SPAR/AIModule/BWTA/vendors/CGAL/CGAL/Handle_with_policy.h

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// Copyright (c) 2001-2007 Max-Planck-Institute Saarbruecken (Germany).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; version 2.1 of the License.
// See the file LICENSE.LGPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.5-branch/STL_Extension/include/CGAL/Handle_with_policy.h $
// $Id: Handle_with_policy.h 44351 2008-07-23 13:19:15Z hoffmann $
//
// Author(s)     : Michael Seel <seel@mpi-inf.mpg.de>
//                 Arno Eigenwillig <arno@mpi-inf.mpg.de>
//                 Lutz Kettner <kettner@mpi-inf.mpg.de>

#ifndef CGAL_HANDLE_WITH_POLICY_H
#define CGAL_HANDLE_WITH_POLICY_H

#include <CGAL/basic.h>
#include <CGAL/memory.h>
#include <CGAL/type_traits.h>

#include <boost/static_assert.hpp>
#include <boost/mpl/if.hpp>

#include <cstddef>

#ifdef CGAL_USE_LEDA
#  if CGAL_LEDA_VERSION < 500
#    include <LEDA/memory.h>
#  else
#    include <LEDA/system/memory.h>
#  endif
#endif



CGAL_BEGIN_NAMESPACE


// Forward declarations of HandlePolicy classes
class Handle_policy_in_place;
class Handle_policy_no_union;
class Handle_policy_union;
class Handle_policy_union_and_reset;

// Reference counted representation
// ================================

template <class T>
class Reference_counted {
public:
    typedef Reference_counted<T> Self;
    typedef T*  Rep_pointer;
private:
    mutable unsigned int count;  // reference counter
    T                    rep;
public:
    Reference_counted() : count(1) {}
    Reference_counted( const T& t) : count(1), rep(t) {}
    Reference_counted( const Self& r) : count(1), rep(r.rep) {}

    void clear() { rep = T(); }
    Rep_pointer  base_ptr()  { return &rep; }
    void add_reference()     { ++count; }
    void remove_reference()  { --count; }
    bool is_shared() const   { return count > 1; }
    int  union_size() const  { return 1+count; }
    void add_union_size(int) {}
};

template <class T>
class Reference_counted_with_forwarding {
public:
    typedef Reference_counted_with_forwarding<T> Self;
    typedef T*  Rep_pointer;
    friend class Handle_policy_union;
    friend class Handle_policy_union_and_reset;
private:
    mutable unsigned int count;  // reference counter
    mutable Self*        next;   // forwarding pointer to valid rep or 0
    mutable int          u_size; // union set size incl this rep and its handle
    mutable T            rep;
public:
    Reference_counted_with_forwarding()
        : count(1), next(0), u_size(2) {}
    Reference_counted_with_forwarding( const T& t)
        : count(1), next(0), u_size(2), rep(t) {}
    Reference_counted_with_forwarding( const Self& r)
        : count(1), next(0), u_size(2), rep(r.rep) {}

    void clear() { rep = T(); }
    Rep_pointer  base_ptr()    { return &rep; }
    void add_reference()       { ++count; }
    void remove_reference()    { --count; }
    bool is_shared() const     { return count > 1; }
    bool is_forwarding() const { return next != 0; }
    int  union_size() const    { return u_size; }
    void add_union_size(int a) {  
        CGAL_precondition( u_size + a > 0);
        u_size += a;
    }
};


struct Reference_counted_hierarchy_base {};


template <class Allocator_  = CGAL_ALLOCATOR(char)>
class Reference_counted_hierarchy : public Reference_counted_hierarchy_base {
    // make sure it's always a char allocator
    typedef typename Allocator_::template rebind< char> Char_alloc_rebind;
    typedef typename Char_alloc_rebind::other   Char_allocator;

    static Char_allocator alloc;

public:
    void* operator new(size_t bytes) { return alloc.allocate( bytes); }
    void  operator delete(void* p, size_t bytes) { 
        alloc.deallocate((char*)p, bytes);
    }

public:
    typedef Allocator_ Allocator;
    typedef Reference_counted_hierarchy<Allocator> Self;
    typedef Self*  Rep_pointer;
private:
    mutable unsigned int count;  // reference counter
public:
    Reference_counted_hierarchy() : count(1) {}
    Reference_counted_hierarchy( const Self&) : count(1) {}

