Oracle Coherence for C++ API
Release 3.6.0.0

E15728-01

coherence/util/transformer/ExtractorEventTransformer.hpp

00001 /*
00002 * ExtractorEventTransformer.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_EXTRACTOR_EVENT_TRANSFORMER_HPP
00017 #define COH_EXTRACTOR_EVENT_TRANSFORMER_HPP
00018 
00019 #include "coherence/lang.ns"
00020 
00021 #include "coherence/io/pof/PofReader.hpp"
00022 #include "coherence/io/pof/PofWriter.hpp"
00023 #include "coherence/io/pof/PortableObject.hpp"
00024 #include "coherence/util/MapEvent.hpp"
00025 #include "coherence/util/MapEventTransformer.hpp"
00026 #include "coherence/util/ValueExtractor.hpp"
00027 
00028 COH_OPEN_NAMESPACE3(coherence,util,transformer)
00029 
00030 using coherence::io::pof::PofReader;
00031 using coherence::io::pof::PofWriter;
00032 using coherence::io::pof::PortableObject;
00033 
00034 
00035 /**
00036 * ExtractorEventTransformer is a special purpose MapEventTransformer
00037 * implementation that transforms emitted events, extracting one or more
00038 * properties from either the OldValue or the NewValue. This transformation
00039 * will generally result in the change of the values' data type.
00040 * <p/>
00041 * Example: the following code will register a listener to receive events only
00042 * if the value of the AccountBalance property changes. The transformed
00043 * event's NewValue will be a List containing the LastTransactionTime and
00044 * AccountBalance properties. The OldValue will always be null.
00045 * <pre>
00046 *    Filter::View vFilter =
00047 *       ValueChangeEventFilter::create("getAccountBalance");
00048 *    ValueExtractor::View vExtractor =
00049 *       MultiExtractor::create(MultiExtractor::createExtractors(
00050 *           "getLastTransactionTime,getAccountBalance"));
00051 *    MapEventTransformer::Handle hTransformer =
00052 *       ExtractorEventTransformer::create(NULL, vExtractor);
00053 *
00054 *    cache->addMapListener(listener,
00055 *       MapEventTransformerFilter::create(vFilter, hTransformer), false);
00056 * </pre>
00057 *
00058 * @author djl  2008.06.17
00059 */
00060 class COH_EXPORT ExtractorEventTransformer
00061     : public class_spec<ExtractorEventTransformer,
00062         extends<Object>,
00063         implements<PortableObject, MapEventTransformer> >
00064     {
00065     friend class factory<ExtractorEventTransformer>;
00066 
00067     // ----- constructors ---------------------------------------------------
00068 
00069     protected:
00070         /**
00071         * Default constructor (necessary for the PortableObject interface).
00072         */
00073         ExtractorEventTransformer();
00074 
00075         /**
00076         * Construct a ExtractorEventTransformer that transforms MapEvent
00077         * values based on the specified extractor.
00078         *
00079         * Note: The specified extractor will be applied to both old and new
00080         * values.
00081         *
00082         * @param vExtractor  ValueExtractor to extract MapEvent values
00083         */
00084         ExtractorEventTransformer(ValueExtractor::View vExtractor);
00085 
00086         /**
00087         * Construct a ExtractorEventTransformer that transforms MapEvent
00088         * values based on the specified extractors. Passing null indicates
00089         * that the corresponding values should be skipped completely.
00090         *
00091         * @param vExtractorOld  extractor to extract the OldValue property(s)
00092         * @param vExtractorNew  extractor to extract the NewValue property(s)
00093         */
00094         ExtractorEventTransformer(ValueExtractor::View vExtractorOld,
00095                 ValueExtractor::View vExtractorNew);
00096 
00097 
00098     // ----- MapEventTransformer interface ----------------------------------
00099 
00100     public:
00101         /**
00102         * {@inheritDoc}
00103         */
00104         virtual MapEvent::Handle transform(MapEvent::Handle hEvent) const;
00105 
00106 
00107    // ----- PortableObject interface ---------------------------------------
00108 
00109     public:
00110         /**
00111         * {@inheritDoc}
00112         */
00113         virtual void readExternal(PofReader::Handle hIn);
00114 
00115         /**
00116         * {@inheritDoc}
00117         */
00118         virtual void writeExternal(PofWriter::Handle hOut) const;
00119 
00120 
00121     // ----- Object interface -----------------------------------------------
00122 
00123     public:
00124         /**
00125         * {@inheritDoc}
00126         */
00127         virtual bool equals(Object::View v) const;
00128 
00129         /**
00130         * {@inheritDoc}
00131         */
00132         virtual size32_t hashCode() const;
00133 
00134         /**
00135         * {@inheritDoc}
00136         */
00137         virtual void toStream(std::ostream& out) const;
00138 
00139 
00140     // ----- data member accessors ------------------------------------------
00141 
00142     public:
00143         /**
00144         * Return a ValueExtractor used to transfrom the event's OldValue.
00145         *
00146         * @return an extractor from the OldValue
00147         */
00148         virtual ValueExtractor::View getOldValueExtractor() const;
00149 
00150         /**
00151         * Return a ValueExtractor used to transfrom the event's NewValue.
00152         *
00153         * @return an extractor from the NewValue
00154         */
00155         virtual ValueExtractor::View getNewValueExtractor() const;
00156 
00157 
00158     // ----- data members ---------------------------------------------------
00159 
00160     private:
00161         /**
00162         * The OldValueExtractor.
00163         */
00164         MemberView<ValueExtractor> m_vExtractorOld;
00165 
00166         /**
00167         * The NewValueExtractor.
00168         */
00169         MemberView<ValueExtractor> m_vExtractorNew;
00170     };
00171 
00172 COH_CLOSE_NAMESPACE3
00173 
00174 #endif // COH_EXTRACTOR_EVENT_TRANSFORMER_HPP
Copyright © 2000, 2010, Oracle and/or its affiliates. All rights reserved.