Class representing a functional programming closure. More...

#include <Closure.h>

Inheritance diagram for CXXR::Closure:

Collaboration diagram for CXXR::Closure:

Public Member Functions
	Closure (const PairList formal_args, RObject body, Environment *env=Environment::global())
	Closure (const Closure &pattern)
	Copy constructor.
const RObject *	body () const
	Access the body of the Closure.
bool	debugging () const
	Is debugging enabled?
Environment *	environment () const
	Access the environment of the Closure.
RObject *	execute (Environment *env) const
	Evaluate the Closure's body in a given environment.
RObject *	invoke (Environment env, const ArgList arglist, const Expression call, const Frame method_bindings=0) const
	Invoke the function.
const ArgMatcher *	matcher () const
	Access the ArgMatcher of this Closure.
void	setDebugging (bool on)
	Set debugging status.
void	setEnvironment (Environment *new_env)
	Replace the environment of the closure.
void	stripFormals (Frame *input_frame) const
	Strip formal argument bindings from a Frame.
RObject *	apply (ArgList arglist, Environment env, const Expression *call) const
	Apply the function.
Closure *	clone () const
	Return pointer to a copy of this 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::FunctionBase
void	maybeTrace (const Expression *call) const
	Produce a tracing report if appropriate.
void	setTracing (bool on)
	Set tracing status.
bool	traced () const
	Is this function being traced?
Public Member Functions inherited from CXXR::RObject
virtual const PairList *	attributes () const
	Get object attributes.
virtual void	clearAttributes ()
	Remove all attributes.
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::FunctionBase
static void	enableTracing (bool on)
	Enable/disable function tracing.
static bool	isA (const RObject *obj)
	Is an RObject a FunctionBase?
static bool	tracingEnabled ()
	If function tracing currently enabled?
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::FunctionBase
	FunctionBase (SEXPTYPE stype)
	FunctionBase (const FunctionBase &pattern)
	Copy constructor.
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

Detailed Description

Class representing a functional programming closure.

A closure associates a function definition (the body) with a list of formal arguments and an environment. In evaluating the function, non-local variables within the function definition are interpreted by reference to the specified environment (and its enclosing environments).

Constructor & Destructor Documentation

Closure::Closure	(	const PairList *	formal_args,
		RObject *	body,
		Environment *	env = `Environment::global()`
	)

Parameters:

formal_args	List of formal arguments.
body	Pointer to the body of the Closure. This must be either a null pointer or a pointer to an object of one of the following types: PairList, Expression, Symbol, ExpressionVector, ListVector or ByteCode (checked).
env	pointer to the environment in which the Closure is to be evaluated.

CXXR::Closure::Closure ( const Closure & pattern )

inline

Copy constructor.

Parameters:

pattern Closure to be copied.

Member Function Documentation

RObject * Closure::apply	(	ArgList *	arglist,
		Environment *	env,
		const Expression *	call
	)		const

virtual

Apply the function.

Parameters:

arglist	Non-null pointer to the ArgList containing the list of arguments with which the function is to be invoked.
env	Pointer to the Environment in which the function is to be evaluated.
call	Pointer to the Expression calling the function.

Returns:: The result of applying the function.

Implements CXXR::FunctionBase.

const RObject* CXXR::Closure::body ( ) const

inline

Access the body of the Closure.

Returns:: Pointer to the body of the Closure.

Closure * Closure::clone ( ) const

virtual

Return pointer to a copy of this object.

This function creates a copy of this object, and returns a pointer to that copy.

Generally this function (and the copy constructors it utilises) will attempt to create a 'deep' copy of the object; this follows standard practice within C++, and it is intended to extend this practice as CXXR development continues.

However, if the pattern object contains unclonable subobjects, then the created copy will at the relevant places simply contain pointers to those subobjects, i.e. to that extent the copy is 'shallow'. This is managed using the smart pointers defined by nested class RObject::Handle.

Returns:: a pointer to a clone of this object, or a null pointer if this object cannot be cloned.

Note:: Derived classes should exploit the covariant return type facility to return a pointer to the type of object being cloned.

Reimplemented from CXXR::RObject.

bool CXXR::Closure::debugging ( ) const

inline

Is debugging enabled?

Returns:: true iff debugging is currently enabled for this Closure.

void Closure::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.

Environment* CXXR::Closure::environment ( ) const

inline

Access the environment of the Closure.

Returns:: Pointer to the environment of the Closure.

RObject * Closure::execute ( Environment * env ) const

Evaluate the Closure's body in a given environment.

This function evaluates the Closure's body with env as the working environment, handling debugging if currently enabled for this Closure.

Parameters:

env	Non-null pointer to the working environment in which evaluation of the body is to be carried out.

Returns:: the result of evaluation.

Note:: This is a low-level function that is called by invoke() but may also be called directly. The function does not carry out argument matching, nor does it create a ClosureContext: both these operations must be handled by the calling code.

RObject * Closure::invoke	(	Environment *	env,
		const ArgList *	arglist,
		const Expression *	call,
		const Frame *	method_bindings = `0`
	)		const

Invoke the function.

This differs from apply() in that it is assumed that any required wrapping of the function arguments in Promise objects will have been carried out before invoke() is called, whereas apply() carries out this wrapping itself.

Parameters:

env	Non-null pointer to the Environment in which the function is to be evaluated.
arglist	Non-null pointer to the promise-wrapped ArgList containing the arguments with which the function is to be invoked.
call	Pointer to the Expression calling the function.
method_bindings	This pointer will be non-null if and only if this invocation represents a method call, in which case it points to a Frame containing Bindings that should be added to the working environment, for example bindings of the Symbols .Generic and .Class.

Returns:: The result of applying the function.

const ArgMatcher* CXXR::Closure::matcher ( ) const

inline

Access the ArgMatcher of this Closure.

Returns:: const pointer to this Closure's ArgMatcher object.

void CXXR::Closure::setDebugging ( bool on )

inline

Set debugging status.

Parameters:

on	The required new debugging status (true = enabled).

void CXXR::Closure::setEnvironment ( Environment * new_env )

inline

Replace the environment of the closure.

Parameters:

new_env Pointer to the environment now to be considered as the environment of this Closure. A null pointer is not permissible (not checked).

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

inlinestatic

The name by which this type is known in R.

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

Reimplemented from CXXR::FunctionBase.

void CXXR::Closure::stripFormals ( Frame * input_frame ) const

inline

Strip formal argument bindings from a Frame.

This function removes from input_frame any bindings of the formal arguments of this Closure. It is used in creating the working environment of an S3 method from the working environment of its generic.

Parameters:

input_frame Non-null pointer to the Frame from which bindings are to be stripped.

const char * Closure::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 Closure::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

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation