// ==========================================================================
//                 SeqAn - The Library for Sequence Analysis
// ==========================================================================
// Copyright (c) 2006-2024, Knut Reinert, FU Berlin
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are met:
//
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//       notice, this list of conditions and the following disclaimer in the
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//
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//
// ==========================================================================
// Author: Manuel Holtgrewe <manuel.holtgrewe@fu-berlin.de>
// ==========================================================================
// This is a simple example of template subclassing.
//
// Referenced by TemplateSubclassing.
// ==========================================================================

#include <iostream>

// Setup class hierarchy by using inheritance for the specialization tags.

struct SpecA {};
struct SpecB {};
struct SpecC :
    SpecB {};
struct SpecD :
    SpecB {};

// Base class -- most generic and thus a fallback.
template <typename TSpec>
struct MyClass
{
    int x;

    MyClass() :
        x(0)
    {}
};

// Specialization for classes B and D.  C automatically inherits everything
// from B and does not overwrite anything.
template <>
struct MyClass<SpecB>
{
    int x;

    MyClass() :
        x(1)
    {}
};

template <>
struct MyClass<SpecD>
{
    int x;

    MyClass() :
        x(2)
    {}
};

// Define some functions that demostrate overloading.

// Most generic case, "base implementation".
template <typename TSpec>
void foo(MyClass<TSpec> const & obj)
{
    std::cout << "foo(MyClass<typename TSpec> const & obj) called!  obj.x == " << obj.x << "\n";
}

// This function overwrites the generic implementation of foo() for the
// specialization B.
template <>
void foo(MyClass<SpecB> const & obj)
{
    std::cout << "foo(MyClass<SpecB> const & obj) called!  obj.x == " << obj.x << "\n";
}

// This function overwrites the generic implementation of foo() for the
// specialization C.
template <>
void foo(MyClass<SpecC> const & obj)
{
    std::cout << "foo(MyClass<SpecC> const & obj) called!  obj.x == " << obj.x << "\n";
}

// The main function calls the functions from above.
int main()
{
    std::cout << "Template Subclassing Demo\n";

    MyClass<SpecA> a;
    MyClass<SpecB> b;
    MyClass<SpecC> c;
    MyClass<SpecD> d;

    foo(a);  // => foo(MyClass<typename TSpec> const & obj) called!  obj.x == 0
    foo(b);  // => foo(MyClass<SpecB> const & obj) called!  obj.x == 1
    foo(c);  // => foo(MyClass<SpecC> const & obj) called!  obj.x == 0
    foo(d);  // => foo(MyClass<typename TSpec> const & obj) called!  obj.x == 2

    return 0;
}
