mdf::ISampleObserver Class Reference

Interface to a sample observer that handle incoming samples events.

#include <isampleobserver.h>

Inheritance diagram for mdf::ISampleObserver:

Collaboration diagram for mdf::ISampleObserver:

Public Member Functions
	ISampleObserver (const IDataGroup &data_group)
	Sample observer constructor.
virtual	~ISampleObserver ()
	Destructor.
virtual void	AttachObserver ()
	Attach the observer to an observer list (publisher).
virtual void	DetachObserver ()
	Detach the observer from an observer list.
virtual bool	OnSample (uint64_t sample, uint64_t record_id, const std::vector< uint8_t > &record)
	Observer function that receives the sample record and parse out a channel value.
bool	IsRecordIdNeeded (uint64_t record_id) const
	Function that test if this observer needs to read a specific record.
template<typename V >
bool	GetChannelValue (const IChannel &channel, uint64_t sample, const std::vector< uint8_t > &record, V &value, uint64_t array_index=0) const
	The function returns a channel value.
template<typename V >
bool	GetEngValue (const IChannel &channel, uint64_t sample, const std::vector< uint8_t > &record, V &value, uint64_t array_index=0) const
	Returns the scaled sample value for the channel with the record bytes as input. This function is mainly for internal use but is used together with sample observers.

Public Attributes
std::function< bool(uint64_t sample, uint64_t record_id, const std::vector< uint8_t > &record)>	DoOnSample
	Function object that is called if assigned.

Protected Attributes
std::set< uint64_t >	record_id_list_
	List of subscribed channel groups.
const IDataGroup &	data_group_
	Reference to the data group (DG) block.

Member Function Documentation

AttachObserver()

virtual void mdf::ISampleObserver::AttachObserver ( )

virtual

This function is normally called in the constructor of an observer, so there is normally no need to call it.

DetachObserver()

virtual void mdf::ISampleObserver::DetachObserver ( )

virtual

This function detach the observer from the observer list. This function shall be called when OnSample() function is not needed anymore. This function is needed to handle dangling pointers. For example it is called after the ReadData() function in a reader.

GetChannelValue()

template<typename V >

bool mdf::ISampleObserver::GetChannelValue ( const IChannel & channel, uint64_t sample, const std::vector< uint8_t > & record, V & value, uint64_t array_index = 0 ) const

inline

Use this function to get a channel value from a sample record buffer. Note that the array index should only be used if the channel is a so-called channel array (CA block).

Template Parameters

V	Type of value.

Parameters

channel	Reference to a channel.
sample	Sample number (0..N).
record	Record buffer.
value	Reference to the returning value.
array_index	Array index in case of an array channel object.

Returns

True if the value is valid.

GetEngValue()

template<typename V >

bool mdf::ISampleObserver::GetEngValue ( const IChannel & channel, uint64_t sample, const std::vector< uint8_t > & record, V & value, uint64_t array_index = 0 ) const

inline

The engineering value is the scaled value of the channel value. The attached conversion block defines the type of scaling to apply. Note that the channel value and the scaled value may have different type and unit.

Template Parameters

V	Type of value to return.

Parameters

channel	Reference to the channel.
sample	Sample index.
record	Record data bytes excluding the record ID bytes
value	Returns the scaled value.
array_index	Optional array index in case of channel array.

Returns

Return true if the value is valid.

IsRecordIdNeeded()

bool mdf::ISampleObserver::IsRecordIdNeeded ( uint64_t record_id ) const

inlinenodiscard

Parameters

record_id

The channel groups record ID

Returns

True if this channel subscribe on this record (channel group).

OnSample()

virtual bool mdf::ISampleObserver::OnSample ( uint64_t sample, uint64_t record_id, const std::vector< uint8_t > & record )

virtual

The function may be override by an inheritance for more complex implementations but in simpler use cases the DoOnSample function should be used instead.

The function normally returns true indicating that more reading is expected. If any observer want to stop further parsing, the function should return false.

Parameters

sample	Sample number.
record_id	Record ID (channel group identity).
record	Sample record (excluding the record ID.

Returns

If this function returns false it indicate that reading should be aborted.

Member Data Documentation

DoOnSample

std::function<bool(uint64_t sample, uint64_t record_id, const std::vector<uint8_t>& record)> mdf::ISampleObserver::DoOnSample

The function object is typically assigned to a lambda function. See also OnSample() function.

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

• include/mdf/isampleobserver.h