Add metafunctions

3 files changed, 534 insertions, 28 deletions

diff --git a/source/tanya/meta/metafunction.d b/source/tanya/meta/metafunction.d
new file mode 100644
index 0000000..75c717c
--- /dev/null
+++ b/source/tanya/meta/metafunction.d
@@ -0,0 +1,208 @@
+/* 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/. */
+
+/**
+ * This module contains functions that manipulate template type lists as well
+ * as algorithms to perform arbitrary compile-time computations.
+ *
+ * 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/metafunction.d,
+ *                 tanya/meta/metafunction.d)
+ */
+module tanya.meta.metafunction;
+
+version (unittest)
+{
+    import std.traits;
+}
+
+/**
+ * Creates an alias for $(D_PARAM T).
+ *
+ * In contrast to the $(D_KEYWORD alias)-keyword $(D_PSYMBOL Alias) can alias
+ * any kind of D symbol that can be used as argument to template alias
+ * parameters.
+ *
+ * $(UL
+ *  $(LI Types)
+ *  $(LI Local and global names)
+ *  $(LI Module names)
+ *  $(LI Template names)
+ *  $(LI Template instance names)
+ *  $(LI Literals)
+ * )
+ *
+ * Params:
+ *  T = A symbol.
+ *
+ * Returns: An alias for $(D_PARAM T).
+ *
+ * See_Also: $(LINK2 https://dlang.org/spec/template.html#aliasparameters,
+ *                   Template Alias Parameters).
+ */
+alias Alias(alias T) = T;
+
+/// Ditto.
+alias Alias(T) = T;
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(is(Alias!int));
+
+    static assert(is(typeof(Alias!5)));
+    static assert(is(typeof(Alias!(() {}))));
+
+    int i;
+    static assert(is(typeof(Alias!i)));
+}
+
+/**
+ * Params:
+ *  Args = List of symbols.
+ *
+ * Returns: An alias for sequence $(D_PARAM Args).
+ *
+ * See_Also: $(D_PSYMBOL Alias).
+ */
+alias AliasSeq(Args...) = Args;
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(is(typeof({ alias T = AliasSeq!(short, 5); })));
+    static assert(is(typeof({ alias T = AliasSeq!(int, short, 5); })));
+    static assert(is(typeof({ alias T = AliasSeq!(() {}, short, 5); })));
+    static assert(is(typeof({ alias T = AliasSeq!(); })));
+
+    static assert(AliasSeq!().length == 0);
+    static assert(AliasSeq!(int, short, 5).length == 3);
+}
+
+/**
+ * Tests whether all the items of $(D_PARAM L) satisfy the condition
+ * $(D_PARAM F).
+ *
+ * $(D_PARAM F) is a template that accepts one parameter and returns a boolean,
+ * so $(D_INLINECODE F!([0]) && F!([1])) and so on, can be called.
+ *
+ * Params:
+ *  F = Template predicate. 
+ *  L = List of items to test.
+ *
+ * Returns: $(D_KEYWORD true) if all the items of $(D_PARAM L) satisfy
+ *          $(D_PARAM F), $(D_KEYWORD false) otherwise.
+ */
+template allSatisfy(alias F, L...)
+{
+    static if (L.length == 0)
+    {
+        enum bool allSatisfy = true;
+    }
+    else static if (F!(L[0]))
