001    /*
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    
018    package org.apache.commons.math.linear;
019    
020    import org.apache.commons.math.FieldElement;
021    import org.apache.commons.math.linear.MatrixVisitorException;
022    
023    /**
024     * Default implementation of the {@link FieldMatrixChangingVisitor} interface.
025     * <p>
026     * This class is a convenience to create custom visitors without defining all
027     * methods. This class provides default implementations that do nothing.
028     * </p>
029     *
030     * @param <T> the type of the field elements
031     * @version $Revision: 1073158 $ $Date: 2011-02-21 22:46:52 +0100 (lun. 21 f??vr. 2011) $
032     * @since 2.0
033     */
034    public class DefaultFieldMatrixChangingVisitor<T extends FieldElement<T>>
035        implements FieldMatrixChangingVisitor<T> {
036    
037        /** Zero element of the field. */
038        private final T zero;
039    
040        /** Build a new instance.
041         * @param zero additive identity of the field
042         */
043        public DefaultFieldMatrixChangingVisitor(final T zero) {
044            this.zero = zero;
045        }
046    
047        /** {@inheritDoc} */
048        public void start(int rows, int columns,
049                          int startRow, int endRow, int startColumn, int endColumn) {
050        }
051    
052        /** {@inheritDoc} */
053        public T visit(int row, int column, T value) throws MatrixVisitorException {
054            return value;
055        }
056    
057        /** {@inheritDoc} */
058        public T end() {
059            return zero;
060        }
061    
062    }