    Rep_pointer base_ptr()   { return this; }
    void add_reference()     { ++count; }
    void remove_reference()  { --count; }
    bool is_shared() const   { return count > 1; }
    int  union_size() const  { return 1+count; }
    void add_union_size(int) {}

    virtual Self* clone() = 0;
    virtual ~Reference_counted_hierarchy() {}
    virtual void clear() {}
};

template <class Alloc>
typename Reference_counted_hierarchy<Alloc>::Char_allocator
    Reference_counted_hierarchy<Alloc>::alloc;

template <class Allocator_  = CGAL_ALLOCATOR(char)>
class Reference_counted_hierarchy_with_union 
    : public Reference_counted_hierarchy<Allocator_> 
{
    friend class Handle_policy_union;
    friend class Handle_policy_union_and_reset;
public:
    typedef Allocator_ Allocator;
    typedef Reference_counted_hierarchy_with_union<Allocator> Self;
private:
    mutable Self*        next;   // forwarding pointer to valid rep or 0
    mutable int          u_size; // union set size incl this rep and its handle
public:
    Reference_counted_hierarchy_with_union() : 
        Reference_counted_hierarchy<Allocator_>(), next(0), u_size(2) {}
    bool is_forwarding() const { return next != 0; }
    int  union_size() const    { return u_size; }
    void add_union_size(int a) {  
        CGAL_precondition( u_size + a > 0);
        u_size += a;
    }
};


// Handle for reference counted representation
// ===========================================

namespace Intern {
    // Some helper classes to select representation between single class
    // representations and class hierarchy representations.

    // the representation type including a reference counter. 
    // The handle allocates objects of this type. This is the version
    // for the single representation type.
    template <class T, int HandleHierarchyPolicy>
    struct Rep_bind_reference_counted {
        typedef Reference_counted<T> Rep;
    };

    // the representation type including a reference counter. 
    // The handle allocates objects of this type. This is the version
    // for the class hierarchy of representation types.
    template <class T>
    struct Rep_bind_reference_counted<T, true> {
        typedef T Rep;
    };

    // the two versions for Reference_counted_with_forwarding
    template <class T, int HandleHierarchyPolicy>
    struct Rep_bind_reference_counted_with_forwarding {
        typedef Reference_counted_with_forwarding<T> Rep;
    };

    // the representation type including a reference counter. 
    // The handle allocates objects of this type. This is the version
    // for the class hierarchy of representation types.
    template <class T>
    struct Rep_bind_reference_counted_with_forwarding<T, true> {
        Rep_bind_reference_counted_with_forwarding() {
            // make sure we derived from the right type 
            typedef typename T::Allocator Alloc;
            typedef ::CGAL::Reference_counted_hierarchy_with_union<Alloc> 
                Reference_counted_hierarchy_with_union;
            BOOST_STATIC_ASSERT((
              ::CGAL::is_same_or_derived< Reference_counted_hierarchy_with_union, T >::value ));
        }
        typedef T Rep;
    };

}

class Handle_policy_in_place {};

class Handle_policy_no_union {
public:
    template <class T, int hierarchy>
    struct Rep_bind {
        typedef typename 
            Intern::Rep_bind_reference_counted<T,hierarchy>::Rep Rep;
    };

    template <class Alloc>
    struct Hierarchy_base {
        typedef Reference_counted_hierarchy<Alloc> Type;
    };
    
    template <class H>
    static void unify( const H& h, const H& g) {
        (void)h; // avoid warnings for unused parameters
        (void)g; // but keep the names in the definition for the doc.
    }

    template <class H>
    static typename H::Rep_pointer find( const H& h) {
        return h.ptr_->base_ptr();
    }
};

class Handle_policy_union {
public:
    template <class T, int hierarchy>
    struct Rep_bind {
        Rep_bind() {
          //Intern::Rep_bind_reference_counted_with_forwarding<T, hierarchy>
          //     check;
          //  (void)check;
          (void)Intern::Rep_bind_reference_counted_with_forwarding<T, hierarchy>();
        }
        typedef typename Intern::Rep_bind_reference_counted_with_forwarding<T,
            hierarchy>::Rep Rep;
    };

