contrib/mul/mbl/mbl_cloneable_ptr.h

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// This is mul/mbl/mbl_cloneable_ptr.h
#ifndef mbl_cloneable_ptr_h
#define mbl_cloneable_ptr_h
//:
// \file

#include <vsl/vsl_binary_loader.h>
#include <vcl_cassert.h>

//=======================================================================
//: Cunning pointer for objects that can be cloned.
//  Used to record base class pointers to objects
//  When copied, the object pointed to gets cloned.
//  When written or read to/from binary streams,
//  suitable polymorphic I/O is invoked.
//
// \code
// vcl_auto_ptr<T> inst = get_from_some_factory_function();
// mbl_cloneable_ptr<T> long_term_store;
// long_term_store = inst.release();
// \endcode
template <class BaseClass>
class mbl_cloneable_ptr
{
  BaseClass* ptr_;
 public:
  //: Default constructor (zeros pointer)
  mbl_cloneable_ptr() : ptr_(0) {}

  //: Delete object pointed to and set pointer to zero
  void deleteObject() { delete ptr_; ptr_=0; }

  //: Destructor
  ~mbl_cloneable_ptr() { deleteObject(); }

  //: Copy constructor
  mbl_cloneable_ptr(const mbl_cloneable_ptr<BaseClass>& p) : ptr_(0) { *this = p; }

  //: Construct from pointer, making a clone of r.
  mbl_cloneable_ptr(const BaseClass& r) : ptr_(r.clone()) { assert(ptr_); }

  //: Constructor from pointer, taking ownership of *p.
  mbl_cloneable_ptr(BaseClass* p) : ptr_(p) { assert(ptr_); }

  //: Copy operator
  mbl_cloneable_ptr<BaseClass>& operator=(const mbl_cloneable_ptr<BaseClass>& p)
  {
    if (this==&p) return *this;
    deleteObject(); if (p.ptr_!=0) ptr_=p.ptr_->clone();
    return *this;
  }

  //: Copy operator - takes clone of p
  mbl_cloneable_ptr<BaseClass>& operator=(const BaseClass& p)
  {
    if (ptr_==&p) return *this;
    deleteObject();
    ptr_= p.clone();
    return *this;
  }

  //: Copy operator - takes responsibility for *p
  //  Sets internal pointer to p, and takes responsibility
  //  for deleting *p
  mbl_cloneable_ptr<BaseClass>& operator=(BaseClass* p)
  {
    if (ptr_==p) return *this;
    deleteObject();
    ptr_= p;
    return *this;
  }

  //: Return true if pointer defined
  bool isDefined() const { return ptr_!=0; }

  //: Make object behave like pointer to BaseClass
  const BaseClass* operator->() const { return ptr_; }

  //: Make object behave like pointer to BaseClass
  BaseClass* operator->() { return ptr_; }

  //: Return actual pointer
  const BaseClass* ptr() const { return ptr_; }

  //: Return actual pointer
  BaseClass* ptr() { return ptr_; }

  //: Return wrapped pointer and give up ownership
  BaseClass* release()
  { BaseClass* p = ptr_; ptr_=0; return p; }

  //: Cast to allow object to look like thing pointed to
  operator BaseClass&() { assert(ptr_!=0); return *ptr_; }

  //: Dereferencing the pointer
  BaseClass &operator * () { return *ptr_; }

  //: Dereferencing the pointer
  const BaseClass &operator * () const { return *ptr_; }

  //: Cast to allow object to look like thing pointed to
  operator const BaseClass&() const { assert(ptr_!=0); return *ptr_; }

  //: Save to binary stream
  void b_write(vsl_b_ostream& bfs) const
  {
    vsl_b_write(bfs,ptr_);
  }

  //: Load from binary stream
  void b_read(vsl_b_istream& bfs)
  {
    deleteObject();
    vsl_b_read(bfs,ptr_);
  }
};

template <class BaseClass>
void vsl_b_write(vsl_b_ostream& bfs, const mbl_cloneable_ptr<BaseClass>& p)
{ p.b_write(bfs); }

template <class BaseClass>
void vsl_b_read(vsl_b_istream& bfs, mbl_cloneable_ptr<BaseClass>& p)
{ p.b_read(bfs); }


//=======================================================================
//: Cunning non-zero pointer for objects that can be cloned.
//  The pointer is guaranteed to always point to something.
//  Used to record base class pointers to objects
//  When copied, the object pointed to gets cloned.
//  When written or read to/from binary streams,
//  suitable polymorphic I/O is invoked.
//
// To take ownership of the contents of a vcl_auto_ptr<T> use
// \code
// vcl_auto_ptr<T> inst = get_from_some_factory_function();
// mbl_cloneable_nzptr<T> long_term_store(inst.release());
// \endcode
template <class BaseClass>
class mbl_cloneable_nzptr
{
  BaseClass* ptr_;
 public:

