// Written in the D programming language.

/**
 * Templates with which to extract information about types and symbols at
 * compile time.
 *
 * Macros:
 *  WIKI = Phobos/StdTraits
 *
 * Copyright: Copyright Digital Mars 2005 - 2009.
 * License:   <a href="http://www.boost.org/LICENSE_1_0.txt">Boost License 1.0</a>.
 * Authors:   $(WEB digitalmars.com, Walter Bright),
 *            Tomasz Stachowiak ($(D isExpressionTuple)),
 *            $(WEB erdani.org, Andrei Alexandrescu),
 *            Shin Fujishiro
 * Source:    $(PHOBOSSRC std/_traits.d)
 */
/*          Copyright Digital Mars 2005 - 2009.
 * Distributed under the Boost Software License, Version 1.0.
 *    (See accompanying file LICENSE_1_0.txt or copy at
 *          http://www.boost.org/LICENSE_1_0.txt)
 */
module std.traits;
import std.typetuple;
import core.vararg;

//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://
// Functions
//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://

// Petit demangler
// (this or similar thing will eventually go to std.demangle if necessary
//  ctfe stuffs are available)
private
{
    struct Demangle(T)
    {
        T       value;  // extracted information
        string  rest;
    }

    /* Demangles mstr as the storage class part of Argument. */
    Demangle!uint demangleParameterStorageClass(string mstr)
    {
        uint pstc = 0; // parameter storage class

        // Argument --> Argument2 | M Argument2
        if (mstr.length > 0 && mstr[0] == 'M')
        {
            pstc |= ParameterStorageClass.SCOPE;
            mstr  = mstr[1 .. $];
        }

        // Argument2 --> Type | J Type | K Type | L Type
        ParameterStorageClass stc2;

        switch (mstr.length ? mstr[0] : char.init)
        {
            case 'J': stc2 = ParameterStorageClass.OUT;  break;
            case 'K': stc2 = ParameterStorageClass.REF;  break;
            case 'L': stc2 = ParameterStorageClass.LAZY; break;
            default : break;
        }
        if (stc2 != ParameterStorageClass.init)
        {
            pstc |= stc2;
            mstr  = mstr[1 .. $];
        }

        return Demangle!uint(pstc, mstr);
    }

    /* Demangles mstr as FuncAttrs. */
    Demangle!uint demangleFunctionAttributes(string mstr)
    {
        enum LOOKUP_ATTRIBUTE =
        [
            'a': FunctionAttribute.PURE,
            'b': FunctionAttribute.NOTHROW,
            'c': FunctionAttribute.REF,
            'd': FunctionAttribute.PROPERTY,
            'e': FunctionAttribute.TRUSTED,
            'f': FunctionAttribute.SAFE
        ];
        uint atts = 0;

        // FuncAttrs --> FuncAttr | FuncAttr FuncAttrs
        // FuncAttr  --> empty | Na | Nb | Nc | Nd | Ne | Nf
        while (mstr.length >= 2 && mstr[0] == 'N')
        {
            if (FunctionAttribute att = LOOKUP_ATTRIBUTE[ mstr[1] ])
            {
                atts |= att;
                mstr  = mstr[2 .. $];
            }
            else assert(0);
        }
        return Demangle!uint(atts, mstr);
    }
}

// workaround @@@BUG4333@@@
private template staticLength(tuple...)
{
    enum size_t staticLength = tuple.length;
}


/***
 * Get the type of the return value from a function,
 * a pointer to function, a delegate, a struct
 * with an opCall, a pointer to a struct with an opCall,
 * or a class with an opCall.
 * Example:
 * ---
 * import std.traits;
 * int foo();
 * ReturnType!(foo) x;   // x is declared as int
 * ---
 */
template ReturnType(/+@@@BUG4217@@@+/func...)
    if (/+@@@BUG4333@@@+/staticLength!(func) == 1)
{
    static if (is(FunctionTypeOf!(func) R == return))
        alias R ReturnType;
    else
        static assert(0, "argument has no return type");
}

unittest
{
    struct G
    {
        int opCall (int i) { return 1;}
    }

    alias ReturnType!(G) ShouldBeInt;
    static assert(is(ShouldBeInt == int));

    G g;
    static assert(is(ReturnType!(g) == int));

    G* p;
    alias ReturnType!(p) pg;
    static assert(is(pg == int));

    class C
    {
        int opCall (int i) { return 1;}
    }

    static assert(is(ReturnType!(C) == int));

    C c;
    static assert(is(ReturnType!(c) == int));

    class Test
    {
        int prop() @property { return 0; }
    }
    alias ReturnType!(Test.prop) R_Test_prop;
    static assert(is(R_Test_prop == int));

    alias ReturnType!((int a) { return a; }) R_dglit;
    static assert(is(R_dglit == int));
}

/***
Get, as a tuple, the types of the parameters to a function, a pointer
to function, a delegate, a struct with an $(D opCall), a pointer to a
struct with an $(D opCall), or a class with an $(D opCall).

Example:
---
import std.traits;
int foo(int, long);
void bar(ParameterTypeTuple!(foo));      // declares void bar(int, long);
void abc(ParameterTypeTuple!(foo)[1]);   // declares void abc(long);
---
*/
template ParameterTypeTuple(/+@@@BUG4217@@@+/dg...)
    if (/+@@@BUG4333@@@+/staticLength!(dg) == 1)
{
    static if (is(FunctionTypeOf!(dg) P == function))
        alias P ParameterTypeTuple;
    else
        static assert(0, "argument has no parameters");
}

unittest
{
    int foo(int i, bool b) { return 0; }
    static assert (is(ParameterTypeTuple!(foo) == TypeTuple!(int, bool)));
    static assert (is(ParameterTypeTuple!(typeof(&foo))
        == TypeTuple!(int, bool)));
    struct S { real opCall(real r, int i) { return 0.0; } }
    S s;
    static assert (is(ParameterTypeTuple!(S) == TypeTuple!(real, int)));
    static assert (is(ParameterTypeTuple!(S*) == TypeTuple!(real, int)));
    static assert (is(ParameterTypeTuple!(s) == TypeTuple!(real, int)));

    class Test
    {
        int prop() @property { return 0; }
    }
    alias ParameterTypeTuple!(Test.prop) P_Test_prop;
    static assert(P_Test_prop.length == 0);

    alias ParameterTypeTuple!((int a){}) P_dglit;
    static assert(P_dglit.length == 1);
    static assert(is(P_dglit[0] == int));
}


/**
Returns a tuple consisting of the storage classes of the parameters of a
function $(D func).

Example:
--------------------
alias ParameterStorageClass STC; // shorten the enum name

void func(ref int ctx, out real result, real param)
{
}
alias ParameterStorageClassTuple!(func) pstc;
static assert(pstc.length == 3); // three parameters
static assert(pstc[0] == STC.REF);
static assert(pstc[1] == STC.OUT);
static assert(pstc[2] == STC.NONE);
--------------------
 */
enum ParameterStorageClass : uint
{
    /**
     * These flags can be bitwise OR-ed together to represent complex storage
     * class.
     */
    NONE    = 0,
    SCOPE   = 0b000_1,  /// ditto
    OUT     = 0b001_0,  /// ditto
    REF     = 0b010_0,  /// ditto
    LAZY    = 0b100_0,  /// ditto
}

/// ditto
template ParameterStorageClassTuple(/+@@@BUG4217@@@+/func...)
    if (/+@@@BUG4333@@@+/staticLength!(func) == 1)
{
    static if (is(FunctionTypeOf!(func) F))
        alias ParameterStorageClassTupleImpl!(Unqual!(F)).Result
                ParameterStorageClassTuple;
    else
        static assert(0, "argument has no parameters");
}

private template ParameterStorageClassTupleImpl(Func)
{
    /*
     * TypeFuncion:
     *     CallConvention FuncAttrs Arguments ArgClose Type
     */
    alias ParameterTypeTuple!(Func) Params;

    // chop off CallConvention and FuncAttrs
    enum margs = demangleFunctionAttributes(mangledName!(Func)[1 .. $]).rest;

    // demangle Arguments and store parameter storage classes in a tuple
    template demangleNextParameter(string margs, size_t i = 0)
    {
        static if (i < Params.length)
        {
            enum demang = demangleParameterStorageClass(margs);
            enum skip = mangledName!(Params[i]).length; // for bypassing Type
            enum rest = demang.rest;

            alias TypeTuple!(
                    demang.value + 0, // workaround: "not evaluatable at ..."
                    demangleNextParameter!(rest[skip .. $], i + 1).Result
                ) Result;
        }
        else // went thru all the parameters
        {
            alias TypeTuple!() Result;
        }
    }
    alias demangleNextParameter!(margs).Result Result;
}

unittest
{
    alias ParameterStorageClass STC;

    void noparam() {}
    static assert(ParameterStorageClassTuple!(noparam).length == 0);

    void test(scope int, ref int, out int, lazy int, int) { }
    alias ParameterStorageClassTuple!(test) test_pstc;
    static assert(test_pstc.length == 5);
    static assert(test_pstc[0] == STC.SCOPE);
    static assert(test_pstc[1] == STC.REF);
    static assert(test_pstc[2] == STC.OUT);
    static assert(test_pstc[3] == STC.LAZY);
    static assert(test_pstc[4] == STC.NONE);

    interface Test
    {
        void test_const(int) const;
        void test_sharedconst(int) shared const;
    }
    Test testi;

    alias ParameterStorageClassTuple!(Test.test_const) test_const_pstc;
    static assert(test_const_pstc.length == 1);
    static assert(test_const_pstc[0] == STC.NONE);

    alias ParameterStorageClassTuple!(testi.test_sharedconst) test_sharedconst_pstc;
    static assert(test_sharedconst_pstc.length == 1);
    static assert(test_sharedconst_pstc[0] == STC.NONE);

    alias ParameterStorageClassTuple!((ref int a) {}) dglit_pstc;
    static assert(dglit_pstc.length == 1);
    static assert(dglit_pstc[0] == STC.REF);
}


/**
Returns the attributes attached to a function $(D func).

Example:
--------------------
alias FunctionAttribute FA; // shorten the enum name

real func(real x) pure nothrow @safe
{
    return x;
}
static assert(functionAttributes!(func) & FA.PURE);
static assert(functionAttributes!(func) & FA.SAFE);
static assert(!(functionAttributes!(func) & FA.TRUSTED)); // not @trusted
--------------------
 */
enum FunctionAttribute : uint
{
    /**
     * These flags can be bitwise OR-ed together to represent complex attribute.
     */
    NONE      = 0,
    PURE      = 0b00000001, /// ditto
    NOTHROW   = 0b00000010, /// ditto
    REF       = 0b00000100, /// ditto
    PROPERTY  = 0b00001000, /// ditto
    TRUSTED   = 0b00010000, /// ditto
    SAFE      = 0b00100000, /// ditto
}

/// ditto
template functionAttributes(/+@@@BUG4217@@@+/func...)
    if (/+@@@BUG4333@@@+/staticLength!(func) == 1)
{
    static if (is(FunctionTypeOf!(func) F))
        enum uint functionAttributes = demangleFunctionAttributes(
                mangledName!(Unqual!(F))[1 .. $] ).value;
    else
        static assert(0, "argument is not a function");
}

unittest
{
    alias FunctionAttribute FA;
    interface Set
    {
        int pureF() pure;
        int nothrowF() nothrow;
        ref int refF();
        int propertyF() @property;
        int trustedF() @trusted;
        int safeF() @safe;
    }
    static assert(functionAttributes!(Set.pureF) == FA.PURE);
    static assert(functionAttributes!(Set.nothrowF) == FA.NOTHROW);
    static assert(functionAttributes!(Set.refF) == FA.REF);
    static assert(functionAttributes!(Set.propertyF) == FA.PROPERTY);
    static assert(functionAttributes!(Set.trustedF) == FA.TRUSTED);
    static assert(functionAttributes!(Set.safeF) == FA.SAFE);
    static assert(!(functionAttributes!(Set.safeF) & FA.TRUSTED));

    int pure_nothrow() pure nothrow { return 0; }
    static assert(functionAttributes!(pure_nothrow) == (FA.PURE | FA.NOTHROW));
    //ref int ref_property() @property { return *(new int); } // @@@BUG2509@@@
    //static assert(functionAttributes!(ref_property) == (FA.REF | FA.PROPERTY));
    void safe_nothrow() @safe nothrow { }
    static assert(functionAttributes!(safe_nothrow) == (FA.SAFE | FA.NOTHROW));

    interface Test2
    {
        int pure_const() pure const;
        int pure_sharedconst() pure shared const;
    }
    static assert(functionAttributes!(Test2.pure_const) == FA.PURE);
    static assert(functionAttributes!(Test2.pure_sharedconst) == FA.PURE);

    static assert(functionAttributes!((int a) {}) == FA.NONE);
}


private @safe void dummySafeFunc(alias func)()
{
        alias ParameterTypeTuple!func Params;
        static if (Params.length)
        {
                Params args;
                func(args);
        }
        else
        {
                func();
        }
}



/**
Checks the func that is @safe or @trusted

Example:
--------------------
@system int add(int a, int b) {return a+b;}
@safe int sub(int a, int b) {return a-b;}
@trusted int mul(int a, int b) {return a*b;}

bool a = isSafe!(add);
assert(a == false);
bool b = isSafe!(sub);
assert(b == true);
bool c = isSafe!(mul);
assert(c == true);
--------------------
 */
template isSafe(alias func)
{
    static if (is(typeof(func) == function))
    {
        enum isSafe = (functionAttributes!(func) == FunctionAttribute.SAFE
                    || functionAttributes!(func) == FunctionAttribute.TRUSTED);
    }
    else
    {
        enum isSafe = is(typeof({dummySafeFunc!func();}()));
    }
}


@safe
unittest
{
    interface Set
    {
        int systemF() @system;
        int trustedF() @trusted;
        int safeF() @safe;
    }
    static assert(isSafe!((int a){}));
    static assert(isSafe!(Set.safeF));
    static assert(isSafe!(Set.trustedF));
    static assert(!isSafe!(Set.systemF));
}


/**
Checks the all functions are @safe or @trusted

Example:
--------------------
@system int add(int a, int b) {return a+b;}
@safe int sub(int a, int b) {return a-b;}
@trusted int mul(int a, int b) {return a*b;}

bool a = areAllSafe!(add, sub);
assert(a == false);
bool b = areAllSafe!(sub, mul);
assert(b == true);
--------------------
 */
template areAllSafe(funcs...)
    if (funcs.length > 0)
{
    static if (funcs.length == 1)
    {
        enum areAllSafe = isSafe!(funcs[0]);
    }
    else static if (isSafe!(funcs[0]))
    {
        enum areAllSafe = areAllSafe!(funcs[1..$]);
    }
    else
    {
        enum areAllSafe = false;
    }
}


@safe
unittest
{
    interface Set
    {
        int systemF() @system;
        int trustedF() @trusted;
        int safeF() @safe;
    }
    static assert(areAllSafe!((int a){}, Set.safeF));
    static assert(!areAllSafe!(Set.trustedF, Set.systemF));
}

/**
Checks the func that is @system

Example:
--------------------
@system int add(int a, int b) {return a+b;}
@safe int sub(int a, int b) {return a-b;}
@trusted int mul(int a, int b) {return a*b;}

bool a = isUnsafe!(add);
assert(a == true);
bool b = isUnsafe!(sub);
assert(b == false);
bool c = isUnsafe!(mul);
assert(c == false);
--------------------
 */
template isUnsafe(alias func)
{
    enum isUnsafe = !isSafe!func;
}

@safe
unittest
{
    interface Set
    {
        int systemF() @system;
        int trustedF() @trusted;
        int safeF() @safe;
    }
    static assert(!isUnsafe!((int a){}));
    static assert(!isUnsafe!(Set.safeF));
    static assert(!isUnsafe!(Set.trustedF));
    static assert(isUnsafe!(Set.systemF));
}

/**
Returns the calling convention of function as a string.

Example:
--------------------
string a = functionLinkage!(writeln!(string, int));
assert(a == "D"); // extern(D)

auto fp = &printf;
string b = functionLinkage!(fp);
assert(b == "C"); // extern(C)
--------------------
 */
template functionLinkage(/+@@@BUG4217@@@+/func...)
    if (/+@@@BUG4333@@@+/staticLength!(func) == 1)
{
    static if (is(FunctionTypeOf!(func) F))
        enum string functionLinkage =
            LOOKUP_LINKAGE[ mangledName!(Unqual!(F))[0] ];
    else
        static assert(0, "argument is not a function");
}

private enum LOOKUP_LINKAGE =
[
    'F': "D",
    'U': "C",
    'W': "Windows",
    'V': "Pascal",
    'R': "C++"
];

unittest
{
    extern(D) void Dfunc() {}
    extern(C) void Cfunc() {}
    static assert(functionLinkage!(Dfunc) == "D");
    static assert(functionLinkage!(Cfunc) == "C");

    interface Test
    {
        void const_func() const;
        void sharedconst_func() shared const;
    }
    static assert(functionLinkage!(Test.const_func) == "D");
    static assert(functionLinkage!(Test.sharedconst_func) == "D");

    static assert(functionLinkage!((int a){}) == "D");
}


/**
Determines what kind of variadic parameters function has.

Example:
--------------------
void func() {}
static assert(variadicFunctionStyle!(func) == Variadic.NO);

extern(C) int printf(in char*, ...);
static assert(variadicFunctionStyle!(printf) == Variadic.C);
--------------------
 */
enum Variadic
{
    NO,         /// Function is not variadic.
    C,          /// Function is a _C-style variadic function.
                /// Function is a _D-style variadic function, which uses
    D,          /// __argptr and __arguments.
    TYPESAFE,   /// Function is a typesafe variadic function.
}

/// ditto
template variadicFunctionStyle(/+@@@BUG4217@@@+/func...)
    if (/+@@@BUG4333@@@+/staticLength!(func) == 1)
{
    static if (is(FunctionTypeOf!(func) F))
        enum Variadic variadicFunctionStyle =
            determineVariadicity!(Unqual!(F))();
    else
        static assert(0, "argument is not a function");
}

private Variadic determineVariadicity(Func)()
{
    // TypeFuncion --> CallConvention FuncAttrs Arguments ArgClose Type
    immutable callconv = functionLinkage!(Func);
    immutable mfunc = mangledName!(Func);
    immutable mtype = mangledName!(ReturnType!(Func));
    debug assert(mfunc[$ - mtype.length .. $] == mtype, mfunc ~ "|" ~ mtype);

    immutable argclose = mfunc[$ - mtype.length - 1];
    final switch (argclose)
    {
        case 'X': return Variadic.TYPESAFE;
        case 'Y': return (callconv == "C") ? Variadic.C : Variadic.D;
        case 'Z': return Variadic.NO;
    }
}

unittest
{
    extern(D) void novar() {};
    extern(C) void cstyle(int, ...) {};
    extern(D) void dstyle(...) {};
    extern(D) void typesafe(int[]...) {};

    static assert(variadicFunctionStyle!(novar) == Variadic.NO);
    static assert(variadicFunctionStyle!(cstyle) == Variadic.C);
    static assert(variadicFunctionStyle!(dstyle) == Variadic.D);
    static assert(variadicFunctionStyle!(typesafe) == Variadic.TYPESAFE);

    static assert(variadicFunctionStyle!((int[] a...) {}) == Variadic.TYPESAFE);
}


/**
Get the function type from a callable object $(D func).

Using builtin $(D typeof) on a property function yields the types of the
property value, not of the property function itself.  Still,
$(D FunctionTypeOf) is able to obtain function types of properties.
--------------------
class C {
    int value() @property;
}
static assert(is( typeof(C.value) == int ));
static assert(is( FunctionTypeOf!(C.value) == function ));
--------------------

Note:
Do not confuse function types with function pointer types; function types are
usually used for compile-time reflection purposes.
 */
template FunctionTypeOf(/+@@@BUG4217@@@+/func...)
    if (/+@@@BUG4333@@@+/staticLength!(func) == 1)
{
    alias FunctionTypeOf_bug4333!(func).FunctionTypeOf FunctionTypeOf;
}
private template FunctionTypeOf_bug4333(func...)
{
    /+@@@BUG4333@@@+/enum dummy__ = func.length;

    static if (is(typeof(& func[0]) Fsym : Fsym*) && is(Fsym == function))
    {
        alias Fsym FunctionTypeOf; // HIT: function symbol
    }
    else static if (is(typeof(& func[0].opCall) Fobj == delegate))
    {
        alias Fobj FunctionTypeOf; // HIT: callable object
    }
    else static if (is(typeof(& func[0].opCall) Ftyp : Ftyp*) && is(Ftyp == function))
    {
        alias Ftyp FunctionTypeOf; // HIT: callable type
    }
    else static if (is(func[0] T) || is(typeof(func[0]) T))
    {
        static if (is(T == function))
            alias T    FunctionTypeOf; // HIT: function
        else static if (is(T Fptr : Fptr*) && is(Fptr == function))
            alias Fptr FunctionTypeOf; // HIT: function pointer
        else static if (is(T Fdlg == delegate))
            alias Fdlg FunctionTypeOf; // HIT: delegate
    }
    else static assert(0, "argument is not a callable object");
}

unittest
{
    int test(int a) { return 0; }
    int function(int) test_fp;
    int delegate(int) test_dg;
    static assert(is( typeof(test) == FunctionTypeOf!(typeof(test)) ));
    static assert(is( typeof(test) == FunctionTypeOf!(test) ));
    static assert(is( typeof(test) == FunctionTypeOf!(test_fp) ));
    static assert(is( typeof(test) == FunctionTypeOf!(test_dg) ));

    interface Prop { int prop() @property; }
    Prop prop;
    static assert(is( FunctionTypeOf!(Prop.prop) == function ));
    static assert(is( FunctionTypeOf!(prop.prop) == function ));

    class Callable { int opCall(int) { return 0; } }
    auto call = new Callable;
    static assert(is( FunctionTypeOf!(call) == typeof(test) ));

    struct StaticCallable { static int opCall(int) { return 0; } }
    StaticCallable stcall_val;
    StaticCallable* stcall_ptr;
    static assert(is( FunctionTypeOf!(stcall_val) == typeof(test) ));
    static assert(is( FunctionTypeOf!(stcall_ptr) == typeof(test) ));

    interface Overloads {
        void test(string);
        real test(real);
        int  test();
        int  test() @property;
    }
    alias TypeTuple!(__traits(getVirtualFunctions, Overloads, "test")) ov;
    alias FunctionTypeOf!(ov[0]) F_ov0;
    alias FunctionTypeOf!(ov[1]) F_ov1;
    alias FunctionTypeOf!(ov[2]) F_ov2;
    alias FunctionTypeOf!(ov[3]) F_ov3;
    static assert(is(F_ov0* == void function(string)));
    static assert(is(F_ov1* == real function(real)));
    static assert(is(F_ov2* == int function()));
    static assert(is(F_ov3* == int function() @property));

    alias FunctionTypeOf!((int a){ return a; }) F_dglit;
    static assert(is(F_dglit* == int function(int)));
}


//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://
// Aggregate Types
//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://

/***
 * Get the types of the fields of a struct or class.
 * This consists of the fields that take up memory space,
 * excluding the hidden fields like the virtual function
 * table pointer.
 */

template FieldTypeTuple(S)
{
    static if (is(S == struct) || is(S == class) || is(S == union))
        alias typeof(S.tupleof) FieldTypeTuple;
    else
        alias TypeTuple!(S) FieldTypeTuple;
        //static assert(0, "argument is not struct or class");
}

// // FieldOffsetsTuple
// private template FieldOffsetsTupleImpl(size_t n, T...)
// {
//     static if (T.length == 0)
//     {
//         alias TypeTuple!() Result;
//     }
//     else
//     {
//         //private alias FieldTypeTuple!(T[0]) Types;
//         private enum size_t myOffset =
//             ((n + T[0].alignof - 1) / T[0].alignof) * T[0].alignof;
//         static if (is(T[0] == struct))
//         {
//             alias FieldTypeTuple!(T[0]) MyRep;
//             alias FieldOffsetsTupleImpl!(myOffset, MyRep, T[1 .. $]).Result
//                 Result;
//         }
//         else
//         {
//             private enum size_t mySize = T[0].sizeof;
//             alias TypeTuple!(myOffset) Head;
//             static if (is(T == union))
//             {
//                 alias FieldOffsetsTupleImpl!(myOffset, T[1 .. $]).Result
//                     Tail;
//             }
//             else
//             {
//                 alias FieldOffsetsTupleImpl!(myOffset + mySize,
//                                              T[1 .. $]).Result
//                     Tail;
//             }
//             alias TypeTuple!(Head, Tail) Result;
//         }
//     }
// }

// template FieldOffsetsTuple(T...)
// {
//     alias FieldOffsetsTupleImpl!(0, T).Result FieldOffsetsTuple;
// }

// unittest
// {
//     alias FieldOffsetsTuple!(int) T1;
//     assert(T1.length == 1 && T1[0] == 0);
//     //
//     struct S2 { char a; int b; char c; double d; char e, f; }
//     alias FieldOffsetsTuple!(S2) T2;
//     //pragma(msg, T2);
//     static assert(T2.length == 6
//            && T2[0] == 0 && T2[1] == 4 && T2[2] == 8 && T2[3] == 16
//                   && T2[4] == 24&& T2[5] == 25);
//     //
//     class C { int a, b, c, d; }
//     struct S3 { char a; C b; char c; }
//     alias FieldOffsetsTuple!(S3) T3;
//     //pragma(msg, T2);
//     static assert(T3.length == 3
//            && T3[0] == 0 && T3[1] == 4 && T3[2] == 8);
//     //
//     struct S4 { char a; union { int b; char c; } int d; }
//     alias FieldOffsetsTuple!(S4) T4;
//     //pragma(msg, FieldTypeTuple!(S4));
//     static assert(T4.length == 4
//            && T4[0] == 0 && T4[1] == 4 && T4[2] == 8);
// }

// /***
// Get the offsets of the fields of a struct or class.
// */

// template FieldOffsetsTuple(S)
// {
//     static if (is(S == struct) || is(S == class))
//         alias typeof(S.tupleof) FieldTypeTuple;
//     else
//         static assert(0, "argument is not struct or class");
// }

/***
Get the primitive types of the fields of a struct or class, in
topological order.

Example:
----
struct S1 { int a; float b; }
struct S2 { char[] a; union { S1 b; S1 * c; } }
alias RepresentationTypeTuple!(S2) R;
assert(R.length == 4
    && is(R[0] == char[]) && is(R[1] == int)
    && is(R[2] == float) && is(R[3] == S1*));
----
*/

template RepresentationTypeTuple(T)
{
    static if (is(T == struct) || is(T == union) || is(T == class))
    {
        alias RepresentationTypeTupleImpl!(FieldTypeTuple!T)
            RepresentationTypeTuple;
    }
    else static if (is(T U == typedef))
    {
        alias RepresentationTypeTuple!U RepresentationTypeTuple;
    }
    else
    {
        alias RepresentationTypeTupleImpl!T
            RepresentationTypeTuple;
    }
}

private template RepresentationTypeTupleImpl(T...)
{
    static if (T.length == 0)
    {
        alias TypeTuple!() RepresentationTypeTupleImpl;
    }
    else
    {
        static if (is(T[0] == struct) || is(T[0] == union))
// @@@BUG@@@ this should work
//             alias .RepresentationTypes!(T[0].tupleof)
//                 RepresentationTypes;
            alias .RepresentationTypeTupleImpl!(FieldTypeTuple!(T[0]),
                                            T[1 .. $])
                RepresentationTypeTupleImpl;
        else static if (is(T[0] U == typedef))
        {
            alias .RepresentationTypeTupleImpl!(FieldTypeTuple!(U),
                                            T[1 .. $])
                RepresentationTypeTupleImpl;
        }
        else
        {
            alias TypeTuple!(T[0], RepresentationTypeTupleImpl!(T[1 .. $]))
                RepresentationTypeTupleImpl;
        }
    }
}

unittest
{
    alias RepresentationTypeTuple!(int) S1;
    static assert(is(S1 == TypeTuple!(int)));
    struct S2 { int a; }
    static assert(is(RepresentationTypeTuple!(S2) == TypeTuple!(int)));
    struct S3 { int a; char b; }
    static assert(is(RepresentationTypeTuple!(S3) == TypeTuple!(int, char)));
    struct S4 { S1 a; int b; S3 c; }
    static assert(is(RepresentationTypeTuple!(S4) ==
                     TypeTuple!(int, int, int, char)));

    struct S11 { int a; float b; }
    struct S21 { char[] a; union { S11 b; S11 * c; } }
    alias RepresentationTypeTuple!(S21) R;
    assert(R.length == 4
           && is(R[0] == char[]) && is(R[1] == int)
           && is(R[2] == float) && is(R[3] == S11*));

    class C { int a; float b; }
    alias RepresentationTypeTuple!C R1;
    static assert(R1.length == 2 && is(R1[0] == int) && is(R1[1] == float));
}

/*
RepresentationOffsets
*/

// private template Repeat(size_t n, T...)
// {
//     static if (n == 0) alias TypeTuple!() Repeat;
//     else alias TypeTuple!(T, Repeat!(n - 1, T)) Repeat;
// }

// template RepresentationOffsetsImpl(size_t n, T...)
// {
//     static if (T.length == 0)
//     {
//         alias TypeTuple!() Result;
//     }
//     else
//     {
//         private enum size_t myOffset =
//             ((n + T[0].alignof - 1) / T[0].alignof) * T[0].alignof;
//         static if (!is(T[0] == union))
//         {
//             alias Repeat!(n, FieldTypeTuple!(T[0])).Result
//                 Head;
//         }
//         static if (is(T[0] == struct))
//         {
//             alias .RepresentationOffsetsImpl!(n, FieldTypeTuple!(T[0])).Result
//                 Head;
//         }
//         else
//         {
//             alias TypeTuple!(myOffset) Head;
//         }
//         alias TypeTuple!(Head,
//                          RepresentationOffsetsImpl!(
//                              myOffset + T[0].sizeof, T[1 .. $]).Result)
//             Result;
//     }
// }

// template RepresentationOffsets(T)
// {
//     alias RepresentationOffsetsImpl!(0, T).Result
//         RepresentationOffsets;
// }

// unittest
// {
//     struct S1 { char c; int i; }
//     alias RepresentationOffsets!(S1) Offsets;
//     static assert(Offsets[0] == 0);
//     //pragma(msg, Offsets[1]);
//     static assert(Offsets[1] == 4);
// }

// hasRawAliasing

private template hasRawPointerImpl(T...)
{
    static if (T.length == 0)
    {
        enum result = false;
    }
    else
    {
        static if (is(T[0] foo : U*, U) && !isFunctionPointer!(T[0]))
            enum hasRawAliasing = !is(U == immutable);
        else static if (is(T[0] foo : U[], U) && !isStaticArray!(T[0]))
            enum hasRawAliasing = !is(U == immutable);
        else static if (isAssociativeArray!(T[0]))
            enum hasRawAliasing = !is(T[0] == immutable);
        else
            enum hasRawAliasing = false;
        enum result = hasRawAliasing || hasRawPointerImpl!(T[1 .. $]).result;
    }
}

private template HasRawLocalPointerImpl(T...)
{
    static if (T.length == 0)
    {
        enum result = false;
    }
    else
    {
        static if (is(T[0] foo : U*, U) && !isFunctionPointer!(T[0]))
            enum hasRawLocalAliasing = !is(U == immutable) && !is(U == shared);
        else static if (is(T[0] foo : U[], U) && !isStaticArray!(T[0]))
            enum hasRawLocalAliasing = !is(U == immutable) && !is(U == shared);
        else static if (isAssociativeArray!(T[0]))
            enum hasRawLocalAliasing = !is(T[0] == immutable) && !is(T[0] == shared);
        else
            enum hasRawLocalAliasing = false;
        enum result = hasRawLocalAliasing || HasRawLocalPointerImpl!(T[1 .. $]).result;
    }
}

/*
Statically evaluates to $(D true) if and only if $(D T)'s
representation contains at least one field of pointer or array type.
Members of class types are not considered raw pointers. Pointers to
immutable objects are not considered raw aliasing.

Example:
---
// simple types
static assert(!hasRawAliasing!(int));
static assert(hasRawAliasing!(char*));
// references aren't raw pointers
static assert(!hasRawAliasing!(Object));
// built-in arrays do contain raw pointers
static assert(hasRawAliasing!(int[]));
// aggregate of simple types
struct S1 { int a; double b; }
static assert(!hasRawAliasing!(S1));
// indirect aggregation
struct S2 { S1 a; double b; }
static assert(!hasRawAliasing!(S2));
// struct with a pointer member
struct S3 { int a; double * b; }
static assert(hasRawAliasing!(S3));
// struct with an indirect pointer member
struct S4 { S3 a; double b; }
static assert(hasRawAliasing!(S4));
----
*/
private template hasRawAliasing(T...)
{
    enum hasRawAliasing
        = hasRawPointerImpl!(RepresentationTypeTuple!T).result;
}

unittest
{
// simple types
    static assert(!hasRawAliasing!(int));
    static assert(hasRawAliasing!(char*));
// references aren't raw pointers
    static assert(!hasRawAliasing!(Object));
    static assert(!hasRawAliasing!(int));
    struct S1 { int z; }
    static assert(!hasRawAliasing!(S1));
    struct S2 { int* z; }
    static assert(hasRawAliasing!(S2));
    struct S3 { int a; int* z; int c; }
    static assert(hasRawAliasing!(S3));
    struct S4 { int a; int z; int c; }
    static assert(!hasRawAliasing!(S4));
    struct S5 { int a; Object z; int c; }
    static assert(!hasRawAliasing!(S5));
    union S6 { int a; int b; }
    static assert(!hasRawAliasing!(S6));
    union S7 { int a; int * b; }
    static assert(hasRawAliasing!(S7));
    typedef int* S8;
    static assert(hasRawAliasing!(S8));
    enum S9 { a };
    static assert(!hasRawAliasing!(S9));
    // indirect members
    struct S10 { S7 a; int b; }
    static assert(hasRawAliasing!(S10));
    struct S11 { S6 a; int b; }
    static assert(!hasRawAliasing!(S11));
    static assert(hasRawAliasing!(int[string]));
    static assert(!hasRawAliasing!(immutable(int[string])));
}

/*
Statically evaluates to $(D true) if and only if $(D T)'s
representation contains at least one non-shared field of pointer or
array type.  Members of class types are not considered raw pointers.
Pointers to immutable objects are not considered raw aliasing.

Example:
---
// simple types
static assert(!hasRawLocalAliasing!(int));
static assert(hasRawLocalAliasing!(char*));
static assert(!hasRawLocalAliasing!(shared char*));
// references aren't raw pointers
static assert(!hasRawLocalAliasing!(Object));
// built-in arrays do contain raw pointers
static assert(hasRawLocalAliasing!(int[]));
static assert(!hasRawLocalAliasing!(shared int[]));
// aggregate of simple types
struct S1 { int a; double b; }
static assert(!hasRawLocalAliasing!(S1));
// indirect aggregation
struct S2 { S1 a; double b; }
static assert(!hasRawLocalAliasing!(S2));
// struct with a pointer member
struct S3 { int a; double * b; }
static assert(hasRawLocalAliasing!(S3));
struct S4 { int a; shared double * b; }
static assert(hasRawLocalAliasing!(S4));
// struct with an indirect pointer member
struct S5 { S3 a; double b; }
static assert(hasRawLocalAliasing!(S5));
struct S6 { S4 a; double b; }
static assert(!hasRawLocalAliasing!(S6));
----
*/

private template hasRawUnsharedAliasing(T...)
{
    enum hasRawUnsharedAliasing
        = HasRawLocalPointerImpl!(RepresentationTypeTuple!(T)).result;
}

unittest
{
// simple types
    static assert(!hasRawUnsharedAliasing!(int));
    static assert(hasRawUnsharedAliasing!(char*));
    static assert(!hasRawUnsharedAliasing!(shared char*));
// references aren't raw pointers
    static assert(!hasRawUnsharedAliasing!(Object));
    static assert(!hasRawUnsharedAliasing!(int));
    struct S1 { int z; }
    static assert(!hasRawUnsharedAliasing!(S1));
    struct S2 { int* z; }
    static assert(hasRawUnsharedAliasing!(S2));
    struct S3 { shared int* z; }
    static assert(!hasRawUnsharedAliasing!(S3));
    struct S4 { int a; int* z; int c; }
    static assert(hasRawUnsharedAliasing!(S4));
    struct S5 { int a; shared int* z; int c; }
    static assert(!hasRawUnsharedAliasing!(S5));
    struct S6 { int a; int z; int c; }
    static assert(!hasRawUnsharedAliasing!(S6));
    struct S7 { int a; Object z; int c; }
    static assert(!hasRawUnsharedAliasing!(S7));
    union S8 { int a; int b; }
    static assert(!hasRawUnsharedAliasing!(S8));
    union S9 { int a; int * b; }
    static assert(hasRawUnsharedAliasing!(S9));
    union S10 { int a; shared int * b; }
    static assert(!hasRawUnsharedAliasing!(S10));
    typedef int* S11;
    static assert(hasRawUnsharedAliasing!(S11));
    typedef shared int* S12;
    static assert(hasRawUnsharedAliasing!(S12));
    enum S13 { a };
    static assert(!hasRawUnsharedAliasing!(S13));
    // indirect members
    struct S14 { S9 a; int b; }
    static assert(hasRawUnsharedAliasing!(S14));
    struct S15 { S10 a; int b; }
    static assert(!hasRawUnsharedAliasing!(S15));
    struct S16 { S6 a; int b; }
    static assert(!hasRawUnsharedAliasing!(S16));
    static assert(hasRawUnsharedAliasing!(int[string]));
    static assert(!hasRawUnsharedAliasing!(shared(int[string])));
    static assert(!hasRawUnsharedAliasing!(immutable(int[string])));
}

/*
Statically evaluates to $(D true) if and only if $(D T)'s
representation includes at least one non-immutable object reference.
*/

private template hasObjects(T...)
{
    static if (T.length == 0)
    {
        enum hasObjects = false;
    }
    else static if (is(T[0] U == typedef))
    {
        enum hasObjects = hasObjects!(U, T[1 .. $]);
    }
    else static if (is(T[0] == struct))
    {
        enum hasObjects = hasObjects!(
            RepresentationTypeTuple!(T[0]), T[1 .. $]);
    }
    else
    {
        enum hasObjects = ((is(T[0] == class) || is(T[0] == interface))
            && !is(T[0] == immutable)) || hasObjects!(T[1 .. $]);
    }
}

/*
Statically evaluates to $(D true) if and only if $(D T)'s
representation includes at least one non-immutable non-shared object
reference.
*/

private template hasUnsharedObjects(T...)
{
    static if (T.length == 0)
    {
        enum hasUnsharedObjects = false;
    }
    else static if (is(T[0] U == typedef))
    {
        enum hasUnsharedObjects = hasUnsharedObjects!(U, T[1 .. $]);
    }
    else static if (is(T[0] == struct))
    {
        enum hasUnsharedObjects = hasUnsharedObjects!(
            RepresentationTypeTuple!(T[0]), T[1 .. $]);
    }
    else
    {
        enum hasUnsharedObjects = ((is(T[0] == class) || is(T[0] == interface)) &&
                                !is(T[0] == immutable) && !is(T[0] == shared)) ||
            hasUnsharedObjects!(T[1 .. $]);
    }
}

/**
Returns $(D true) if and only if $(D T)'s representation includes at
least one of the following: $(OL $(LI a raw pointer $(D U*) and $(D U)
is not immutable;) $(LI an array $(D U[]) and $(D U) is not
immutable;) $(LI a reference to a class or interface type $(D C) and $(D C) is
not immutable.) $(LI an associative array that is not immutable.)
$(LI a delegate.))
*/

template hasAliasing(T...)
{
    enum hasAliasing = hasRawAliasing!(T) || hasObjects!(T) ||
        anySatisfy!(isDelegate, T);
}

unittest
{
    struct S1 { int a; Object b; }
    static assert(hasAliasing!(S1));
    struct S2 { string a; }
    static assert(!hasAliasing!(S2));
    struct S3 { int a; immutable Object b; }
    static assert(!hasAliasing!(S3));
    struct X { float[3] vals; }
    static assert(!hasAliasing!X);
    static assert(hasAliasing!(uint[uint]));
    static assert(!hasAliasing!(immutable(uint[uint])));
    static assert(hasAliasing!(void delegate()));
    static assert(!hasAliasing!(void function()));

    interface I;
    static assert(hasAliasing!I);
}

/**
Returns $(D true) if and only if $(D T)'s representation includes at
least one of the following: $(OL $(LI a raw pointer $(D U*);) $(LI an
array $(D U[]);) $(LI a reference to a class type $(D C).)
$(LI an associative array.) $(LI a delegate.))
 */

template hasIndirections(T)
{
    enum hasIndirections = hasIndirectionsImpl!(RepresentationTypeTuple!T);
}

template hasIndirectionsImpl(T...)
{
    static if (!T.length)
    {
        enum hasIndirectionsImpl = false;
    }
    else static if(isFunctionPointer!(T[0]))
    {
        enum hasIndirectionsImpl = hasIndirectionsImpl!(T[1 .. $]);
    }
    else
    {
        enum hasIndirectionsImpl = isPointer!(T[0]) || isDynamicArray!(T[0]) ||
            is (T[0] : const(Object)) || isAssociativeArray!(T[0]) ||
            isDelegate!(T[0]) || is(T[0] == interface)
            || hasIndirectionsImpl!(T[1 .. $]);
    }
}

unittest
{
    struct S1 { int a; Object b; }
    static assert(hasIndirections!(S1));
    struct S2 { string a; }
    static assert(hasIndirections!(S2));
    struct S3 { int a; immutable Object b; }
    static assert(hasIndirections!(S3));
    static assert(hasIndirections!(int[string]));
    static assert(hasIndirections!(void delegate()));

    interface I;
    static assert(hasIndirections!I);
    static assert(!hasIndirections!(void function()));
}

// These are for backwards compatibility, are intentionally lacking ddoc,
// and should eventually be deprecated.
alias hasUnsharedAliasing hasLocalAliasing;
alias hasRawUnsharedAliasing hasRawLocalAliasing;
alias hasUnsharedObjects hasLocalObjects;

/**
Returns $(D true) if and only if $(D T)'s representation includes at
least one of the following: $(OL $(LI a raw pointer $(D U*) and $(D U)
is not immutable or shared;) $(LI an array $(D U[]) and $(D U) is not
immutable or shared;) $(LI a reference to a class type $(D C) and
$(D C) is not immutable or shared.) $(LI an associative array that is not
immutable or shared.) $(LI a delegate that is not shared.))
*/

template hasUnsharedAliasing(T...)
{
    enum hasUnsharedAliasing = hasRawUnsharedAliasing!(T) ||
        anySatisfy!(unsharedDelegate, T) || hasUnsharedObjects!(T);
}

private template unsharedDelegate(T)
{
    enum bool unsharedDelegate = isDelegate!T && !is(T == shared);
}

unittest
{
    struct S1 { int a; Object b; }
    static assert(hasUnsharedAliasing!(S1));
    struct S2 { string a; }
    static assert(!hasUnsharedAliasing!(S2));
    struct S3 { int a; immutable Object b; }
    static assert(!hasUnsharedAliasing!(S3));

    struct S4 { int a; shared Object b; }
    static assert(!hasUnsharedAliasing!(S4));
    struct S5 { char[] a; }
    static assert(hasUnsharedAliasing!(S5));
    struct S6 { shared char[] b; }
    static assert(!hasUnsharedAliasing!(S6));
    struct S7 { float[3] vals; }
    static assert(!hasUnsharedAliasing!(S7));

    static assert(hasUnsharedAliasing!(uint[uint]));
    static assert(hasUnsharedAliasing!(void delegate()));
    static assert(!hasUnsharedAliasing!(shared(void delegate())));
    static assert(!hasUnsharedAliasing!(void function()));

    interface I {}
    static assert(hasUnsharedAliasing!I);
}

/**
 True if $(D S) or any type embedded directly in the representation of $(D S)
 defines an elaborate copy constructor. Elaborate copy constructors are
 introduced by defining $(D this(this)) for a $(D struct). (Non-struct types
 never have elaborate copy constructors.)
 */
template hasElaborateCopyConstructor(S)
{
    static if(!is(S == struct))
    {
        enum bool hasElaborateCopyConstructor = false;
    }
    else
    {
        enum hasElaborateCopyConstructor = is(typeof({
            S s;
            return &s.__postblit;
        })) || anySatisfy!(.hasElaborateCopyConstructor, typeof(S.tupleof));
    }
}

unittest
{
    static assert(!hasElaborateCopyConstructor!int);
    struct S
    {
        this(this) {}
    }
    static assert(hasElaborateCopyConstructor!S);

    struct S2
    {
        uint num;
    }

    struct S3
    {
        uint num;
        S s;
    }

    static assert(!hasElaborateCopyConstructor!S2);
    static assert(hasElaborateCopyConstructor!S3);
}

/**
   True if $(D S) or any type directly embedded in the representation of $(D S)
   defines an elaborate assignmentq. Elaborate assignments are introduced by
   defining $(D opAssign(typeof(this))) or $(D opAssign(ref typeof(this)))
   for a $(D struct). (Non-struct types never have elaborate assignments.)
 */
template hasElaborateAssign(S)
{
    static if(!is(S == struct))
    {
        enum bool hasElaborateAssign = false;
    }
    else
    {
        enum hasElaborateAssign = is(typeof(S.init.opAssign(S.init))) ||
            anySatisfy!(.hasElaborateAssign, typeof(S.tupleof));
    }
}

unittest
{
    static assert(!hasElaborateAssign!int);
    struct S { void opAssign(S) {} }
    static assert(hasElaborateAssign!S);
    struct S1 { void opAssign(ref S1) {} }
    static assert(hasElaborateAssign!S1);
    struct S2 { void opAssign(S1) {} }
    static assert(!hasElaborateAssign!S2);
    struct S3 { S s; }
    static assert(hasElaborateAssign!S3);
}

/**
   True if $(D S) or any type directly embedded in the representation
   of $(D S) defines an elaborate destructor. Elaborate destructors
   are introduced by defining $(D ~this()) for a $(D
   struct). (Non-struct types never have elaborate destructors, even
   though classes may define $(D ~this()).)
 */
template hasElaborateDestructor(S)
{
    static if(!is(S == struct))
    {
        enum bool hasElaborateDestructor = false;
    }
    else
    {
        enum hasElaborateDestructor = is(typeof({S s; return &s.__dtor;}))
            || anySatisfy!(.hasElaborateDestructor, typeof(S.tupleof));
    }
}

unittest
{
    static assert(!hasElaborateDestructor!int);
    static struct S1 { }
    static assert(!hasElaborateDestructor!S1);
    static struct S2 { ~this() {} }
    static assert(hasElaborateDestructor!S2);
    static struct S3 { S2 field; }
    static assert(hasElaborateDestructor!S3);
}

/**
   Yields $(D true) if and only if $(D T) is a $(D struct) or a $(D
   class) that defines a symbol called $(D name).
 */
template hasMember(T, string name)
{
    static if (is(T == struct) || is(T == class))
    {
        enum bool hasMember =
            staticIndexOf!(name, __traits(allMembers, T)) != -1;
    }
    else
    {
        enum bool hasMember = false;
    }
}

unittest
{
    //pragma(msg, __traits(allMembers, void delegate()));
    static assert(!hasMember!(int, "blah"));
    struct S1 { int blah; }
    static assert(hasMember!(S1, "blah"));
    struct S2 { int blah(); }
    static assert(hasMember!(S2, "blah"));
    struct C1 { int blah; }
    static assert(hasMember!(C1, "blah"));
    struct C2 { int blah(); }
    static assert(hasMember!(C2, "blah"));
}


/**
Retrieves the members of an enumerated type $(D enum E).

Params:
 E = An enumerated type. $(D E) may have duplicated values.

Returns:
 Static tuple composed of the members of the enumerated type $(D E).
 The members are arranged in the same order as declared in $(D E).

Note:
 Returned values are strictly typed with $(D E). Thus, the following code
 does not work without the explicit cast:
--------------------
enum E : int { a, b, c }
int[] abc = cast(int[]) [ EnumMembers!E ];
--------------------
 Cast is not necessary if the type of the variable is inferred. See the
 example below.

Examples:
 Creating an array of enumerated values:
--------------------
enum Sqrts : real
{
    one   = 1,
    two   = 1.41421,
    three = 1.73205,
}
auto sqrts = [ EnumMembers!Sqrts ];
assert(sqrts == [ Sqrts.one, Sqrts.two, Sqrts.three ]);
--------------------

 A generic function $(D rank(v)) in the following example uses this
 template for finding a member $(D e) in an enumerated type $(D E).
--------------------
// Returns i if e is the i-th enumerator of E.
size_t rank(E)(E e)
    if (is(E == enum))
{
    foreach (i, member; EnumMembers!E)
    {
        if (e == member)
            return i;
    }
    assert(0, "Not an enum member");
}

enum Mode
{
    read  = 1,
    write = 2,
    map   = 4,
}
assert(rank(Mode.read ) == 0);
assert(rank(Mode.write) == 1);
assert(rank(Mode.map  ) == 2);
--------------------
 */
template EnumMembers(E)
    if (is(E == enum))
{
    alias EnumSpecificMembers!(E, __traits(allMembers, E)) EnumMembers;
}

private template EnumSpecificMembers(Enum, names...)
{
    static if (names.length > 0)
    {
        alias TypeTuple!(
                WithIdentifier!(names[0])
                    .Symbolize!(__traits(getMember, Enum, names[0])),
                EnumSpecificMembers!(Enum, names[1 .. $])
            ) EnumSpecificMembers;
    }
    else
    {
        alias TypeTuple!() EnumSpecificMembers;
    }
}

unittest
{
    enum A { a }
    static assert([ EnumMembers!A ] == [ A.a ]);
    enum B { a, b, c, d, e }
    static assert([ EnumMembers!B ] == [ B.a, B.b, B.c, B.d, B.e ]);
}

unittest    // typed enums
{
    enum A : string { a = "alpha", b = "beta" }
    static assert([ EnumMembers!A ] == [ A.a, A.b ]);

    static struct S
    {
        int value;
        int opCmp(S rhs) const nothrow { return value - rhs.value; }
    }
    enum B : S { a = S(1), b = S(2), c = S(3) }
    static assert([ EnumMembers!B ] == [ B.a, B.b, B.c ]);
}

unittest    // duplicated values
{
    enum A
    {
        a = 0, b = 0,
        c = 1, d = 1, e
    }
    static assert([ EnumMembers!A ] == [ A.a, A.b, A.c, A.d, A.e ]);
}

// Supply the specified identifier to an constant value.
//
// The identifier of each enum member will be exposed via this template
// once the BUG4732 is fixed.
//
//   enum E { member }
//   assert(__traits(identifier, EnumMembers!E[0]) == "member");
//
private template WithIdentifier(string ident)
{
    static if (ident == "Symbolize")
    {
        template Symbolize(alias value)
        {
            enum Symbolize = value;
        }
    }
    else
    {
        mixin("template Symbolize(alias "~ ident ~")"
             ~"{"
                 ~"alias "~ ident ~" Symbolize;"
             ~"}");
    }
}


//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://
// Classes and Interfaces
//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://

/***
 * Get a $(D_PARAM TypeTuple) of the base class and base interfaces of
 * this class or interface. $(D_PARAM BaseTypeTuple!(Object)) returns
 * the empty type tuple.
 *
 * Example:
 * ---
 * import std.traits, std.typetuple, std.stdio;
 * interface I { }
 * class A { }
 * class B : A, I { }
 *
 * void main()
 * {
 *     alias BaseTypeTuple!(B) TL;
 *     writeln(typeid(TL));        // prints: (A,I)
 * }
 * ---
 */

template BaseTypeTuple(A)
{
    static if (is(A P == super))
        alias P BaseTypeTuple;
    else
            static assert(0, "argument is not a class or interface");
}

unittest
{
    interface I1 { }
    interface I2 { }
    interface I12 : I1, I2 { }
    static assert(is(BaseTypeTuple!I12 == TypeTuple!(I1, I2)));
    interface I3 : I1 { }
    interface I123 : I1, I2, I3 { }
    static assert(is(BaseTypeTuple!I123 == TypeTuple!(I1, I2, I3)));
}

unittest
{
    interface I1 { }
    interface I2 { }
    class A { }
    class C : A, I1, I2 { }

    alias BaseTypeTuple!(C) TL;
    assert(TL.length == 3);
    assert(is (TL[0] == A));
    assert(is (TL[1] == I1));
    assert(is (TL[2] == I2));

    assert(BaseTypeTuple!(Object).length == 0);
}

/**
 * Get a $(D_PARAM TypeTuple) of $(I all) base classes of this class,
 * in decreasing order. Interfaces are not included. $(D_PARAM
 * BaseClassesTuple!(Object)) yields the empty type tuple.
 *
 * Example:
 * ---
 * import std.traits, std.typetuple, std.stdio;
 * interface I { }
 * class A { }
 * class B : A, I { }
 * class C : B { }
 *
 * void main()
 * {
 *     alias BaseClassesTuple!(C) TL;
 *     writeln(typeid(TL));        // prints: (B,A,Object)
 * }
 * ---
 */

template BaseClassesTuple(T)
{
    static if (is(T == Object))
    {
        alias TypeTuple!() BaseClassesTuple;
    }
    static if (is(BaseTypeTuple!(T)[0] == Object))
    {
        alias TypeTuple!(Object) BaseClassesTuple;
    }
    else
    {
        alias TypeTuple!(BaseTypeTuple!(T)[0],
                         BaseClassesTuple!(BaseTypeTuple!(T)[0]))
            BaseClassesTuple;
    }
}

/**
 * Get a $(D_PARAM TypeTuple) of $(I all) interfaces directly or
 * indirectly inherited by this class or interface. Interfaces do not
 * repeat if multiply implemented. $(D_PARAM InterfacesTuple!(Object))
 * yields the empty type tuple.
 *
 * Example:
 * ---
 * import std.traits, std.typetuple, std.stdio;
 * interface I1 { }
 * interface I2 { }
 * class A : I1, I2 { }
 * class B : A, I1 { }
 * class C : B { }
 *
 * void main()
 * {
 *     alias InterfacesTuple!(C) TL;
 *     writeln(typeid(TL));        // prints: (I1, I2)
 * }
 * ---
 */

template InterfacesTuple(T)
{
    static if (is(T S == super) && S.length)
        alias NoDuplicates!(InterfacesTuple_Flatten!(S))
            InterfacesTuple;
    else
        alias TypeTuple!() InterfacesTuple;
}

// internal
private template InterfacesTuple_Flatten(H, T...)
{
    static if (T.length)
    {
        alias TypeTuple!(
                InterfacesTuple_Flatten!(H),
                InterfacesTuple_Flatten!(T))
            InterfacesTuple_Flatten;
    }
    else
    {
        static if (is(H == interface))
            alias TypeTuple!(H, InterfacesTuple!(H))
                InterfacesTuple_Flatten;
        else
            alias InterfacesTuple!(H) InterfacesTuple_Flatten;
    }
}

unittest
{
    struct Test1_WorkaroundForBug2986 {
        // doc example
        interface I1 {}
        interface I2 {}
        class A : I1, I2 { }
        class B : A, I1 { }
        class C : B { }
        alias InterfacesTuple!(C) TL;
        static assert(is(TL[0] == I1) && is(TL[1] == I2));
     }
    struct Test2_WorkaroundForBug2986 {
        interface Iaa {}
        interface Iab {}
        interface Iba {}
        interface Ibb {}
        interface Ia : Iaa, Iab {}
        interface Ib : Iba, Ibb {}
        interface I : Ia, Ib {}
        interface J {}
        class B : J {}
        class C : B, Ia, Ib {}
        static assert(is(InterfacesTuple!(I) ==
                        TypeTuple!(Ia, Iaa, Iab, Ib, Iba, Ibb)));
        static assert(is(InterfacesTuple!(C) ==
                        TypeTuple!(J, Ia, Iaa, Iab, Ib, Iba, Ibb)));
    }
}

/**
 * Get a $(D_PARAM TypeTuple) of $(I all) base classes of $(D_PARAM
 * T), in decreasing order, followed by $(D_PARAM T)'s
 * interfaces. $(D_PARAM TransitiveBaseTypeTuple!(Object)) yields the
 * empty type tuple.
 *
 * Example:
 * ---
 * import std.traits, std.typetuple, std.stdio;
 * interface I { }
 * class A { }
 * class B : A, I { }
 * class C : B { }
 *
 * void main()
 * {
 *     alias TransitiveBaseTypeTuple!(C) TL;
 *     writeln(typeid(TL));        // prints: (B,A,Object,I)
 * }
 * ---
 */

template TransitiveBaseTypeTuple(T)
{
    static if (is(T == Object))
        alias TypeTuple!() TransitiveBaseTypeTuple;
    else
        alias TypeTuple!(BaseClassesTuple!(T),
            InterfacesTuple!(T))
            TransitiveBaseTypeTuple;
}

unittest
{
    interface J1 {}
    interface J2 {}
    class B1 {}
    class B2 : B1, J1, J2 {}
    class B3 : B2, J1 {}
    alias TransitiveBaseTypeTuple!(B3) TL;
    assert(TL.length == 5);
    assert(is (TL[0] == B2));
    assert(is (TL[1] == B1));
    assert(is (TL[2] == Object));
    assert(is (TL[3] == J1));
    assert(is (TL[4] == J2));

    assert(TransitiveBaseTypeTuple!(Object).length == 0);
}


/**
Returns a tuple of non-static functions with the name $(D name) declared in the
class or interface $(D C).  Covariant duplicates are shrunk into the most
derived one.

Example:
--------------------
interface I { I foo(); }
class B
{
    real foo(real v) { return v; }
}
class C : B, I
{
    override C foo() { return this; } // covariant overriding of I.foo()
}
alias MemberFunctionsTuple!(C, "foo") foos;
static assert(foos.length == 2);
static assert(__traits(isSame, foos[0], C.foo));
static assert(__traits(isSame, foos[1], B.foo));
--------------------
 */
template MemberFunctionsTuple(C, string name)
    if (is(C == class) || is(C == interface))
{
    static if (__traits(hasMember, C, name))
        alias MemberFunctionTupleImpl!(C, name).result MemberFunctionsTuple;
    else
        alias TypeTuple!() MemberFunctionsTuple;
}

private template MemberFunctionTupleImpl(C, string name)
{
    /*
     * First, collect all overloads in the class hierarchy.
     */
    template CollectOverloads(Node)
    {
        static if (__traits(hasMember, Node, name))
        {
            // Get all overloads in sight (not hidden).
            alias TypeTuple!(__traits(getVirtualFunctions, Node, name)) inSight;

            // And collect all overloads in ancestor classes to reveal hidden
            // methods.  The result may contain duplicates.
            template walkThru(Parents...)
            {
                static if (Parents.length > 0)
                    alias TypeTuple!(
                                CollectOverloads!(Parents[0]).result,
                                walkThru!(Parents[1 .. $])
                            ) walkThru;
                else
                    alias TypeTuple!() walkThru;
            }

            static if (is(Node Parents == super))
                alias TypeTuple!(inSight, walkThru!(Parents)) result;
            else
                alias TypeTuple!(inSight) result;
        }
        else
            alias TypeTuple!() result; // no overloads in this hierarchy
    }

    // duplicates in this tuple will be removed by shrink()
    alias CollectOverloads!(C).result overloads;

    /*
     * Now shrink covariant overloads into one.
     */
    template shrink(overloads...)
    {
        static if (overloads.length > 0)
        {
            alias shrinkOne!(overloads).result temp;
            alias TypeTuple!(temp[0], shrink!(temp[1 .. $]).result) result;
        }
        else
            alias TypeTuple!() result; // done
    }

    // .result[0]    = the most derived one in the covariant siblings of target
    // .result[1..$] = non-covariant others
    template shrinkOne(/+ alias target, rest... +/ args...)
    {
        alias args[0 .. 1] target; // prevent property functions from being evaluated
        alias args[1 .. $] rest;

        static if (rest.length > 0)
        {
            alias FunctionTypeOf!(target) Target;
            alias FunctionTypeOf!(rest[0]) Rest0;

            static if (isCovariantWith!(Target, Rest0))
                // target overrides rest[0] -- erase rest[0].
                alias shrinkOne!(target, rest[1 .. $]).result result;
            else static if (isCovariantWith!(Rest0, Target))
                // rest[0] overrides target -- erase target.
                alias shrinkOne!(rest[0], rest[1 .. $]).result result;
            else
                // target and rest[0] are distinct.
                alias TypeTuple!(
                            shrinkOne!(target, rest[1 .. $]).result,
                            rest[0] // keep
                        ) result;
        }
        else
            alias TypeTuple!(target) result; // done
    }

    // done.
    alias shrink!(overloads).result result;
}

unittest
{
    interface I     { I test(); }
    interface J : I { J test(); }
    interface K     { K test(int); }
    class B : I, K
    {
        K test(int) { return this; }
        B test() { return this; }
        static void test(string) { }
    }
    class C : B, J
    {
        override C test() { return this; }
    }
    alias MemberFunctionsTuple!(C, "test") test;
    static assert(test.length == 2);
    static assert(is(FunctionTypeOf!(test[0]) == FunctionTypeOf!(C.test)));
    static assert(is(FunctionTypeOf!(test[1]) == FunctionTypeOf!(B.test)));
    alias MemberFunctionsTuple!(C, "noexist") noexist;
    static assert(noexist.length == 0);

    interface L { int prop() @property; }
    alias MemberFunctionsTuple!(L, "prop") prop;
    static assert(prop.length == 1);

    interface Test_I
    {
        void foo();
        void foo(int);
        void foo(int, int);
    }
    interface Test : Test_I {}
    alias MemberFunctionsTuple!(Test, "foo") Test_foo;
    static assert(Test_foo.length == 3);
    static assert(is(typeof(&Test_foo[0]) == void function()));
    static assert(is(typeof(&Test_foo[2]) == void function(int)));
    static assert(is(typeof(&Test_foo[1]) == void function(int, int)));
}


//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://
// Type Conversion
//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://

/**
Get the type that all types can be implicitly converted to. Useful
e.g. in figuring out an array type from a bunch of initializing
values. Returns $(D_PARAM void) if passed an empty list, or if the
types have no common type.

Example:

----
alias CommonType!(int, long, short) X;
assert(is(X == long));
alias CommonType!(int, char[], short) Y;
assert(is(Y == void));
----
*/
template CommonType(T...)
{
    static if (!T.length)
        alias void CommonType;
    else static if (T.length == 1)
    {
        static if(is(typeof(T[0])))
        {
            alias typeof(T[0]) CommonType;
        }
        else
        {
            alias T[0] CommonType;
        }
    }
    else static if (is(typeof(true ? T[0].init : T[1].init) U))
        alias CommonType!(U, T[2 .. $]) CommonType;
    else
        alias void CommonType;
}

unittest
{
    alias CommonType!(int, long, short) X;
    static assert(is(X == long));
    alias CommonType!(char[], int, long, short) Y;
    static assert(is(Y == void), Y.stringof);
    static assert(is(CommonType!(3) == int));
    static assert(is(CommonType!(double, 4, float) == double));
    static assert(is(CommonType!(string, char[]) == const(char)[]));
    static assert(is(CommonType!(3, 3U) == uint));
}


/**
 * Returns a tuple with all possible target types of an implicit
 * conversion of a value of type $(D_PARAM T).
 *
 * Important note:
 *
 * The possible targets are computed more conservatively than the D
 * 2.005 compiler does, eliminating all dangerous conversions. For
 * example, $(D_PARAM ImplicitConversionTargets!(double)) does not
 * include $(D_PARAM float).
 */

template ImplicitConversionTargets(T)
{
    static if (is(T == bool))
        alias TypeTuple!(byte, ubyte, short, ushort, int, uint, long, ulong,
            float, double, real, char, wchar, dchar)
            ImplicitConversionTargets;
    else static if (is(T == byte))
        alias TypeTuple!(short, ushort, int, uint, long, ulong,
            float, double, real, char, wchar, dchar)
            ImplicitConversionTargets;
    else static if (is(T == ubyte))
        alias TypeTuple!(short, ushort, int, uint, long, ulong,
            float, double, real, char, wchar, dchar)
            ImplicitConversionTargets;
    else static if (is(T == short))
        alias TypeTuple!(ushort, int, uint, long, ulong,
            float, double, real)
            ImplicitConversionTargets;
    else static if (is(T == ushort))
        alias TypeTuple!(int, uint, long, ulong, float, double, real)
            ImplicitConversionTargets;
    else static if (is(T == int))
        alias TypeTuple!(long, ulong, float, double, real)
            ImplicitConversionTargets;
    else static if (is(T == uint))
        alias TypeTuple!(long, ulong, float, double, real)
            ImplicitConversionTargets;
    else static if (is(T == long))
        alias TypeTuple!(float, double, real)
            ImplicitConversionTargets;
    else static if (is(T == ulong))
        alias TypeTuple!(float, double, real)
            ImplicitConversionTargets;
    else static if (is(T == float))
        alias TypeTuple!(double, real)
            ImplicitConversionTargets;
    else static if (is(T == double))
        alias TypeTuple!(real)
            ImplicitConversionTargets;
    else static if (is(T == char))
        alias TypeTuple!(wchar, dchar, byte, ubyte, short, ushort,
            int, uint, long, ulong, float, double, real)
            ImplicitConversionTargets;
    else static if (is(T == wchar))
        alias TypeTuple!(wchar, dchar, short, ushort, int, uint, long, ulong,
            float, double, real)
            ImplicitConversionTargets;
    else static if (is(T == dchar))
        alias TypeTuple!(wchar, dchar, int, uint, long, ulong,
            float, double, real)
            ImplicitConversionTargets;
    else static if(is(T : Object))
        alias TransitiveBaseTypeTuple!(T) ImplicitConversionTargets;
    // @@@BUG@@@ this should work
    // else static if (isDynamicArray!T && !is(typeof(T.init[0]) == const))
    //     alias TypeTuple!(const(typeof(T.init[0]))[]) ImplicitConversionTargets;
    else static if (is(T == char[]))
        alias TypeTuple!(const(char)[]) ImplicitConversionTargets;
    else static if (isDynamicArray!T && !is(typeof(T.init[0]) == const))
        alias TypeTuple!(const(typeof(T.init[0]))[]) ImplicitConversionTargets;
    else static if (is(T : void*))
        alias TypeTuple!(void*) ImplicitConversionTargets;
    else
        alias TypeTuple!() ImplicitConversionTargets;
}

unittest
{
    assert(is(ImplicitConversionTargets!(double)[0] == real));
}

/**
Is $(D From) implicitly convertible to $(D To)?
 */

template isImplicitlyConvertible(From, To)
{
    enum bool isImplicitlyConvertible = is(typeof({
                        void fun(To) {}
                        From f;
                        fun(f);
                    }()));
}

unittest
{
    static assert(isImplicitlyConvertible!(immutable(char), char));
    static assert(isImplicitlyConvertible!(const(char), char));
    static assert(isImplicitlyConvertible!(char, wchar));
    static assert(!isImplicitlyConvertible!(wchar, char));
}

/**
Returns $(D true) iff a value of type $(D Rhs) can be assigned to a variable of
type $(D Lhs).

Examples:
---
static assert(isAssignable!(long, int));
static assert(!isAssignable!(int, long));
static assert(isAssignable!(const(char)[], string));
static assert(!isAssignable!(string, char[]));
---
*/
template isAssignable(Lhs, Rhs) {
    enum bool isAssignable = is(typeof({
        Lhs l;
        Rhs r;
        l = r;
        return l;
    }));
}

unittest {
    static assert(isAssignable!(long, int));
    static assert(!isAssignable!(int, long));
    static assert(isAssignable!(const(char)[], string));
    static assert(!isAssignable!(string, char[]));
}


/*
Works like $(D isImplicitlyConvertible), except this cares only about storage
classes of the arguments.
 */
private template isStorageClassImplicitlyConvertible(From, To)
{
    enum isStorageClassImplicitlyConvertible = isImplicitlyConvertible!(
            ModifyTypePreservingSTC!(Pointify, From),
            ModifyTypePreservingSTC!(Pointify,   To) );
}
private template Pointify(T) { alias void* Pointify; }

unittest
{
    static assert(isStorageClassImplicitlyConvertible!(          int, const int));
    static assert(isStorageClassImplicitlyConvertible!(immutable int, const int));
    static assert(! isStorageClassImplicitlyConvertible!(const int,           int));
    static assert(! isStorageClassImplicitlyConvertible!(const int, immutable int));
    static assert(! isStorageClassImplicitlyConvertible!(int, shared int));
    static assert(! isStorageClassImplicitlyConvertible!(shared int, int));
}


/**
Determines whether the function type $(D F) is covariant with $(D G), i.e.,
functions of the type $(D F) can override ones of the type $(D G).

Example:
--------------------
interface I { I clone(); }
interface J { J clone(); }
class C : I
{
    override C clone()   // covariant overriding of I.clone()
    {
        return new C;
    }
}

// C.clone() can override I.clone(), indeed.
static assert(isCovariantWith!(typeof(C.clone), typeof(I.clone)));

// C.clone() can't override J.clone(); the return type C is not implicitly
// convertible to J.
static assert(isCovariantWith!(typeof(C.clone), typeof(J.clone)));
--------------------
 */
template isCovariantWith(F, G)
    if (is(F == function) && is(G == function))
{
    static if (is(F : G))
        enum isCovariantWith = true;
    else
        enum isCovariantWith = isCovariantWithImpl!(F, G).yes;
}

private template isCovariantWithImpl(Upr, Lwr)
{
    /*
     * Check for calling convention: require exact match.
     */
    template checkLinkage()
    {
        enum ok = functionLinkage!(Upr) == functionLinkage!(Lwr);
    }
    /*
     * Check for variadic parameter: require exact match.
     */
    template checkVariadicity()
    {
        enum ok = variadicFunctionStyle!(Upr) == variadicFunctionStyle!(Lwr);
    }
    /*
     * Check for function storage class:
     *  - overrider can have narrower storage class than base
     */
    template checkSTC()
    {
        // Note the order of arguments.  The convertion order Lwr -> Upr is
        // correct since Upr should be semantically 'narrower' than Lwr.
        enum ok = isStorageClassImplicitlyConvertible!(Lwr, Upr);
    }
    /*
     * Check for function attributes:
     *  - require exact match for ref and @property
     *  - overrider can add pure and nothrow, but can't remove them
     *  - @safe and @trusted are covariant with each other, unremovable
     */
    template checkAttributes()
    {
        alias FunctionAttribute FA;
        enum uprAtts = functionAttributes!(Upr);
        enum lwrAtts = functionAttributes!(Lwr);
        //
        enum WANT_EXACT = FA.REF | FA.PROPERTY;
        enum SAFETY = FA.SAFE | FA.TRUSTED;
        enum ok =
            (  (uprAtts & WANT_EXACT) ==   (lwrAtts & WANT_EXACT)) &&
            (  (uprAtts & FA.PURE   ) >=   (lwrAtts & FA.PURE   )) &&
            (  (uprAtts & FA.NOTHROW) >=   (lwrAtts & FA.NOTHROW)) &&
            (!!(uprAtts & SAFETY    ) >= !!(lwrAtts & SAFETY    )) ;
    }
    /*
     * Check for return type: usual implicit convertion.
     */
    template checkReturnType()
    {
        enum ok = is(ReturnType!(Upr) : ReturnType!(Lwr));
    }
    /*
     * Check for parameters:
     *  - require exact match for types (cf. bugzilla 3075)
     *  - require exact match for in, out, ref and lazy
     *  - overrider can add scope, but can't remove
     */
    template checkParameters()
    {
        alias ParameterStorageClass STC;
        alias ParameterTypeTuple!(Upr) UprParams;
        alias ParameterTypeTuple!(Lwr) LwrParams;
        alias ParameterStorageClassTuple!(Upr) UprPSTCs;
        alias ParameterStorageClassTuple!(Lwr) LwrPSTCs;
        //
        template checkNext(size_t i)
        {
            static if (i < UprParams.length)
            {
                enum uprStc = UprPSTCs[i];
                enum lwrStc = LwrPSTCs[i];
                //
                enum WANT_EXACT = STC.OUT | STC.REF | STC.LAZY;
                enum ok =
                    ((uprStc & WANT_EXACT) == (lwrStc & WANT_EXACT)) &&
                    ((uprStc & STC.SCOPE ) >= (lwrStc & STC.SCOPE )) &&
                    checkNext!(i + 1).ok;
            }
            else
                enum ok = true; // done
        }
        static if (UprParams.length == LwrParams.length)
            enum ok = is(UprParams == LwrParams) && checkNext!(0).ok;
        else
            enum ok = false;
    }

    /* run all the checks */
    enum bool yes =
        checkLinkage    !().ok &&
        checkVariadicity!().ok &&
        checkSTC        !().ok &&
        checkAttributes !().ok &&
        checkReturnType !().ok &&
        checkParameters !().ok ;
}

version (unittest) private template isCovariantWith(alias f, alias g)
{
    enum bool isCovariantWith = isCovariantWith!(typeof(f), typeof(g));
}
unittest
{
    // covariant return type
    interface I     {}
    interface J : I {}
    interface BaseA            {          const(I) test(int); }
    interface DerivA_1 : BaseA { override const(J) test(int); }
    interface DerivA_2 : BaseA { override       J  test(int); }
    static assert(isCovariantWith!(DerivA_1.test, BaseA.test));
    static assert(isCovariantWith!(DerivA_2.test, BaseA.test));
    static assert(! isCovariantWith!(BaseA.test, DerivA_1.test));
    static assert(! isCovariantWith!(BaseA.test, DerivA_2.test));
    static assert(isCovariantWith!(BaseA.test, BaseA.test));
    static assert(isCovariantWith!(DerivA_1.test, DerivA_1.test));
    static assert(isCovariantWith!(DerivA_2.test, DerivA_2.test));

    // scope parameter
    interface BaseB            {          void test(      int,       int); }
    interface DerivB_1 : BaseB { override void test(scope int,       int); }
    interface DerivB_2 : BaseB { override void test(      int, scope int); }
    interface DerivB_3 : BaseB { override void test(scope int, scope int); }
    static assert(isCovariantWith!(DerivB_1.test, BaseB.test));
    static assert(isCovariantWith!(DerivB_2.test, BaseB.test));
    static assert(isCovariantWith!(DerivB_3.test, BaseB.test));
    static assert(! isCovariantWith!(BaseB.test, DerivB_1.test));
    static assert(! isCovariantWith!(BaseB.test, DerivB_2.test));
    static assert(! isCovariantWith!(BaseB.test, DerivB_3.test));

    // function storage class
    interface BaseC            {          void test()      ; }
    interface DerivC_1 : BaseC { override void test() const; }
    static assert(isCovariantWith!(DerivC_1.test, BaseC.test));
    static assert(! isCovariantWith!(BaseC.test, DerivC_1.test));

    // increasing safety
    interface BaseE            {          void test()         ; }
    interface DerivE_1 : BaseE { override void test() @safe   ; }
    interface DerivE_2 : BaseE { override void test() @trusted; }
    static assert(isCovariantWith!(DerivE_1.test, BaseE.test));
    static assert(isCovariantWith!(DerivE_2.test, BaseE.test));
    static assert(! isCovariantWith!(BaseE.test, DerivE_1.test));
    static assert(! isCovariantWith!(BaseE.test, DerivE_2.test));

    // @safe and @trusted
    interface BaseF
    {
        void test1() @safe;
        void test2() @trusted;
    }
    interface DerivF : BaseF
    {
        override void test1() @trusted;
        override void test2() @safe;
    }
    static assert(isCovariantWith!(DerivF.test1, BaseF.test1));
    static assert(isCovariantWith!(DerivF.test2, BaseF.test2));
}


//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://
// isSomething
//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://

/**
 * Detect whether T is a built-in integral type. Types $(D bool), $(D
 * char), $(D wchar), and $(D dchar) are not considered integral.
 */

template isIntegral(T)
{
    enum bool isIntegral = staticIndexOf!(Unqual!(T), byte,
            ubyte, short, ushort, int, uint, long, ulong) >= 0;
}

unittest
{
    static assert(isIntegral!(byte));
    static assert(isIntegral!(const(byte)));
    static assert(isIntegral!(immutable(byte)));
    static assert(isIntegral!(shared(byte)));
    static assert(isIntegral!(shared(const(byte))));

    static assert(isIntegral!(ubyte));
    static assert(isIntegral!(const(ubyte)));
    static assert(isIntegral!(immutable(ubyte)));
    static assert(isIntegral!(shared(ubyte)));
    static assert(isIntegral!(shared(const(ubyte))));

    static assert(isIntegral!(short));
    static assert(isIntegral!(const(short)));
    static assert(isIntegral!(immutable(short)));
    static assert(isIntegral!(shared(short)));
    static assert(isIntegral!(shared(const(short))));

    static assert(isIntegral!(ushort));
    static assert(isIntegral!(const(ushort)));
    static assert(isIntegral!(immutable(ushort)));
    static assert(isIntegral!(shared(ushort)));
    static assert(isIntegral!(shared(const(ushort))));

    static assert(isIntegral!(int));
    static assert(isIntegral!(const(int)));
    static assert(isIntegral!(immutable(int)));
    static assert(isIntegral!(shared(int)));
    static assert(isIntegral!(shared(const(int))));

    static assert(isIntegral!(uint));
    static assert(isIntegral!(const(uint)));
    static assert(isIntegral!(immutable(uint)));
    static assert(isIntegral!(shared(uint)));
    static assert(isIntegral!(shared(const(uint))));

    static assert(isIntegral!(long));
    static assert(isIntegral!(const(long)));
    static assert(isIntegral!(immutable(long)));
    static assert(isIntegral!(shared(long)));
    static assert(isIntegral!(shared(const(long))));

    static assert(isIntegral!(ulong));
    static assert(isIntegral!(const(ulong)));
    static assert(isIntegral!(immutable(ulong)));
    static assert(isIntegral!(shared(ulong)));
    static assert(isIntegral!(shared(const(ulong))));

    static assert(!isIntegral!(float));
}

/**
 * Detect whether T is a built-in floating point type.
 */

template isFloatingPoint(T)
{
    enum bool isFloatingPoint = staticIndexOf!(Unqual!(T),
            float, double, real) >= 0;
}

unittest
{
    foreach (F; TypeTuple!(float, double, real))
    {
        F a = 5.5;
        static assert(isFloatingPoint!(typeof(a)));
        const F b = 5.5;
        static assert(isFloatingPoint!(typeof(b)));
        immutable F c = 5.5;
        static assert(isFloatingPoint!(typeof(c)));
    }
    foreach (T; TypeTuple!(int, long, char))
    {
        T a;
        static assert(!isFloatingPoint!(typeof(a)));
        const T b = 0;
        static assert(!isFloatingPoint!(typeof(b)));
        immutable T c = 0;
        static assert(!isFloatingPoint!(typeof(c)));
    }
}

/**
Detect whether T is a built-in numeric type (integral or floating
point).
 */

template isNumeric(T)
{
    enum bool isNumeric = isIntegral!(T) || isFloatingPoint!(T);
}

/**
Detect whether $(D T) is a built-in unsigned numeric type.
 */
template isUnsigned(T)
{
    enum bool isUnsigned = staticIndexOf!(Unqual!T,
            ubyte, ushort, uint, ulong) >= 0;
}

/**
Detect whether $(D T) is a built-in signed numeric type.
 */
template isSigned(T)
{
    enum bool isSigned = staticIndexOf!(Unqual!T,
            byte, short, int, long, float, double, real) >= 0;
}

/**
Detect whether T is one of the built-in string types
 */

template isSomeString(T)
{
    enum isSomeString = isNarrowString!T || is(T : const(dchar[]));
}

unittest
{
    static assert(!isSomeString!(int));
    static assert(!isSomeString!(int[]));
    static assert(!isSomeString!(byte[]));
    static assert(isSomeString!(char[]));
    static assert(isSomeString!(dchar[]));
    static assert(isSomeString!(string));
    static assert(isSomeString!(wstring));
    static assert(isSomeString!(dstring));
    static assert(isSomeString!(char[4]));
}

template isNarrowString(T)
{
    enum isNarrowString = is(T : const(char[])) || is(T : const(wchar[]));
}

unittest
{
    static assert(!isNarrowString!(int));
    static assert(!isNarrowString!(int[]));
    static assert(!isNarrowString!(byte[]));
    static assert(isNarrowString!(char[]));
    static assert(!isNarrowString!(dchar[]));
    static assert(isNarrowString!(string));
    static assert(isNarrowString!(wstring));
    static assert(!isNarrowString!(dstring));
    static assert(isNarrowString!(char[4]));
}

/**
Detect whether T is one of the built-in character types
 */

template isSomeChar(T)
{
    enum isSomeChar = staticIndexOf!(Unqual!T, char, wchar, dchar) >= 0;
}

unittest
{
    static assert(!isSomeChar!(int));
    static assert(!isSomeChar!(int));
    static assert(!isSomeChar!(byte));
    static assert(isSomeChar!(char));
    static assert(isSomeChar!(dchar));
    static assert(!isSomeChar!(string));
    static assert(!isSomeChar!(wstring));
    static assert(!isSomeChar!(dstring));
    static assert(!isSomeChar!(char[4]));
    static assert(isSomeChar!(immutable(char)));
}

/**
 * Detect whether T is an associative array type
 */

template isAssociativeArray(T)
{
    enum bool isAssociativeArray = __traits(isAssociativeArray, T);
}

unittest
{
    struct Foo {
        @property uint[] keys() {
            return null;
        }

        @property uint[] values() {
            return null;
        }
    }

    static assert(!isAssociativeArray!(Foo));
    static assert(!isAssociativeArray!(int));
    static assert(!isAssociativeArray!(int[]));
    static assert(isAssociativeArray!(int[int]));
    static assert(isAssociativeArray!(int[string]));
    static assert(isAssociativeArray!(immutable(char[5])[int]));
}

/**
 * Detect whether type T is a static array.
 */
template isStaticArray(T : U[N], U, size_t N)
{
    enum bool isStaticArray = true;
}

template isStaticArray(T)
{
    enum bool isStaticArray = false;
}

unittest
{
    static assert (isStaticArray!(int[51]));
    static assert (isStaticArray!(int[][2]));
    static assert (isStaticArray!(char[][int][11]));
    static assert (!isStaticArray!(const(int)[]));
    static assert (!isStaticArray!(immutable(int)[]));
    static assert (!isStaticArray!(const(int)[4][]));
    static assert (!isStaticArray!(int[]));
    static assert (!isStaticArray!(int[char]));
    static assert (!isStaticArray!(int[1][]));
    static assert (isStaticArray!(immutable char[13u]));
    static assert (isStaticArray!(const(real)[1]));
    static assert (isStaticArray!(const(real)[1][1]));
    static assert (isStaticArray!(void[0]));
    static assert (!isStaticArray!(int[int]));
    static assert (!isStaticArray!(int));
}

/**
 * Detect whether type T is a dynamic array.
 */
template isDynamicArray(T, U = void)
{
    enum bool isDynamicArray = false;
}

template isDynamicArray(T : U[], U)
{
  enum bool isDynamicArray = !isStaticArray!(T);
}

unittest
{
    static assert(isDynamicArray!(int[]));
    static assert(!isDynamicArray!(int[5]));
}

/**
 * Detect whether type T is an array.
 */
template isArray(T)
{
    enum bool isArray = isStaticArray!(T) || isDynamicArray!(T);
}

unittest
{
    static assert(isArray!(int[]));
    static assert(isArray!(int[5]));
    static assert(!isArray!(uint));
    static assert(!isArray!(uint[uint]));
    static assert(isArray!(void[]));
}

/**
 * Detect whether type $(D T) is a pointer.
 */
template isPointer(T)
{
    static if (is(T P == U*, U))
    {
        enum bool isPointer = true;
    }
    else
    {
        enum bool isPointer = false;
    }
}

unittest
{
    static assert(isPointer!(int*));
    static assert(!isPointer!(uint));
    static assert(!isPointer!(uint[uint]));
    static assert(!isPointer!(char[]));
    static assert(isPointer!(void*));
}

/**
Returns the target type of a pointer.
*/
template pointerTarget(T : T*) {
    alias T pointerTarget;
}

unittest {
    static assert(is(pointerTarget!(int*) == int));
    static assert(!is(pointerTarget!int));
    static assert(is(pointerTarget!(long*) == long));
}

/**
 * Returns $(D true) if T can be iterated over using a $(D foreach) loop with
 * a single loop variable of automatically inferred type, regardless of how
 * the $(D foreach) loop is implemented.  This includes ranges, structs/classes
 * that define $(D opApply) with a single loop variable, and builtin dynamic,
 * static and associative arrays.
 */
template isIterable(T)
{
    static if (is(typeof({foreach(elem; T.init) {}}))) {
        enum bool isIterable = true;
    } else {
        enum bool isIterable = false;
    }
}

unittest {
    struct OpApply
    {
        int opApply(int delegate(ref uint) dg) { assert(0); }
    }

    struct Range
    {
        uint front() { assert(0); }
        void popFront() { assert(0); }
        enum bool empty = false;
    }

    static assert(isIterable!(uint[]));
    static assert(!isIterable!(uint));
    static assert(isIterable!(OpApply));
    static assert(isIterable!(uint[string]));
    static assert(isIterable!(Range));
}

/*
 * Returns true if T is not const or immutable.  Note that isMutable is true for
 * string, or immutable(char)[], because the 'head' is mutable.
 */
template isMutable(T)
{
    enum isMutable = !is(T == const) && !is(T == immutable);
}

unittest
{
    static assert(isMutable!int);
    static assert(isMutable!string);
    static assert(isMutable!(shared int));
    static assert(isMutable!(shared const(int)[]));

    static assert(!isMutable!(const int));
    static assert(!isMutable!(shared(const int)));
    static assert(!isMutable!(immutable string));
}

/**
 * Tells whether the tuple T is an expression tuple.
 */
template isExpressionTuple(T ...)
{
    static if (T.length > 0)
        enum bool isExpressionTuple =
            !is(T[0]) && __traits(compiles, { auto ex = T[0]; }) &&
            isExpressionTuple!(T[1 .. $]);
    else
        enum bool isExpressionTuple = true; // default
}

unittest
{
    void foo();
    static int bar() { return 42; }
    enum aa = [ 1: -1 ];
    alias int myint;

    static assert(isExpressionTuple!(42));
    static assert(isExpressionTuple!(aa));
    static assert(isExpressionTuple!("cattywampus", 2.7, aa));
    static assert(isExpressionTuple!(bar()));

    static assert(! isExpressionTuple!(isExpressionTuple));
    static assert(! isExpressionTuple!(foo));
    static assert(! isExpressionTuple!( (a) { } ));
    static assert(! isExpressionTuple!(int));
    static assert(! isExpressionTuple!(myint));
}


/**
Detect whether tuple $(D T) is a type tuple.
 */
template isTypeTuple(T...)
{
    static if (T.length > 0)
        enum bool isTypeTuple = is(T[0]) && isTypeTuple!(T[1 .. $]);
    else
        enum bool isTypeTuple = true; // default
}

unittest
{
    class C {}
    void func(int) {}
    auto c = new C;
    enum CONST = 42;

    static assert(isTypeTuple!(int));
    static assert(isTypeTuple!(string));
    static assert(isTypeTuple!(C));
    static assert(isTypeTuple!(typeof(func)));
    static assert(isTypeTuple!(int, char, double));

    static assert(! isTypeTuple!(c));
    static assert(! isTypeTuple!(isTypeTuple));
    static assert(! isTypeTuple!(CONST));
}


/**
Detect whether symbol or type $(D T) is a function pointer.
 */
template isFunctionPointer(T...)
    if (/+@@@BUG4333@@@+/staticLength!(T) == 1)
{
    static if (is(T[0] U) || is(typeof(T[0]) U))
    {
        static if (is(U F : F*) && is(F == function))
            enum bool isFunctionPointer = true;
        else
            enum bool isFunctionPointer = false;
    }
    else
        enum bool isFunctionPointer = false;
}

unittest
{
    static void foo() {}
    void bar() {}

    auto fpfoo = &foo;
    static assert(isFunctionPointer!(fpfoo));
    static assert(isFunctionPointer!(void function()));

    auto dgbar = &bar;
    static assert(! isFunctionPointer!(dgbar));
    static assert(! isFunctionPointer!(void delegate()));
    static assert(! isFunctionPointer!(foo));
    static assert(! isFunctionPointer!(bar));

    static assert(!isFunctionPointer!((int a) {}));
}

/**
Detect whether $(D T) is a delegate.
*/
template isDelegate(T...)
if(staticLength!T == 1)
{
    enum bool isDelegate = is(T[0] == delegate);
}

unittest
{
    static assert(isDelegate!(void delegate()));
    static assert(isDelegate!(uint delegate(uint)));
    static assert(isDelegate!(shared uint delegate(uint)));
    static assert(!isDelegate!(uint));
    static assert(!isDelegate!(void function()));
}


/**
Detect whether symbol or type $(D T) is a function, a function pointer or a delegate.
 */
template isSomeFunction(/+@@@BUG4217@@@+/T...)
    if (/+@@@BUG4333@@@+/staticLength!(T) == 1)
{
    enum bool isSomeFunction = isSomeFunction_bug4333!(T).isSomeFunction;
}
private template isSomeFunction_bug4333(T...)
{
    /+@@@BUG4333@@@+/enum dummy__ = T.length;

    static if (is(typeof(& T[0]) U : U*) && is(U == function))
    {
        // T is a function symbol.
        enum bool isSomeFunction = true;
    }
    else static if (is(T[0] W) || is(typeof(T[0]) W))
    {
        // T is an expression or a type.  Take the type of it and examine.
        static if (is(W F : F*) && is(F == function))
            enum bool isSomeFunction = true; // function pointer
        else
            enum bool isSomeFunction = is(W == function) || is(W == delegate);
    }
    else
        enum bool isSomeFunction = false;
}

unittest
{
    static real func(ref int) { return 0; }
    class C
    {
        real method(ref int) { return 0; }
        real prop() @property { return 0; }
    }
    auto c = new C;
    auto fp = &func;
    auto dg = &c.method;
    real val;

    static assert(isSomeFunction!(func));
    static assert(isSomeFunction!(C.method));
    static assert(isSomeFunction!(C.prop));
    static assert(isSomeFunction!(c.prop));
    static assert(isSomeFunction!(c.prop));
    static assert(isSomeFunction!(fp));
    static assert(isSomeFunction!(dg));
    static assert(isSomeFunction!(typeof(func)));
    static assert(isSomeFunction!(real function(ref int)));
    static assert(isSomeFunction!(real delegate(ref int)));

    static assert(! isSomeFunction!(int));
    static assert(! isSomeFunction!(val));
    static assert(! isSomeFunction!(isSomeFunction));

    static assert(isSomeFunction!((int a) { return a; }));
}


/**
Detect whether $(D T) is a callable object, which can be called with the
function call operator $(D $(LPAREN)...$(RPAREN)).
 */
template isCallable(/+@@@BUG4217@@@+/T...)
    if (/+@@@BUG4333@@@+/staticLength!(T) == 1)
{
    enum bool isCallable = isCallable_bug4333!(T).isCallable;
}
private template isCallable_bug4333(T...)
{
    /+@@@BUG4333@@@+/enum dummy__ = T.length;

    static if (is(typeof(& T[0].opCall) == delegate))
        // T is a object which has a member function opCall().
        enum bool isCallable = true;
    else static if (is(typeof(& T[0].opCall) V : V*) && is(V == function))
        // T is a type which has a static member function opCall().
        enum bool isCallable = true;
    else
        enum bool isCallable = isSomeFunction!(T);
}

unittest
{
    interface I { real value() @property; }
    struct S { static int opCall(int) { return 0; } }
    class C { int opCall(int) { return 0; } }
    auto c = new C;

    static assert( isCallable!(c));
    static assert( isCallable!(S));
    static assert( isCallable!(c.opCall));
    static assert( isCallable!(I.value));
    static assert(!isCallable!(I));

    static assert(isCallable!((int a) { return a; }));
}


/**
Exactly the same as the builtin traits:
$(D ___traits(_isAbstractFunction, method)).
 */
template isAbstractFunction(/+@@@BUG4217@@@+/method...)
    if (/+@@@BUG4333@@@+/staticLength!(method) == 1)
{
    enum bool isAbstractFunction  = __traits(isAbstractFunction, method[0]);
}



//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://
// General Types
//::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://

/**
Removes all qualifiers, if any, from type $(D T).

Example:
----
static assert(is(Unqual!(int) == int));
static assert(is(Unqual!(const int) == int));
static assert(is(Unqual!(immutable int) == int));
static assert(is(Unqual!(shared int) == int));
static assert(is(Unqual!(shared(const int)) == int));
----
 */
template Unqual(T)
{
    version (none) // Error: recursive alias declaration @@@BUG1308@@@
    {
             static if (is(T U ==     const U)) alias Unqual!U Unqual;
        else static if (is(T U == immutable U)) alias Unqual!U Unqual;
        else static if (is(T U ==    shared U)) alias Unqual!U Unqual;
        else                                    alias        T Unqual;
    }
    else // workaround
    {
             static if (is(T U == shared(const U))) alias U Unqual;
        else static if (is(T U ==        const U )) alias U Unqual;
        else static if (is(T U ==    immutable U )) alias U Unqual;
        else static if (is(T U ==       shared U )) alias U Unqual;
        else                                        alias T Unqual;
    }
}

unittest
{
    static assert(is(Unqual!(int) == int));
    static assert(is(Unqual!(const int) == int));
    static assert(is(Unqual!(immutable int) == int));
    static assert(is(Unqual!(shared int) == int));
    static assert(is(Unqual!(shared(const int)) == int));
    alias immutable(int[]) ImmIntArr;
    static assert(is(Unqual!(ImmIntArr) == immutable(int)[]));
}

// [For internal use]
private template ModifyTypePreservingSTC(alias Modifier, T)
{
         static if (is(T U == shared(const U))) alias shared(const Modifier!U) ModifyTypePreservingSTC;
    else static if (is(T U ==        const U )) alias        const(Modifier!U) ModifyTypePreservingSTC;
    else static if (is(T U ==    immutable U )) alias    immutable(Modifier!U) ModifyTypePreservingSTC;
    else static if (is(T U ==       shared U )) alias       shared(Modifier!U) ModifyTypePreservingSTC;
    else                                        alias              Modifier!T  ModifyTypePreservingSTC;
}

unittest
{
    static assert(is(ModifyTypePreservingSTC!(Intify, const real) == const int));
    static assert(is(ModifyTypePreservingSTC!(Intify, immutable real) == immutable int));
    static assert(is(ModifyTypePreservingSTC!(Intify, shared real) == shared int));
    static assert(is(ModifyTypePreservingSTC!(Intify, shared(const real)) == shared(const int)));
}
version (unittest) private template Intify(T) { alias int Intify; }

/*
*/
template StringTypeOf(T) if (isSomeString!T)
{
    static if (is(T == class) || is(T == struct))
    {
        static if (is(T : const(char[])))
        {
            static if (is(T : char[]))
                alias char[] StringTypeOf;
            else static if (is(T : immutable(char[])))
                alias immutable(char)[] StringTypeOf;
            else
                alias const(char)[] StringTypeOf;
        }
        else static if (is(T : const(wchar[])))
        {
            static if (is(T : wchar[]))
                alias wchar[] StringTypeOf;
            else static if (is(T : immutable(wchar[])))
                alias immutable(wchar)[] StringTypeOf;
            else
                alias const(wchar)[] StringTypeOf;
        }
        else
        {
            static if (is(T : dchar[]))
                alias dchar[] StringTypeOf;
            else static if (is(T : immutable(dchar[])))
                alias immutable(dchar)[] StringTypeOf;
            else
                alias const(dchar)[] StringTypeOf;
        }
    }
    else
    {
        alias T StringTypeOf;
    }
}
unittest
{
    class C(Char, int n)
    {
        static if (n==0) Char[]            val;
        static if (n==1) const(Char)[]     val;
        static if (n==2) const(Char[])     val;
        static if (n==3) immutable(Char)[] val;
        static if (n==4) immutable(Char[]) val;
        alias val this;
    }
    struct S(Char, int n)
    {
        static if (n==0) Char[]            val;
        static if (n==1) const(Char)[]     val;
        static if (n==2) const(Char[])     val;
        static if (n==3) immutable(Char)[] val;
        static if (n==4) immutable(Char[]) val;
        alias val this;
    }
    foreach (Char; TypeTuple!(char, wchar, dchar))
    {
        static assert(is(StringTypeOf!(C!(Char, 0)) == Char[]));
        static assert(is(StringTypeOf!(C!(Char, 1)) == const(Char)[]));
        static assert(is(StringTypeOf!(C!(Char, 2)) == const(Char)[]));     // cannot get exact string type
        static assert(is(StringTypeOf!(C!(Char, 3)) == immutable(Char)[]));
        static assert(is(StringTypeOf!(C!(Char, 4)) == immutable(Char)[])); // cannot get exact string type
        
        static assert(is(StringTypeOf!(S!(Char, 0)) == Char[]));
        static assert(is(StringTypeOf!(S!(Char, 1)) == const(Char)[]));
        static assert(is(StringTypeOf!(S!(Char, 2)) == const(Char)[]));     // cannot get exact string type
        static assert(is(StringTypeOf!(S!(Char, 3)) == immutable(Char)[]));
        static assert(is(StringTypeOf!(S!(Char, 4)) == immutable(Char)[])); // cannot get exact string type
    }
}

/**
Returns the inferred type of the loop variable when a variable of type T
is iterated over using a $(D foreach) loop with a single loop variable and
automatically inferred return type.  Note that this may not be the same as
$(D std.range.ElementType!(Range)) in the case of narrow strings, or if T
has both opApply and a range interface.
*/
template ForeachType(T)
{
    alias ReturnType!(typeof(
    {
        foreach(elem; T.init) {
            return elem;
        }
        assert(0);
    })) ForeachType;
}

unittest
{
    static assert(is(ForeachType!(uint[]) == uint));
    static assert(is(ForeachType!(string) == immutable(char)));
    static assert(is(ForeachType!(string[string]) == string));
}


/**
Strips off all $(D typedef)s (including $(D enum) ones) from type $(D T).

Example:
--------------------
enum E : int { a }
typedef E F;
typedef const F G;
static assert(is(OriginalType!G == const int));
--------------------
 */
template OriginalType(T)
{
    alias ModifyTypePreservingSTC!(OriginalTypeImpl, T) OriginalType;
}

private template OriginalTypeImpl(T)
{
         static if (is(T U == typedef)) alias OriginalType!U OriginalTypeImpl;
    else static if (is(T U ==    enum)) alias OriginalType!U OriginalTypeImpl;
    else                                alias              T OriginalTypeImpl;
}

unittest
{
    typedef real T;
    typedef T    U;
    enum V : U { a }
    static assert(is(OriginalType!T == real));
    static assert(is(OriginalType!U == real));
    static assert(is(OriginalType!V == real));
    enum E : real { a }
    enum F : E    { a = E.a }
    typedef const F G;
    static assert(is(OriginalType!E == real));
    static assert(is(OriginalType!F == real));
    static assert(is(OriginalType!G == const real));
}


/**
 * Returns the corresponding unsigned type for T. T must be a numeric
 * integral type, otherwise a compile-time error occurs.
 */

template Unsigned(T)
{
    alias ModifyTypePreservingSTC!(UnsignedImpl, OriginalType!T) Unsigned;
}

private template UnsignedImpl(T)
{
    static if (isUnsigned!(T)) alias T UnsignedImpl;
    else static if (is(T == byte)) alias ubyte UnsignedImpl;
    else static if (is(T == short)) alias ushort UnsignedImpl;
    else static if (is(T == int)) alias uint UnsignedImpl;
    else static if (is(T == long)) alias ulong UnsignedImpl;
    else static assert(false, "Type " ~ T.stringof
                       ~ " does not have an Unsigned counterpart");
}

unittest
{
    alias Unsigned!(int) U;
    assert(is(U == uint));
    alias Unsigned!(const(int)) U1;
    assert(is(U1 == const(uint)), U1.stringof);
    alias Unsigned!(immutable(int)) U2;
    assert(is(U2 == immutable(uint)), U2.stringof);
    //struct S {}
    //alias Unsigned!(S) U2;
    //alias Unsigned!(double) U3;
}

/**
Returns the largest type, i.e. T such that T.sizeof is the largest.  If more
than one type is of the same size, the leftmost argument of these in will be
returned.
*/
template Largest(T...) if(T.length >= 1) {
    static if(T.length == 1) {
        alias T[0] Largest;
    } static if(T.length == 2) {
        static if(T[0].sizeof >= T[1].sizeof) {
            alias T[0] Largest;
        } else {
            alias T[1] Largest;
        }
    } else {
        alias Largest!(Largest!(T[0], T[1]), T[2..$]) Largest;
    }
}

unittest {
    static assert(is(Largest!(uint, ubyte, ulong, real) == real));
    static assert(is(Largest!(ulong, double) == ulong));
    static assert(is(Largest!(double, ulong) == double));
    static assert(is(Largest!(uint, byte, double, short) == double));
}

/**
Returns the corresponding signed type for T. T must be a numeric integral type,
otherwise a compile-time error occurs.
 */
template Signed(T)
{
    alias ModifyTypePreservingSTC!(SignedImpl, OriginalType!T) Signed;
}

private template SignedImpl(T)
{
    static if (isSigned!(T)) alias T SignedImpl;
    else static if (is(T == ubyte)) alias byte SignedImpl;
    else static if (is(T == ushort)) alias short SignedImpl;
    else static if (is(T == uint)) alias int SignedImpl;
    else static if (is(T == ulong)) alias long SignedImpl;
    else static assert(false, "Type " ~ T.stringof
                       ~ " does not have an Signed counterpart");
}

unittest
{
    alias Signed!(uint) S;
    assert(is(S == int));
    alias Signed!(const(uint)) S1;
    assert(is(S1 == const(int)), S1.stringof);
    alias Signed!(immutable(uint)) S2;
    assert(is(S2 == immutable(int)), S2.stringof);
}


/**
Returns the most negative value of the numeric type T.
*/

template mostNegative(T)
{
    static if (is(typeof(T.min_normal))) enum mostNegative = -T.max;
    else static if (T.min == 0) enum byte mostNegative = 0;
    else enum mostNegative = T.min;
}

unittest
{
    static assert(mostNegative!(float) == -float.max);
    static assert(mostNegative!(uint) == 0);
    static assert(mostNegative!(long) == long.min);
}


//:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://
// Misc.
//:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::://

/**
Returns the mangled name of symbol or type $(D sth).

$(D mangledName) is the same as builtin $(D .mangleof) property, except that
the correct names of property functions are obtained.
--------------------
module test;
import std.traits : mangledName;

class C {
    int value() @property;
}
pragma(msg, C.value.mangleof);      // prints "i"
pragma(msg, mangledName!(C.value)); // prints "_D4test1C5valueMFNdZi"
--------------------
 */
template mangledName(sth...)
    if (/+@@@BUG4333@@@+/staticLength!(sth) == 1)
{
    enum string mangledName = removeDummyEnvelope(Dummy!(sth).Hook.mangleof);
}

private template Dummy(T...) { struct Hook {} }

private string removeDummyEnvelope(string s)
{
    // remove --> S3std6traits ... Z4Hook
    s = s[12 .. $ - 6];

    // remove --> DIGIT+ __T5Dummy
    foreach (i, c; s)
    {
        if (c < '0' || '9' < c)
        {
            s = s[i .. $];
            break;
        }
    }
    s = s[9 .. $]; // __T5Dummy

    // remove --> T | V | S
    immutable kind = s[0];
    s = s[1 .. $];

    if (kind == 'S') // it's a symbol
    {
        /*
         * The mangled symbol name is packed in LName --> Number Name.  Here
         * we are chopping off the useless preceding Number, which is the
         * length of Name in decimal notation.
         *
         * NOTE: n = m + Log(m) + 1;  n = LName.length, m = Name.length.
         */
        immutable n = s.length;
        size_t m_upb = 10;

        foreach (k; 1 .. 5) // k = Log(m_upb)
        {
            if (n < m_upb + k + 1)
            {
                // Now m_upb/10 <= m < m_upb; hence k = Log(m) + 1.
                s = s[k .. $];
                break;
            }
            m_upb *= 10;
        }
    }

    return s;
}

unittest
{
    typedef int MyInt;
    MyInt test() { return 0; }
    class C { int value() @property { return 0; } }
    static assert(mangledName!(int) == int.mangleof);
    static assert(mangledName!(C) == C.mangleof);
    //static assert(mangledName!(MyInt)[$ - 7 .. $] == "T5MyInt"); // XXX depends on bug 4237
    //static assert(mangledName!(test)[$ - 7 .. $] == "T5MyInt");
    static assert(mangledName!(C.value)[$ - 12 .. $] == "5valueMFNdZi");
    static assert(mangledName!(mangledName) == "3std6traits11mangledName");
    static assert(mangledName!(removeDummyEnvelope) ==
            "_D3std6traits19removeDummyEnvelopeFAyaZAya");
    int x;
    static assert(mangledName!((int a) { return a+x; })[$ - 5 .. $] == "MFiZi");
}


/*
workaround for @@@BUG2234@@@ "allMembers does not return interface members"
 */
package template traits_allMembers(Agg)
{
    static if (is(Agg == class) || is(Agg == interface))
        alias NoDuplicates!( __traits(allMembers, Agg),
                    traits_allMembers_ifaces!(InterfacesTuple!(Agg)) )
                traits_allMembers;
    else
        alias TypeTuple!(__traits(allMembers, Agg)) traits_allMembers;
}
private template traits_allMembers_ifaces(I...)
{
    static if (I.length > 0)
        alias TypeTuple!( __traits(allMembers, I[0]),
                    traits_allMembers_ifaces!(I[1 .. $]) )
                traits_allMembers_ifaces;
    else
        alias TypeTuple!() traits_allMembers_ifaces;
}

unittest
{
    interface I { void test(); }
    interface J : I { }
    interface K : J { }
    alias traits_allMembers!(K) names;
    static assert(names.length == 1);
    static assert(names[0] == "test");
}



// XXX Select & select should go to another module. (functional or algorithm?)

/**
Aliases itself to $(D T) if the boolean $(D condition) is $(D true)
and to $(D F) otherwise.

Example:
----
alias Select!(size_t.sizeof == 4, int, long) Int;
----
 */
template Select(bool condition, T, F)
{
    static if (condition) alias T Select;
    else alias F Select;
}

unittest
{
    static assert(is(Select!(true, int, long) == int));
    static assert(is(Select!(false, int, long) == long));
}

/**
If $(D cond) is $(D true), returns $(D a) without evaluating $(D
b). Otherwise, returns $(D b) without evaluating $(D a).
 */
A select(bool cond : true, A, B)(A a, lazy B b) { return a; }
/// Ditto
B select(bool cond : false, A, B)(lazy A a, B b) { return b; }

unittest
{
    real pleasecallme() { return 0; }
    int dontcallme() { assert(0); }
    auto a = select!true(pleasecallme(), dontcallme());
    auto b = select!false(dontcallme(), pleasecallme());
    static assert(is(typeof(a) == real));
    static assert(is(typeof(b) == real));
}
