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1
56 package org.objectstyle.cayenne.dataview;
57
58 import java.util.HashMap  ;
59 import java.util.Iterator ;
60 import java.util.List ;
61 import java.util.Map ;
62
63 import org.objectstyle.cayenne.DataObject;
64
65
69 public class LookupCache {
70
71 private Map fieldCache = new HashMap ();
72 private static final Object [] EMPTY_ARRAY = new Object [] {};
73
74 public LookupCache() {
75 }
76
77 public void cache(ObjEntityViewField field, List dataObjects) {
78 Lookup lookup = getLookup(field);
79 if (lookup == null) {
80 lookup = new Lookup();
81 fieldCache.put(field, lookup);
82 }
83 lookup.cache(field, dataObjects);
84 }
85
86 public void clear() {
87 fieldCache.clear();
88 }
89
90 public boolean removeFromCache(ObjEntityViewField field) {
91 return fieldCache.remove(field) != null;
92 }
93
94 public Object [] getCachedValues(ObjEntityViewField field) {
95 Lookup lookup = getLookup(field);
96 Object [] values = (lookup != null ? lookup.values : EMPTY_ARRAY);
97 if (values.length == 0)
98 return values;
99 else {
100 Object [] valuesCopy = new Object [values.length];
101 System.arraycopy(values, 0, valuesCopy, 0, values.length);
102 return valuesCopy;
103 }
104 }
105
106 public DataObject getDataObject(ObjEntityViewField field, Object value) {
107 Lookup lookup = getLookup(field);
108 if (lookup == null)
109 return null;
110 return lookup.getDataObject(value);
111 }
112
113 private Lookup getLookup(ObjEntityViewField field) {
114 if (field == null)
115 return null;
116 return (Lookup) fieldCache.get(field);
117 }
118
119 private class Lookup {
120
121 ObjEntityViewField field;
122 Object [] values = EMPTY_ARRAY;
123 Map valueDataObjectMap;
124
125 void cache(ObjEntityViewField field, List dataObjects) {
126 this.field = field;
127 if (values.length != dataObjects.size())
128 values = new Object [dataObjects.size()];
129 valueDataObjectMap = new HashMap (values.length + 1);
130 int index = 0;
131 for (Iterator i = dataObjects.iterator(); i.hasNext();) {
132 DataObject item = (DataObject) i.next();
133 values[index] = field.getValue(item);
134 valueDataObjectMap.put(values[index], item);
135 index++;
136 }
137 }
138
139 DataObject getDataObject(Object value) {
140 return (DataObject) valueDataObjectMap.get(value);
141 }
142 }
143 } |
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