  //: Destructor
  ~mbl_cloneable_nzptr() { delete ptr_; }

  //: Copy constructor
  // There is no default constructor.
  mbl_cloneable_nzptr(const mbl_cloneable_nzptr<BaseClass>& cp):
    ptr_(cp.ptr_->clone()) { assert(ptr_); }

  //: Construct from pointer, making a clone of r.
  // There is no default constructor.
  mbl_cloneable_nzptr(const BaseClass& r) : ptr_(r.clone()) { assert(ptr_); }

  //: Constructor from pointer, taking ownership of *p.
  // There is no default constructor.
  mbl_cloneable_nzptr(BaseClass* p) : ptr_(p) { assert(ptr_); }

  //: Copy operator
  mbl_cloneable_nzptr<BaseClass>& operator=(const mbl_cloneable_nzptr<BaseClass>& cp)
  {
    if (this==&cp) return *this;
    BaseClass * tmp=cp.ptr_->clone();
    assert(tmp);
    delete ptr_;
    ptr_ = tmp;
    return *this;
  }

  //: Copy operator - takes clone of r
  mbl_cloneable_nzptr<BaseClass>& operator=(const BaseClass& r)
  {
    if (ptr_==&r) return *this;
    BaseClass * tmp=r.clone();  // Do it in this order, in case clone throws an exception.
    assert(tmp);
    delete ptr_;
    ptr_= tmp;
    return *this;
  }

  //: Copy operator - takes responsibility for *p
  //  Sets internal pointer to p, and takes responsibility
  //  for deleting *p
  mbl_cloneable_nzptr<BaseClass>& operator=(BaseClass* p)
  {
    assert(p);
    if (ptr_==p) return *this;
    delete ptr_;
    ptr_= p;
    return *this;
  }

  //: Return true.
  bool isDefined() const { return true; }

  //: Make object behave like pointer to BaseClass
  const BaseClass* operator->() const { return ptr_; }

  //: Make object behave like pointer to BaseClass
  BaseClass* operator->() { return ptr_; }

  //: Return actual pointer
  const BaseClass* ptr() const { return ptr_; }

  //: Return actual pointer
  BaseClass* ptr() { return ptr_; }

  //: Return and give up ownership of wrapped pointer, while taking ownership a new pointer.
  BaseClass* replace(BaseClass* p)
  { BaseClass* old = ptr_; ptr_=p; return old; }

  //: Cast to allow object to look like thing pointed to
  operator BaseClass&() { return *ptr_; }

  //: Cast to allow object to look like thing pointed to
  operator const BaseClass&() const { return *ptr_; }

  //: Dereferencing the pointer
  BaseClass &operator * () { return *ptr_; }

  //: Dereferencing the pointer
  const BaseClass &operator * () const { return *ptr_; }

  //: Save to binary stream
  void b_write(vsl_b_ostream& bfs) const
  {
    vsl_b_write(bfs,ptr_);
  }

  //: Load from binary stream
  void b_read(vsl_b_istream& bfs)
  {
    delete ptr_;
    ptr_ = 0;
    vsl_b_read(bfs,ptr_);
  }
};

template <class BaseClass>
void vsl_b_write(vsl_b_ostream& bfs, const mbl_cloneable_nzptr<BaseClass>& p)
{ p.b_write(bfs); }

template <class BaseClass>
void vsl_b_read(vsl_b_istream& bfs, mbl_cloneable_nzptr<BaseClass>& p)
{ p.b_read(bfs); }

#define MBL_CLONEABLE_PTR_INSTANTIATE(T) /* nothing */
#if 0 // was:
VCL_DEFINE_SPECIALIZATION class mbl_cloneable_ptr<T >; \
VCL_DEFINE_SPECIALIZATION void vsl_b_write(vsl_b_ostream& bfs, const mbl_cloneable_ptr<T >& p);\
VCL_DEFINE_SPECIALIZATION void vsl_b_read(vsl_b_istream& bfs, mbl_cloneable_ptr<T >& p);\
VCL_DEFINE_SPECIALIZATION class mbl_cloneable_nzptr<T >; \
VCL_DEFINE_SPECIALIZATION void vsl_b_write(vsl_b_ostream& bfs, const mbl_cloneable_nzptr<T >& p);\
VCL_DEFINE_SPECIALIZATION void vsl_b_read(vsl_b_istream& bfs, mbl_cloneable_nzptr<T >& p)
#endif // 0

#endif  // mbl_cloneable_ptr_h