+    {
+        enum bool allSatisfy = allSatisfy!(F, L[1 .. $]);
+    }
+    else
+    {
+        enum bool allSatisfy = false;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(allSatisfy!(isSigned, int, short, byte, long));
+    static assert(!allSatisfy!(isUnsigned, uint, ushort, float, ulong));
+}
+
+/**
+ * Tests whether any of the items of $(D_PARAM L) satisfy the condition
+ * $(D_PARAM F).
+ *
+ * $(D_PARAM F) is a template that accepts one parameter and returns a boolean,
+ * so $(D_INLINECODE F!([0]) && F!([1])) and so on, can be called.
+ *
+ * Params:
+ *  F = Template predicate. 
+ *  L = List of items to test.
+ *
+ * Returns: $(D_KEYWORD true) if any of the items of $(D_PARAM L) satisfy
+ *          $(D_PARAM F), $(D_KEYWORD false) otherwise.
+ */
+template anySatisfy(alias F, L...)
+{
+    static if (L.length == 0)
+    {
+        enum bool anySatisfy = false;
+    }
+    else static if (F!(L[0]))
+    {
+        enum bool anySatisfy = true;
+    }
+    else
+    {
+        enum bool anySatisfy = anySatisfy!(F, L[1 .. $]);
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(anySatisfy!(isSigned, int, short, byte, long));
+    static assert(anySatisfy!(isUnsigned, uint, ushort, float, ulong));
+    static assert(!anySatisfy!(isSigned, uint, ushort, ulong));
+}
+
+private template indexOf(ptrdiff_t i, Args...)
+if (Args.length > 0)
+{
+    static if (Args.length == 1)
+    {
+        enum ptrdiff_t indexOf = -1;
+    }
+    else static if (is(Args[0] == Args[1])
+                 || (is(typeof(Args[0] == Args[1])) && (Args[0] == Args[1])))
+    {
+        enum ptrdiff_t indexOf = i;
+    }
+    else
+    {
+        enum ptrdiff_t indexOf = indexOf!(i + 1,
+                                          AliasSeq!(Args[0], Args[2 .. $]));
+    }
+}
+
+/**
+ * Returns the index of the first occurrence of $(D_PARAM T) in $(D_PARAM L).
+ * `-1` is returned if $(D_PARAM T) is not found.
+ *
+ * Params:
+ *  T = The type to search for.
+ *  L = Type list.
+ *
+ * Returns: The index of the first occurence of $(D_PARAM T) in $(D_PARAM L).
+ */
+template staticIndexOf(T, L...)
+{
+    enum ptrdiff_t staticIndexOf = indexOf!(0, AliasSeq!(T, L));
+}
+
+/// Ditto.
+template staticIndexOf(alias T, L...)
+{
+    enum ptrdiff_t staticIndexOf = indexOf!(0, AliasSeq!(T, L));
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(staticIndexOf!(int) == -1);
+    static assert(staticIndexOf!(int, int) == 0);
+    static assert(staticIndexOf!(int, float, double, int, real) == 2);
+    static assert(staticIndexOf!(3, () {}, uint, 5, 3) == 3);
+}
diff --git a/source/tanya/meta/package.d b/source/tanya/meta/package.d
index 5002849..4b74287 100644
--- a/source/tanya/meta/package.d
+++ b/source/tanya/meta/package.d
@@ -14,5 +14,6 @@
  */
 module tanya.meta;
 