    template <class Alloc>
    struct Hierarchy_base {
        typedef Reference_counted_hierarchy_with_union<Alloc> Type;
    };
    
    template <class H>
    static void unify_large_small( const H& h, const H& g) {
        typename H::Rep* hrep = h.ptr_;
        typename H::Rep* grep = g.ptr_;
        CGAL_precondition( ! grep->is_forwarding());
        CGAL_precondition( hrep->union_size() >= grep->union_size());
        grep->add_union_size(-1);
        // make g point to h's rep.
        if ( grep->is_shared()) {
            // grep survises the loss of one reference 
            // and hrep gets one more reference
            grep->remove_reference();
            hrep->add_reference();
            hrep->add_union_size( grep->union_size());
            grep->next = hrep;
        } else {
            g.delete_rep( grep); // did not survive loss of handle g
        }
        // redirect handle g and incr. hrep's counter
        g.ptr_ = hrep;
        hrep->add_reference();
        hrep->add_union_size(1);
    }

    template <class H>
    static void unify( const H& h, const H& g) {
        if ( find(h) !=  find(g)) {
            if ( h.ptr_->union_size() > g.ptr_->union_size())
                unify_large_small( h, g); // make g point to h's rep.
            else
                unify_large_small( g, h); // make h point to g's rep.
        }
    }

    template <class H>
    static typename H::Rep_pointer find( const H& h) {
        typedef typename H::Rep Rep;
        if ( h.ptr_->is_forwarding()) {
            // find new valid representation
            Rep* new_rep = h.ptr_;
            while ( new_rep->next != 0)
                new_rep = static_cast<Rep*>(new_rep->next);
            // path compression: assign new rep to all reps seen on the path
            // update reference count properly: all reps on the path loose
            // one reference, and the new_rep gains all of them unless
            // the rep on the path get actually deleted.
            Rep* rep = h.ptr_;
            while ( rep != new_rep) {
                Rep* tmp = static_cast<Rep*>(rep->next);
                if ( rep->is_shared()) {
                    // rep survives the loss of one reference 
                    // and new_rep gets one more reference
                    rep->remove_reference();
                    if ( tmp != new_rep) {
                        // re-link rep to the new_rep
                        rep->next = new_rep;
                        new_rep->add_reference();
                    }
                } else {
                    h.delete_rep( rep); // we have to delete the current rep
                }                
                rep = tmp;
            }
            // hook h to new_rep
            h.ptr_ = new_rep;
            new_rep->add_reference();
        }
        return h.ptr_->base_ptr();
    }
};

class Handle_policy_union_and_reset {
public:
    template <class T, int hierarchy>
    struct Rep_bind {
        Rep_bind() {
          //Intern::Rep_bind_reference_counted_with_forwarding<T, hierarchy>
          //     check;
          // (void)check;
          (void)Intern::Rep_bind_reference_counted_with_forwarding<T, hierarchy>();
        }
        typedef typename Intern::Rep_bind_reference_counted_with_forwarding<T,
            hierarchy>::Rep Rep;
    };

    template <class Alloc>
    struct Hierarchy_base {
        typedef Reference_counted_hierarchy_with_union<Alloc> Type;
    };

    // abbreviation to re-use its implementation below.
    typedef Handle_policy_union U;

    template <class H>
    static void unify( const H& h, const H& g) {
        if ( find(h) !=  find(g)) {
            if ( h.ptr_->union_size() > g.ptr_->union_size()) {
                // reset representation in g to default construction of T
                if ( g.ptr_->is_shared())
                    g.ptr_->clear();
                U::unify_large_small( h, g); // make g point to h's rep.
            } else {
                // reset representation in h to default construction of T
                if ( h.ptr_->is_shared())
                    h.ptr_->clear();
                U::unify_large_small( g, h); // make h point to g's rep.
            }
        }
    }

    template <class H>
    static typename H::Rep_pointer find( const H& h) { return U::find(h); }
};


template <class T, 
          class HandlePolicy = Handle_policy_no_union, 
          class Allocator_ = CGAL_ALLOCATOR(T)>
class Handle_with_policy {
public:
    typedef Handle_with_policy< T, HandlePolicy, Allocator_>    Self;

    typedef HandlePolicy                Handle_policy;

    typedef Allocator_                  Allocator;

    enum { is_class_hierarchy  = 
        ::CGAL::is_same_or_derived< Reference_counted_hierarchy_base, T>::value };
    typedef typename Handle_policy::template Rep_bind< T, is_class_hierarchy > Bind;
    // instantiate Rep_bind to activate compile time check in there
    static Bind bind;
    // Define type that is used for function matching 
    typedef typename ::boost::mpl::if_c< 
         is_class_hierarchy, 
           ::CGAL::Tag_true, 
           ::CGAL::Tag_false >::type 
         Class_hierarchy;

    typedef typename Bind::Rep  Rep;

    typedef typename Rep::Rep_pointer  Rep_pointer;

    typedef typename Allocator_::template rebind<Rep>::other  Rep_allocator;


    typedef std::ptrdiff_t              Id_type;

    friend class Handle_policy_no_union;
    friend class Handle_policy_union;
    friend class Handle_policy_union_and_reset;
private:
    mutable Rep*  ptr_;

    // We have to distinguish between allocating single representations
    // and where we have a class hierarchy of representations, where the
    // user is responsible for allocating the first representations
    // and we can just \c clone and delete them.
    static Rep_allocator allocator;

    static Rep* new_rep( const Rep& rep) { 
        BOOST_STATIC_ASSERT( !(
           ::CGAL::is_same_or_derived< Reference_counted_hierarchy_base, T >::value ));
        Rep* p = allocator.allocate(1);
        allocator.construct(p, rep);
        return p;
    }
    static void delete_rep( Rep* p, ::CGAL::Tag_false ) {
        allocator.destroy( p);
        allocator.deallocate( p, 1);
    }
    static void delete_rep( Rep* p, ::CGAL::Tag_true ) {
        delete p;
    }
    static void delete_rep( Rep* p) { delete_rep(p, Class_hierarchy()); }

    static Rep* clone_rep( Rep* p, ::CGAL::Tag_false ) {
        return new_rep( *p);
    }
    static Rep* clone_rep( Rep* p, ::CGAL::Tag_true ) {
        return static_cast<Rep*>(p->clone());
    }
    static Rep* clone_rep( Rep* p) { return clone_rep( p, Class_hierarchy()); }

    void remove_reference() {
        // cleans up the possible chain of forwarding reps
        Handle_policy::find( *this);
        if ( ! is_shared()) {
            delete_rep( ptr_);
        } else {
            ptr_->remove_reference();
            ptr_->add_union_size( -1);
        }
    }

    template <class TT>
    Rep* make_from_single_arg( const TT& t, ::CGAL::Tag_false ) {
        return new_rep( Rep( T(t)));
    }
    template <class TT>
    Rep* make_from_single_arg( TT t, ::CGAL::Tag_true ) {
      //Bind bind_; // trigger compile-time check
      // (void)bind_;
      (void)Bind(); // shouldn't this be enough to trigger?
        return t; // has to be a pointer convertible to Rep*
    }

protected:
    T*       ptr()       { return static_cast<T*>(Handle_policy::find(*this));}
    const T* ptr() const { 
        return static_cast<const T*>(Handle_policy::find( *this));
    }

    void unify( const Self& h) const { Handle_policy::unify( *this, h); }

    void copy_on_write() {
        Handle_policy::find( *this);
        if ( is_shared() ) {
            Rep* tmp_ptr = clone_rep( ptr_);
            ptr_->remove_reference();
            ptr_->add_union_size( -1);
            ptr_ = tmp_ptr;
        }
    }

    enum Use_with_initialize_with {
        USE_WITH_INITIALIZE_WITH 

    };

