00001 /* 00002 * ComparisonValueExtractor.hpp 00003 * 00004 * Copyright (c) 2000, 2020, 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_COMPARISON_EXTRACTOR_HPP 00017 #define COH_COMPARISON_EXTRACTOR_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/util/Comparator.hpp" 00024 #include "coherence/util/extractor/AbstractCompositeExtractor.hpp" 00025 00026 COH_OPEN_NAMESPACE3(coherence,util,extractor) 00027 00028 using coherence::io::pof::PofReader; 00029 using coherence::io::pof::PofWriter; 00030 00031 00032 /** 00033 * A synthetic ValueExtractor that returns a result of comparison between two 00034 * values extracted from the same target. In a most general case, the extracted 00035 * value represents an Integer value calculated accordingly to the contract of 00036 * Comparable#compareTo or Comparator#compare methods. However, in more 00037 * specific cases, when the compared values are of common numeric type, the 00038 * ComparisonValueExtractor will return a numeric difference between those 00039 * values. The type of the comparing values will dictate the type of 00040 * the result. 00041 * 00042 * For example, lets assume that a cache contains business objects that have two 00043 * properties: SellPrice and BuyPrice (both double). Then, to query for all 00044 * objects that have SellPrice less than BuyPrice we would use the following: 00045 * <pre> 00046 * ValueExtractor::View extractDiff = ComparisonValueExtractor::create( 00047 * ReflectionExtractor::create(String::create("getSellPrice")), 00048 * ReflectionExtractor::create(String::create("getBuyPrice"))); 00049 * Filter::View vfilter = LessFilter::create(extractDiff, Double::create(0.0)); 00050 * Set::View entries = cache->entrySet(vfilter); 00051 * </pre> 00052 * 00053 * @author djl 2008.04.11 00054 * 00055 * @see ChainedExtractor 00056 */ 00057 class COH_EXPORT ComparisonValueExtractor 00058 : public class_spec<ComparisonValueExtractor, 00059 extends<AbstractCompositeExtractor> > 00060 { 00061 friend class factory<ComparisonValueExtractor>; 00062 00063 // ----- constructors --------------------------------------------------- 00064 00065 protected: 00066 /** 00067 * Construct an empty ComparisonValueExtractor 00068 * (necessary for the PortableObject interface). 00069 */ 00070 ComparisonValueExtractor(); 00071 00072 /** 00073 * Construct a ComparisonValueExtractor based on two specified extractors and 00074 * a Comparator object. 00075 * 00076 * @param vE1 the ValueExtractor for the first value 00077 * @param vE2 the ValueExtractor for the second value 00078 * @param vComp the comparator used to compare the extracted values 00079 * (optional); if NULL, the values returned by both 00080 * extractors must be Comparable 00081 */ 00082 ComparisonValueExtractor(ValueExtractor::View vE1, 00083 ValueExtractor::View vE2, 00084 Comparator::View vComp = NULL); 00085 00086 00087 // ----- ValueExtractor interface --------------------------------------- 00088 00089 public: 00090 /** 00091 * {@inheritDoc} 00092 * 00093 * @throws UnsupportedOperationException always 00094 */ 00095 virtual Object::Holder extract(Object::Holder ohTarget) const; 00096 00097 00098 // ----- PortableObject interface --------------------------------------- 00099 00100 public: 00101 /** 00102 * {@inheritDoc} 00103 */ 00104 virtual void readExternal(PofReader::Handle hIn); 00105 00106 /** 00107 * {@inheritDoc} 00108 */ 00109 virtual void writeExternal(PofWriter::Handle hOut) const; 00110 00111 00112 // ----- data member accessors ------------------------------------------ 00113 00114 public: 00115 /** 00116 * Return a Comparator used by this extractor. 00117 * 00118 * @return a Comparator used by this extractor; null if the natural value 00119 * comparison should be used 00120 */ 00121 virtual Comparator::View getComparator() const; 00122 00123 00124 // ----- data members --------------------------------------------------- 00125 00126 protected: 00127 /** 00128 * An underlying Comparator object (optional). 00129 */ 00130 FinalView<Comparator> f_vComparator; 00131 }; 00132 00133 COH_CLOSE_NAMESPACE3 00134 00135 #endif // #ifndef COH_COMPARISON_EXTRACTOR_HPP