SharedPtr< T, TSize > Class Template Reference

#include <evo/ptr.h>

Inheritance diagram for SharedPtr< T, TSize >:

Detailed Description

template<class T, class TSize = SizeT>
class evo::SharedPtr< T, TSize >

Shared smart pointer to single object.

• Similar to SmartPtr except copying uses reference counting to make shared copies
• Takes ownership of a given pointer and frees the pointer automatically by calling delete when no longer used
  • A reference count is incremented for each copy, and decremented when each copy is destroyed
  • The last owner automatically frees the pointer
• Overrides pointer operators so shared smart pointer can be used like a raw pointer
• Copying a shared smart pointer makes a shared copy, incrementing the reference count – ok for containers
  • Modifying a shared object affects all pointers referencing it
• The following method requires T implement a proper copy-constructor: unshare()
• Caution: Not thread safe

SharedPtr<T[]> is specialized for arrays so the pointer is freed with delete[]. However an array SharedPtr<T[]> doesn't support unshare() (array size isn't known).

See Managed Pointers

C++11:

• Move semantics

Template Parameters

T	Type to use pointer to (not the raw pointer type)

Example

#include <evo/ptr.h>
#include <evo/string.h>
#include <evo/io.h>
using namespace evo;
static Console& c = con();

int main() {
    // Create shared pointer, set a value
    SharedPtr<String> ptr(new String);
    *ptr = "testing";    // use dereference operator* like normal pointer

    // Copying shared pointer makes a shared copy
    {
        SharedPtr<String> ptr2(ptr);
        *ptr2 = "foo";   // dereference ptr2 and change value (affects ptr as well)
    }

    // Print ptr value as terminated string (just for example) -- use operator-> like normal pointer
    c.out << ptr->cstr() << NL;

    // May use Ptr to reference a shared pointer without sharing it (does not increment reference count)
    {
        Ptr<String> ptr2(ptr);  // this can be dangerous if Ptr outlives SharedPtr
        *ptr2 = "bar";          // dereference ptr2 and change value again (affects ptr as well)
    }

    // Print ptr value as terminated string (just for example) -- use operator-> like normal pointer
    c.out << ptr->cstr() << NL;

    return 0;
} // ptr automatically freed

Output:

foo
bar

Public Types
typedef PtrBase< T, T * >	Base
	This pointer base type. More...
typedef void	EvoNullableType
	Identify as nullable type. More...
typedef T	Item
	Item type dereferenced to. More...
typedef SharedPtr< T, TSize >	This
	This pointer type. More...

Public Member Functions
	SharedPtr ()
	Constructor to start with null pointer. More...
	SharedPtr (T *ptr)
	Constructor. More...
	SharedPtr (const This &src)
	Copy constructor. More...
	SharedPtr (This &&src)
	Move constructor (C++11). More...
	~SharedPtr ()
	Destructor. More...
This &	clear ()
	Release pointer and set as null. More...
bool	null () const
	Get whether pointer is null. More...
	operator SafeBoolType () const
	Safe (explicit) evaluation as bool type. More...
bool	operator! () const
	Negation operator checks if NULL. More...
bool	operator!= (const Base &ptr) const
	Inequality operator. More...
bool	operator!= (void *ptr) const
	Inequality operator. More...
const T &	operator* () const
	Dereference operator (const). More...
T &	operator* ()
	Dereference operator (mutable). More...
const T *	operator-> () const
	Member access operator (const). More...
T *	operator-> ()
	Member access operator (mutable). More...
bool	operator< (const Base &ptr) const
	Less-than operator. More...
bool	operator< (void *ptr) const
	Less-than operator. More...
bool	operator<= (const Base &ptr) const
	Less-than-or-equals operator. More...
bool	operator<= (void *ptr) const
	Less-than-or-equals operator. More...
This &	operator= (const This &src)
	Copy/Assignment operator. More...
This &	operator= (T *ptr)
	Assignment operator for new pointer. More...
This &	operator= (This &&src)
	Move assignment operator (C++11). More...
bool	operator== (const Base &ptr) const
	Equality operator. More...
bool	operator== (void *ptr) const
	Equality operator. More...
bool	operator> (const Base &ptr) const
	Greater-than operator. More...
bool	operator> (void *ptr) const
	Greater-than operator. More...
bool	operator>= (const Base &ptr) const
	Greater-than-or-equals operator. More...
bool	operator>= (void *ptr) const
	Greater-than-or-equals operator. More...
const T &	operator[] (ulong index) const
	Array access operator (const). More...
T &	operator[] (ulong index)
	Array access operator (mutable). More...
const T *	ptr () const
	Get current pointer (const). More...
T *	ptr ()
	Get current pointer (mutable). More...
This &	set ()
	Set as null – same as clear(). More...
bool	shared () const
	Get whether pointer is shared (reference count > 1). More...
This &	unshare ()
	Unshare pointer by setting as a new copy, if shared. More...
bool	valid () const
	Get whether pointer is valid (not null). More...

