AbstractConstraint


1   /*****************************************************************************
2    * Copyright (C) PicoContainer Organization. All rights reserved.            *
3    * ------------------------------------------------------------------------- *
4    * The software in this package is published under the terms of the BSD      *
5    * style license a copy of which has been included with this distribution in *
6    * the LICENSE.txt file.                                                     *
7    *****************************************************************************/
8   
9   package org.picocontainer.gems.constraints;
10  
11  import org.picocontainer.ComponentAdapter;
12  import org.picocontainer.PicoContainer;
13  import org.picocontainer.PicoIntrospectionException;
14  import org.picocontainer.defaults.AmbiguousComponentResolutionException;
15  import org.picocontainer.defaults.CollectionComponentParameter;
16  
17  import java.lang.reflect.Array  ;
18  import java.util.Map  ;
19  
20  /**
21   * Base class for parameter constraints.
22   *
23   * @author Nick Sieger
24   * @version 1.1
25   */
26  public abstract class AbstractConstraint extends CollectionComponentParameter implements Constraint {
27  
28      /**
29       * Construct an AbstractContraint.
30       */
31      protected AbstractConstraint() {
32          super(false);
33      }
34      
35      public Object   resolveInstance(PicoContainer container, ComponentAdapter adapter, Class   expectedType) throws PicoIntrospectionException {
36          final Object  [] array = (Object  []) super.resolveInstance(container, adapter, getArrayType(expectedType));
37          if (array.length == 1) {
38              return array[0];
39          }
40          return null;
41      }
42  
43      public boolean isResolvable(PicoContainer container, ComponentAdapter adapter, Class   expectedType) throws PicoIntrospectionException {
44          return super.isResolvable(container, adapter, getArrayType(expectedType));
45      }
46  
47      public void verify(PicoContainer container, ComponentAdapter adapter, Class   expectedType) throws PicoIntrospectionException {
48          super.verify(container, adapter, getArrayType(expectedType));
49      }
50      
51      public abstract boolean evaluate(ComponentAdapter adapter);
52  
53      protected Map   getMatchingComponentAdapters(PicoContainer container, ComponentAdapter adapter, Class   keyType, Class   valueType) {
54          final Map   map = super.getMatchingComponentAdapters(container, adapter, keyType, valueType);
55          if (map.size() > 1) {
56              throw new AmbiguousComponentResolutionException(valueType, map.keySet().toArray(new Object  [map.size()]));
57          }
58          return map;
59      }
60      
61      private Class   getArrayType(Class   expectedType) {
62          return Array.newInstance(expectedType, 0).getClass();
63      }
64  }
65
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