ScopeQuery< MO > Class Template Reference

#include "steam/mobject/session/scope-query.hpp"

Description

template<class MO>
class steam::mobject::session::ScopeQuery< MO >

Query a scope to discover it's contents or location.

This is a special kind of query, wired up such as to enumerate the contents or parents of a scope, filtered by a subtype-check. For the actual resolution of the elements to discover, this query relies on an index like facility (usually Session's PlacementIndex), which is abstracted as a QueryResolver, but actually is expected to cooperate especially with this Query subclass to retrieve the scope to be enumerated and the definition of the actual filter predicate. Currently (11/09), there is a special, hard-wired Query-kind-ID Goal::DISCOVERY to distinguish this special kind of a Query.

Contrary to the usual handling of a generic query, a ScopeQuery object holds it's own discovery iterator and thus is completely self contained. The query is issued automatically on construction, thus the embedded iterator immediately points at the first result. Moreover, since any Lumiera Forward Iterator is bool checkable, a ScopeQuery not yielding any results will evaluate to false immediately after construction, allowing convenient inline checks. The query can be re-issued by the function operator, and the embedded result iterator can of course be copied to a bare iterator instance, e.g. for passing it on (ScopeQuery itself is intended to be used polymorphically and thus defined to be not assignable)

Definition at line 135 of file scope-query.hpp.

Public Types
typedef _Parent::ContentFilter	ContentFilter
typedef _Parent::iterator	iterator
Public Types inherited from DiscoveryQuery< MO >
typedef function< bool(PlacementMO const &)>	ContentFilter
typedef _Query::iterator	iterator
Public Types inherited from Query< RES >
typedef lib::IterAdapter< Cursor, PReso >	iterator
Public Types inherited from Goal
enum	Kind {   EMPTY = 0,   GENERIC = 1,   DISCOVERY,   PLACEMENT }

Public Member Functions
	ScopeQuery (PlacementMO const &scope, ScopeQueryKind direction)
ScopeQueryKind	searchDirection () const
PlacementMO::ID const &	searchScope () const
Public Member Functions inherited from DiscoveryQuery< MO >
ContentFilter	contentFilter () const
Public Member Functions inherited from Query< RES >
	Query (string querySpec)
string	extractID (Symbol predicate) const
	convenience shortcut to extract a desired name-ID. More...
	operator QueryKey () const
	automatic conversion from Query to QueryKey for indexing and ordering. More...
iterator	operator() (QueryResolver const &resolver) const
	notational convenience shortcut, synonymous to Query<RES>::resolveBy()
Builder	rebuild () const
iterator	resolveBy (QueryResolver const &resolver) const
bool	usesPredicate (Symbol predicate) const
Public Member Functions inherited from Goal
virtual	~Goal ()
	this is a marker baseclass
QueryID const &	getQID () const

Private Types
typedef DiscoveryQuery< MO >	_Parent
typedef Query< Placement< MO > >	_Query

Private Member Functions
ContentFilter	buildContentFilter () const
	the default implementation of the content filtering builds on the downcast-function available on each Placement instance. More...
lib::QueryText	buildSyntacticRepresentation () const
	supplement a syntactic representation (as generic query in predicate form). More...

Private Attributes
PlacementMO::ID	startPoint_
ScopeQueryKind	to_discover_

Additional Inherited Members
Static Public Member Functions inherited from Query< RES >
static Builder	build (Kind queryType=Goal::GENERIC)
Protected Member Functions inherited from Query< RES >
	Query (QueryID typeID, lib::QueryText const &genericQuerySpec)
	Query (QueryID typeID, string querySpec)
lib::QueryText	getQueryDefinition () const
	access the complete syntactical representation of this query. More...
Protected Member Functions inherited from Goal
	Goal (QueryID qid)
Static Protected Member Functions inherited from Query< RES >
static QueryID	defineQueryTypeID (Kind queryType=Goal::GENERIC)
Protected Attributes inherited from Goal
QueryID	id_

Member Function Documentation

buildContentFilter()

ContentFilter buildContentFilter ( ) const

inlineprivatevirtual

the default implementation of the content filtering builds on the downcast-function available on each Placement instance.

By parametrising this function with our template parameter MO, we pick out only those elements of the scope being subclasses of MO

Implements DiscoveryQuery< MO >.

Reimplemented in SpecificContentsQuery< MO >.

Definition at line 180 of file scope-query.hpp.

buildSyntacticRepresentation()

lib::QueryText buildSyntacticRepresentation ( ) const

inlineprivatevirtual

supplement a syntactic representation (as generic query in predicate form).

Building this representation is done on demand for performance reasons; typically a ScopeQuery is issued immediately into a known sub scope of the Session/Model and resolved by the PlacementIndex

Todo:

we need a readable and sensible representation as generic query ///////////////////TICKET #901

Reimplemented from Query< RES >.

Definition at line 192 of file scope-query.hpp.

Inheritance diagram for ScopeQuery< MO >:

Collaboration diagram for ScopeQuery< MO >:

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

• scope-query.hpp