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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.commons.math4.legacy.linear;
19  
20  import org.apache.commons.math4.legacy.core.FieldElement;
21  
22  /**
23   * Default implementation of the {@link FieldMatrixPreservingVisitor} interface.
24   * <p>
25   * This class is a convenience to create custom visitors without defining all
26   * methods. This class provides default implementations that do nothing.
27   * </p>
28   *
29   * @param <T> the type of the field elements
30   * @since 2.0
31   */
32  public class DefaultFieldMatrixPreservingVisitor<T extends FieldElement<T>>
33      implements FieldMatrixPreservingVisitor<T> {
34      /** Zero element of the field. */
35      private final T zero;
36  
37      /** Build a new instance.
38       * @param zero additive identity of the field
39       */
40      public DefaultFieldMatrixPreservingVisitor(final T zero) {
41          this.zero = zero;
42      }
43  
44      /** {@inheritDoc} */
45      @Override
46      public void start(int rows, int columns,
47                        int startRow, int endRow, int startColumn, int endColumn) {
48      }
49  
50      /** {@inheritDoc} */
51      @Override
52      public void visit(int row, int column, T value) {}
53  
54      /** {@inheritDoc} */
55      @Override
56      public T end() {
57          return zero;
58      }
59  }