Public Attributes
T *	ptr_
	Pointer. More...

Protected Member Functions
void	free ()

Protected Attributes
TSize *	refs_

Member Typedef Documentation

Base

typedef PtrBase<T,T* > Base

inherited

This pointer base type.

EvoNullableType

typedef void EvoNullableType

inherited

Identify as nullable type.

Item

typedef T Item

Item type dereferenced to.

This

typedef SharedPtr<T,TSize> This

This pointer type.

Constructor & Destructor Documentation

SharedPtr() [1/4]

SharedPtr ( )

inline

Constructor to start with null pointer.

SharedPtr() [2/4]

SharedPtr ( T *  ptr )

inline

Constructor.

• This takes ownership of the pointer and will free it later – starts reference count at 1

Parameters

ptr	Pointer to set, NULL for none

SharedPtr() [3/4]

SharedPtr ( const This &  src )

inline

Copy constructor.

• This makes a shared copy of source object, incrementing reference count

Parameters

src	Source pointer

~SharedPtr()

~SharedPtr ( )

inline

Destructor.

SharedPtr() [4/4]

SharedPtr ( This &&  src )

inline

Move constructor (C++11).

Parameters

src	Source to move

Member Function Documentation

clear()

This& clear ( )

inline

Release pointer and set as null.

• This will decrement the reference count, and free the pointer if not shared

Returns

This

free()

void free ( )

inlineprotected

null()

bool null ( ) const

inlineinherited

Get whether pointer is null.

Returns

Whether null

operator SafeBoolType()

operator SafeBoolType ( ) const

inlineinherited

Safe (explicit) evaluation as bool type.

• This is called when object is directly evaluated as a bool, and is equivalent to: !operator!()
• See SafeBool

operator!()

bool operator! ( ) const

inlineinherited

Negation operator checks if NULL.

Returns

Whether NULL

operator!=() [1/2]

bool operator!= ( const Base &  ptr ) const

inlineinherited

Inequality operator.

Parameters

ptr	Pointer to compare to

Returns

Whether not equal

operator!=() [2/2]

bool operator!= ( void *  ptr ) const

inlineinherited

Inequality operator.

Parameters

ptr	Pointer to compare to

Returns

Whether not equal

operator*() [1/2]

const T& operator* ( ) const

inlineinherited

Dereference operator (const).

• Results are undefined if pointer is NULL

Returns

Dereferenced pointer

operator*() [2/2]

T& operator* ( )

inlineinherited

Dereference operator (mutable).

• Results are undefined if pointer is NULL

Returns

Dereferenced pointer

operator->() [1/2]

const T* operator-> ( ) const

inlineinherited

Member access operator (const).

• Results are undefined if pointer is NULL

Returns

Pointer

operator->() [2/2]

T* operator-> ( )

inlineinherited

Member access operator (mutable).

• Results are undefined if pointer is NULL

Returns

Pointer

operator<() [1/2]

bool operator< ( const Base &  ptr ) const

inlineinherited

Less-than operator.

