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.math3.linear;
019    
020    import org.apache.commons.math3.FieldElement;
021    
022    /**
023     * Interface defining a visitor for matrix entries.
024     *
025     * @param <T> the type of the field elements
026     * @version $Id: FieldMatrixPreservingVisitor.java 1416643 2012-12-03 19:37:14Z tn $
027     * @since 2.0
028     */
029    public interface FieldMatrixPreservingVisitor<T extends FieldElement<?>> {
030        /**
031         * Start visiting a matrix.
032         * <p>This method is called once before any entry of the matrix is visited.</p>
033         * @param rows number of rows of the matrix
034         * @param columns number of columns of the matrix
035         * @param startRow Initial row index
036         * @param endRow Final row index (inclusive)
037         * @param startColumn Initial column index
038         * @param endColumn Final column index (inclusive)
039         */
040        void start(int rows, int columns,
041                   int startRow, int endRow, int startColumn, int endColumn);
042    
043        /**
044         * Visit one matrix entry.
045         * @param row row index of the entry
046         * @param column column index of the entry
047         * @param value current value of the entry
048         */
049        void visit(int row, int column, T value);
050    
051        /**
052         * End visiting a matrix.
053         * <p>This method is called once after all entries of the matrix have been visited.</p>
054         * @return the value that the <code>walkInXxxOrder</code> must return
055         */
056        T end();
057    }