Add tanya.typecons.Pair

source/tanya/typecons.d

@@ -0,0 +1,41 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * Type constructors.
+ *
+ * Copyright: Eugene Wissner 2017.
+ * License: $(LINK2 https://www.mozilla.org/en-US/MPL/2.0/,
+ *                  Mozilla Public License, v. 2.0).
+ * Authors: $(LINK2 mailto:info@caraus.de, Eugene Wissner)
+ */
+module tanya.typecons;
+
+import std.meta;
+
+/**
+ * $(D_PSYMBOL Pair) can store two heterogeneous objects. The objects can be
+ * accessed than by the index. The objects can by accessed by index as
+ * $(D_INLINECODE obj[0]) and $(D_INLINECODE obj[1]).
+ */
+template Pair(Field1, Field2)
+{
+    /// Field types.
+    alias Types = AliasSeq!(Field1, Field2);
+
+    struct Pair
+    {
+        /// Represents the values of the $(D_PSYMBOL Pair) as a list of values.
+        Types expand;
+
+        alias expand this;
+    }
+}
+
+///
+unittest
+{
+    static assert(is(Pair!(int, int)));
+    static assert(!is(Pair!(int, 5)));
+}