor", "empty"]))
-
     let `where`: Expression?
     if components.count >= 6 {
       `where` = try parseExpression(components: Array(components.suffix(from: 5)), tokenParser: parser, token: token)
@@ -35,10 +31,13 @@ class ForNode : NodeType {
       `where` = nil
     }
 
+    let forNodes = try parser.parse(until(["endfor", "empty"]))
+
     guard let token = parser.nextToken() else {
       throw TemplateSyntaxError("`endfor` was not found.")
     }
 
+    var emptyNodes = [NodeType]()
     if token.contents == "empty" {
       emptyNodes = try parser.parse(until(["endfor"]))
       _ = parser.nextToken()
@@ -90,7 +89,7 @@ class ForNode : NodeType {
     var values: [Any]
 
     if let dictionary = resolved as? [String: Any], !dictionary.isEmpty {
-      values = dictionary.map { ($0.key, $0.value) } as [(String, Any)]
+      values = dictionary.map { ($0.key, $0.value) }
     } else if let array = resolved as? [Any] {
       values = array
     } else if let range = resolved as? CountableClosedRange<Int> {

Sources/Inheritence.swift

@@ -4,11 +4,12 @@ class BlockContext {
   // contains mapping of block names to their nodes and templates where they are defined
   var blocks: [String: [BlockNode]]
 
-  init(blocks: [String: [BlockNode]]) {
-    self.blocks = blocks
+  init(blocks: [String: BlockNode]) {
+    self.blocks = [:]
+    blocks.forEach { self.blocks[$0.key] = [$0.value] }
   }
 
-  func pushBlock(_ block: BlockNode, named blockName: String) {
+  func push(_ block: BlockNode, forKey blockName: String) {
     if var blocks = blocks[blockName] {
       blocks.append(block)
       self.blocks[blockName] = blocks
@@ -17,7 +18,7 @@ class BlockContext {
     }
   }
 
-  func popBlock(named blockName: String) -> BlockNode? {
+  func pop(_ blockName: String) -> BlockNode? {
     if var blocks = blocks[blockName] {
       let block = blocks.removeFirst()
       if blocks.isEmpty {
@@ -88,14 +89,12 @@ class ExtendsNode : NodeType {
     let baseTemplate = try context.environment.loadTemplate(name: templateName)
 
     let blockContext: BlockContext
-    if let _blockContext = context[BlockContext.contextKey] as? BlockContext {
-      blockContext = _blockContext
+    if let currentBlockContext = context[BlockContext.contextKey] as? BlockContext {
+      blockContext = currentBlockContext
       for (name, block) in blocks {
-        blockContext.pushBlock(block, named: name)
+        blockContext.push(block, forKey: name)
       }
     } else {
-      var blocks = [String: [BlockNode]]()
-      self.blocks.forEach { blocks[$0.key] = [$0.value] }
       blockContext = BlockContext(blocks: blocks)
     }
 
@@ -144,18 +143,32 @@ class BlockNode : NodeType {
   }
 
   func render(_ context: Context) throws -> String {
-    if let blockContext = context[BlockContext.contextKey] as? BlockContext, let child = blockContext.popBlock(named: name) {
-      // child node is a block node from child template that extends this node (has the same name)
+    if let blockContext = context[BlockContext.contextKey] as? BlockContext, let child = blockContext.pop(name) {
+      let childContext = try self.childContext(child, blockContext: blockContext, context: context)
+      // render extension node
+      do {
+        return try context.push(dictionary: childContext) {
+          return try child.render(context)
+        }
+      } catch {
+        throw error.withToken(child.token)
+      }
+    }
 
-      var newContext: [String: Any] = [BlockContext.contextKey: blockContext]
+    return try renderNodes(nodes, context)
+  }
+
+  // child node is a block node from child template that extends this node (has the same name)
+  func childContext(_ child: BlockNode, blockContext: BlockContext, context: Context) throws -> [String: Any?] {
+    var childContext: [String: Any?] = [BlockContext.contextKey: blockContext]
 
     if let blockSuperNode = child.nodes.first(where: {
       if case .variable(let variable, _)? = $0.token, variable == "block.super" { return true }
       else { return false}
     }) {
       do {
-          // render current (base) node so that its content can be used as part of node that extends it
-          newContext["block"] = ["super": try self.render(context)]
+        // render base node so that its content can be used as part of child node that extends it
+        childContext["block"] = ["super": try self.render(context)]
       } catch {
         if let error = error as? TemplateSyntaxError {
           throw TemplateSyntaxError(
@@ -170,22 +183,7 @@ class BlockNode : NodeType {
         }
       }
     }
-
-      // render extension node
-      do {
-        return try context.push(dictionary: newContext) {
-          return try child.render(context)
-        }
-      } catch {
-        if var error = error as? TemplateSyntaxError {
-          error.token = error.token ?? child.token
-          throw error
-        } else {
-          throw error
-        }
-      }
+    return childContext
   }
 
-    return try renderNodes(nodes, context)
-  }
 }

Sources/Node.swift

@@ -15,12 +15,7 @@ public func renderNodes(_ nodes:[NodeType], _ context:Context) throws -> String
     do {
       return try $0.render(context)
     } catch {
-      if var error = error as? TemplateSyntaxError {
-        error.token = error.token ?? $0.token
-        throw error
-      } else {
-        throw error
-      }
+      throw error.withToken($0.token)
     }
   }).joined(separator: "")
 }

Sources/Parser.swift

@@ -54,12 +54,7 @@ public class TokenParser {
             let node = try parser(self, token)
             nodes.append(node)
           } catch {
-            if var error = error as? TemplateSyntaxError {
-              error.token = error.token ?? token
-              throw error
-            } else {
-              throw error
-            }
+            throw error.withToken(token)
           }
         }
       case .comment: