org.semanticweb.owlapi.util.NamedConjunctChecker Maven / Gradle / Ivy

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/*
 * This file is part of the OWL API.
 *
 * The contents of this file are subject to the LGPL License, Version 3.0.
 *
 * Copyright (C) 2011, The University of Manchester
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see http://www.gnu.org/licenses/.
 *
 *
 * Alternatively, the contents of this file may be used under the terms of the Apache License, Version 2.0
 * in which case, the provisions of the Apache License Version 2.0 are applicable instead of those above.
 *
 * Copyright 2011, University of Manchester
 *
 * Licensed 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.semanticweb.owlapi.util;

import java.util.HashSet;
import java.util.Set;

import org.semanticweb.owlapi.model.OWLClass;
import org.semanticweb.owlapi.model.OWLClassExpression;
import org.semanticweb.owlapi.model.OWLObjectIntersectionOf;

/**
 * A utility class which checks if a class expression has a named conjunct or a
 * specific named conjunct.
 * 
 * @author Matthew Horridge, The University Of Manchester, Bio-Health
 *         Informatics Group, Date: 16-Feb-2007
 */
public class NamedConjunctChecker {

    OWLClass conjunct;
    boolean found;
    boolean collect;
    final Set conjuncts;
    private final NamedConjunctCheckerVisitor visitor;

    /** default constructor */
    public NamedConjunctChecker() {
        visitor = new NamedConjunctCheckerVisitor();
        conjuncts = new HashSet();
    }

    /**
     * @return true ifa named class is a conjunct in a given class expression.
     *         For class expressions which aren't named classes or object
     *         intersections this method will always return false.
     * @param conj
     *        The conjunct to check for
     * @param classExpression
     *        The expression to be checked
     */
    public boolean isNamedConjunct(OWLClass conj,
            OWLClassExpression classExpression) {
        reset();
        conjunct = conj;
        classExpression.accept(visitor);
        return found;
    }

    /**
     * Checks whether the specified expression has a named conjunct. For For
     * class expressions which aren't named classes or object intersections this
     * method will always return false.
     * 
     * @param classExpression
     *        The expression to be checked.
     * @return {@code true} if the expression is in fact a named class (
     *         {@code OWLClass}) or if the expression is an intersection that
     *         has a named operand (included nested intersections), otherwise
     *         {@code false}
     */
    public boolean hasNamedConjunct(OWLClassExpression classExpression) {
        reset();
        conjunct = null;
        classExpression.accept(visitor);
        return found;
    }

    private void reset() {
        found = false;
        collect = false;
    }

    /**
     * Gets the named conjuncts for the specified expression.
     * 
     * @param classExpression
     *        The expression whose conjuncts are to be retrieved.
     * @return A set containing the named conjuncts of the specified expression.
     *         If the expression is not a named class or an intersection then
     *         the set will definitely be empty.
     */
    public Set getNamedConjuncts(OWLClassExpression classExpression) {
        conjuncts.clear();
        reset();
        collect = true;
        classExpression.accept(visitor);
        return conjuncts;
    }

    private class NamedConjunctCheckerVisitor extends
            OWLClassExpressionVisitorAdapter {

        public NamedConjunctCheckerVisitor() {}

        @Override
        public void visit(OWLClass desc) {
            if (conjunct == null) {
                found = true;
                if (collect) {
                    conjuncts.add(desc);
                }
            } else if (desc.equals(conjunct)) {
                found = true;
                if (collect) {
                    conjuncts.add(desc);
                }
            }
        }

        @Override
        public void visit(OWLObjectIntersectionOf desc) {
            for (OWLClassExpression op : desc.getOperands()) {
                op.accept(this);
                // Early termination if we have found a named conjunct
                // and we don't need to collect
                if (found && !collect) {
                    break;
                }
            }
        }
    }
}