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/*******************************************************************************
* Copyright (c) 2010-2015, Bergmann Gabor, Istvan Rath and Daniel Varro
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-v20.html.
*
* SPDX-License-Identifier: EPL-2.0
*******************************************************************************/
package tools.refinery.viatra.runtime.matchers.context;
import java.util.Collection;
import java.util.Comparator;
import java.util.Map;
import java.util.Set;
/**
* Provides metamodel information (relationship of input keys) to query evaluator backends at runtime and at query planning time.
*
* @noimplement Implementors should extend {@link AbstractQueryMetaContext} instead of directly implementing this interface.
* @author Bergmann Gabor
*/
public interface IQueryMetaContext {
/**
* Returns true iff instance tuples of the given key can be enumerated.
* <p> If false, the runtime can only test tuple membership in the extensional relation identified by the key, but not enumerate member tuples in general.
* <p> Equivalent to {@link IInputKey#isEnumerable()}.
*/
boolean isEnumerable(IInputKey key);
/**
* Returns true iff the set of instance tuples of the given key is immutable.
* <p> If false, the runtime provides notifications upon change.
*/
boolean isStateless(IInputKey key);
/**
* Returns a set of implications (weakened alternatives),
* with a suggestion for the query planner that satisfying them first may help in satisfying the implying key.
* <p> Note that for the obvious reasons, enumerable keys can only be implied by enumerable keys.
* <p> Must follow directly or transitively from implications of {@link #getImplications(IInputKey)}.
* @since 1.6
*/
Collection<InputKeyImplication> getWeakenedAlternatives(IInputKey implyingKey);
/**
* Returns known direct implications, e.g. edge supertypes, edge opposites, node type constraints, etc.
* <p> Note that for the obvious reasons, enumerable keys can only be implied by enumerable keys.
*/
Collection<InputKeyImplication> getImplications(IInputKey implyingKey);
/**
* Returns known "double dispatch" implications, where the given implying key implies other input keys under certain additional conditions (themselves input keys).
* For example, a "type x, unscoped" input key may imply the "type x, in scope" input key under the condition of the input key "x is in scope"
*
* <p> Note that for the obvious reasons, enumerable keys can only be implied by enumerable keys (either as the implying key or as the additional condition).
* <p> Note that symmetry is not required, i.e. the additional conditions do not have to list the same conditional implication.
* @return multi-map, where the keys are additional conditions and the values are input key implications jointly implied by the condition and the given implying key.
* @since 2.0
*/
Map<InputKeyImplication, Set<InputKeyImplication>> getConditionalImplications(IInputKey implyingKey);
/**
* Returns functional dependencies of the input key expressed in terms of column indices.
*
* <p> Each entry of the map is a functional dependency rule, where the entry key specifies source columns and the entry value specifies target columns.
*/
Map<Set<Integer>, Set<Integer>> getFunctionalDependencies(IInputKey key);
/**
* For query normalizing, this is the order suggested for trying to eliminate input keys.
* @since 1.6
*/
Comparator<IInputKey> getSuggestedEliminationOrdering();
/**
* Tells whether the given {@link IInputKey} is an edge and may lead out of scope.
*
* @since 1.6
*/
boolean canLeadOutOfScope(IInputKey key);
/**
* Returns true if the given {@link IInputKey} represents a poset type.
* @since 1.6
*/
boolean isPosetKey(IInputKey key);
/**
* Returns an {@link IPosetComparator} for the given set of {@link IInputKey}s.
*
* @param keys an iterable collection of input keys
* @return the poset comparator
* @since 1.6
*/
IPosetComparator getPosetComparator(Iterable<IInputKey> keys);
}
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