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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  package org.apache.commons.jexl.parser;
    17
    18  import org.apache.commons.jexl.JexlContext;
    19
    20  /***
    21   *  reference - any variable expression
    22   *
    23   *  @author <a href="mailto:geirm@apache.org">Geir Magnusson Jr.</a>
    24   *  @version $Id: ASTReference.java,v 1.4 2004/09/01 00:35:38 dion Exp $
    25   */
    26  public class ASTReference extends SimpleNode
    27  {
    28      SimpleNode root;
    29
    30      public ASTReference(int id)
    31      {
    32          super(id);
    33      }
    34
    35      public ASTReference(Parser p, int id)
    36      {
    37          super(p, id);
    38      }
    39
    40
    41      /*** Accept the visitor. **/
    42      public Object jjtAccept(ParserVisitor visitor, Object data)
    43      {
    44          return visitor.visit(this, data);
    45      }
    46
    47      public Object value(JexlContext jc)
    48          throws Exception
    49      {
    50          return  execute(null,jc);
    51      }
    52
    53      public void jjtClose()
    54      {
    55          root = (SimpleNode) jjtGetChild(0);
    56      }
    57
    58      public Object execute(Object obj, JexlContext jc)
    59               throws Exception
    60       {
    61           Object o = root.value(jc);
    62
    63           /*
    64            * ignore the first child - it's our identifier
    65            */
    66           for(int i=1; i<jjtGetNumChildren(); i++)
    67           {
    68               o = ( (SimpleNode) jjtGetChild(i)).execute(o,jc);
    69
    70               // check for a variable in the context named
    71               // child0.child1.child2 etc
    72               if(o == null) {
    73                   String varName = getIdentifierToDepth(i);
    74                   o = jc.getVars().get(varName);
    75               }
    76           }
    77
    78           return o;
    79       }
    80
    81      /***
    82       * This method returns a variable from this identifier and
    83       * it's children. For an expression like 'a.b.c', a is child
    84       * zero, b is child 1 and c is child 2.
    85       *
    86       * @param i the depth of the child nodes to go to
    87       * @return the a dotted variable from this identifier and it's
    88       *    child nodes.
    89       */
    90      private String getIdentifierToDepth(int i) {
    91          StringBuffer varName = new StringBuffer();
    92           for (int j = 0; j <=i; j++) {
    93               SimpleNode node = (SimpleNode) jjtGetChild(j);
    94               if (node instanceof ASTIdentifier) {
    95                 varName.append(((ASTIdentifier)node).getIdentifierString());
    96                 if (j != i) varName.append('.');
    97               }
    98           }
    99          return varName.toString();
    100     }
    101
    102     public String getRootString()
    103         throws Exception
    104     {
    105         if ( root instanceof ASTIdentifier)
    106             return ((ASTIdentifier) root).getIdentifierString();
    107
    108         if (root instanceof ASTArrayAccess)
    109             return ((ASTArrayAccess) root).getIdentifierString();
    110
    111         throw new Exception("programmer error : ASTReference : root not known"
    112                     + root );
    113     }
    114 }