epics::pvData::PVRequestMapper Class Reference

#include <copy/pv/createRequest.h>

Public Types
enum	mode_t { Mask, Slice }

Public Member Functions
	PVRequestMapper (const PVStructure &base, const PVStructure &pvRequest, mode_t mode=Mask)
void	reset ()
	return to state of default ctor
const StructureConstPtr &	base () const
const StructureConstPtr &	requested () const
const BitSet &	requestedMask () const
PVStructurePtr	buildRequested () const
PVStructurePtr	buildBase () const
void	compute (const PVStructure &base, const PVStructure &pvRequest, mode_t mode=Mask)
const std::string &	warnings () const
	After compute(), check if !warnings().empty()
void	copyBaseToRequested (const PVStructure &base, const BitSet &baseMask, PVStructure &request, BitSet &requestMask) const
void	copyBaseFromRequested (PVStructure &base, BitSet &baseMask, const PVStructure &request, const BitSet &requestMask) const
void	maskBaseToRequested (const BitSet &baseMask, BitSet &requestMask) const
void	maskBaseFromRequested (BitSet &baseMask, const BitSet &requestMask) const
void	swap (PVRequestMapper &other)
	Exchange contents of two mappers. O(0) and never throws.

Detailed Description

Helper for implementations of epics::pvAccess::ChannelProvider in interpreting the 'field' substructure of a pvRequest. Copies between an internal (base) Structure, and a client/user visible (requested) Structure.

Note

PVRequestMapper is not re-entrant. It is copyable and swap()able.

Definition at line 74 of file createRequest.h.

Member Enumeration Documentation

enum epics::pvData::PVRequestMapper::mode_t

Enumerator
Mask	Masking mode. Requested Structure is identical to Base. The 'field' substructure of the provided pvRequest is used to construct a BitSet where the bits corresponding to the "selected" fields are set. This mask can be access via. requestedMask(). The copy* and mask* methods operate only on "selected" fields.
Slice	Slice mode The Requested Structure is a strict sub-set of the Base Structure containing those fields "selected" by the 'field' substructure of the provided pvRequest.

Definition at line 76 of file createRequest.h.

Constructor & Destructor Documentation

epics::pvData::PVRequestMapper::PVRequestMapper	(	const PVStructure &	base,
		const PVStructure &	pvRequest,
		mode_t	mode = Mask
	)

See Also

compute()

Member Function Documentation

const StructureConstPtr& epics::pvData::PVRequestMapper::base ( ) const

inline

Returns

the Structure of the PVStructure previously passed to compute(). NULL if never computed()'d

Definition at line 104 of file createRequest.h.

PVStructurePtr epics::pvData::PVRequestMapper::buildBase

(

)

const

Returns

A new instance of the base() Structure

PVStructurePtr epics::pvData::PVRequestMapper::buildRequested

(

)

const

Returns

A new instance of the requested() Structure

void epics::pvData::PVRequestMapper::compute	(	const PVStructure &	base,
		const PVStructure &	pvRequest,
		mode_t	mode = Mask
	)

(re)compute the selected subset of provided base structure.

Parameters

base	A full base structure. Must be "top level" (field offset zero).
pvRequest	The user/client provided request modifier
mode	Control how the mapping is constructed.

See Also

mode_t for a description of mapping modes.

Postcondition

Updates warnings()

Exceptions

std::runtime_error	For errors involving invalid pvRequest
std::logic_error	if the provided base is not a "top level" PVStructure.

void epics::pvData::PVRequestMapper::copyBaseFromRequested	(	PVStructure &	base,
		BitSet &	baseMask,
		const PVStructure &	request,
		const BitSet &	requestMask
	)		const

Copy field values into Base structure from Requested structure

Parameters

base	An instance of the base Structure. Field values are copied into it. Need not be the same instance passed to compute().
baseMask	A bit mask indicating which base fields were copied. BitSet::clear() is not called.
request	An instance of the requested() Structure. Field values are copied from it.
requestMask	A bit mask selecting those requested fields to copy.

void epics::pvData::PVRequestMapper::copyBaseToRequested	(	const PVStructure &	base,
		const BitSet &	baseMask,
		PVStructure &	request,
		BitSet &	requestMask
	)		const

Copy field values from Base structure into Requested structure

Parameters

base	An instance of the base Structure. Field values are copied from it. Need not be the same instance passed to compute().
baseMask	A bit mask selecting those base fields to copy.
request	An instance of the requested() Structure. Field values are copied to it.
requestMask	A bit mask indicating which requested fields were copied. BitSet::clear() is not called.

void epics::pvData::PVRequestMapper::maskBaseFromRequested ( BitSet &  baseMask, const BitSet &  requestMask  ) const

inline

Translate requested bit mask into base bit mask. BitSet::clear() is not called.

Definition at line 187 of file createRequest.h.

void epics::pvData::PVRequestMapper::maskBaseToRequested ( const BitSet &  baseMask, BitSet &  requestMask  ) const

inline

Translate Base bit mask into requested bit mask. BitSet::clear() is not called.

Definition at line 179 of file createRequest.h.

const StructureConstPtr& epics::pvData::PVRequestMapper::requested ( ) const

inline

Returns

the Structure which is the selected sub-set of the base Structure. NULL if never computed()'d

Definition at line 106 of file createRequest.h.

const BitSet& epics::pvData::PVRequestMapper::requestedMask ( ) const

inline

A mask of all fields in the base structure which are also in the requested structure, and any parent/structure "compress" bits. eg. bit 0 is always set.

PVRequestMapper mapper(...);
...
BitSet changed = ...; // a base changed mask
bool wouldcopy = changed.logical_and(mapper.requestedMask());
// wouldcopy==false means that copyBaseToRequested(..., changed, ...) would be a no-op

eg. allows early detection of empty monitor updates.

Definition at line 121 of file createRequest.h.

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

• copy/pv/createRequest.h