Element of a singly linked list. More...

#include <ConsCell.h>

Inheritance diagram for CXXR::ConsCell:

Collaboration diagram for CXXR::ConsCell:

Classes
class	const_iterator
	const_iterator for iterating over a ConsCell list. More...
class	iterator
	iterator for iterating over a HeterogeneousList. More...

Public Member Functions
iterator	begin ()
const_iterator	begin () const
RObject *	car () const
iterator	end ()
const_iterator	end () const
void	setCar (RObject *cr)
	Set the 'car' value.
void	setTag (const RObject *tg)
	Set the 'tag' value.
void	setTail (PairList *tl)
	Set the 'tail' value.
const RObject *	tag () const
const PairList *	tail () const
PairList *	tail ()
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 const char *	typeName () const
	Name within R of this type of object.
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
template<class T >
static T *	convert (ConsCell *cc)
	Convert a ConsCell to a (possibly) different ConsCell type.
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
	ConsCell (SEXPTYPE st, RObject cr=0, PairList tl=0, const RObject *tg=0)
	ConsCell (const ConsCell &pattern)
	Copy constructor.
	ConsCell (const ConsCell &pattern, int dummy)
	Tailless copy constructor.
	~ConsCell ()
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
class	PairList

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

Element of a singly linked list.

Element of a LISP-like singly-linked list, containing pointers to a 'car' object (this is LISP terminology, and has nothing to do with automobiles) and to a 'tag' object, as well as a pointer to the next element of the list, which must be of the derived type PairList. (Any of these pointers may be null.)

When the object is copied, the copy thus created will contain copies of the 'car' and of subsequent elements of the list. However, the tag is not copied: the copy object will simply contain a pointer to the tag of the original object. Despite this, the tag is considered to be part of the object.

Note:: This class is used as a base class to implement CR's LISTSXP, LANGSXP, DOTSXP and (for the time being) BCODESXP. Because what these SEXPTYPEs have in common is implementation rather than meaning in the application domain, canons of object-oriented design would argue against their publicly inheriting from a common base class. Without doing this, however, it would have been difficult efficiently to implement functions such as CAR(), which are ubiquitous in the CR code.; The semantics of this class are somewhat inconsistent. When a ConsCell is copied, the copy constructor tries to copy the 'car', implying that the car is considered part of the object. But the const member function car() passes back a non-const pointer to the car. See the discussion in the documentation of class RObject regarding the handling of const pointers.

Constructor & Destructor Documentation

CXXR::ConsCell::ConsCell	(	SEXPTYPE	st,
		RObject *	cr = `0`,
		PairList *	tl = `0`,
		const RObject *	tg = `0`
	)

inlineexplicitprotected

Parameters:

st	The required SEXPTYPE of the ConsCell. Must be one of LISTSXP, LANGSXP, DOTSXP or BCODESXP (not normally checked).
cr	Pointer to the 'car' of the element to be constructed.
tl	Pointer to the 'tail' (LISP cdr) of the element to be constructed.
tg	Pointer to the 'tag' of the element to be constructed.

CXXR::ConsCell::ConsCell ( const ConsCell & pattern )

inlineprotected

Copy constructor.

Parameters:

pattern ConsCell to be copied. Beware that if this ConsCell or any of its successors have unclonable 'car' objects, they will be shared between pattern and the created object.

CXXR::ConsCell::ConsCell	(	const ConsCell &	pattern,
		int	dummy
	)

inlineprotected

Tailless copy constructor.

Copies the node without copying its tail. Used in implementing the PairList copy constructor proper.

Parameters:

pattern	ConsCell to be copied. Beware that if this ConsCell or any of its successors have unclonable 'car' objects, they will be shared between pattern and the created object.
dummy	This parameter is used simply to provide the constructor with a distinct signature. Its value is ignored.

CXXR::ConsCell::~ConsCell ( )

inlineprotected

Declared protected to ensure that ConsCell objects are allocated only using 'new'.

Member Function Documentation

RObject* CXXR::ConsCell::car ( ) const

inline

Returns:: a const pointer to the 'car' of this ConsCell element.

template<class T >

static T* CXXR::ConsCell::convert ( ConsCell * cc )

inlinestatic

Convert a ConsCell to a (possibly) different ConsCell type.

Template Parameters:

T	A (non-abstract) class derived from ConsCell.

Parameters:

cc	Pointer to a ConsCell (possibly null). The effect of the method on cc is undefined; consequently cc should not be used subsequently to the method call.

Returns:: Pointer to the converted object, or a null pointer if cc is null. If cc is already of the desired type, the method simply returns cc.

void ConsCell::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.

void CXXR::ConsCell::setCar ( RObject * cr )

inline

Set the 'car' value.

Parameters:

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

void CXXR::ConsCell::setTag ( const RObject * tg )

inline

Set the 'tag' value.

Parameters:

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

void CXXR::ConsCell::setTail ( PairList * tl )

inline

Set the 'tail' value.

Parameters:

tl	Pointer to the new tail list (or a null pointer).

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

inlinestatic

The name by which this type is known in R.

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

Reimplemented in CXXR::PairList, CXXR::Expression, and CXXR::DottedArgs.

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

inline

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

const PairList * CXXR::ConsCell::tail ( ) const

inline

Returns:: a const pointer to the 'tail' of this ConsCell element.

PairList * CXXR::ConsCell::tail ( )

inline

Returns:: a pointer to the 'tail' of this ConsCell.

void ConsCell::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:

Classes

Public Member Functions

Static Public Member Functions

Protected Member Functions

Friends

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation