org.eclipse.incquery.runtime.api

Class IncQueryEngine

java.lang.Object

org.eclipse.incquery.runtime.api.IncQueryEngine

Direct Known Subclasses:

AdvancedIncQueryEngine

public abstract class IncQueryEngine
extends java.lang.Object

An IncQuery incremental evaluation engine, attached to a model such as an EMF resource. The engine hosts pattern matchers, and will listen on model update notifications stemming from the given model in order to maintain live results.

By default, IncQueryEngines do not need to be separately disposed; they will be garbage collected along with the model. Advanced users: see AdvancedIncQueryEngine if you want fine control over the lifecycle of an engine.

Pattern matchers within this engine may be instantiated in the following ways:

• Recommended: instantiate the specific matcher class generated for the pattern by e.g. MyPatternMatcher.on(engine).
• Use getMatcher(IQuerySpecification) if the pattern-specific generated matcher API is not available.
• Advanced: use the query specification associated with the generated matcher class to achieve the same.

Additionally, a group of patterns (see IQueryGroup) can be initialized together before usage; this may improve the performance of pattern matcher construction by trying to gather all necessary information from the model in one go. Note that no such improvement is to be expected if the engine is specifically constructed in wildcard mode, an option available in some scope implementations (see EMFScope.EMFScope(Notifier, BaseIndexOptions) and BaseIndexOptions.withWildcardMode(boolean)).

Author:

Bergmann Gábor

Constructor Summary

Constructors

Constructor and Description
IncQueryEngine()

Method Summary

Modifier and Type	Method and Description
abstract IBaseIndex	getBaseIndex() Provides access to the internal base index component of the engine, responsible for keeping track of basic contents of the model.
abstract java.util.Set<? extends IncQueryMatcher<? extends IPatternMatch>>	getCurrentMatchers() Access a copy of available IncQueryMatcher pattern matchers.
abstract org.eclipse.emf.common.notify.Notifier	getEMFRoot() Deprecated. only valid for EMF scopes; use getScope() to get scope information in the general case.
abstract <Matcher extends IncQueryMatcher<? extends IPatternMatch>> Matcher	getExistingMatcher(IQuerySpecification<Matcher> querySpecification) Access an existing pattern matcher based on a IQuerySpecification.
abstract <Matcher extends IncQueryMatcher<? extends IPatternMatch>> Matcher	getMatcher(IQuerySpecification<Matcher> querySpecification) Access a pattern matcher based on a IQuerySpecification.
abstract IncQueryMatcher<? extends IPatternMatch>	getMatcher(java.lang.String patternFQN) Access a pattern matcher for the graph pattern with the given fully qualified name.
java.util.Set<IQuerySpecification<? extends IncQueryMatcher<? extends IPatternMatch>>>	getRegisteredQuerySpecifications()
abstract IncQueryScope	getScope()
static IncQueryEngine	on(IncQueryScope scope) Obtain a (managed) IncQueryEngine to evaluate queries over a given scope specified by an IncQueryScope.
static IncQueryEngine	on(org.eclipse.emf.common.notify.Notifier emfScopeRoot) Deprecated. use on(IncQueryScope) instead to evaluate queries on both EMF and non-EMF scopes.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

IncQueryEngine

public IncQueryEngine()

Method Detail

on

@Deprecated
public static IncQueryEngine on(org.eclipse.emf.common.notify.Notifier emfScopeRoot)
                                     throws IncQueryException

Deprecated. use on(IncQueryScope) instead to evaluate queries on both EMF and non-EMF scopes.

Obtain a (managed) IncQueryEngine on a matcher scope specified by a scope root of type Notifier.

For a given matcher scope, the same engine will be returned to any client. This facilitates the reuse of internal caches of the engine, greatly improving performance.

The lifecycle of this engine is centrally managed, and will not be disposed as long as the model is retained in memory. The engine will be garbage collected along with the model.

Advanced users: see AdvancedIncQueryEngine.createUnmanagedEngine(Notifier) to obtain a private, unmanaged engine that is not shared with other clients and allows tight control over its lifecycle.

Parameters:

emfScopeRoot - the scope in which matches supported by the engine should be registered

Returns:

a (managed) IncQueryEngine instance

Throws:

IncQueryException - on initialization errors.

on

public static IncQueryEngine on(IncQueryScope scope)
                         throws IncQueryException

Obtain a (managed) IncQueryEngine to evaluate queries over a given scope specified by an IncQueryScope.

For a given matcher scope, the same engine will be returned to any client. This facilitates the reuse of internal caches of the engine, greatly improving performance.

The lifecycle of this engine is centrally managed, and will not be disposed as long as the model is retained in memory. The engine will be garbage collected along with the model.

Advanced users: see AdvancedIncQueryEngine.createUnmanagedEngine(IncQueryScope) to obtain a private, unmanaged engine that is not shared with other clients and allows tight control over its lifecycle.

Parameters:

scope - the scope of query evaluation; the definition of the set of model elements that this engine is operates on. Provide e.g. a EMFScope for evaluating queries on an EMF model.

Returns:

a (managed) IncQueryEngine instance

Throws:

IncQueryException - on initialization errors.

getBaseIndex

public abstract IBaseIndex getBaseIndex()
                                 throws IncQueryException

Provides access to the internal base index component of the engine, responsible for keeping track of basic contents of the model.

If using an EMFScope, consider EMFScope.extractUnderlyingEMFIndex(IncQueryEngine) instead to access EMF-specific details.

Returns:

the baseIndex the NavigationHelper maintaining the base index

Throws:

IncQueryException - if the base index could not be constructed

getMatcher

public abstract <Matcher extends IncQueryMatcher<? extends IPatternMatch>> Matcher getMatcher(IQuerySpecification<Matcher> querySpecification)
                                                                                       throws IncQueryException

Access a pattern matcher based on a IQuerySpecification. Multiple calls will return the same matcher.

Parameters:

querySpecification - a IQuerySpecification that describes an IncQuery query

Returns:

a pattern matcher corresponding to the specification

Throws:

IncQueryException - if the matcher could not be initialized

getMatcher

public abstract IncQueryMatcher<? extends IPatternMatch> getMatcher(java.lang.String patternFQN)
                                                             throws IncQueryException

Access a pattern matcher for the graph pattern with the given fully qualified name. Will succeed only if a matcher for this pattern has already been constructed in this engine, or else if the matcher for the pattern has been generated and registered. Multiple calls will return the same matcher.

Parameters:

patternFQN - the fully qualified name of an IncQuery graph pattern

Returns:

a pattern matcher corresponding to the specification

Throws:

IncQueryException - if the matcher could not be initialized

getExistingMatcher

public abstract <Matcher extends IncQueryMatcher<? extends IPatternMatch>> Matcher getExistingMatcher(IQuerySpecification<Matcher> querySpecification)

Access an existing pattern matcher based on a IQuerySpecification.

Parameters:

querySpecification - a IQuerySpecification that describes an IncQuery query

Returns:

a pattern matcher corresponding to the specification, null if a matcher does not exist yet.

getCurrentMatchers

public abstract java.util.Set<? extends IncQueryMatcher<? extends IPatternMatch>> getCurrentMatchers()

Access a copy of available IncQueryMatcher pattern matchers.

Returns:

a copy of the set of currently available pattern matchers registered on this engine instance

getRegisteredQuerySpecifications

public java.util.Set<IQuerySpecification<? extends IncQueryMatcher<? extends IPatternMatch>>> getRegisteredQuerySpecifications()

getEMFRoot

@Deprecated
public abstract org.eclipse.emf.common.notify.Notifier getEMFRoot()

Deprecated. only valid for EMF scopes; use getScope() to get scope information in the general case.

Returns:

the scope of pattern matching, i.e. the root of the EMF model tree that this engine is attached to.

getScope

public abstract IncQueryScope getScope()

Returns:

the scope of query evaluation; the definition of the set of model elements that this engine is operates on.