External pointer. More...

#include <ExternalPointer.h>

Inheritance diagram for CXXR::ExternalPointer:

Collaboration diagram for CXXR::ExternalPointer:

Public Member Functions
	ExternalPointer (void ptr=0, RObject tag=0, RObject *prot=0)
const RObject *	protege () const
	Get const pointer to protege object.
RObject *	protege ()
	Get pointer to protege object.
const void *	ptr () const
	Get the encapsulated pointer, qualified by const.
void *	ptr ()
	Get the encapsulated pointer.
void	setProtege (RObject *prot)
	Designate the protege object.
void	setPtr (void *ptr)
	Set the value of the encapsulated pointer.
void	setTag (RObject *tag)
	Set the 'tag' value.
const RObject *	tag () const
	Get const pointer to tag object.
RObject *	tag ()
	Get pointer to tag object.
const char *	typeName () const
	Name within R of this type of object.
void	visitReferents (const_visitor *v) const
	Conduct a visitor to the nodes referred to by this one.
Public Member Functions inherited from CXXR::RObject
virtual const PairList *	attributes () const
	Get object attributes.
virtual void	clearAttributes ()
	Remove all attributes.
virtual RObject *	clone () const
	Return pointer to a copy of this object.
void	copyAttribute (const Symbol name, const RObject source)
	Copy an attribute from one RObject to another.
void	copyAttributes (const RObject *source, bool copyS4)
	Copy attributes from one RObject to another.
virtual RObject *	evaluate (Environment *env)
	Evaluate object in a specified Environment.
virtual RObject *	getAttribute (const Symbol *name) const
	Get the value a particular attribute.
virtual bool	hasAttributes () const
	Has this object any attributes?
bool	hasClass () const
	Has this object the class attribute?
bool	isS4Object () const
	Is this an S4 object?
void	maybeTraceMemory (const RObject *src)
	Carry out memory tracing.
void	maybeTraceMemory (const RObject src1, const RObject src2)
	Carry out memory tracing.
void	maybeTraceMemory (const RObject src1, const RObject src2, const RObject *src3)
	Carry out memory tracing.
bool	memoryTraced () const
	Is copying etc. of this object being traced?
virtual unsigned int	packGPBits () const
	Reproduce the `gp` bits field used in CR.
virtual void	setAttribute (const Symbol name, RObject value)
	Set or remove an attribute.
void	setAttributes (const PairList *new_attributes)
	Replace the attributes of an object.
void	setMemoryTracing (bool on)
	Enable/disable tracing of copying etc.
void	setS4Object (bool on)
	Set the status of this RObject as an S4 object.
SEXPTYPE	sexptype () const
	Get an object's SEXPTYPE.
virtual void	unpackGPBits (unsigned int gpbits)
	Interpret the `gp` bits field used in CR.
Public Member Functions inherited from CXXR::GCNode
void	expose () const
	Record that construction of a node is complete.
bool	isExposed () const
	Has this node been exposed to garbage collection?
Public Member Functions inherited from CXXR::HeterogeneousListBase::Link
	Link ()
	Default constructor.
	Link (HeterogeneousListBase *list)
	Appending constructor.
void	freeLink ()
	Detach Link from any list.

Static Public Member Functions
static const char *	staticTypeName ()
	The name by which this type is known in R.
Static Public Member Functions inherited from CXXR::RObject
template<class T >
static T *	clone (const T *pattern)
	Return a pointer to a copy of an object.
Static Public Member Functions inherited from CXXR::GCNode
static void *	operator new (size_t bytes)
	Allocate memory.
static void *	operator new (size_t, void *where)
	Placement new for GCNode.
static void	operator delete (void *p, size_t bytes)
	Deallocate memory.
static bool	check ()
	Integrity check.
template<class T >
static T *	expose (T *node)
	Record that construction of a node is complete.
static void	gc ()
	Initiate a garbage collection.
static void	gclite ()
	Lightweight garbage collection.
static void	maybeCheckExposed (const GCNode *node)
	Subject to configuration, check that a GCNode is exposed.
static size_t	numNodes ()
	Number of GCNode objects in existence.

Protected Member Functions
void	detachReferents ()
	Null out all references from this node to other nodes.
Protected Member Functions inherited from CXXR::RObject
	RObject (SEXPTYPE stype=CXXSXP)
	RObject (const RObject &pattern)
	Copy constructor.
Protected Member Functions inherited from CXXR::GCNode
virtual	~GCNode ()
Protected Member Functions inherited from CXXR::HeterogeneousListBase::Link
virtual	~Link ()

Friends
class	boost::serialization::access

Additional Inherited Members
Public Attributes inherited from CXXR::RObject
unsigned char	m_named
unsigned	m_missing: 2
unsigned	m_argused: 2
bool	m_active_binding: 1
bool	m_binding_locked: 1

Detailed Description

External pointer.

