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1   package org.apache.commons.ognl.enhance;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *   http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import org.apache.commons.ognl.Node;
23  import org.apache.commons.ognl.OgnlContext;
24  
25  /**
26   * Provides pure java expression paths to get/set values from an ognl expression. This is achieved by taking an existing
27   * {@link Node} parsed expression and using bytecode enhancements to do the same work using pure java vs the ognl
28   * interpreter.
29   */
30  public interface ExpressionAccessor
31  {
32  
33      /**
34       * Gets the value represented by this expression path, if any.
35       * 
36       * @param context The standard ognl context used for variable substitution/etc.
37       * @param target The root object this expression is meant for.
38       * @return The evaluated value, if any.
39       */
40      Object get( OgnlContext context, Object target );
41  
42      /**
43       * Sets the value represented by this expression path, if possible.
44       * 
45       * @param context The standard ognl context used for variable substitution/etc.
46       * @param target The root object this expression is meant for.
47       * @param value The new value to set if this expression references a settable property.
48       */
49      void set( OgnlContext context, Object target, Object value );
50  
51      /**
52       * Used to set the original root expression node on instances where the compiled version has to fall back to
53       * interpreted syntax because of compilation failures.
54       * 
55       * @param expression The root expression node used to generate this accessor.
56       */
57      void setExpression( Node expression );
58  }