dlibs/dlib/any/any.h

// Copyright (C) 2010  Davis E. King (davis@dlib.net)
// License: Boost Software License   See LICENSE.txt for the full license.
#ifndef DLIB_AnY_H_
#define DLIB_AnY_H_

#include "any_abstract.h"
#include "../algs.h"

#include <memory>
#include <typeinfo>

namespace dlib
{

// ----------------------------------------------------------------------------------------

    class bad_any_cast : public std::bad_cast 
    {
    public:
          virtual const char * what() const throw()
          {
              return "bad_any_cast";
          }
    };

// ----------------------------------------------------------------------------------------

    class any
    {

    public:

        any()
        {
        }

        any (
            const any& item
        )
        {
            if (item.data)
            {
                item.data->copy_to(data);
            }
        }

        template <typename T>
        any (
            const T& item
        )
        {
            typedef typename basic_type<T>::type U;
            data.reset(new derived<U>(item));
        }

        void clear (
        )
        {
            data.reset();
        }

        template <typename T>
        bool contains (
        ) const
        {
            typedef typename basic_type<T>::type U;
            return dynamic_cast<derived<U>*>(data.get()) != 0;
        }

        bool is_empty(
        ) const
        {
            return data.get() == 0;
        }

        template <typename T>
        T& cast_to(
        ) 
        {
            typedef typename basic_type<T>::type U;
            derived<U>* d = dynamic_cast<derived<U>*>(data.get());
            if (d == 0)
            {
                throw bad_any_cast();
            }

            return d->item;
        }

        template <typename T>
        const T& cast_to(
        ) const
        {
            typedef typename basic_type<T>::type U;
            derived<U>* d = dynamic_cast<derived<U>*>(data.get());
            if (d == 0)
            {
                throw bad_any_cast();
            }

            return d->item;
        }

        template <typename T>
        T& get(
        ) 
        {
            typedef typename basic_type<T>::type U;
            derived<U>* d = dynamic_cast<derived<U>*>(data.get());
            if (d == 0)
            {
                d = new derived<U>();
                data.reset(d);
            }

            return d->item;
        }

        any& operator= (
            const any& item
        )
        {
            any(item).swap(*this);
            return *this;
        }

        void swap (
            any& item
        )
        {
            data.swap(item.data);
        }

    private:

        struct base
        {
            virtual ~base() {}

            virtual void copy_to (
                std::unique_ptr<base>& dest
            ) const = 0;
        };

        template <typename T>
        struct derived : public base
        {
            T item;
            derived() {}
            derived(const T& val) : item(val) {}

            virtual void copy_to (
                std::unique_ptr<base>& dest
            ) const
            {
                dest.reset(new derived<T>(item));
            }
        };

        std::unique_ptr<base> data;
    };

// ----------------------------------------------------------------------------------------

    inline void swap (
        any& a,
        any& b
    ) { a.swap(b); }

// ----------------------------------------------------------------------------------------

    template <typename T> T& any_cast(any& a) { return a.cast_to<T>(); }
    template <typename T> const T& any_cast(const any& a) { return a.cast_to<T>(); }

// ----------------------------------------------------------------------------------------

}


#endif // DLIB_AnY_H_