dds::sub::Query Class Reference

Query objects contain expressions that allow the application to specify a filter on the locally available data. More...

#include "Query.hpp"

Inherits dds::core::Reference< DELEGATE >.

Inherited by dds::sub::cond::QueryCondition.

Public Types
typedef DELEGATE::const_iterator	const_iterator
typedef DELEGATE::iterator	iterator

Public Member Functions
	Query (const dds::sub::AnyDataReader &dr, const std::string &expression)
template<typename FWIterator >
	Query (const dds::sub::AnyDataReader &dr, const std::string &expression, const FWIterator &params_begin, const FWIterator &params_end)
	Query (const dds::sub::AnyDataReader &dr, const std::string &expression, const std::vector< std::string > &params)
void	add_parameter (const std::string &param)
iterator	begin ()
const_iterator	begin () const
const AnyDataReader &	data_reader () const
iterator	end ()
const_iterator	end () const
const std::string &	expression () const
void	expression (const std::string &expr)
bool	is_nil () const
bool	operator!= (const null_type nil) const
template<typename R >
bool	operator!= (const R &ref) const
DELEGATE *	operator-> ()
const DELEGATE *	operator-> () const
bool	operator== (const null_type) const
template<typename R >
bool	operator== (const R &ref) const
template<typename FWIterator >
void	parameters (const FWIterator &begin, const FWIterator end)
uint32_t	parameters_length () const

Detailed Description

Query objects contain expressions that allow the application to specify a filter on the locally available data.

A Query is used in a QueryCondition or DataReader::Selector and is associated with one DataReader.

SQL Expression

The SQL query string is set by expression which must be a subset of the SQL query language. In this query expression, parameters may be used, which must be set in the sequence of strings defined by the parameter query_parameters. A parameter is a string which can define an integer, float, string or enumeration. The number of values in query_parameters must be equal or greater than the highest referenced n token in the query_expression (e.g. if %1 and %8 are used as parameters in the query_expression, the query_parameters should at least contain n+1 = 9 values).
Look here for the specific query expression syntax.

See also

dds::sub::cond::QueryCondition

dds::sub::DataReader::Selector

dds::sub::DataReader::ManipulatorSelector

Subscription concept

Definition at line 61 of file Query.hpp.

Member Typedef Documentation

const_iterator

typedef DELEGATE::const_iterator dds::sub::Query::const_iterator

Iterator for the query expression parameters.

Definition at line 75 of file Query.hpp.

iterator

typedef DELEGATE::iterator dds::sub::Query::iterator

Iterator for the query expression parameters.

Definition at line 70 of file Query.hpp.

Constructor & Destructor Documentation

Query() [1/3]

dds::sub::Query::Query	(	const dds::sub::AnyDataReader &	dr,
		const std::string &	expression
	)

Create a dds::sub::Query associated with an dds::sub::AnyDataReader.

Parameters

dr	The AnyDataReader to associate with the Query.
expression	SQL expression

Exceptions

dds::core::Exception

Query() [2/3]

template<typename FWIterator >

dds::sub::Query::Query	(	const dds::sub::AnyDataReader &	dr,
		const std::string &	expression,
		const FWIterator &	params_begin,
		const FWIterator &	params_end
	)

Create a dds::sub::Query associated with an dds::sub::AnyDataReader.

Parameters

dr	The AnyDataReader to associate with the Query.
expression	SQL expression

Template Parameters

params_begin	Iterator pointing to the beginning of the parameters to set
params_end	Iterator pointing to the end of the parameters to set

Exceptions

dds::core::Exception

Query() [3/3]

dds::sub::Query::Query	(	const dds::sub::AnyDataReader &	dr,
		const std::string &	expression,
		const std::vector< std::string > &	params
	)

Create a dds::sub::Query associated with an dds::sub::AnyDataReader.

Parameters

dr	The AnyDataReader to associate with the Query.
expression	SQL expression

Template Parameters

params

Vector containing SQL expression parameters

Exceptions

dds::core::Exception

Member Function Documentation

add_parameter()

void dds::sub::Query::add_parameter

(

const std::string &

param

)

Adds a parameter to the query.

See SQL expression info

Parameters

param

The parameter to add

Exceptions

dds::core::Exception

begin() [1/2]

iterator dds::sub::Query::begin

(

)

Provides the begin iterator to the SQL expression parameter list.

See SQL expression info

Returns

dds::sub::Query::iterator The begin iterator

Exceptions

dds::core::Exception

begin() [2/2]

const_iterator dds::sub::Query::begin

(

)

const

Provides the begin iterator to the SQL expression parameter list.

