storing full sourcemap in token, refactored error reporting

Sources/Tokenizer.swift

@@ -40,18 +40,34 @@ extension String {
   }
 }
 
+public struct SourceMap: Equatable {
+  public let filename: String?
+  public let line: RangeLine
+  
+  init(filename: String? = nil, line: RangeLine = ("", 0, 0)) {
+    self.filename = filename
+    self.line = line
+  }
+  
+  static let unknown = SourceMap()
+  
+  public static func ==(lhs: SourceMap, rhs: SourceMap) -> Bool {
+    return lhs.filename == rhs.filename && lhs.line == rhs.line
+  }
+}
+
 public enum Token : Equatable {
   /// A token representing a piece of text.
-  case text(value: String, at: Range<String.Index>)
+  case text(value: String, at: SourceMap)
 
   /// A token representing a variable.
-  case variable(value: String, at: Range<String.Index>)
+  case variable(value: String, at: SourceMap)
 
   /// A token representing a comment.
-  case comment(value: String, at: Range<String.Index>)
+  case comment(value: String, at: SourceMap)
 
   /// A token representing a template block.
-  case block(value: String, at: Range<String.Index>)
+  case block(value: String, at: SourceMap)
 
   /// Returns the underlying value as an array seperated by spaces
   public func components() -> [String] {
@@ -74,29 +90,29 @@ public enum Token : Equatable {
     }
   }
   
-  public var range: Range<String.Index> {
+  public var sourceMap: SourceMap {
     switch self {
-    case .block(_, let range),
-         .variable(_, let range),
-         .text(_, let range),
-         .comment(_, let range):
-      return range
+    case .block(_, let sourceMap),
+         .variable(_, let sourceMap),
+         .text(_, let sourceMap),
+         .comment(_, let sourceMap):
+      return sourceMap
     }
   }
-  
+
 }
 
 
 public func == (lhs: Token, rhs: Token) -> Bool {
   switch (lhs, rhs) {
-  case (.text(let lhsValue), .text(let rhsValue)):
-    return lhsValue == rhsValue
-  case (.variable(let lhsValue), .variable(let rhsValue)):
-    return lhsValue == rhsValue
-  case (.block(let lhsValue), .block(let rhsValue)):
-    return lhsValue == rhsValue
-  case (.comment(let lhsValue), .comment(let rhsValue)):
-    return lhsValue == rhsValue
+  case let (.text(lhsValue, lhsAt), .text(rhsValue, rhsAt)):
+    return lhsValue == rhsValue && lhsAt == rhsAt
+  case let (.variable(lhsValue, lhsAt), .variable(rhsValue, rhsAt)):
+    return lhsValue == rhsValue && lhsAt == rhsAt
+  case let (.block(lhsValue, lhsAt), .block(rhsValue, rhsAt)):
+    return lhsValue == rhsValue && lhsAt == rhsAt
+  case let (.comment(lhsValue, lhsAt), .comment(rhsValue, rhsAt)):
+    return lhsValue == rhsValue && lhsAt == rhsAt
   default:
     return false
   }