+public import tanya.meta.metafunction;
 public import tanya.meta.traits;
 public import tanya.meta.transform;
diff --git a/source/tanya/meta/traits.d b/source/tanya/meta/traits.d
index f603ea1..a15b5db 100644
--- a/source/tanya/meta/traits.d
+++ b/source/tanya/meta/traits.d
@@ -17,6 +17,7 @@
  */
 module tanya.meta.traits;
 
+import tanya.meta.metafunction;
 import tanya.meta.transform;
 
 /**
@@ -966,14 +967,13 @@ pure nothrow @safe @nogc unittest
  * Abstract class is a class marked as such or a class that has any abstract
  * methods or doesn't implement all methods of abstract base classes.
  *
- * For all non-classes $(D_INLINECODE isAbstractClass!T) evaluates to
- * $(D_KEYWORD false).
- *
  * Params:
  *  T = A type.
  *
  * Returns: $(D_KEYWORD true) if $(D_PARAM T) is an abstract class,
  *          $(D_KEYWORD false) otherwise.
+ *
+ * See_Also: $(D_PSYMBOL isAbstractFunction).
  */
 enum bool isAbstractClass(T) = __traits(isAbstractClass, T);
 
@@ -1004,20 +1004,18 @@ pure nothrow @safe @nogc unittest
     static assert(isAbstractClass!C);
     static assert(isAbstractClass!D);
     static assert(!isAbstractClass!E);
-    static assert(!isAbstractClass!int);
 }
 
 /**
  * Determines whether $(D_PARAM T) is a final class.
  *
- * For all non-classes $(D_INLINECODE isFinalClass!T) evaluates to
- * $(D_KEYWORD false).
- *
  * Params:
  *  T = A type.
  *
  * Returns: $(D_KEYWORD true) if $(D_PARAM T) is a final class,
  *          $(D_KEYWORD false) otherwise.
+ *
+ * See_Also: $(D_PSYMBOL isFinalFunction).
  */
 enum bool isFinalClass(T) = __traits(isFinalClass, T);
 
@@ -1038,20 +1036,15 @@ pure nothrow @safe @nogc unittest
 /**
  * Determines whether $(D_PARAM T) is an abstract method.
  *
- * For all non-methods $(D_INLINECODE isAbstractFunction!T) evaluates to
- * $(D_KEYWORD false).
- *
  * Params:
  *  F = A symbol.
  *
  * Returns: $(D_KEYWORD true) if $(D_PARAM F) is an abstract method,
  *          $(D_KEYWORD false) otherwise.
+ *
+ * See_Also: $(D_PSYMBOL isAbstractClass).
  */
-template isAbstractFunction(F...)
-if (F.length == 1)
-{
-    enum bool isAbstractFunction = __traits(isAbstractFunction, F[0]);
-}
+enum bool isAbstractFunction(alias F) = __traits(isAbstractFunction, F);
 
 ///
 pure nothrow @safe @nogc unittest
@@ -1075,26 +1068,20 @@ pure nothrow @safe @nogc unittest
     static assert(!isAbstractFunction!(A.func));
     static assert(isAbstractFunction!(B.func));
     static assert(!isAbstractFunction!(C.func));
-    static assert(!isAbstractFunction!int);
 }
 
 /**
  * Determines whether $(D_PARAM T) is a final method.
  *
- * For all non-methods $(D_INLINECODE isFinalFunction!T) evaluates to
- * $(D_KEYWORD false).
- *
  * Params:
  *  F = A symbol.
  *
  * Returns: $(D_KEYWORD true) if $(D_PARAM F) is a final method,
  *          $(D_KEYWORD false) otherwise.
+ *
+ * See_Also: $(D_PSYMBOL isFinalClass).
  */
-template isFinalFunction(F...)
-if (F.length == 1)
-{
-    enum bool isFinalFunction = __traits(isFinalFunction, F[0]);
-}
+enum bool isFinalFunction(alias F) = __traits(isFinalFunction, F);
 
 ///
 pure nothrow @safe @nogc unittest
@@ -1111,7 +1098,6 @@ pure nothrow @safe @nogc unittest
 
     static assert(isFinalFunction!(A.finalFunc));
     static assert(!isFinalFunction!(A.virtualFunc));
-    static assert(!isFinalFunction!int);
 }
 
 /**
@@ -1252,7 +1238,7 @@ template isFunction(F...)
 if (F.length == 1)
 {
     static if (is(F[0] == function)
-            || is(typeof(&F[0]) U == delegate)
+            || is(typeof(&F[0]) T == delegate)
             || (is(typeof(&F[0]) T : T*) && is(T == function)))
     {
         enum bool isFunction = true;
@@ -1348,7 +1334,8 @@ pure nothrow @safe @nogc unittest
 template isCallable(F...)
 if (F.length == 1)
 {
-    static if (isSomeFunction!F || (is(typeof(F[0].opCall) U) && isFunction!U))
+    static if (isSomeFunction!F
+            || (is(typeof(F[0].opCall)) && isFunction!(F[0].opCall)))
     {
         enum bool isCallable = true;
     }
@@ -1384,6 +1371,20 @@ pure nothrow @safe @nogc unittest
     static assert(!isCallable!I);
 }
 
