DGtal::CowPtr< T > Class Template Reference

Aim: Copy on write shared pointer. More...

#include <DGtal/base/CowPtr.h>

Inheritance diagram for DGtal::CowPtr< T >:

Public Types
typedef T	element_type

Public Member Functions
	CowPtr (T *p=0) noexcept
	CowPtr (const CowPtr &r) noexcept
	CowPtr (const CountedPtr< T > &r, bool)
CowPtr &	operator= (const CowPtr &r)
const T &	operator* () const noexcept
const T *	operator-> () const noexcept
const T *	get () const noexcept
template<typename U = T, typename std::enable_if< ! std::is_const< U >::value >::type * = nullptr>
T &	operator* ()
template<typename U = T, typename std::enable_if< ! std::is_const< U >::value >::type * = nullptr>
T *	operator-> ()
template<typename U = T, typename std::enable_if< ! std::is_const< U >::value >::type * = nullptr>
T *	get ()
bool	operator== (const T *other) const
bool	operator!= (const T *other) const
unsigned int	count () const
T *	drop ()
bool	unique () const noexcept
void	selfDisplay (std::ostream &out) const
bool	isValid () const

Private Member Functions
void	copy ()

Private Attributes
CountedPtr< T >	myPtr

Detailed Description

template<typename T>
class DGtal::CowPtr< T >

Aim: Copy on write shared pointer.

Description of template class 'CowPtr'

Use reference counting as long as the pointed object is not modified. When it is about to be modified, copy it and modify the copy.

Taken from http://ootips.org/yonat/4dev/smart-pointers.html

Definition at line 67 of file CowPtr.h.

Member Typedef Documentation

element_type

template<typename T>

typedef T DGtal::CowPtr< T >::element_type

Definition at line 72 of file CowPtr.h.

Constructor & Destructor Documentation

CowPtr() [1/3]

template<typename T>

DGtal::CowPtr< T >::CowPtr ( T * p = 0 )

inlineexplicitnoexcept

Definition at line 74 of file CowPtr.h.

: myPtr(p) {}

CowPtr() [2/3]

template<typename T>

DGtal::CowPtr< T >::CowPtr ( const CowPtr< T > & r )

inlinenoexcept

Definition at line 76 of file CowPtr.h.

: myPtr(r.myPtr) {}

CowPtr() [3/3]

template<typename T>

DGtal::CowPtr< T >::CowPtr ( const CountedPtr< T > & r, bool  )

inline

Builds a copy-on-write pointer from a counted pointer. Requires an extra dummy parameter in order to solve ambiguities when casting from Clone<T> to CowPtr<T>.

Parameters

r	any counted pointer

Note

Since 1.0, there is no more the direct constructor CowPtr<T>::CowPtr( CountedPtr<T> ). Indeed, it was creating an ambiguity when using conversion operator in class Clone<T>. More precisely it was impossible to have two conversion operators: Clone<T>::operator CountedPtr<T> and Clone<T>::operator CowPtr<T> since this was creating a compilation ambiguity. This is why there is now a dummy bool parameter in this constructor while both conversion operators Clone<T>::operator CountedPtr<T> and Clone<T>::operator CowPtr<T> are present.

struct B {};
struct A {
  CowPtr<B> _bcow;
  CountedPtr<B> _bcounted;
  // both constructions below are valid and do lazy copy if possible.
  A( Clone<B> b1, Clone<B> b2 ) : _bcow( b1 ), _bcounted( b2 ) {}
};

Definition at line 106 of file CowPtr.h.

: myPtr( r ) {}

Member Function Documentation

copy()

template<typename T>

void DGtal::CowPtr< T >::copy ( )

inlineprivate

Definition at line 186 of file CowPtr.h.

    {
        if (!myPtr.unique()) {
            T* old_p = myPtr.get();
            myPtr = CountedPtr<T>(new T(*old_p));
        }
    }

Referenced by DGtal::CowPtr< StabbingLineComputer< ConstIterator > >::get(), DGtal::CowPtr< StabbingLineComputer< ConstIterator > >::operator*(), and DGtal::CowPtr< StabbingLineComputer< ConstIterator > >::operator->().

count()

template<typename T>

unsigned int DGtal::CowPtr< T >::count ( ) const

inline

For debug.