Parameters

ptr	Pointer to compare to

Returns

Whether less than ptr

operator<() [2/2]

bool operator< ( void *  ptr ) const

inlineinherited

Less-than operator.

Parameters

ptr	Pointer to compare to

Returns

Whether less than ptr

operator<=() [1/2]

bool operator<= ( const Base &  ptr ) const

inlineinherited

Less-than-or-equals operator.

Parameters

ptr	Pointer to compare to

Returns

Whether less than or equal to ptr

operator<=() [2/2]

bool operator<= ( void *  ptr ) const

inlineinherited

Less-than-or-equals operator.

Parameters

ptr	Pointer to compare to

Returns

Whether less than or equal to ptr

operator=() [1/3]

This& operator= ( const This &  src )

inline

Copy/Assignment operator.

• This makes a copy of source object using T copy constructor
• The previous pointer is released (freed, if applicable)

Parameters

src	Source pointer

Returns

This

operator=() [2/3]

This& operator= ( T *  ptr )

inline

Assignment operator for new pointer.

• This takes ownership of the pointer and will free it later – starts reference count at 1
• The previous pointer is released (freed, if applicable)

Parameters

ptr	Pointer to set

Returns

This

operator=() [3/3]

This& operator= ( This &&  src )

inline

Move assignment operator (C++11).

Parameters

src	Source to move

Returns

This

operator==() [1/2]

bool operator== ( const Base &  ptr ) const

inlineinherited

Equality operator.

Parameters

ptr	Pointer to compare to

Returns

Whether equal

operator==() [2/2]

bool operator== ( void *  ptr ) const

inlineinherited

Equality operator.

Parameters

ptr	Pointer to compare to

Returns

Whether equal

operator>() [1/2]

bool operator> ( const Base &  ptr ) const

inlineinherited

Greater-than operator.

Parameters

ptr	Pointer to compare to

Returns

Whether greater than ptr

operator>() [2/2]

bool operator> ( void *  ptr ) const

inlineinherited

Greater-than operator.

Parameters

ptr	Pointer to compare to

Returns

Whether greater than ptr

operator>=() [1/2]

bool operator>= ( const Base &  ptr ) const

inlineinherited

Greater-than-or-equals operator.

Parameters

ptr	Pointer to compare to

Returns

Whether greater than or equal to ptr

operator>=() [2/2]

bool operator>= ( void *  ptr ) const

inlineinherited

Greater-than-or-equals operator.

Parameters

ptr	Pointer to compare to

Returns

Whether greater than or equal to ptr

operator[]() [1/2]

const T& operator[] ( ulong  index ) const

inlineinherited

Array access operator (const).

• Results are undefined if pointer is NULL or index is out of bounds

Returns

Item reference

operator[]() [2/2]

T& operator[] ( ulong  index )

inlineinherited

Array access operator (mutable).

• Results are undefined if pointer is NULL or index is out of bounds

Returns

Item reference

ptr() [1/2]

const T* ptr ( ) const

inlineinherited

Get current pointer (const).

• Caution: This does not release ownership of the pointer

Returns

Current pointer, or NULL if none

ptr() [2/2]

T* ptr ( )

inlineinherited

Get current pointer (mutable).

• Caution: This does not release ownership of the pointer

Returns

Current pointer, or NULL if none

set()

This& set ( )

inline

Set as null – same as clear().

Returns

This

shared()

bool shared ( ) const

inline

Get whether pointer is shared (reference count > 1).

Returns

Whether shared

unshare()

This& unshare ( )

inline

Unshare pointer by setting as a new copy, if shared.

• Disabled if array T[]

Returns

This

valid()

bool valid ( ) const

inlineinherited

Get whether pointer is valid (not null).

Returns

Whether valid

Member Data Documentation

ptr_

T* ptr_

inherited

Pointer.

refs_

TSize* refs_

protected

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

• evo/ptr.h