copy_on_write Class Template Reference
[copy_on_write]

#include <copy_on_write.hpp>

List of all members.

---

Detailed Description

template<typename T>
class adobe::copy_on_write< T >

Model Of:

• Movable

• T models Regular (supports T models Movable).

Copy-on-write sematics allow for object to be lazily copied - only creating a copy when the value is modified and there is more than one reference to the value.

Note:

copy_on_write is thread safe when complier with BOOST_HAS_THREADS defined.

Definition at line 57 of file copy_on_write.hpp.

Public Types
typedef T	value_type
Public Member Functions
	copy_on_write (move_from< copy_on_write > x)
	copy_on_write (const copy_on_write &x)
template<typename U>
	copy_on_write (const U &x, typename copy_sink< U, T >::type=0)
template<typename U>
	copy_on_write (U x, typename move_sink< U, T >::type=0)
	copy_on_write ()
bool	identity (const copy_on_write &x) const
	operator const value_type & () const
const value_type &	operator* () const
const value_type *	operator-> () const
template<typename U>
copy_sink< U, T, copy_on_write & > ::type	operator= (const U &x)
template<typename U>
move_sink< U, T, copy_on_write & > ::type	operator= (U x)
copy_on_write &	operator= (copy_on_write x)
const value_type &	read () const
bool	unique_instance () const
value_type &	write ()
	~copy_on_write ()
Friends
bool	operator< (const copy_on_write &x, const copy_on_write &y)
bool	operator== (const copy_on_write &x, const copy_on_write &y)
void	swap (copy_on_write &x, copy_on_write &y)

---

Member Typedef Documentation

typedef T value_type

The type of value stored.

Definition at line 63 of file copy_on_write.hpp.

---

Constructor & Destructor Documentation

copy_on_write

(

)

The first call to the default constructor will construct a default instance of value_type which will be used for subsequent calls to the default constructor. The default instance will be released at exit.

Definition at line 70 of file copy_on_write.hpp.

copy_on_write	(	U	x,
		typename move_sink< U, T >::type	= 0
	)			[explicit]

Constructs a new copy_on_write object with a value x.

Parameters:

\c

x A default value to assign to this object

Note:

This constructor is for value types which do not support the move library.

Definition at line 86 of file copy_on_write.hpp.

copy_on_write	(	const U &	x,
		typename copy_sink< U, T >::type	= 0
	)			[explicit]

Constructs a new copy_on_write object with a value x.

Parameters:

\c

x A default value to assign to this object

Note:

This constructor is for value types which do support the move library.

Definition at line 99 of file copy_on_write.hpp.

copy_on_write

(

const copy_on_write< T > &

x

)

Copy construction is a non-throwing operation and simply increments the reference count on the stored object.

Definition at line 108 of file copy_on_write.hpp.

copy_on_write

(

move_from< copy_on_write< T > >

x

)

Definition at line 114 of file copy_on_write.hpp.

~copy_on_write

(

)

Definition at line 120 of file copy_on_write.hpp.

---

Member Function Documentation

bool identity

(

const copy_on_write< T > &

x

)

const

identity is used to see if two copy_on_write items refer to the same instance.

Returns:

Boolean; true if the underlying object instance is shared by both objects.

Definition at line 265 of file copy_on_write.hpp.

operator const value_type &

(

)

const

Obtain a const reference to the underlying object.

Returns:

A const reference to the underlying object

Definition at line 206 of file copy_on_write.hpp.

const value_type& operator*

(

)

const

Obtain a const reference to the underlying object.

Returns:

A const reference to the underlying object

Obtain a pointer to the underlying object. This is provided because you cannot override operator.(). It allows copy_on_write to be used with common transformation techniques, such as boost indirect_iterator and transform_iterator. It does not imply "pointer" semantics.

Returns:

A pointer to the underlying object

Definition at line 228 of file copy_on_write.hpp.

const value_type* operator->

(

)

const

Obtain a const reference to the underlying object.

This is provided because you cannot override operator.(). It allows copy_on_write to be used with common transformation techniques, such as boost indirect_iterator and transform_iterator. It does not imply "pointer" semantics.

Returns:

A const reference to the underlying object

Definition at line 245 of file copy_on_write.hpp.

copy_sink<U, T, copy_on_write&>::type operator=

(

const U &

x

)

Definition at line 153 of file copy_on_write.hpp.

move_sink<U, T, copy_on_write&>::type operator=

(

U

x

)

Assign a value which is convertible to value_type directly to a copy_on_write object.

Definition at line 138 of file copy_on_write.hpp.

copy_on_write& operator=

(

copy_on_write< T >

x

)

As with copy construction, assignment is a non-throwing operation which releases the old value and incriments the reference count of the item being assigned to.

Definition at line 130 of file copy_on_write.hpp.

const value_type& read

(

)

const

Obtain a const reference to the underlying object.

Returns:

A const reference to the underlying object

Definition at line 194 of file copy_on_write.hpp.

bool unique_instance

(

)

const

unique_instance returns whether or not the reference count to the object instance is one. This is useful to determine if writing will cause a copy.

Returns:

true if the ref count for the instance is one.

Definition at line 258 of file copy_on_write.hpp.

value_type& write

(

)

Obtain a reference to the value the object is referencing. This will copy the underlying value (if necessary) so changes to the value do not affect other copy_on_write objects.

Returns:

A reference to the underlying object

Definition at line 175 of file copy_on_write.hpp.

---

Friends And Related Function Documentation

bool operator<	(	const copy_on_write< T > &	x,
		const copy_on_write< T > &	y
	)			[friend]

Definition at line 270 of file copy_on_write.hpp.

bool operator==	(	const copy_on_write< T > &	x,
		const copy_on_write< T > &	y
	)			[friend]

Definition at line 273 of file copy_on_write.hpp.

void swap	(	copy_on_write< T > &	x,
		copy_on_write< T > &	y
	)			[friend]

Definition at line 267 of file copy_on_write.hpp.