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    1   /*
    2    * Copyright 1999-2004 The Apache Software Foundation
    3    *
    4    * Licensed under the Apache License, Version 2.0 (the "License");
    5    * you may not use this file except in compliance with the License.
    6    * You may obtain a copy of the License at
    7    *
    8    *     http://www.apache.org/licenses/LICENSE-2.0
    9    *
    10   * Unless required by applicable law or agreed to in writing, software
    11   * distributed under the License is distributed on an "AS IS" BASIS,
    12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13   * See the License for the specific language governing permissions and
    14   * limitations under the License.
    15   */
    16  package org.apache.commons.jxpath;
    17
    18  import java.util.ArrayList;
    19  import java.util.Collections;
    20  import java.util.List;
    21
    22  /***
    23   * A simple implementation of NodeSet that behaves as a collection of pointers.
    24   * @author Dmitri Plotnikov
    25   * @version $Revision: 1.3 $ $Date: 2004/02/29 14:17:42 $
    26   */
    27  public class BasicNodeSet implements NodeSet {
    28      private List pointers = new ArrayList();
    29      private List readOnlyPointers;
    30      private List nodes;
    31      private List values;
    32
    33      public void add(Pointer pointer) {
    34          pointers.add(pointer);
    35          readOnlyPointers = null;
    36      }
    37
    38      public void remove(Pointer pointer) {
    39          pointers.remove(pointer);
    40          readOnlyPointers = null;
    41      }
    42
    43      public List getPointers() {
    44          if (readOnlyPointers == null) {
    45              readOnlyPointers = Collections.unmodifiableList(pointers);
    46          }
    47          return readOnlyPointers;
    48      }
    49
    50      public List getNodes() {
    51          if (nodes == null) {
    52              nodes = new ArrayList();
    53              for (int i = 0; i < pointers.size(); i++) {
    54                  Pointer pointer = (Pointer) pointers.get(i);
    55                  nodes.add(pointer.getValue());
    56              }
    57              nodes = Collections.unmodifiableList(nodes);
    58          }
    59          return nodes;
    60      }
    61
    62      public List getValues() {
    63          if (values == null) {
    64              values = new ArrayList();
    65              for (int i = 0; i < pointers.size(); i++) {
    66                  Pointer pointer = (Pointer) pointers.get(i);
    67                  values.add(pointer.getValue());
    68              }
    69              values = Collections.unmodifiableList(values);
    70          }
    71          return values;
    72      }
    73
    74      public String toString() {
    75          return pointers.toString();
    76      }
    77  }