See SQL expression info

Returns

dds::sub::Query::const_iterator The begin iterator

Exceptions

dds::core::Exception

data_reader()

const AnyDataReader& dds::sub::Query::data_reader

(

)

const

This operation returns the DataReader associated with the Query.

Note that there is exactly one DataReader associated with each Query.

Returns

dds::sub::AnyDataReader The associated DataReader

Exceptions

dds::core::Exception

end() [1/2]

iterator dds::sub::Query::end

(

)

The end iterator to the SQL expression parameter list.

See SQL expression info

Returns

dds::sub::Query::iterator The end iterator

Exceptions

dds::core::Exception

end() [2/2]

const_iterator dds::sub::Query::end

(

)

const

The end iterator to the SQL expression parameter list.

See SQL expression info

Returns

dds::sub::Query::const_iterator The end iterator

Exceptions

dds::core::Exception

expression() [1/2]

const std::string& dds::sub::Query::expression

(

)

const

Get expression.

Returns

std::string The SQL expression.

Exceptions

dds::core::Exception

expression() [2/2]

void dds::sub::Query::expression

(

const std::string &

expr

)

Set new expression.

Parameters

expr	ref anchor_dds_sub_query_expression "SQL expression"

Exceptions

dds::core::Exception

is_nil()

template<typename DELEGATE>

bool dds::core::Reference< DELEGATE >::is_nil ( ) const

inherited

Check if the referenced object is nil.

In other words, check if the reference is pointing to a null object.

Returns

true if the referenced object is null.

operator!=() [1/2]

template<typename DELEGATE>

bool dds::core::Reference< DELEGATE >::operator!= ( const null_type  nil ) const

inherited

Special operator!= used to check if this reference object does not equal the dds::core::null reference.

The non-null-check can be done like this:

if (r != dds::core::null) {
   // Use the dds reference object r
}

Returns

true if this reference is not null.

operator!=() [2/2]

template<typename DELEGATE>

template<typename R >

bool dds::core::Reference< DELEGATE >::operator!= ( const R &  ref ) const

inherited

Compares two Reference objects and returns true if they are not equal.

Inequality is based on the referential inequality of the object being pointed to.

Parameters

ref	the other Reference object

Returns

true when not equal

operator->() [1/2]

template<typename DELEGATE>

DELEGATE* dds::core::Reference< DELEGATE >::operator-> ( )

inherited

The operator->() is provided to be able to directly invoke functions on the delegate.

The decision to provide direct access to the delegate was motivated by the need for providing a way that was not invasive with respect to the CXXDDS API and yet would allow for vendor-specific extension. Thus vendor-specific extensions can be invoked on the Reference and on all its subclasses as follows:

my_dds_entity.standard_function();
my_dds_entity->vendor_specific_extension();

Returns

a reference to delegate.

operator->() [2/2]

template<typename DELEGATE>

const DELEGATE* dds::core::Reference< DELEGATE >::operator-> ( ) const

inherited

The operator->() is provided to be able to directly invoke functions on the delegate.

The decision to provide direct access to the delegate was motivated by the need for providing a way that was not invasive with respect to the CXXDDS API and yet would allow for vendor-specific extension. Thus vendor-specific extensions can be invoked on the Reference and on all its subclasses as follows:

my_dds_entity.standard_function();
my_dds_entity->vendor_specific_extension();

Returns

a reference to delegate.

operator==() [1/2]

template<typename DELEGATE>

bool dds::core::Reference< DELEGATE >::operator== ( const  null_type ) const

inherited

Special operator== used to check if this reference object equals the dds::core::null reference.

The null-check can be done like this:

if (r == dds::core::null) {
   // Do not use the dds reference object r in its current state
}

Returns

true if this reference is null.

operator==() [2/2]

template<typename DELEGATE>

template<typename R >

bool dds::core::Reference< DELEGATE >::operator== ( const R &  ref ) const

inherited

Compares two Reference objects and returns true if they are equal.

Equality is based on the referential equality of the object being pointed.

Parameters

ref	the other Reference object

Returns

true when equal

parameters()

template<typename FWIterator >

void dds::sub::Query::parameters	(	const FWIterator &	begin,
		const FWIterator	end
	)

Sets the query parameters.

See SQL expression info

Template Parameters

begin	Iterator pointing to the beginning of the parameters to set
end	Iterator pointing to the end of the parameters to set

Exceptions

dds::core::Exception

parameters_length()

uint32_t dds::sub::Query::parameters_length

(

)

const

Gets the number of parameters in the query.

See SQL expression info

Returns

uint32_t The number of parameters in the query

Exceptions

dds::core::Exception

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

• dds/sub/Query.hpp