RObject encapsulating a pointer to some entity that is not an RObject. An ExternalPointer also comprises two pointers to objects of a type derived from RObject, here designated the 'tag' and the 'protege', each of which is protected from garbage collection for the lifetime of the ExternalPointer object. The tag and the protege are treated identically by the ExternalPointer class, but the 'Writing R Extensions' document (in recent revisions) suggests that the tag be used for some sort of type identification, and that the protege be used for protecting memory (or other resources) used by the entity pointed to by the ExternalPointer.

Note:: Writers of C++ packages are recommended to derive their own classes from RObject rather than use this class, which is provided primarily to support the established C interface.

Constructor & Destructor Documentation

CXXR::ExternalPointer::ExternalPointer	(	void *	ptr = `0`,
		RObject *	tag = `0`,
		RObject *	prot = `0`
	)

inlineexplicit

Parameters:

ptr	The pointer that the ExternalPointer object is to encapsulate.
tag	Pointer to the tag object. May be null (and often is).
prot	Pointer to the protege object. May be null (and often is).

Member Function Documentation

void ExternalPointer::detachReferents ( )

protectedvirtual

Null out all references from this node to other nodes.

The referents of this node are those objects (derived from GCNode) designated by a GCEdge within this object. This function changes all GCEdges within this object to encapsulate a null pointer. It is used during the sweep phase of a mark-sweep garbage collection to break up unreachable subgraphs, and in particular to remove reference loops from them. After the application of this method, the GCNode should be regarded as a 'zombie', kept in existence only so other nodes can detach their references to it cleanly (using decRefCount()).

Note:: If this method is reimplemented in a derived class, the reimplemented version must remember to invoke detachReferents() for the immediate base class of the derived class, to ensure that all referents of the object get detached.

Reimplemented from CXXR::RObject.

const RObject* CXXR::ExternalPointer::protege ( ) const

inline

Get const pointer to protege object.

Returns:: a const pointer to the protege object of this ExternalPointer.

RObject* CXXR::ExternalPointer::protege ( )

inline

Get pointer to protege object.

Returns:: a pointer to the protege object of this ExternalPointer.

const void* CXXR::ExternalPointer::ptr ( ) const

inline

Get the encapsulated pointer, qualified by const.

Returns:: the encapsulated pointer, qualified by const.

void* CXXR::ExternalPointer::ptr ( )

inline

Get the encapsulated pointer.

Returns:: the encapsulated pointer.

void CXXR::ExternalPointer::setProtege ( RObject * prot )

inline

Designate the protege object.

Parameters:

prot	Pointer to the new protege object (or a null pointer).

void CXXR::ExternalPointer::setPtr ( void * ptr )

inline

Set the value of the encapsulated pointer.

Parameters:

ptr	New pointer value (may be null).

void CXXR::ExternalPointer::setTag ( RObject * tag )

inline

Set the 'tag' value.

Parameters:

tag	Pointer to the new tag object (or a null pointer).

static const char* CXXR::ExternalPointer::staticTypeName ( )

inlinestatic

The name by which this type is known in R.

Returns:: the name by which this type is known in R.

const RObject* CXXR::ExternalPointer::tag ( ) const

inline

Get const pointer to tag object.

Returns:: a const pointer to the 'tag' of this ExternalPointer.

RObject* CXXR::ExternalPointer::tag ( )

inline

Get pointer to tag object.

Returns:: a pointer to the 'tag' of this ExternalPointer.

const char * ExternalPointer::typeName ( ) const

virtual

Name within R of this type of object.

Returns:: the name by which this type of object is known within R.

Reimplemented from CXXR::RObject.

void ExternalPointer::visitReferents ( const_visitor * v ) const

virtual

Conduct a visitor to the nodes referred to by this one.

The referents of this node are those objects (derived from GCNode) designated by a GCEdge within this object.

Parameters:

v	Pointer to the visitor object.

Note:: If this method is reimplemented in a derived class, the reimplemented version must remember to invoke visitReferents() for the immediate base class of the derived class, to ensure that all referents of the object get visited. It is suggested that implementations set up stack-based pointers to all the referents of a node before visiting any of them; in that case, if the (recursive) visiting pushes the node out of the processor cache, there is no need to fetch it back in.

Reimplemented from CXXR::RObject.

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

Public Member Functions

Static Public Member Functions

Protected Member Functions

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation