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    1   /*
    2    * Copyright 2002-2006 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
    17  package org.apache.commons.jexl.parser;
    18
    19  import org.apache.commons.jexl.JexlContext;
    20
    21  import java.util.Collection;
    22  import java.util.Map;
    23
    24  /***
    25   * function to see if reference doesn't exist in context.
    26   *
    27   * @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
    28   * @author <a href="mailto:tobrien@apache.org">Tim O'Brien</a>
    29   * @version $Id: ASTEmptyFunction.java 398190 2006-04-29 16:04:10Z dion $
    30   */
    31  public class ASTEmptyFunction extends SimpleNode {
    32      /***
    33       * Create the node given an id.
    34       *
    35       * @param id node id.
    36       */
    37      public ASTEmptyFunction(int id) {
    38          super(id);
    39      }
    40
    41      /***
    42       * Create a node with the given parser and id.
    43       *
    44       * @param p a parser.
    45       * @param id node id.
    46       */
    47      public ASTEmptyFunction(Parser p, int id) {
    48          super(p, id);
    49      }
    50
    51      /*** {@inheritDoc} */
    52      public Object jjtAccept(ParserVisitor visitor, Object data) {
    53          return visitor.visit(this, data);
    54      }
    55
    56      /*** {@inheritDoc} */
    57      public Object value(JexlContext jc) throws Exception {
    58          SimpleNode sn = (SimpleNode) jjtGetChild(0);
    59
    60          /*
    61           * I can't believe this
    62           */
    63
    64          Object o = sn.value(jc);
    65
    66          if (o == null) {
    67              return Boolean.TRUE;
    68          }
    69
    70          if (o instanceof String && "".equals(o)) {
    71              return Boolean.TRUE;
    72          }
    73
    74          if (o.getClass().isArray() && ((Object[]) o).length == 0) {
    75              return Boolean.TRUE;
    76          }
    77
    78          if (o instanceof Collection && ((Collection) o).isEmpty()) {
    79              return Boolean.TRUE;
    80          }
    81
    82          /*
    83           * Map isn't a collection
    84           */
    85          if (o instanceof Map && ((Map) o).isEmpty()) {
    86              return Boolean.TRUE;
    87          }
    88
    89          return Boolean.FALSE;
    90      }
    91  }