+private pure nothrow @safe @nogc unittest
+{
+    struct S
+    {
+        @property int opCall()
+        {
+            return 0;
+        }
+    }
+    S s;
+    static assert(isCallable!S);
+    static assert(isCallable!s);
+}
+
 /**
  * Params:
  *  T      = Aggregate type.
@@ -1403,8 +1404,304 @@ pure nothrow @safe @nogc unittest
          void member2()
          {
          }
+         static int member3;
+         static void member4()
+         {
+         }
     }
     static assert(hasMember!(S, "member1"));
     static assert(hasMember!(S, "member2"));
-    static assert(!hasMember!(S, "member3"));
+    static assert(hasMember!(S, "member3"));
+    static assert(hasMember!(S, "member4"));
+    static assert(!hasMember!(S, "member6"));
+}
+
+/**
+ * Params:
+ *  T      = Aggregate type.
+ *  member = Symbol name.
+ *
+ * Returns: $(D_KEYWORD true) if $(D_PARAM member) is a static method of
+ *          $(D_PARAM T), $(D_KEYWORD false) otherwise.
+ */
+template hasStaticMember(T, string member)
+{
+    static if (hasMember!(T, member))
+    {
+        alias Member = Alias!(__traits(getMember, T, member));
+
+        static if (__traits(isStaticFunction, Member)
+                || (!isFunction!Member && is(typeof(&Member))))
+        {
+            enum bool hasStaticMember = true;
+        }
+        else
+        {
+            enum bool hasStaticMember = false;
+        }
+    }
+    else
+    {
+        enum bool hasStaticMember = false;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    struct S
+    {
+         int member1;
+         void member2()
+         {
+         }
+         static int member3;
+         static void member4()
+         {
+         }
+         static void function() member5;
+    }
+    static assert(!hasStaticMember!(S, "member1"));
+    static assert(!hasStaticMember!(S, "member2"));
+    static assert(hasStaticMember!(S, "member3"));
+    static assert(hasStaticMember!(S, "member4"));
+    static assert(hasStaticMember!(S, "member5"));
+}
+
+/**
+ * Determines whether $(D_PARAM T) is mutable, i.e. has one of the following
+ * qualifiers or a combination of them:
+ *
+ * $(UL
+ *  $(LI $(D_KEYWORD const))
+ *  $(LI $(D_KEYWORD immutable))
+ *  $(LI $(D_KEYWORD const))
+ * )
+ *
+ * Params:
+ *  T = A type.
+ *
+ * Returns: $(D_KEYWORD true) if $(D_PARAM T) is mutable,
+ *          $(D_KEYWORD false) otherwise.
+ */
+template isMutable(T)
+{
+    static if (is(T U == const U)
+            || is(T U == inout U)
+            || is(T U == inout const U)
+            || is(T U == immutable U)
+            || is(T U == shared const U)
+            || is(T U == shared inout U)
+            || is(T U == shared inout const U))
+    {
+        enum bool isMutable = false;
+    }
+    else
+    {
+        enum bool isMutable = true;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    struct S
+    {
+        void method()
+        {
+            static assert(isMutable!(typeof(this)));
+        }
+
+        void method() inout
+        {
+            static assert(!isMutable!(typeof(this)));
+        }
+
+        void immMethod() const
+        {
+            static assert(!isMutable!(typeof(this)));
+        }
+        void immMethod() immutable
+        {
+            static assert(!isMutable!(typeof(this)));
+        }
+    }
+}
+
+/**
+ * POD (Plain Old Data) is a $(D_KEYWORD struct) without constructors,
+ * destructors and member functions.
+ *
+ * Params:
+ *  T = A type.
+ *
+ * Returns: $(D_KEYWORD true) if $(D_PARAM T) is a POD type,