    Handle_with_policy( Use_with_initialize_with) : ptr_( 0) {}

    Handle_with_policy( Rep* p) : ptr_( p) {
        BOOST_STATIC_ASSERT((
           ::CGAL::is_same_or_derived< Reference_counted_hierarchy_base, T >::value ));
        //Bind bind_; // trigger compile-time check
        //(void)bind_;
        (void)Bind();
    }

    void initialize_with( Rep* p) {
        BOOST_STATIC_ASSERT((
           ::CGAL::is_same_or_derived< Reference_counted_hierarchy_base, T >::value ));
        //Bind bind_; // trigger compile-time check
        //(void)bind_;
        (void)Bind();
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = p;
    }

    template <class T1>
    void initialize_with( const T1& t1) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = make_from_single_arg( t1, Class_hierarchy());
    }

    template <class T1, class T2>
    void initialize_with( const T1& t1, const T2& t2) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = new_rep( Rep( T(t1,t2)));
    }

    template <class T1, class T2, class T3>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = new_rep( Rep( T(t1,t2,t3)));
    }

    template <class T1, class T2, class T3, class T4>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = new_rep( Rep( T(t1,t2,t3,t4)));
    }

    template <class T1, class T2, class T3, class T4, class T5>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = new_rep( Rep( T(t1,t2,t3,t4,t5)));
    }

    template <class T1, class T2, class T3, class T4, class T5, class T6>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5, const T6& t6) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = new_rep( Rep( T(t1,t2,t3,t4,t5,t6)));
    }

    template <class T1, class T2, class T3, class T4, class T5, class T6,
              class T7>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5, const T6& t6,
                          const T7& t7) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = new_rep( Rep( T(t1,t2,t3,t4,t5,t6,t7)));
    }

    template <class T1, class T2, class T3, class T4, class T5, class T6,
              class T7, class T8>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5, const T6& t6,
                          const T7& t7, const T8& t8) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = new_rep( Rep( T(t1,t2,t3,t4,t5,t6,t7,t8)));
    }

    template <class T1, class T2, class T3, class T4, class T5, class T6,
              class T7, class T8, class T9>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5, const T6& t6,
                          const T7& t7, const T8& t8, const T9& t9) {
        CGAL_precondition_msg( ptr_ == 0, "Handle_with_policy::initialize_with(): the "
                         "representation has already been initialized.");
        ptr_ = new_rep( Rep( T(t1,t2,t3,t4,t5,t6,t7,t8,t9)));
    }

public:
    Handle_with_policy() : ptr_( new_rep( Rep())) {}

    Handle_with_policy(const Self& h) {
        CGAL_precondition_msg( h.ptr_ != 0, "Handle_with_policy::Handle_with_policy( Self): probably "
                         "used special protected constructor and not the "
                         "'initialize_with()' function.");
        Handle_policy::find( h);
        ptr_ = h.ptr_;
        ptr_->add_reference();
        ptr_->add_union_size( 1);
    }

    template <class T1>
    explicit Handle_with_policy( const T1& t) 
        : ptr_( make_from_single_arg( t, Class_hierarchy())) {}

    template <class T1, class T2>
    Handle_with_policy( const T1& t1, const T2& t2) : ptr_( new_rep( Rep( T( t1, t2)))) {}

    template <class T1, class T2, class T3>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3) 
        : ptr_( new_rep( Rep( T( t1, t2, t3)))) {}

    template <class T1, class T2, class T3, class T4>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4) 
        : ptr_( new_rep( Rep( T( t1, t2, t3, t4)))) {}

    template <class T1, class T2, class T3, class T4, class T5>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5) 
        : ptr_( new_rep( Rep( T( t1, t2, t3, t4, t5)))) {}

    template <class T1, class T2, class T3, class T4, class T5, class T6>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5, const T6& t6) 
        : ptr_( new_rep( Rep( T( t1, t2, t3, t4, t5, t6)))) {}

    template <class T1, class T2, class T3, class T4, class T5, class T6, 
              class T7>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5, const T6& t6, const T7& t7) 
        : ptr_( new_rep( Rep( T( t1, t2, t3, t4, t5, t6, t7)))) {}

    template <class T1, class T2, class T3, class T4, class T5, class T6, 
              class T7, class T8>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5, const T6& t6, const T7& t7, const T8& t8) 
        : ptr_( new_rep( Rep( T( t1, t2, t3, t4, t5, t6, t7, t8)))) {}

    template <class T1, class T2, class T3, class T4, class T5, class T6, 
              class T7, class T8, class T9>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5, const T6& t6, const T7& t7, const T8& t8,
            const T9& t9) 
        : ptr_( new_rep( Rep( T( t1, t2, t3, t4, t5, t6, t7, t8, t9)))) {}