Definition at line 173 of file CowPtr.h.

{ return myPtr.count(); }

drop()

template<typename T>

T * DGtal::CowPtr< T >::drop ( )

inline

Definition at line 174 of file CowPtr.h.

{ return myPtr.drop(); }

get() [1/2]

template<typename T>

template<typename U = T, typename std::enable_if< ! std::is_const< U >::value >::type * = nullptr>

T * DGtal::CowPtr< T >::get ( )

inline

Definition at line 145 of file CowPtr.h.

{copy(); return myPtr.get();}

get() [2/2]

template<typename T>

const T * DGtal::CowPtr< T >::get ( ) const

inlinenoexcept

Definition at line 117 of file CowPtr.h.

{return myPtr.get();}

Referenced by DGtal::CowPtr< StabbingLineComputer< ConstIterator > >::operator!=(), and DGtal::CowPtr< StabbingLineComputer< ConstIterator > >::operator==().

isValid()

template<typename T>

bool DGtal::CowPtr< T >::isValid

(

)

const

Checks the validity/consistency of the object.

Returns

'true' if the object is valid, 'false' otherwise.

operator!=()

template<typename T>

bool DGtal::CowPtr< T >::operator!= ( const T * other ) const

inline

Inequality operator !=

Parameters

other

any other pointer.

Returns

'true' if pointed address is different from other.

Definition at line 164 of file CowPtr.h.

    {
      return get() != other;
    }

operator*() [1/2]

template<typename T>

template<typename U = T, typename std::enable_if< ! std::is_const< U >::value >::type * = nullptr>

T & DGtal::CowPtr< T >::operator* ( )

inline

Definition at line 139 of file CowPtr.h.

{copy(); return *myPtr;}

operator*() [2/2]

template<typename T>

const T & DGtal::CowPtr< T >::operator* ( ) const

inlinenoexcept

Definition at line 115 of file CowPtr.h.

{return *myPtr;}

operator->() [1/2]

template<typename T>

template<typename U = T, typename std::enable_if< ! std::is_const< U >::value >::type * = nullptr>

T * DGtal::CowPtr< T >::operator-> ( )

inline

Definition at line 142 of file CowPtr.h.

{copy(); return myPtr.get();}

operator->() [2/2]

template<typename T>

const T * DGtal::CowPtr< T >::operator-> ( ) const

inlinenoexcept

Definition at line 116 of file CowPtr.h.

{return myPtr.get();}

operator=()

template<typename T>

CowPtr & DGtal::CowPtr< T >::operator= ( const CowPtr< T > & r )

inline

Definition at line 107 of file CowPtr.h.

    {
        if (this != &r)
            myPtr = r.myPtr;
        return *this;
    }

operator==()

template<typename T>

bool DGtal::CowPtr< T >::operator== ( const T * other ) const

inline

Equality operator ==

Parameters

other

any other pointer.

Returns

'true' if pointed address is equal to other.

Definition at line 153 of file CowPtr.h.

    {
      return get() == other;
    }

selfDisplay()

template<typename T>

void DGtal::CowPtr< T >::selfDisplay

(

std::ostream &

out

)

const

Writes/Displays the object on an output stream.

Parameters

out	the output stream where the object is written.

unique()

template<typename T>

bool DGtal::CowPtr< T >::unique ( ) const

inlinenoexcept

Definition at line 175 of file CowPtr.h.

{ return myPtr.unique(); }

Field Documentation

myPtr

template<typename T>

CountedPtr<T> DGtal::CowPtr< T >::myPtr

private

Definition at line 182 of file CowPtr.h.

Referenced by DGtal::CowPtr< StabbingLineComputer< ConstIterator > >::operator=().

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The documentation for this class was generated from the following file:

• CowPtr.h