+ *          $(D_KEYWORD false) otherwise.
+ */
+enum bool isPOD(T) = __traits(isPOD, T);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    struct S1
+    {
+        void method()
+        {
+        }
+    }
+    static assert(!isPOD!S1);
+
+    struct S2
+    {
+        void function() val; // Function pointer, not a member function.
+    }
+    static assert(isPOD!S2);
+
+    struct S3
+    {
+        this(this)
+        {
+        }
+    }
+    static assert(!isPOD!S3);
+}
+
+/**
+ * Params:
+ *  T = $(D_KEYWORD class), $(D_KEYWORD struct) or $(D_KEYWORD union) type.
+ *
+ * Returns: $(D_KEYWORD true) if the argument is a nested type which internally
+ *          stores a context pointer, $(D_KEYWORD false) otherwise.
+ */
+template isNested(T)
+if (is(T == class) || is(T == struct) || is(T == union))
+{
+    enum bool isNested = __traits(isNested, T);
+}
+
+///
+pure nothrow @safe unittest
+{
+    static struct S
+    {
+    }
+    static assert(!isNested!S);
+
+    class C
+    {
+        void method()
+        {
+        }
+    }
+    static assert(isNested!C);
+}
+
+/**
+ * Params:
+ *  T = A function.
+ *
+ * Returns $(D_KEYWORD true) if the $(D_PARAM T) is a nested function,
+ *         $(D_KEYWORD false) otherwise.
+ */
+enum bool isNestedFunction(alias F) = __traits(isNested, F);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    void func()
+    {
+        void nestedFunc()
+        {
+        }
+        static assert(isNestedFunction!nestedFunc);
+    }
+}
+
+/**
+ * Params:
+ *  F = A function.
+ *
+ * Returns: Type of the function $(D_PARAM F).
+ */
+template FunctionTypeOf(F...)
+if (F.length == 1 && isCallable!F)
+{
+    static if ((is(typeof(F[0]) T : T*) && is(T == function))
+            || (is(F[0] T : T*) && is(T == function))
+            || is(F[0] T == delegate)
+            || is(typeof(F[0]) T == delegate)
+            || is(F[0] T == function)
+            || is(typeof(&F[0]) T == delegate)
+            || (is(typeof(&F[0]) T : T*) && is(T == function)))
+    {
+        alias FunctionTypeOf = T;
+    }
+    else
+    {
+        alias FunctionTypeOf = FunctionTypeOf!(F[0].opCall);
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(is(FunctionTypeOf!(void function()) == function));
+    static assert(is(FunctionTypeOf!(() {}) == function));
+}
+
+private pure nothrow @safe @nogc unittest
+{
+    static assert(is(FunctionTypeOf!(void delegate()) == function));
+
+    static void staticFunc()
+    {
+    }
+    auto functionPointer = &staticFunc;
+    static assert(is(FunctionTypeOf!staticFunc == function));
+    static assert(is(FunctionTypeOf!functionPointer == function));
+
+    void func()
+    {
+    }
+    auto dg = &func;
+    static assert(is(FunctionTypeOf!func == function));
+    static assert(is(FunctionTypeOf!dg == function));
+
+    interface I
+    {
+        @property int prop();
+    }
+    static assert(is(FunctionTypeOf!(I.prop) == function));
+
+    struct S
+    {
+        void opCall()
+        {
+        }
+    }
+    class C
+    {
+        static void opCall()
+        {
+        }
+    }
+    S s;
+
+    static assert(is(FunctionTypeOf!s == function));
+    static assert(is(FunctionTypeOf!C == function));
+    static assert(is(FunctionTypeOf!S == function));
+}
+
+private pure nothrow @safe @nogc unittest
+{
+    struct S2
+    {
+        @property int opCall()
+        {
+            return 0;
+        }
+    }
+    S2 s2;
+    static assert(is(FunctionTypeOf!S2 == function));
+    static assert(is(FunctionTypeOf!s2 == function));
 }