Add meta.traits module

2 files changed, 581 insertions, 0 deletions

diff --git a/source/tanya/meta/package.d b/source/tanya/meta/package.d
index 9520c4b..5002849 100644
--- a/source/tanya/meta/package.d
+++ b/source/tanya/meta/package.d
@@ -14,4 +14,5 @@
  */
 module tanya.meta;
 
+public import tanya.meta.traits;
 public import tanya.meta.transform;
diff --git a/source/tanya/meta/traits.d b/source/tanya/meta/traits.d
new file mode 100644
index 0000000..6d34e4a
--- /dev/null
+++ b/source/tanya/meta/traits.d
@@ -0,0 +1,580 @@
+/* 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 traits.
+ *
+ * Templates in this module are used to obtain type information at compile
+ * time.
+ *
+ * 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/traits.d,
+ *                 tanya/meta/traits.d)
+ */
+module tanya.meta.traits;
+
+import tanya.meta.transform;
+
+/**
+ * Determines whether $(D_PARAM T) is a floating point type.
+ *
+ * Floating point types are:
+ * $(UL
+ *  $(LI float)
+ *  $(LI double)
+ *  $(LI real)
+ * )
+ *
+ * Params:
+ *  T = A type.
+ */
+enum bool isFloatingPoint(T) = is(Unqual!(OriginalType!T) == double)
+                            || is(Unqual!(OriginalType!T) == float)
+                            || is(Unqual!(OriginalType!T) == real);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isFloatingPoint!float);
+    static assert(isFloatingPoint!double);
+    static assert(isFloatingPoint!real);
+    static assert(isFloatingPoint!(const float));
+    static assert(isFloatingPoint!(shared float));
+    static assert(isFloatingPoint!(shared const float));
+    static assert(!isFloatingPoint!int);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a signed numeric type.
+ *
+ * Signed numeric types are:
+ * $(UL
+ *  $(LI byte)
+ *  $(LI short)
+ *  $(LI int)
+ *  $(LI long)
+ *  $(LI float)
+ *  $(LI double)
+ *  $(LI real)
+ * )
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isUnsigned).
+ */
+enum bool isSigned(T) = is(Unqual!(OriginalType!T) == byte)
+                     || is(Unqual!(OriginalType!T) == short)
+                     || is(Unqual!(OriginalType!T) == int)
+                     || is(Unqual!(OriginalType!T) == long)
+                     || isFloatingPoint!T;
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isSigned!byte);
+    static assert(isSigned!short);
+    static assert(isSigned!int);
+    static assert(isSigned!long);
+    static assert(isSigned!float);
+    static assert(isSigned!double);
+    static assert(isSigned!real);
+
+    static assert(!isSigned!ubyte);
+    static assert(!isSigned!ushort);
+    static assert(!isSigned!uint);
+    static assert(!isSigned!ulong);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is an unsigned numeric type.
+ *
+ * Unsigned numeric types are:
+ * $(UL
+ *  $(LI ubyte)
+ *  $(LI ushort)
+ *  $(LI uint)
+ *  $(LI ulong)
+ * )
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isSigned).
+ */
+enum bool isUnsigned(T) = is(Unqual!(OriginalType!T) == ubyte)
+                       || is(Unqual!(OriginalType!T) == ushort)
+                       || is(Unqual!(OriginalType!T) == uint)
+                       || is(Unqual!(OriginalType!T) == ulong);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isUnsigned!ubyte);
+    static assert(isUnsigned!ushort);
+    static assert(isUnsigned!uint);
+    static assert(isUnsigned!ulong);
+
+    static assert(!isUnsigned!byte);
+    static assert(!isUnsigned!short);
+    static assert(!isUnsigned!int);
+    static assert(!isUnsigned!long);
+    static assert(!isUnsigned!float);
+    static assert(!isUnsigned!double);
+    static assert(!isUnsigned!real);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is an integral type.
+ *
+ * Integral types are:
+ * $(UL
+ *  $(LI ubyte)
+ *  $(LI ushort)
+ *  $(LI uint)
+ *  $(LI ulong)
+ *  $(LI byte)
+ *  $(LI short)
+ *  $(LI int)
+ *  $(LI long)
+ * )
+ *
+ * Params:
+ *  T = A type.
+ */
+enum bool isIntegral(T) = isUnsigned!T
+                       || is(Unqual!(OriginalType!T) == byte)
+                       || is(Unqual!(OriginalType!T) == short)
+                       || is(Unqual!(OriginalType!T) == int)
+                       || is(Unqual!(OriginalType!T) == long);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isIntegral!ubyte);
+    static assert(isIntegral!byte);
+    static assert(!isIntegral!float);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a complex type.
