Oracle Coherence for C++ API
Release 3.6.0.0

E15728-01

coherence/util/extractor/AbstractExtractor.hpp

00001 /*
00002 * AbstractExtractor.hpp
00003 *
00004 * Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
00005 *
00006 * Oracle is a registered trademarks of Oracle Corporation and/or its
00007 * affiliates.
00008 *
00009 * This software is the confidential and proprietary information of Oracle
00010 * Corporation. You shall not disclose such confidential and proprietary
00011 * information and shall use it only in accordance with the terms of the
00012 * license agreement you entered into with Oracle.
00013 *
00014 * This notice may not be removed or altered.
00015 */
00016 #ifndef COH_ABSTRACT_EXTRACTOR_HPP
00017 #define COH_ABSTRACT_EXTRACTOR_HPP
00018 
00019 #include "coherence/lang.ns"
00020 
00021 #include "coherence/io/pof/PortableObject.hpp"
00022 #include "coherence/util/QueryMap.hpp"
00023 #include "coherence/util/ValueExtractor.hpp"
00024 #include "coherence/util/comparator/QueryMapComparator.hpp"
00025 
00026 COH_OPEN_NAMESPACE3(coherence,util,extractor)
00027 
00028 using coherence::io::pof::PortableObject;
00029 using coherence::util::comparator::QueryMapComparator;
00030 
00031 
00032 /**
00033 * Abstract base for ValueExtractor implementations.  It provides common
00034 * functionality that allows any extending extractor to be used as a value
00035 * Comparator.
00036 *
00037 * Starting with Coherence 3.5, when used to extract information that is
00038 * coming from a Map, subclasses have the additional ability to operate
00039 * against the Map::Entry instead of just the value. In other words, like the
00040 * EntryExtractor class, this allows an extractor implementation to
00041 * extract a desired value using all available information on the
00042 * corresponding Map::Entry object and is intended to be used in advanced
00043 * custom scenarios, when application code needs to look at both key and
00044 * value at the same time or can make some very specific assumptions regarding
00045 * to the implementation details of the underlying Entry object. To maintain
00046 * full backwards compatibility, the default behavior remains to extract from
00047 * the Value property of the Map::Entry.
00048 *
00049 * <b>Note:</b> subclasses are responsible for initialization and POF
00050 * serialization of the {@link #m_nTarget} field.
00051 *
00052 * @author djl  2008.03.10
00053 */
00054 class COH_EXPORT AbstractExtractor
00055     : public abstract_spec<AbstractExtractor,
00056         extends<Object>,
00057         implements<ValueExtractor, QueryMapComparator, PortableObject> >
00058     {
00059     // ----- constructors ---------------------------------------------------
00060 
00061     protected:
00062         /**
00063         * @internal
00064         */
00065         AbstractExtractor();
00066 
00067 
00068     // ----- ValueExtractor interface ---------------------------------------
00069 
00070     public:
00071         /**
00072         * {@inheritDoc}
00073         */
00074         virtual Object::Holder extract(Object::Holder ohTarget) const;
00075 
00076 
00077     // ----- QueryMapComparator interface -----------------------------------
00078 
00079     public:
00080         /**
00081         * {@inheritDoc}
00082         */
00083         virtual int32_t compareEntries(QueryMap::Entry::View vEntry1,
00084                 QueryMap::Entry::View vEntry2) const;
00085 
00086 
00087     // ----- Comparator interface -------------------------------------------
00088 
00089     public:
00090         /**
00091         * {@inheritDoc}
00092         */
00093         virtual int32_t compare(Object::View v1, Object::View v2) const;
00094 
00095 
00096     // ----- subclassing support --------------------------------------------
00097 
00098     public:
00099         /**
00100         * Extract the value from the passed Entry object. The returned value
00101         * should follow the conventions outlined in the {@link #extract}
00102         * method. By overriding this method, an extractor implementation is
00103         * able to extract a desired value using all available information on
00104         * the corresponding Map::Entry object and is intended to be used in
00105         * advanced custom scenarios, when application code needs to look at
00106         * both key and value at the same time or can make some very specific
00107         * assumptions regarding to the implementation details of the
00108         * underlying Entry object.
00109         *
00110         * @param entry  an Entry object to extract a desired value from
00111         *
00112         * @return the extracted value
00113         *
00114         * @since Coherence 3.5
00115         */
00116         virtual Object::Holder extractFromEntry(Map::Entry::Holder ohEntry) const;
00117 
00118 
00119     // ----- constants ------------------------------------------------------
00120 
00121     public:
00122         /**
00123         * Indicates that the {@link #extractFromEntry} operation should use
00124         * the Entry's value.
00125         *
00126         * @since Coherence 3.5
00127         */
00128         static const int32_t VALUE = 0;
00129 
00130         /**
00131         * Indicates that the {@link #extractFromEntry} operation should use
00132         * the Entry's value.
00133         *
00134         * @since Coherence 3.5
00135         */
00136         static const int32_t KEY = 1;
00137 
00138 
00139     // ----- data members ---------------------------------------------------
00140 
00141     protected:
00142         /**
00143         * Specifies which part of the entry should be used by the
00144         * {@link #extractFromEntry} operation. Legal values are {@link #VALUE}
00145         * (default) or {@link #KEY}.
00146         *
00147         * <b>Note:</b> subclasses are responsible for initialization and POF
00148         * serialization of this field.
00149         *
00150         * @since Coherence 3.5
00151         */
00152         int32_t m_nTarget;
00153     };
00154 
00155 COH_CLOSE_NAMESPACE3
00156 
00157 #endif // COH_ABSTRACT_EXTRACTOR_HPP
Copyright © 2000, 2010, Oracle and/or its affiliates. All rights reserved.