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_KEY_EXTRACTOR_HPP 00008 #define COH_KEY_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/ValueExtractor.hpp" 00015 #include "coherence/util/extractor/AbstractExtractor.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 * The KeyExtractor is a special purpose ValueExtractor implementation that 00025 * serves as an indicator that a query should be run against the key objects 00026 * rather than the values. The major difference between the KeyExtractor and a 00027 * standard ReflectionExtractor is that when used in various EntryFilter 00028 * implementations it forces the evaluation of entry keys rather than entry 00029 * values. 00030 * 00031 * For example, consider a key object that consists of two properties: 00032 * "FirstName" and "LastName". To retrieve all keys that have a value of the 00033 * "LastName" property equal to "Smith", the following query could be used: 00034 * <pre> 00035 * ValueExtractor::View extractor = KeyExtractor::create("getLastName"); 00036 * Set::View setKeys = cache->keySet(EqualsFilter::create(extractor, "Smith")); 00037 * 00038 * </pre> 00039 * As of Coherence 3.5, the same effect can be achieved for subclasses of the 00040 * AbstractExtractor, for example: 00041 * <pre> 00042 * ValueExtractor::View vExtractor = ReflectionExtractor::create("getLastName", 00043 * NULL, AbstractExtractor::KEY); 00044 * Set::View setKeys = cache->keySet(EqualsFilter::create(vExtractor, "Smith")); 00045 * </pre> 00046 * 00047 * @author djl 2008.03.24 00048 */ 00049 class COH_EXPORT KeyExtractor 00050 : public class_spec<KeyExtractor, 00051 extends<AbstractExtractor> > 00052 { 00053 friend class factory<KeyExtractor>; 00054 00055 // ----- constructors --------------------------------------------------- 00056 00057 protected: 00058 /** 00059 * Create and return a Handle to a new Object instance. 00060 */ 00061 KeyExtractor(); 00062 00063 /** 00064 * Construct a KeyExtractor based on a specified ValueExtractor. 00065 * 00066 * @param vExtractor the underlying ValueExtractor 00067 */ 00068 KeyExtractor(ValueExtractor::View vExtractor); 00069 00070 00071 // ----- ValueExtractor interface --------------------------------------- 00072 00073 public: 00074 /** 00075 * {@inheritDoc} 00076 */ 00077 virtual Object::Holder extract(Object::Holder ohTarget) const; 00078 00079 00080 // ----- PortableObject interface --------------------------------------- 00081 00082 public: 00083 /** 00084 * {@inheritDoc} 00085 */ 00086 virtual void readExternal(PofReader::Handle hIn); 00087 00088 /** 00089 * {@inheritDoc} 00090 */ 00091 virtual void writeExternal(PofWriter::Handle hOut) const; 00092 00093 00094 // ----- Object interface ----------------------------------------------- 00095 00096 public: 00097 /** 00098 * {@inheritDoc} 00099 */ 00100 virtual bool equals(Object::View v) const; 00101 00102 /** 00103 * {@inheritDoc} 00104 */ 00105 virtual size32_t hashCode() const; 00106 00107 /** 00108 * {@inheritDoc} 00109 */ 00110 virtual TypedHandle<const String> toString() const; 00111 00112 00113 // ----- data member accessors ------------------------------------------ 00114 00115 public: 00116 /** 00117 * Obtain the underlying ValueExtractor. 00118 * 00119 * @return the ValueExtractor 00120 */ 00121 virtual ValueExtractor::View getExtractor() const; 00122 00123 00124 // ----- data members --------------------------------------------------- 00125 00126 protected: 00127 /** 00128 * The underlying ValueExtractor. 00129 */ 00130 MemberView<ValueExtractor> m_vExtractor; 00131 }; 00132 00133 COH_CLOSE_NAMESPACE3 00134 00135 #endif // COH_IDENTITY_EXTRACTOR_HPP