View Javadoc

    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  package org.apache.commons.jexl.parser;
    17
    18  import org.apache.commons.jexl.JexlContext;
    19  import org.apache.commons.jexl.util.Introspector;
    20  import org.apache.commons.jexl.util.introspection.Info;
    21  import org.apache.commons.jexl.util.introspection.VelMethod;
    22
    23  import java.util.List;
    24  import java.util.Map;
    25  import java.util.Set;
    26  import java.lang.reflect.Array;
    27
    28  /***
    29   *  generalized size() function for all classes we can think of
    30   *
    31   *  @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
    32   *  @author <a href="hw@kremvax.net">Mark H. Wilkinson</a>
    33   *  @version $Id: ASTSizeFunction.java,v 1.6 2004/08/15 16:01:12 dion Exp $
    34   */
    35  public class ASTSizeFunction extends SimpleNode
    36  {
    37      public ASTSizeFunction(int id)
    38      {
    39          super(id);
    40      }
    41
    42      public ASTSizeFunction(Parser p, int id)
    43      {
    44          super(p, id);
    45      }
    46
    47
    48      /*** Accept the visitor. **/
    49      public Object jjtAccept(ParserVisitor visitor, Object data)
    50      {
    51          return visitor.visit(this, data);
    52      }
    53
    54
    55      public Object value(JexlContext jc)
    56          throws Exception
    57      {
    58          SimpleNode arg = (SimpleNode) jjtGetChild(0);
    59
    60          Object val = arg.value(jc);
    61
    62          if (val == null)
    63          {
    64              throw new Exception("size() : null arg");
    65          }
    66
    67          return new Integer(ASTSizeFunction.sizeOf(val));
    68      }
    69
    70      public static int sizeOf(Object val)
    71          throws Exception
    72      {
    73          if (val instanceof List)
    74          {
    75              return ((List)val).size();
    76          }
    77          else if (val.getClass().isArray())
    78          {
    79              return Array.getLength(val);
    80          }
    81          else if (val instanceof Map)
    82          {
    83              return ((Map)val).size();
    84          }
    85          else if (val instanceof String)
    86          {
    87              return ((String)val).length();
    88          }
    89          else if (val instanceof Set)
    90          {
    91              return ((Set)val).size();
    92          }
    93          else {
    94          	// check if there is a size method on the object that returns an integer
    95          	// and if so, just use it
    96          	Object[] params = new Object[0];
    97          	Info velInfo = new Info("",1,1);
    98              VelMethod vm = Introspector.getUberspect().getMethod(val, "size", params, velInfo);
    99              if (vm != null && vm.getReturnType() == Integer.TYPE)
    100             {
    101             	Integer result = (Integer)vm.invoke(val, params);
    102             	return result.intValue();
    103             }
    104             else
    105             {
    106                 throw new Exception("size() : unknown type : " + val.getClass());
    107             }
    108         }
    109     }
    110
    111 }