+ *
+ * Complex types are:
+ * $(UL
+ *  $(LI cfloat)
+ *  $(LI ifloat)
+ *  $(LI cdouble)
+ *  $(LI idouble)
+ *  $(LI creal)
+ *  $(LI ireal)
+ * )
+ *
+ * Params:
+ *  T = A type.
+ */
+enum bool isComplex(T) = is(Unqual!(OriginalType!T) == cfloat)
+                      || is(Unqual!(OriginalType!T) == ifloat)
+                      || is(Unqual!(OriginalType!T) == cdouble)
+                      || is(Unqual!(OriginalType!T) == idouble)
+                      || is(Unqual!(OriginalType!T) == creal)
+                      || is(Unqual!(OriginalType!T) == ireal);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isComplex!cfloat);
+    static assert(isComplex!ifloat);
+    static assert(isComplex!cdouble);
+    static assert(isComplex!idouble);
+    static assert(isComplex!creal);
+    static assert(isComplex!ireal);
+
+    static assert(!isComplex!float);
+    static assert(!isComplex!double);
+    static assert(!isComplex!real);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a numeric (floating point, integral or
+ * complex) type.
+*
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isIntegral!T),
+ *           $(D_PSYMBOL isFloatingPoint),
+ *           $(D_PSYMBOL isComplex).
+ */
+enum bool isNumeric(T) = isIntegral!T || isFloatingPoint!T || isComplex!T;
+
+///
+pure nothrow @safe @nogc unittest
+{
+    alias F = float;
+    static assert(isNumeric!F);
+    static assert(!isNumeric!bool);
+    static assert(!isNumeric!char);
+    static assert(!isNumeric!wchar);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a boolean type, i.e. $(D_KEYWORD bool).
+ *
+ * Params:
+ *  T = A type.
+ */
+enum bool isBoolean(T) = is(Unqual!(OriginalType!T) == bool);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isBoolean!bool);
+    static assert(isBoolean!(shared const bool));
+    static assert(!isBoolean!(ubyte));
+    static assert(!isBoolean!(byte));
+
+    enum E : bool
+    {
+        t = true,
+        f = false,
+    }
+    static assert(isBoolean!E);
+
+    struct S1
+    {
+        bool b;
+        alias b this;
+    }
+    static assert(!isBoolean!S1);
+
+    struct S2
+    {
+        bool opCast(T : bool)()
+        {
+            return true;
+        }
+    }
+    static assert(!isBoolean!S2);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a character type.
+ *
+ * Character types are:
+ *
+ * $(UL
+ *  $(LI char)
+ *  $(LI wchar)
+ *  $(LI dchar)
+ * )
+ *
+ * Params:
+ *  T = A type.
+ */
+enum bool isSomeChar(T) = is(Unqual!(OriginalType!T) == char)
+                       || is(Unqual!(OriginalType!T) == wchar)
+                       || is(Unqual!(OriginalType!T) == dchar);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isSomeChar!char);
+    static assert(isSomeChar!wchar);
+    static assert(isSomeChar!dchar);
+
+    static assert(!isSomeChar!byte);
+    static assert(!isSomeChar!ubyte);
+    static assert(!isSomeChar!short);
+    static assert(!isSomeChar!ushort);
+    static assert(!isSomeChar!int);
+    static assert(!isSomeChar!uint);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a scalar type.
+ *
+ * Scalar types are numbers, booleans and characters.
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isNumeric),
+ *           $(D_PSYMBOL isBoolean),
+ *           $(D_PSYMBOL isSomeChar).
+ */
+enum bool isScalarType(T) = isNumeric!T || isBoolean!T || isSomeChar!T;
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isScalarType!int);
+    static assert(!isScalarType!(int[]));
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a basic type.
+ *
+ * Basic types are scalar types and $(D_KEYWORD void).
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isScalarType).
+ */
+enum bool isBasicType(T) = isScalarType!T || is(T : void);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    struct S;
+    class C;
+    enum E : int
+    {
+        i = 0,
+    }
+
+    static assert(isBasicType!void);
+    static assert(isBasicType!(shared void));
+    static assert(isBasicType!E);
+    static assert(!isBasicType!(int*));
+    static assert(!isBasicType!(void function()));
+    static assert(!isBasicType!C);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a pointer type.
+ *
+ * Params:
+ *  T = A type.
+ */
+template isPointer(T)
+{
+    static if (is(T U : U*))
+    {
+        enum bool isPointer = true;
+    }
+    else
+    {
+        enum bool isPointer = false;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isPointer!(bool*));
+    static assert(isPointer!(const bool*));
+    static assert(isPointer!(const shared bool*));
+    static assert(!isPointer!bool);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is an array type (dynamic or static, but
+ * not an associative one).
