    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    }