    1   /*
    2    * Copyright 1999-2004 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.jxpath;
    17
    18  import java.io.Serializable;
    19
    20  /***
    21   * Pointers represent locations of objects and their properties
    22   * in Java object graphs. JXPathContext has methods
    23   * ({@link JXPathContext#getPointer(java.lang.String) getPointer()}
    24   * and  ({@link JXPathContext#iteratePointers(java.lang.String)
    25   * iteratePointers()}, which, given an XPath, produce Pointers for the objects
    26   * or properties described the the path. For example, <code>ctx.getPointer
    27   * ("foo/bar")</code> will produce a Pointer that can get and set the property
    28   * "bar" of the object which is the value of the property "foo" of the root
    29   * object. The value of <code>ctx.getPointer("aMap/aKey[3]")</code> will be a
    30   * pointer to the 3'rd element of the array, which is the value for the key
    31   * "aKey" of the map, which is the value of the property "aMap" of the root
    32   * object.
    33   *
    34   * @author Dmitri Plotnikov
    35   * @version $Revision: 1.9 $ $Date: 2004/02/29 14:17:42 $
    36   */
    37  public interface Pointer extends Cloneable, Comparable, Serializable {
    38
    39      /***
    40       * Returns the value of the object, property or collection element
    41       * this pointer represents. May convert the value to one of the
    42       * canonical InfoSet types: String, Number, Boolean, Set.
    43       *
    44       * For example, in the case of an XML element, getValue() will
    45       * return the text contained by the element rather than
    46       * the element itself.
    47       */
    48      Object getValue();
    49
    50      /***
    51       * Returns the raw value of the object, property or collection element
    52       * this pointer represents.  Never converts the object to a
    53       * canonical type: returns it as is.
    54       *
    55       * For example, for an XML element, getNode() will
    56       * return the element itself rather than the text it contains.
    57       */
    58      Object getNode();
    59
    60      /***
    61       * Modifies the value of the object, property or collection element
    62       * this pointer represents.
    63       */
    64      void setValue(Object value);
    65
    66      /***
    67       * Returns the node this pointer is based on.
    68       */
    69      Object getRootNode();
    70
    71      /***
    72       * Returns a string that is a proper "canonical" XPath that corresponds to
    73       * this pointer.  Consider this example:
    74       * <p><code>Pointer  ptr = ctx.getPointer("//employees[firstName = 'John']")
    75       * </code>
    76       * <p>The  value of <code>ptr.asPath()</code> will look something like
    77       * <code>"/departments[2]/employees[3]"</code>, so, basically, it represents
    78       * the concrete location(s) of the result of a search performed by JXPath.
    79       * If an object in the pointer's path is a Dynamic Property object (like a
    80       * Map), the asPath method generates an XPath that looks like this: <code>"
    81       * /departments[@name = 'HR']/employees[3]"</code>.
    82       */
    83      String asPath();
    84
    85      /***
    86       * Pointers are cloneable
    87       */
    88      Object clone();
    89  }