Added an any container object.

--HG--
extra : convert_revision : svn%3Afdd8eb12-d10e-0410-9acb-85c331704f74/trunk%403942

dlib/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_
+#define DLIB_AnY_
+
+#include "any/any.h"
+
+#endif // DLIB_AnY_
+
+

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 "../smart_pointers.h"
+#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
+    {
+        template <typename T> struct basic_type { typedef T type; };
+        template <typename T> struct basic_type<const T> { typedef T type; };
+        template <typename T> struct basic_type<const T&> { typedef T type; };
+        template <typename T> struct basic_type<volatile const T&> { typedef T type; };
+        template <typename T> struct basic_type<T&> { typedef T type; };
+        template <typename T> struct basic_type<volatile T&> { typedef T type; };
+        template <typename T> struct basic_type<volatile T> { typedef T type; };
+        template <typename T> struct basic_type<volatile const T> { typedef T type; };
+
+    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 (
+                scoped_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 (
+                scoped_ptr<base>& dest
+            ) const
+            {
+                dest.reset(new derived<T>(item));
+            }
+        };
+
+        scoped_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_
+
+
+

dlib/any/any_abstract.h

+// Copyright (C) 2010  Davis E. King (davis@dlib.net)
+// License: Boost Software License   See LICENSE.txt for the full license.
+#undef DLIB_AnY_ABSTRACT_H_
+#ifdef DLIB_AnY_ABSTRACT_H_
+
+#include <typeinfo>
+
+namespace dlib
+{
+
+// ----------------------------------------------------------------------------------------
+
+    class bad_any_cast : public std::bad_cast 
+    {
+        /*!
+            WHAT THIS OBJECT REPRESENTS
+                This object is the exception class used by the any object.
+                It is used to indicate when someone attempts to cast an any
+                object into a type which isn't contained in the any object.
+        !*/
+
+    public:
+          virtual const char* what() const throw() { return "bad_any_cast"; }
+    };
+
+// ----------------------------------------------------------------------------------------
+
+    class any
+    {
+        /*!
+            INITIAL VALUE
+                - is_empty() == true
+                - for all T: contains<T>() == false
+
+            WHAT THIS OBJECT REPRESENTS
+                This object is basically a type-safe version of a void*.  In particular,
+                it is a container which can contain only one object but the object may
+                be of any type.  
+
+                It is somewhat like the type_safe_union except you don't have to declare 
+                the set of possible content types beforehand.  So in some sense this is 
+                like a less type-strict version of the type_safe_union.
+        !*/
+
+    public:
+
+        any(
+        );
+        /*!
+            ensures
+                - this object is properly initialized
+        !*/
+
+        any (
+            const any& item
+        );
+        /*!
+            ensures
+                - copies the state of item into *this.  
+                - Note that *this and item will contain independent copies of the
+                  contents of item.  That is, this function performs a deep
+                  copy and therefore does not result in *this containing
+                  any kind of reference to item.
+        !*/
+
+        template < typename T >
+        any (
+            const T& item
+        );
+        /*!
+            ensures
+                - #contains<T>() == true
+                - #cast_to<T>() == item
+                  (i.e. a copy of item will be stored in *this)
+        !*/
+
+        void clear (
+        );
+        /*!
+            ensures
+                - #*this will have its default value.  I.e. #is_empty() == true
+        !*/
+
+        template <typename T>
+        bool contains (
+        ) const;
+        /*!
+            ensures
+                - if (this object currently contains an object of type T) then
+                    - returns true
+                - else
+                    - returns false
+        !*/
+
+        bool is_empty(
+        ) const;
+        /*!
+            ensures
+                - if (this object contains any kind of object) then
+                    - returns true
+                - else
+                    - returns false
+        !*/
+
+        template <typename T>
+        T& cast_to(
+        );
+        /*!
+            ensures
+                - if (contains<T>() == true) then
+                    - returns a non-const reference to the object contained within *this
+                - else
+                    - throws bad_any_cast
+        !*/
+
+        template <typename T>
+        const T& cast_to(
+        ) const;
+        /*!
+            ensures
+                - if (contains<T>() == true) then
+                    - returns a const reference to the object contained within *this
+                - else
+                    - throws bad_any_cast
+        !*/
+
+        template <typename T>
+        T& get(
+        );
+        /*!
+            ensures
+                - #is_empty() == false
+                - #contains<T>() == true
+                - if (contains<T>() == true)
+                    - returns a non-const reference to the object contained in *this.
+                - else
+                    - Constructs an object of type T inside *this
+                    - Any previous object stored in this any object is destructed and its
+                      state is lost.
+                    - returns a non-const reference to the newly created T object.
+        !*/
+
+        any& operator= (
+            const any& item
+        );
+        /*!
+            ensures
+                - copies the state of item into *this.  
+                - Note that *this and item will contain independent copies of the
+                  contents of item.  That is, this function performs a deep
+                  copy and therefore does not result in *this containing
+                  any kind of reference to item.
+        !*/
+
+        void swap (
+            any& item
+        );
+        /*!
+            ensures
+                - swaps *this and item
+        !*/
+
+    };
+
+// ----------------------------------------------------------------------------------------
+
+    inline void swap (
+        any& a,
+        any& b
+    ) { a.swap(b); }
+    /*!
+        provides a global swap function
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T
+        > 
+    T& any_cast(
+        any& a
+    ) { return a.cast_to<T>(); }
+    /*!
+        ensures
+            - returns a.cast_to<T>()
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+    template <
+        typename T
+        > 
+    const T& any_cast(
+        const any& a
+    ) { return a.cast_to<T>(); }
+    /*!
+        ensures
+            - returns a.cast_to<T>()
+    !*/
+
+// ----------------------------------------------------------------------------------------
+
+}
+
+#endif // DLIB_AnY_ABSTRACT_H_
+
+