	QSDK 1.1 Documentation

Q::Query Struct Reference
[Knowledge Base]

#include <Q/q.h>

Inheritance diagram for Q::Query:

List of all members.


Public Member Functions
	Query ()
bool	valid () const
void	reset ()
void	next ()
Concept	key () const
Concept	current () const
bool	light () const
void	removeCurrent ()
bool	setCurrent (const Concept &value)
Concept	operator * () const
Query &	operator++ ()
Static Public Member Functions
Query	create (const Concept &con, const Concept &relation)
Query	create (const Concept &con)
bool	affirm (const Concept &con, const Concept &rel, const Concept &value)
ClassType	classType ()
Query	cast (const ObjectBase &obj)

Detailed Description

Retrieve information from the knowledge database.

See also:: Concept, ConceptIterator, ObjectIterator

Constructor & Destructor Documentation

Q::Query::Query ( ) [inline]

Create a null Query reference.

Member Function Documentation

bool Q::Query::affirm ( const Concept & con,

const Concept & rel,

const Concept & value

) [static]

Concise form of Query that looks up a specific fact, exactly (con rel value). A fully specified fact will be there or not, there is no iteration here. This process is equivalent to Query(con, rel) and expecting (at most) one value Query::current() of value.

Query Q::Query::cast ( const ObjectBase & obj ) [static]

If the object referenced by obj is a Query, then return a suitable reference to the object.

ClassType Q::Query::classType ( ) [static]

Return the type of this class.

Query Q::Query::create ( const Concept & con ) [static]

Same as create(con, Concept()).

Query Q::Query::create ( const Concept & con,

const Concept & relation

) [static]

Create a Query iterating the facts of con subject to the given relation. If relation is the null Concept, all facts of con are retrieved. For each fact, its relation is given by Query::key() and the value given by Query::current(). When relation is defined, Query::key() is relation, and Query::current() ranges over all facts of con with the same relation.

Concept Q::Query::current ( ) const

The current value is the value term of a fact, ie. the last term. For example, when the iteration Query(bob) parks on (bob likes porridge), "porridge" is Query::current().

Note:
Unlike for the relation, the value term of a fact could be a value concept (ie ConceptValue). Use Concept::isValue() to determine this.

Concept Q::Query::key ( ) const

The key is the relation term of the fact, ie. the middle term. For example, when the iteration Query(bob) parks on (bob likes porridge), "likes" is Query::key().

Note:
the key, ie. the relation, is never a value concept.

bool Q::Query::light ( ) const

true if the knowledge database in which the current fact is found is lightweight, and also this fact is light.

void Q::Query::next ( )

Advance the iterator to the next result of the query or if the current result is the last result of the query, then set the state of the query to invalid.

Concept Q::Query::operator * ( ) const [inline]

See also:
current

Query& Q::Query::operator++ ( ) [inline]

See also:
next

void Q::Query::removeCurrent ( )

Delete the current fact, ie. (con relation value) from the knowledge database.

void Q::Query::reset ( )

Set the iterator to point at the first result.

bool Q::Query::setCurrent ( const Concept & value )

Concise way of removing the current fact, eg. (con relation oldVal) and adding (con relation value). This is a handy way to change the value of facts used to store object properties.

bool Q::Query::valid ( ) const

Is the iteration still valid?
Reimplemented from Q::ObjectBase.

Q::Query Struct Reference [Knowledge Base]

Public Member Functions

Static Public Member Functions

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Q::Query Struct Reference
[Knowledge Base]