| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.rya.forwardchain.rule; |
| |
| import java.util.Collection; |
| |
| import org.apache.rya.api.domain.StatementMetadata; |
| import org.apache.rya.forwardchain.ForwardChainException; |
| import org.apache.rya.forwardchain.strategy.AbstractRuleExecutionStrategy; |
| import org.openrdf.query.algebra.StatementPattern; |
| |
| /** |
| * Represents a forward-chaining inference rule. A rule is triggered by some |
| * combination of triples, and may produce some combination of triples when |
| * applied. Potential triggers (antecedents) and potential results (consequents) |
| * are represented in a general form as {@link StatementPattern}s and can be |
| * used to determine relationships between rules. |
| */ |
| public interface Rule { |
| /** |
| * Whether this rule, if applied, could produce triples of a given form. |
| * @param sp A statement pattern describing a possible inferred triple; |
| * assumed not null. |
| * @return true if a consequent of this rule could match the pattern. |
| */ |
| abstract public boolean canConclude(StatementPattern sp); |
| |
| /** |
| * All {@link StatementPattern}s that can, in some combination, trigger this |
| * rule. Should be a complete set, such that if no statements matching any |
| * of the patterns exist, the rule cannot derive any new information. |
| * @return Any number of statement patterns. |
| */ |
| abstract public Collection<StatementPattern> getAntecedentPatterns(); |
| |
| /** |
| * {@link StatementPattern}s completely describing the possible conclusions |
| * of this rule. Any derived statement should match one of these patterns. |
| * @return Any number of statement patterns. |
| */ |
| abstract public Collection<StatementPattern> getConsequentPatterns(); |
| |
| /** |
| * Given an {@link AbstractRuleExecutionStrategy}, executes this rule. |
| * Associates any new or modified triples with the specified statement |
| * metadata. |
| * @param strategy A strategy capable of applying individual rules; should |
| * not be null. |
| * @param metadata StatementMetadata to add to any results. Can be used to |
| * record the circumstances of the derivation. Should not be null; use |
| * {@link StatementMetadata#EMPTY_METADATA} to add none. Implementing |
| * classes may add additional metadata specific to the rule. |
| * @return The number of new inferences made during rule execution. |
| * @throws ForwardChainException if an error was encountered during |
| * rule application. |
| */ |
| abstract public long execute(AbstractRuleExecutionStrategy strategy, |
| StatementMetadata metadata) throws ForwardChainException; |
| } |