Framework for R command evaluation. More...

#include <Evaluator.h>

Classes
class	Context
	Housekeeping information on R call stack. More...

Public Member Functions
Context *	innermostContext () const
	Innermost Context belonging to this Evaluator.

Static Public Member Functions
static Evaluator *	current ()
	The current Evaluator.
static unsigned int	depth ()
	(Not for general use.)
static unsigned int	depthLimit ()
	Maximum depth of R expression nesting.
static void	enableExtraDepth (bool on)
	(Not for general use.)
static void	enableProfiling (bool on)
	(Not for general use.)
static void	enableResultPrinting (bool on)
	Specify whether the result of top-level expression be printed.
static RObject *	evaluate (RObject object, Environment env)
	Evaluate RObject in a specified Environment.
static bool	profiling ()
	Is profiling currently enabled?
static bool	resultPrinted ()
	Is the result of top-level expression evaluation printed?
static void	setDepth (unsigned int depth)
	(Not for general use.)
static void	setDepthLimit (int depth)
	Set maximum depth of R expression nesting.

Friends
class	Context

Detailed Description

Framework for R command evaluation.

An object of this class provides a framework within which evaluation of R commands (i.e. top-level R expressions) takes place, and provides various housekeeping services to control and support that evaluation. Evaluator objects conceptually form a stack, so they must be destroyed in the reverse order of creation: it is therefore recommended that they always be declared on the processor stack, i.e. as C++ automatic variables. The Evaluator at the top of the stack is the current Evaluator.

If an error occurs during R expression evaluation, the resulting exception is caught within the scope of the current Evaluator; the relevant code will then typically request another R command (if interactive), or terminate the scope of the current Evaluator, thus popping it off the Evaluator stack, and return control to code within the scope of the next Evaluator down.

Each Evaluator object contains a nested sequence of zero or more Contexts. A newly created Context is added to the sequence belonging to the current Evaluator. It is therefore an error to declare a Context object outside the scope of any Evaluator object.

Note:: Evaluator objects fulfil many of the roles of TOPLEVEL contexts within CR (which do not exist within CXXR). Note that in CXXR, each Evaluator has its own singly-linked list of Context objects (starting with the innermost); there is no overall list of Context objects spanning different Evaluator objects.

Member Function Documentation

static Evaluator* CXXR::Evaluator::current ( )

inlinestatic

The current Evaluator.

Returns:: Pointer to the current (innermost) Evaluator.

static unsigned int CXXR::Evaluator::depth ( )

inlinestatic

(Not for general use.)

Used in context.cpp to save the evaluation depth associated with an RCNTXT. Also used in do_Cstack_info() in platform.cpp.

Returns:: The current evaluation depth.

static unsigned int CXXR::Evaluator::depthLimit ( )

inlinestatic

Maximum depth of R expression nesting.

Returns:: The current maximum nesting depth (disregarding any extra depth that may have been introduced by extraDepth() ).

static void CXXR::Evaluator::enableExtraDepth ( bool on )

inlinestatic

(Not for general use.)

Parameters:

on	If true, and extra depth is not already enabled, an increase is applied to the permissible depth of nested evaluations to allow error reporting to be carried out. If false, any such extra depth currently in force is removed.

static void CXXR::Evaluator::enableProfiling ( bool on )

inlinestatic

(Not for general use.)

This function is for use by the profiling code in eval.cpp to record whether profiling is currently enabled.

Parameters:

on	true iff printing is required.

static void CXXR::Evaluator::enableResultPrinting ( bool on )

inlinestatic

Specify whether the result of top-level expression be printed.

Parameters:

on	true iff printing is required.

RObject * Evaluator::evaluate	(	RObject *	object,
		Environment *	env
	)

static

Evaluate RObject in a specified Environment.

For most types of RObject, this simply returns a pointer to the RObject itself.

Parameters:

object	Pointer to the RObject to be evaluated. May be null, in which case the function returns a null pointer.
env	Pointer to the environment in which evaluation is to take place. May be null only if object is null.

Returns:: Pointer to the result of evaluation.

Context* CXXR::Evaluator::innermostContext ( ) const

inline

Innermost Context belonging to this Evaluator.

Returns:: Pointer to the innermost Context belonging to this Evaluator.

static bool CXXR::Evaluator::profiling ( )

inlinestatic

Is profiling currently enabled?

Returns:: true iff profiling is currently in progress.

static bool CXXR::Evaluator::resultPrinted ( )

inlinestatic

Is the result of top-level expression evaluation printed?

Returns:: true iff it is currently specified that the result of a top-level R expression evaluation should be printed.

static void CXXR::Evaluator::setDepth ( unsigned int depth )

inlinestatic

(Not for general use.)

Used in context.cpp to restore the evaluation depth associated with an RCNTXT. Also used in main.cpp to reset the evaluation depth to zero.

Parameters:

depth The required depth.

void Evaluator::setDepthLimit ( int depth )

static

Set maximum depth of R expression nesting.

Parameters:

depth The required maximum nesting depth. If the supplied value lies outside the permissible range, an error is reported and the nesting depth is left unchanged.

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

Classes

Public Member Functions

Static Public Member Functions

Friends

Detailed Description

Member Function Documentation