    ~Handle_with_policy() {
      //Bind bind_; // trigger compile-time check
      //(void)bind_;
      (void)Bind();
        CGAL_precondition_msg( ptr_ != 0, "Handle_with_policy::~Handle_with_policy(): probably used "
                         "special protected constructor and not the "
                         "'initialize_with()' function.");
        remove_reference();
    }

    Self& operator=( const Self& h) {
        CGAL_precondition_msg( h.ptr_ != 0, "Handle_with_policy::operator=(): probably "
                         "used special protected constructor and not the "
                         "'initialize_with()' function.");
        Handle_policy::find( h);
        h.ptr_->add_reference();
        h.ptr_->add_union_size( 1);
        remove_reference();
        ptr_ = h.ptr_;
        return *this;
    }

    bool is_identical( const Self& h) const { return ptr() == h.ptr(); }

    Id_type id() const { return reinterpret_cast<Id_type>(&*ptr()); }

    bool is_shared() const { return ptr_->is_shared(); }

    bool is_forwarding() const { return ptr_->is_forwarding(); }

    int  union_size() const { return ptr_->union_size(); }

    // backwards compatible
    bool identical( const Self& h) const { return is_identical(h); }

#ifdef CGAL_HANDLE_WITH_POLICY_INTERNAL_TEST
    // provide access to pointer for testing only!!
    const Rep* test_ptr() const { return ptr_; }
    // provide access to pointer for testing only!!
    bool test_identical_ptr( const Self& h) const { return ptr_ == h.ptr_; }
#endif // CGAL_HANDLE_WITH_POLICY_INTERNAL_TEST
};

// instantiate Rep_bind to activate compile time check in there
template <class T, class Policy, class Alloc>
typename Handle_with_policy<T,Policy,Alloc>::Bind Handle_with_policy<T,Policy,Alloc>::bind;



template <class T, class A>
unsigned long ID_Number(const Handle_with_policy<T, Handle_policy_no_union, A>& h)
    { return h.id(); }

template <class T, class Policy, class Alloc>
typename Handle_with_policy<T, Policy, Alloc>::Rep_allocator 
    Handle_with_policy<T, Policy, Alloc>::allocator;


template <class T, class Allocator_>
class Handle_with_policy<T, Handle_policy_in_place, Allocator_> {
public:
    typedef Handle_with_policy< T, Handle_policy_in_place, Allocator_>   Self;

    typedef Handle_policy_in_place                           Handle_policy;

    typedef Allocator_                                Allocator;

    typedef T                                         Rep;

    typedef std::ptrdiff_t                            Id_type;
private:
    // store the rep in place
    Rep  rep;

protected:
    T*       ptr()       { return &rep; }
    const T* ptr() const { return &rep; }

    void unify( const Self&) const {}

    void copy_on_write() {}

    enum Use_with_initialize_with {
        USE_WITH_INITIALIZE_WITH 
    };

    Handle_with_policy( Use_with_initialize_with) {}
    
    template <class T1>
    void initialize_with( const T1& t1) { rep = Rep(t1); }

    template <class T1, class T2>
    void initialize_with( const T1& t1, const T2& t2) { rep = Rep(t1,t2); }

    template <class T1, class T2, class T3>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3) {
        rep = Rep(t1,t2,t3);
    }

    template <class T1, class T2, class T3, class T4>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4) {
        rep = Rep(t1,t2,t3,t4);
    }

    template <class T1, class T2, class T3, class T4, class T5>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5) {
        rep = Rep(t1,t2,t3,t4,t5);
    }

    template <class T1, class T2, class T3, class T4, class T5, class T6>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5, const T6& t6) {
        rep = Rep(t1,t2,t3,t4,t5,t6);
    }

