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
018package org.apache.commons.math4.linear;
019
020import org.apache.commons.math4.FieldElement;
021
022/**
023 * Default implementation of the {@link FieldMatrixChangingVisitor} interface.
024 * <p>
025 * This class is a convenience to create custom visitors without defining all
026 * methods. This class provides default implementations that do nothing.
027 * </p>
028 *
029 * @param <T> the type of the field elements
030 * @since 2.0
031 */
032public class DefaultFieldMatrixChangingVisitor<T extends FieldElement<T>>
033    implements FieldMatrixChangingVisitor<T> {
034    /** Zero element of the field. */
035    private final T zero;
036
037    /** Build a new instance.
038     * @param zero additive identity of the field
039     */
040    public DefaultFieldMatrixChangingVisitor(final T zero) {
041        this.zero = zero;
042    }
043
044    /** {@inheritDoc} */
045    @Override
046    public void start(int rows, int columns,
047                      int startRow, int endRow, int startColumn, int endColumn) {
048    }
049
050    /** {@inheritDoc} */
051    @Override
052    public T visit(int row, int column, T value) {
053        return value;
054    }
055
056    /** {@inheritDoc} */
057    @Override
058    public T end() {
059        return zero;
060    }
061}