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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 java.util.Iterator;
    20
    21  import org.apache.commons.jexl.JexlContext;
    22  import org.apache.commons.jexl.util.Introspector;
    23  import org.apache.commons.jexl.util.introspection.Info;
    24
    25  /***
    26   * ForEach statement. Syntax: foreach (var in iterable) Statement()
    27   *
    28   * @author Dion Gillard
    29   * @since 1.1
    30   */
    31  public class ASTForeachStatement extends SimpleNode {
    32      /*** dummy velocity info. */
    33      private static final Info DUMMY = new Info("", 1, 1);
    34      /*** index of the loop variable. */
    35      private static final int VAR_INDEX = 0;
    36      /*** index of the items. */
    37      private static final int ITEMS_INDEX = 1;
    38      /*** index of the code to execute. */
    39      private static final int STATEMENT_INDEX = 2;
    40
    41
    42      /***
    43       * Create the node given an id.
    44       *
    45       * @param id node id.
    46       */
    47      public ASTForeachStatement(int id) {
    48          super(id);
    49      }
    50
    51      /***
    52       * Create a node with the given parser and id.
    53       *
    54       * @param p a parser.
    55       * @param id node id.
    56       */
    57      public ASTForeachStatement(Parser p, int id) {
    58          super(p, id);
    59      }
    60
    61      /*** {@inheritDoc} */
    62      public Object jjtAccept(ParserVisitor visitor, Object data) {
    63          return visitor.visit(this, data);
    64      }
    65
    66      /*** {@inheritDoc} */
    67      public Object value(JexlContext jc) throws Exception {
    68          Object result = null;
    69          /* first child is the loop variable */
    70          ASTReference loopVariable = (ASTReference) jjtGetChild(VAR_INDEX);
    71          /* second child is the variable to iterate */
    72          SimpleNode iterable = (SimpleNode) jjtGetChild(ITEMS_INDEX);
    73          Object iterableValue = iterable.value(jc);
    74          // make sure there is a value to iterate on and a statement to execute
    75          if (iterableValue != null && jjtGetNumChildren() >= (STATEMENT_INDEX + 1)) {
    76              /* third child is the statement to execute */
    77              SimpleNode statement = (SimpleNode) jjtGetChild(2);
    78              // get an iterator for the collection/array etc via the
    79              // introspector.
    80              Iterator itemsIterator = Introspector.getUberspect().getIterator(
    81                      iterableValue, DUMMY);
    82              while (itemsIterator.hasNext()) {
    83                  // set loopVariable to value of iterator
    84                  Object value = itemsIterator.next();
    85                  jc.getVars().put(loopVariable.getRootString(), value);
    86                  // execute statement
    87                  result = statement.value(jc);
    88              }
    89          }
    90          return result;
    91      }
    92  }