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    1   /*
    2    * Copyright 2002,2004 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
    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,v 1.6 2004/08/23 13:30:36 dion Exp $
    30   */
    31  public class ASTEmptyFunction extends SimpleNode
    32  {
    33      public ASTEmptyFunction(int id)
    34      {
    35          super(id);
    36      }
    37
    38      public ASTEmptyFunction(Parser p, int id)
    39      {
    40          super(p, id);
    41      }
    42
    43      /*** Accept the visitor. **/
    44      public Object jjtAccept(ParserVisitor visitor, Object data)
    45      {
    46          return visitor.visit(this, data);
    47      }
    48
    49      public Object value(JexlContext jc)
    50          throws Exception
    51      {
    52          SimpleNode sn = (SimpleNode) jjtGetChild(0);
    53
    54          /*
    55           * I can't believe this
    56           */
    57
    58          Object o = sn.value(jc);
    59
    60          if (o == null)
    61              return Boolean.TRUE;
    62
    63          if (o instanceof String && "".equals((String) o))
    64              return Boolean.TRUE;
    65
    66          if (o.getClass().isArray() && ((Object[])o).length == 0)
    67              return Boolean.TRUE;
    68
    69          if (o instanceof Collection && ((Collection)o).isEmpty())
    70              return Boolean.TRUE;
    71
    72          /*
    73           *  Map isn't a collection
    74           */
    75          if (o instanceof Map && ((Map)o).isEmpty())
    76              return Boolean.TRUE;
    77
    78          return Boolean.FALSE;
    79      }
    80  }