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isAssociativeArray).
+ */
+template isArray(T)
+{
+    static if (is(T U : U[]))
+    {
+        enum bool isArray = true;
+    }
+    else
+    {
+        enum bool isArray = false;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isArray!(bool[]));
+    static assert(isArray!(const bool[]));
+    static assert(isArray!(shared bool[]));
+    static assert(isArray!(bool[8]));
+    static assert(!isArray!bool);
+    static assert(!isArray!(bool[string]));
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a static array.
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isArray).
+ */
+template isStaticArray(T)
+{
+    static if (is(T U : U[L], size_t L))
+    {
+        enum bool isStaticArray = true;
+    }
+    else
+    {
+        enum bool isStaticArray = false;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isStaticArray!(bool[8]));
+    static assert(isStaticArray!(const bool[8]));
+    static assert(isStaticArray!(shared bool[8]));
+    static assert(!isStaticArray!(bool[]));
+    static assert(!isStaticArray!bool);
+    static assert(!isStaticArray!(bool[string]));
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a dynamic array.
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isArray).
+ */
+enum bool isDynamicArray(T) = isArray!T && !isStaticArray!T;
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isDynamicArray!(bool[]));
+    static assert(isDynamicArray!(const bool[]));
+    static assert(isDynamicArray!(shared bool[]));
+    static assert(!isDynamicArray!(bool[8]));
+    static assert(!isDynamicArray!bool);
+    static assert(!isDynamicArray!(bool[string]));
+}
+
+/**
+ * Determines whether $(D_PARAM T) is an associative array.
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isArray).
+ */
+template isAssociativeArray(T)
+{
+    static if (is(T U : U[L], L))
+    {
+        enum bool isAssociativeArray = true;
+    }
+    else
+    {
+        enum bool isAssociativeArray = false;
+    }
+}
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isAssociativeArray!(bool[string]));
+    static assert(isAssociativeArray!(const bool[string]));
+    static assert(isAssociativeArray!(shared const bool[string]));
+    static assert(!isAssociativeArray!(bool[]));
+    static assert(!isAssociativeArray!(bool[8]));
+    static assert(!isAssociativeArray!bool);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is a built-in type.
+ *
+ * Built-in types are all basic types and arrays.
+ *
+ * Params:
+ *  T = A type.
+ *
+ * See_Also: $(D_PSYMBOL isBasicType!T),
+ *           $(D_PSYMBOL isArray),
+ *           $(D_PSYMBOL isAssociativeArray).
+ */
+enum bool isBuiltinType(T) = isBasicType!T
+                          || isArray!T
+                          || isAssociativeArray!T;
+
+///
+pure nothrow @safe @nogc unittest
+{
+    static assert(isBuiltinType!int);
+    static assert(isBuiltinType!(int[]));
+    static assert(isBuiltinType!(int[int]));
+    static assert(!isBuiltinType!(int*));
+}
+
+/**
+ * Determines whether $(D_PARAM T) is an aggregate type.
+ *
+ * Aggregate types are:
+ *
+ * $(UL
+ *  $(LI $(D_KEYWORD struct)s)
+ *  $(LI $(D_KEYWORD class)es)
+ *  $(LI $(D_KEYWORD interface)s)
+ *  $(LI $(D_KEYWORD union)s)
+ * )
+ *
+ * Params:
+ *  T = A type.
+ */
+enum bool isAggregateType(T) = is(T == struct)
+                            || is(T == class)
+                            || is(T == interface)
+                            || is(T == union);
+
+///
+pure nothrow @safe @nogc unittest
+{
+    struct S;
+    class C;
+    interface I;
+    union U;
+    enum E;
+
+    static assert(isAggregateType!S);
+    static assert(isAggregateType!C);
+    static assert(isAggregateType!I);
+    static assert(isAggregateType!U);
+    static assert(!isAggregateType!E);
+    static assert(!isAggregateType!void);
+}
+
+/**
+ * Determines whether $(D_PARAM T) is some type.
+ *
+ * Params:
+ *  T = Some symbol.
+ */
+enum bool isType(alias T) = is(T);
+
+/// Ditto.
+enum bool isType(T) = true;
+
+///
+pure nothrow @safe @nogc unittest
+{
+    class C;
+    enum E : bool;
+    union U;
+    struct T();
+
+    static assert(isType!C);
+    static assert(isType!E);
+    static assert(isType!U);
+    static assert(isType!void);
+    static assert(isType!int);
+    static assert(!isType!T);
+    static assert(isType!(T!()));
+    static assert(!isType!5);
+    static assert(!isType!(tanya.meta.traits));
+}