org.eclipse.incquery.runtime.matchers.psystem.queries

Interface PQuery

All Superinterfaces:

PQueryHeader

All Known Subinterfaces:

InitializablePQuery

All Known Implementing Classes:

BaseGeneratedEMFPQuery, BasePQuery, GenericEMFPatternPQuery, GenericReferencedPQuery, GenericTracedPQuery

public interface PQuery
extends PQueryHeader

Internal representation of a query / graph pattern (using a constraint system formalism), to be interpreted by a query evaluator (IQueryBackend). End-users of IncQuery should access a query as an IQuerySpecification instead.

PQuerys are definitions of queries usable inside pattern descriptions. Such description always has (a non-null) name. The query itself is defined as a (non-empty) set of PBody instances, the result is the disjunction of the single PBody instances.

A PQuery might be constructed from erroneous patterns or might be uninitialized - this is represented by its status.

Since:

0.8.0

Author:

Zoltan Ujhelyi

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	PQuery.PQueryStatus

Method Summary

Modifier and Type	Method and Description
void	checkMutability() Before a modification operation is executed, a mutability check is performed (via the getStatus() implementation, and in case of problems an IllegalStateException is thrown.
void	ensureInitialized() If the query definition is uninitialized, initializes it.
java.util.Set<PQuery>	getAllReferredQueries() Returns all queries required to evaluate this query (transitively).
java.util.Set<PQuery>	getDirectReferredQueries() Returns all queries directly referred in the constraints.
PDisjunction	getDisjunctBodies() Returns all bodies associated with the query in their canonical form.
QueryEvaluationHint	getEvaluationHints() Optional hints regarding the query evaluation strategy, to be interpreted by the query engine.
java.util.List<PProblem>	getPProblems() Returns a list describing the problems that were found in this query.
PQuery.PQueryStatus	getStatus() Returns the initialization status of the definition
boolean	isMutable() An option to check mutability of the query.
java.util.List<java.lang.Object>	publishedAs() Returns the end-user query specification API objects that wrap this query.

Methods inherited from interface org.eclipse.incquery.runtime.matchers.psystem.queries.PQueryHeader

getAllAnnotations, getAnnotationsByName, getFirstAnnotationByName, getFullyQualifiedName, getParameterNames, getParameters, getPositionOfParameter

Method Detail

getDisjunctBodies

PDisjunction getDisjunctBodies()

Returns all bodies associated with the query in their canonical form. If called multiple times, the same set with the same contents will be returned.

getDirectReferredQueries

java.util.Set<PQuery> getDirectReferredQueries()

Returns all queries directly referred in the constraints. They are all required to evaluate this query

Returns:

a non-null, but possibly empty list of query definitions

getAllReferredQueries

java.util.Set<PQuery> getAllReferredQueries()

Returns all queries required to evaluate this query (transitively).

Returns:

a non-null, but possibly empty list of query definitions

getStatus

PQuery.PQueryStatus getStatus()

Returns the initialization status of the definition

getPProblems

java.util.List<PProblem> getPProblems()

Returns a list describing the problems that were found in this query.

TODO: formulate invariant connecting getPProblems() and getStatus().

Returns:

a non-null, but possibly empty list of problems

checkMutability

void checkMutability()
              throws java.lang.IllegalStateException

Before a modification operation is executed, a mutability check is performed (via the getStatus() implementation, and in case of problems an IllegalStateException is thrown.

Throws:

java.lang.IllegalStateException

isMutable

boolean isMutable()

An option to check mutability of the query. It can be used to avoid getting an IllegalStateException by the execution of checkMutability().

Returns:

true if the query specification is still editable

getEvaluationHints

QueryEvaluationHint getEvaluationHints()

Optional hints regarding the query evaluation strategy, to be interpreted by the query engine.

To ensure the possibility of external overrides, the evaluation engine should not directly consult this field, but use an IQueryBackendHintProvider instead.

ensureInitialized

void ensureInitialized()
                throws QueryInitializationException

If the query definition is uninitialized, initializes it.

Throws:

QueryInitializationException - if initialization of query specification fails

publishedAs

java.util.List<java.lang.Object> publishedAs()

Returns the end-user query specification API objects that wrap this query.

Intended for traceability and debug purposes, not part of normal operation. Returned list is intended to be appended during query specification construction time.

Returns:

a non-null, but possibly empty list of query specification objects;