Query< RES > Class Template Reference

#include "common/query.hpp"

Description

template<class RES>
class lumiera::Query< RES >

Generic interface to express a query for specifically typed result elements exposing some capabilities or fulfilling some properties.

This is a generic umbrella for several kinds of queries and provides a mechanism for uniform usage of various resolution mechanisms.

Any query bears internal type classification and can be represented in a common syntactical form based on predicate logic. Query instances are created by some facilities allowing to query for objects. These query providers do know the specific kind (type) of query to expose. While client code uses these queries only by reference, there is the possibility to involve a generic QueryResolver, which – behind the scenes – manages a registry of specific resolution mechanisms. This way, clients may retrieve a set of results, where each result represents a possible solution to the original query.

Remarks

lumiera::Query is an interface, but can be used as-is to represent a generic query. Specialised subclasses are required to provide a syntactic representation, but are free to do so only on demand. In this case, generate an empty lib::QueryText definition and implement the Query::buildSyntacticRepresentation function. Every fundamentally different kind of query needs to be listed in Goal::Kind.

Note

until we really integrate a rules based system this can be considered dummy placeholder implementation. Some more specific query resolvers are available already, so, depending on the circumstances the actual resolution might be substantial or just a fake.

Warning

especially the classical resolution-type queries are just faked and use the given query-string as-is, without any normalisation. Moreover, as especially the fake-configrules match by string comparison, this may led to unexpected mis-matches. This is dummy code, after all.

Definition at line 279 of file query.hpp.

Public Types
typedef lib::IterAdapter< Cursor, PReso >	iterator
Public Types inherited from Goal
enum	Kind {   EMPTY = 0,   GENERIC = 1,   DISCOVERY,   PLACEMENT }

Public Member Functions
	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

Static Public Member Functions
static Builder	build (Kind queryType=Goal::GENERIC)

Classes
class	Builder
	Helper for establishing, reworking and remolding queries. More...
class	Cursor

Friends
class	Builder
size_t	hash_value (Query const &q)

Protected Member Functions
	Query (QueryID typeID, lib::QueryText const &genericQuerySpec)
	Query (QueryID typeID, string querySpec)
virtual lib::QueryText	buildSyntacticRepresentation () const
	Extension point to generate a generic query definition on demand. More...
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
static QueryID	defineQueryTypeID (Kind queryType=Goal::GENERIC)

Private Attributes
lib::QueryText	def_
	generic syntactical definition

Additional Inherited Members
Protected Attributes inherited from Goal
QueryID	id_

Member Function Documentation

buildSyntacticRepresentation()

virtual lib::QueryText buildSyntacticRepresentation ( ) const

inlineprotectedvirtual

Extension point to generate a generic query definition on demand.

Some specialised kinds of queries, intended to be treated by a specific resolver, may choose skip constructing a generic query representation, but are then bound to supplement such a generic definition through this function when required. The generated query definition must be sufficient to reconstruct the query in all respects.

Returns

a complete definition of this query in predicate form

Return values

bottom

token to indicate failure to comply to this requirement.

Reimplemented in ScopeQuery< MO >.

Definition at line 304 of file query.hpp.

getQueryDefinition()

lib::QueryText getQueryDefinition ( ) const

inlineprotected

access the complete syntactical representation of this query.

May trigger on-demand initialisation

Definition at line 313 of file query.hpp.

operator QueryKey()

operator QueryKey ( ) const

inline

automatic conversion from Query to QueryKey for indexing and ordering.

By defining a parameter of type QueryKey, any provided Query will be automatically transformed into an generic representation usable for ordered storage in sets, maps and for generation of metrics.

Definition at line 616 of file query.hpp.

extractID()

string extractID ( Symbol  predicate ) const

inline

convenience shortcut to extract a desired name-ID.

Todo:

used extensively for the mock implementation of query resolution. For real resolution queries, such a function is quite nonsensical. To be revisited and (likely) to be removed on the long run

See also

Query::Builder::extractID

Definition at line 595 of file query.hpp.

Referenced by StructFactoryImpl::createIdent(), MockTable::detect_case(), MockTable::fabricate_Sequence_on_demand(), MockTable::fabricate_Timeline_on_demand(), and steam::mobject::_mapping::is_defaults_query_with_channel().

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Inheritance diagram for Query< RES >:

Collaboration diagram for Query< RES >:

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

• query.hpp
• query-resolver.hpp