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_MULTI_EXTRACTOR_HPP 00008 #define COH_MULTI_EXTRACTOR_HPP 00009 00010 #include "coherence/lang.ns" 00011 00012 #include "coherence/util/QueryMap.hpp" 00013 #include "coherence/util/ValueExtractor.hpp" 00014 #include "coherence/util/extractor/AbstractCompositeExtractor.hpp" 00015 00016 COH_OPEN_NAMESPACE3(coherence,util,extractor) 00017 00018 00019 /** 00020 * Composite ValueExtractor implementation based on an array of extractors. 00021 * All extractors in the array are applied to the same target object and the 00022 * result of the extraction is a List of extracted values. 00023 * 00024 * Common scenarios for using the MultiExtractor involve the DistinctValues or 00025 * GroupAggregator aggregators, that allow clients to collect all distinct 00026 * combinations of a given set of attributes or collect and run additional 00027 * aggregation against the corresponding groups of entries. 00028 * 00029 * @author djl 2008.04.09 00030 */ 00031 class COH_EXPORT MultiExtractor 00032 : public class_spec<MultiExtractor, 00033 extends<AbstractCompositeExtractor> > 00034 { 00035 friend class factory<MultiExtractor>; 00036 00037 // ----- constructors --------------------------------------------------- 00038 00039 protected: 00040 /** 00041 * Default constructor (necessary for the PortableObject interface). 00042 */ 00043 MultiExtractor(); 00044 00045 /** 00046 * Construct a MultiExtractor. 00047 * 00048 * @param vaExtractor the ValueExtractor array 00049 */ 00050 MultiExtractor(ObjectArray::View vaExtractor); 00051 00052 private: 00053 /** 00054 * Blocked copy constructor. 00055 */ 00056 MultiExtractor(const MultiExtractor&); 00057 00058 00059 // ----- AbstractExtractor methods -------------------------------------- 00060 00061 public: 00062 /** 00063 * {@inheritDoc} 00064 */ 00065 virtual Object::Holder extract(Object::Holder ohTarget) const; 00066 00067 /** 00068 * Extract the value from the passed entry. The underlying extractors 00069 * are applied sequentially, so a result of a previous extractor serves 00070 * as a target object for a next one. A value of NULL prevents any 00071 * further extractions and is returned immediately. For intrinsic types, 00072 * the returned value is expected to be a standard wrapper type in the 00073 * same manner that reflection works; for example, int32_t would be 00074 * returned as a Integer32. 00075 */ 00076 virtual Object::Holder extractFromEntry(Map::Entry::Holder ohEntry) const; 00077 00078 00079 // ----- QueryMapComparator interface ----------------------------------- 00080 00081 public: 00082 /** 00083 * {@inheritDoc} 00084 */ 00085 virtual int32_t compareEntries(QueryMap::Entry::View vEntry1, 00086 QueryMap::Entry::View vEntry2) const; 00087 00088 00089 // ----- helpers -------------------------------------------------------- 00090 00091 public: 00092 /** 00093 * Parse a comma-delimited sequence of method names and instantiate 00094 * a corresponding array ValueExtractor objects. Individual array 00095 * elements will be either ReflectionExtractor or ChainedExtractor 00096 * objects. 00097 * 00098 * @param vsNames a comma-delimited sequence of method names 00099 * 00100 * @return an array of ValueExtractor objects 00101 */ 00102 static ObjectArray::View createExtractors(String::View vsNames); 00103 }; 00104 00105 COH_CLOSE_NAMESPACE3 00106 00107 #endif // COH_MULTI_EXTRACTOR_HPP