TupleStruct refactoring

Author: andrewvk

Jetbrains.Annotations.cs

@@ -399,7 +399,7 @@ internal enum ImplicitUseKindFlags
 		/// </summary>
 		InstantiatedWithFixedConstructorSignature = 4,
 		/// <summary>Indicates implicit instantiation of a type.</summary>
-		InstantiatedNoFixedConstructorSignature = 8,
+		InstantiatedNoFixedConstructorSignature = 8
 	}
 
 	/// <summary>
@@ -904,7 +904,7 @@ internal enum AssertionConditionType
 		/// <summary>Marked parameter should be evaluated to null value.</summary>
 		IS_NULL = 2,
 		/// <summary>Marked parameter should be evaluated to not null value.</summary>
-		IS_NOT_NULL = 3,
+		IS_NOT_NULL = 3
 	}
 
 	/// <summary>

Main/src/Structures/ITuple.cs

@@ -0,0 +1,22 @@
+using JetBrains.Annotations;
+
+namespace CodeJam
+{
+	/// <summary>
+	/// Common interface for all tuples.
+	/// </summary>
+	[PublicAPI]
+	public interface ITuple
+	{
+		/// <summary>
+		/// Tuple rank (count of values).
+		/// </summary>
+		int Rank { get; }
+
+		/// <summary>
+		/// Returns value by it index.
+		/// </summary>
+		/// <param name="index">Index of value, zero based.</param>
+		object this[int index] { get; }
+	}
+}