    template <class T1, class T2, class T3, class T4, class T5, class T6,
              class T7>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5, const T6& t6,
                          const T7& t7) {
        rep = Rep(t1,t2,t3,t4,t5,t6,t7);
    }

    template <class T1, class T2, class T3, class T4, class T5, class T6,
              class T7, class T8>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5, const T6& t6,
                          const T7& t7, const T8& t8) {
        rep = Rep(t1,t2,t3,t4,t5,t6,t7,t8);
    }

    template <class T1, class T2, class T3, class T4, class T5, class T6,
              class T7, class T8, class T9>
    void initialize_with( const T1& t1, const T2& t2, const T3& t3,
                          const T4& t4, const T5& t5, const T6& t6,
                          const T7& t7, const T8& t8, const T9& t9) {
        rep = Rep(t1,t2,t3,t4,t5,t6,t7,t8,t9);
    }

public:
    Handle_with_policy() {}

    Handle_with_policy(const Self& h) : rep( h.rep) {}

    template <class T1>
    explicit Handle_with_policy( const T1& t) : rep( Rep(t)) {}

    template <class T1, class T2>
    Handle_with_policy( const T1& t1, const T2& t2) : rep( Rep(t1,t2)) {}

    template <class T1, class T2, class T3>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3) : rep( Rep(t1,t2,t3)) {}

    template <class T1, class T2, class T3, class T4>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4) 
        : rep( Rep( t1, t2, t3, t4)) {}

    template <class T1, class T2, class T3, class T4, class T5>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5) 
        : rep( Rep( t1, t2, t3, t4, t5)) {}

    template <class T1, class T2, class T3, class T4, class T5, class T6>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5, const T6& t6) 
        : rep( Rep( t1, t2, t3, t4, t5, t6)) {}

    template <class T1, class T2, class T3, class T4, class T5, class T6, 
              class T7>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5, const T6& t6, const T7& t7) 
        : rep( Rep( t1, t2, t3, t4, t5, t6, t7)) {}

    template <class T1, class T2, class T3, class T4, class T5, class T6, 
              class T7, class T8>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5, const T6& t6, const T7& t7, const T8& t8) 
        : rep( Rep( t1, t2, t3, t4, t5, t6, t7, t8)) {}

    template <class T1, class T2, class T3, class T4, class T5, class T6, 
              class T7, class T8, class T9>
    Handle_with_policy( const T1& t1, const T2& t2, const T3& t3, const T4& t4,
            const T5& t5, const T6& t6, const T7& t7, const T8& t8,
            const T9& t9) 
        : rep( Rep( t1, t2, t3, t4, t5, t6, t7, t8, t9)) {}

    bool is_identical( const Self& h) const { return this == &h; }

    Id_type id() const { return reinterpret_cast<Id_type>(this); }

    bool is_shared() const { return false; }

    bool is_forwarding() const { return false; }

    int  union_size() const { return 1; }

    // backwards compatible
    bool identical( const Self& h) const { return is_identical(h); }

#ifdef CGAL_HANDLE_WITH_POLICY_INTERNAL_TEST
    // provide access to pointer for testing only!!
    const Rep* test_ptr() const { return *rep; }
    // provide access to pointer for testing only!!
    bool test_identical_ptr( const Self& h) const { return this == &h; }
#endif // CGAL_HANDLE_WITH_POLICY_INTERNAL_TEST

#ifdef CGAL_USE_LEDA
    LEDA_MEMORY( Self)
#endif
};

/*\brief
 * This class' function call operator test whether one handle's \c id is
 * less than the \c id of the other handle.
 *
 * "Less" is defined in terms of the second template argument,
 * which defaults to \c std::less<Handle::Id_type>
 */
template <class Handle, class Less = std::less<typename Handle::Id_type> >
class Handle_id_less_than {
public:
    typedef bool result_type;
    typedef Handle first_argument_type;
    typedef Handle second_argument_type;
    bool operator () (Handle h1, Handle h2) {
        Less is_less;
        return is_less(h1.id(), h2.id());
    }
    bool operator () (Handle h1, Handle h2) const {
        Less is_less;
        return is_less(h1.id(), h2.id());
    }
};



CGAL_END_NAMESPACE

#endif // CGAL_HANDLE_WITH_POLICY_H