Add meta.transform package

Templates in this module applied to a type produce a transformed type.

source/tanya/meta/package.d

@@ -0,0 +1,17 @@
+/* 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/. */
+
+/**
+ * Template metaprogramming.
+ *
+ * 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)
+ * Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/meta/package.d,
+ *                 tanya/meta/package.d)
+ */
+module tanya.meta;
+
+public import tanya.meta.transform;

source/tanya/meta/transform.d

@@ -0,0 +1,112 @@
+/* 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 transformations.
+ *
+ * Templates in this module applied to a type produce a transformed type.
+ *
+ * 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)
+ * Source: $(LINK2 https://github.com/caraus-ecms/tanya/blob/master/source/tanya/meta/transform.d,
+ *                 tanya/meta/transform.d)
+ */
+module tanya.meta.transform;
+
+/**
+ * Removes any type qualifiers from $(D_PARAM T).
+ *
+ * Removed qualifiers are:
+ * $(UL
+ *  $(LI const)
+ *  $(LI immutable)
+ *  $(LI inout)
+ *  $(LI shared)
+ * )
+ * and combinations of these.
+ *
+ * If the type $(D_PARAM T) doesn't have any qualifieres,
+ * $(D_INLINECODE Unqual!T) becomes an alias for $(D_PARAM T).
+ *
+ * Params:
+ *  T = A type.
+ */
+template Unqual(T)
+{
+    static if (is(T U == const U)
+            || is(T U == immutable U)
+            || is(T U == inout U)
+            || is(T U == inout const U)
+            || is(T U == shared U)
+            || is(T U == shared const U)
+            || is(T U == shared inout U)
+            || is(T U == shared inout const U))
+    {
+        alias Unqual = U;
+    }
+    else
+    {
+        alias Unqual = T;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(is(Unqual!bool == bool));
+    static assert(is(Unqual!(immutable bool) == bool));
+    static assert(is(Unqual!(inout bool) == bool));
+    static assert(is(Unqual!(inout const bool) == bool));
+    static assert(is(Unqual!(shared bool) == bool));
+    static assert(is(Unqual!(shared const bool) == bool));
+    static assert(is(Unqual!(shared inout const bool) == bool));
+}
+
+/**
+ * If $(D_PARAM T) is an $(D_KEYWORD enum), $(D_INLINECODE OriginalType!T) evaluates to the
+ * most base type of that $(D_KEYWORD enum) and to $(D_PARAM T) otherwise.
+ *
+ * Params:
+ *  T = A type.
+ */
+template OriginalType(T)
+{
+    static if (is(T U == enum))
+    {
+        alias OriginalType = OriginalType!U;
+    }
+    else
+    {
+        alias OriginalType = T;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    enum E1 : const(int)
+    {
+        n = 0,
+    }
+    enum E2 : bool
+    {
+        t = true,
+    }
+    enum E3 : E2
+    {
+        t = E2.t,
+    }
+    enum E4 : const(E2)
+    {
+        t = E2.t,
+    }
+
+    static assert(is(OriginalType!E1 == const int));
+    static assert(is(OriginalType!E2 == bool));
+    static assert(is(OriginalType!E3 == bool));
+    static assert(is(OriginalType!E4 == bool));
+    static assert(is(OriginalType!(const E4) == bool));
+}