1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing,
13 * software distributed under the License is distributed on an
14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15 * KIND, either express or implied. See the License for the
16 * specific language governing permissions and limitations
17 * under the License.
18 */
19 package org.apache.myfaces.custom.validatebeanbehavior;
20
21 import javax.el.ELContext;
22 import javax.el.ELResolver;
23 import javax.el.ValueExpression;
24 import java.beans.FeatureDescriptor;
25 import java.util.Iterator;
26
27 /**
28 * This class inspects the EL expression and returns a ValueReferenceWrapper
29 * when Unified EL is not available.
30 *
31 * Note: Copy from MyFaces Core 2.0.
32 */
33 final class ValueReferenceResolver extends ELResolver {
34 private final ELResolver resolver;
35
36 /**
37 * This is a simple solution to keep track of the resolved objects,
38 * since ELResolver provides no way to know if the current ELResolver
39 * is the last one in the chain. By assigning (and effectively overwriting)
40 * this field, we know that the value after invoking the chain is always
41 * the last one.
42 * <p/>
43 * This solution also deals with nested objects (like: #{myBean.prop.prop.prop}.
44 */
45 private ValueReferenceWrapper lastObject;
46
47 /**
48 * Constructor is only used internally.
49 *
50 * @param elResolver An ELResolver from the current ELContext.
51 */
52 ValueReferenceResolver(final ELResolver elResolver) {
53 this.resolver = elResolver;
54 }
55
56 /**
57 * This method can be used to extract the ValueReferenceWrapper from the given ValueExpression.
58 *
59 * @param valueExpression The ValueExpression to resolve.
60 * @param elCtx The ELContext, needed to parse and execute the expression.
61 * @return The ValueReferenceWrapper.
62 */
63 public static ValueReferenceWrapper resolve(final ValueExpression valueExpression, final ELContext elCtx) {
64 final ValueReferenceResolver resolver = new ValueReferenceResolver(elCtx.getELResolver());
65 valueExpression.getValue(new ELContextDecorator(elCtx, resolver));
66 return resolver.lastObject;
67 }
68
69 /**
70 * This method is the only one that matters. It keeps track of the objects in the EL expression.
71 * <p/>
72 * It creates a new ValueReferenceWrapper and assigns it to lastObject.
73 *
74 * @param context The ELContext.
75 * @param base The base object, may be null.
76 * @param property The property, may be null.
77 * @return The resolved value
78 */
79 @Override
80 public Object getValue(final ELContext context, final Object base, final Object property) {
81 lastObject = new ValueReferenceWrapper(base, property);
82 return resolver.getValue(context, base, property);
83 }
84
85 // ############################ Standard delegating implementations ############################
86
87 public final Class<?> getType(final ELContext ctx, final Object base, final Object property) {
88 return resolver.getType(ctx, base, property);
89 }
90
91 public final void setValue(final ELContext ctx, final Object base, final Object property, final Object value) {
92 resolver.setValue(ctx, base, property, value);
93 }
94
95 public final boolean isReadOnly(final ELContext ctx, final Object base, final Object property) {
96 return resolver.isReadOnly(ctx, base, property);
97 }
98
99 public final Iterator<FeatureDescriptor> getFeatureDescriptors(final ELContext ctx, final Object base) {
100 return resolver.getFeatureDescriptors(ctx, base);
101 }
102
103 public final Class<?> getCommonPropertyType(final ELContext ctx, final Object base) {
104 return resolver.getCommonPropertyType(ctx, base);
105 }
106
107 }