00001 /* 00002 * Copyright (c) 2000, 2020, Oracle and/or its affiliates. 00003 * 00004 * Licensed under the Universal Permissive License v 1.0 as shown at 00005 * http://oss.oracle.com/licenses/upl. 00006 */ 00007 #ifndef COH_COMPARISON_EXTRACTOR_HPP 00008 #define COH_COMPARISON_EXTRACTOR_HPP 00009 00010 #include "coherence/lang.ns" 00011 00012 #include "coherence/io/pof/PofReader.hpp" 00013 #include "coherence/io/pof/PofWriter.hpp" 00014 #include "coherence/util/Comparator.hpp" 00015 #include "coherence/util/extractor/AbstractCompositeExtractor.hpp" 00016 00017 COH_OPEN_NAMESPACE3(coherence,util,extractor) 00018 00019 using coherence::io::pof::PofReader; 00020 using coherence::io::pof::PofWriter; 00021 00022 00023 /** 00024 * A synthetic ValueExtractor that returns a result of comparison between two 00025 * values extracted from the same target. In a most general case, the extracted 00026 * value represents an Integer value calculated accordingly to the contract of 00027 * Comparable#compareTo or Comparator#compare methods. However, in more 00028 * specific cases, when the compared values are of common numeric type, the 00029 * ComparisonValueExtractor will return a numeric difference between those 00030 * values. The type of the comparing values will dictate the type of 00031 * the result. 00032 * 00033 * For example, lets assume that a cache contains business objects that have two 00034 * properties: SellPrice and BuyPrice (both double). Then, to query for all 00035 * objects that have SellPrice less than BuyPrice we would use the following: 00036 * <pre> 00037 * ValueExtractor::View extractDiff = ComparisonValueExtractor::create( 00038 * ReflectionExtractor::create(String::create("getSellPrice")), 00039 * ReflectionExtractor::create(String::create("getBuyPrice"))); 00040 * Filter::View vfilter = LessFilter::create(extractDiff, Double::create(0.0)); 00041 * Set::View entries = cache->entrySet(vfilter); 00042 * </pre> 00043 * 00044 * @author djl 2008.04.11 00045 * 00046 * @see ChainedExtractor 00047 */ 00048 class COH_EXPORT ComparisonValueExtractor 00049 : public class_spec<ComparisonValueExtractor, 00050 extends<AbstractCompositeExtractor> > 00051 { 00052 friend class factory<ComparisonValueExtractor>; 00053 00054 // ----- constructors --------------------------------------------------- 00055 00056 protected: 00057 /** 00058 * Construct an empty ComparisonValueExtractor 00059 * (necessary for the PortableObject interface). 00060 */ 00061 ComparisonValueExtractor(); 00062 00063 /** 00064 * Construct a ComparisonValueExtractor based on two specified extractors and 00065 * a Comparator object. 00066 * 00067 * @param vE1 the ValueExtractor for the first value 00068 * @param vE2 the ValueExtractor for the second value 00069 * @param vComp the comparator used to compare the extracted values 00070 * (optional); if NULL, the values returned by both 00071 * extractors must be Comparable 00072 */ 00073 ComparisonValueExtractor(ValueExtractor::View vE1, 00074 ValueExtractor::View vE2, 00075 Comparator::View vComp = NULL); 00076 00077 00078 // ----- ValueExtractor interface --------------------------------------- 00079 00080 public: 00081 /** 00082 * {@inheritDoc} 00083 * 00084 * @throws UnsupportedOperationException always 00085 */ 00086 virtual Object::Holder extract(Object::Holder ohTarget) const; 00087 00088 00089 // ----- PortableObject interface --------------------------------------- 00090 00091 public: 00092 /** 00093 * {@inheritDoc} 00094 */ 00095 virtual void readExternal(PofReader::Handle hIn); 00096 00097 /** 00098 * {@inheritDoc} 00099 */ 00100 virtual void writeExternal(PofWriter::Handle hOut) const; 00101 00102 00103 // ----- data member accessors ------------------------------------------ 00104 00105 public: 00106 /** 00107 * Return a Comparator used by this extractor. 00108 * 00109 * @return a Comparator used by this extractor; null if the natural value 00110 * comparison should be used 00111 */ 00112 virtual Comparator::View getComparator() const; 00113 00114 00115 // ----- data members --------------------------------------------------- 00116 00117 protected: 00118 /** 00119 * An underlying Comparator object (optional). 00120 */ 00121 FinalView<Comparator> f_vComparator; 00122 }; 00123 00124 COH_CLOSE_NAMESPACE3 00125 00126 #endif // #ifndef COH_COMPARISON_EXTRACTOR_HPP