1 /*
2 * Copyright (c) 2003, 2012, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package sun.reflect.generics.reflectiveObjects;
27
28 import java.lang.annotation.Annotation;
29 import java.lang.reflect.Array;
30 import java.lang.reflect.GenericDeclaration;
31 import java.lang.reflect.Type;
32 import java.lang.reflect.TypeVariable;
33 import java.util.Objects;
34
35 import sun.reflect.generics.factory.GenericsFactory;
36 import sun.reflect.generics.tree.FieldTypeSignature;
37 import sun.reflect.generics.visitor.Reifier;
38
39 /**
40 * Implementation of <tt>java.lang.reflect.TypeVariable</tt> interface
41 * for core reflection.
42 */
43 public class TypeVariableImpl<D extends GenericDeclaration>
44 extends LazyReflectiveObjectGenerator implements TypeVariable<D> {
45 D genericDeclaration;
46 private String name;
47 // upper bounds - evaluated lazily
48 private Type[] bounds;
49
50 // The ASTs for the bounds. We are required to evaluate the bounds
51 // lazily, so we store these at least until we are first asked
52 // for the bounds. This also neatly solves the
53 // problem with F-bounds - you can't reify them before the formal
54 // is defined.
55 private FieldTypeSignature[] boundASTs;
56
57 // constructor is private to enforce access through static factory
58 private TypeVariableImpl(D decl, String n, FieldTypeSignature[] bs,
59 GenericsFactory f) {
60 super(f);
61 genericDeclaration = decl;
62 name = n;
63 boundASTs = bs;
64 }
65
66 // Accessors
67
68 // accessor for ASTs for bounds. Must not be called after
69 // bounds have been evaluated, because we might throw the ASTs
70 // away (but that is not thread-safe, is it?)
71 private FieldTypeSignature[] getBoundASTs() {
72 // check that bounds were not evaluated yet
73 assert(bounds == null);
74 return boundASTs;
75 }
76
77 /**
78 * Factory method.
79 * @param decl - the reflective object that declared the type variable
80 * that this method should create
81 * @param name - the name of the type variable to be returned
82 * @param bs - an array of ASTs representing the bounds for the type
83 * variable to be created
84 * @param f - a factory that can be used to manufacture reflective
85 * objects that represent the bounds of this type variable
86 * @return A type variable with name, bounds, declaration and factory
87 * specified
88 */
89 public static <T extends GenericDeclaration>
90 TypeVariableImpl<T> make(T decl, String name,
91 FieldTypeSignature[] bs,
92 GenericsFactory f) {
93 return new TypeVariableImpl<T>(decl, name, bs, f);
94 }
95
96
97 /**
98 * Returns an array of <tt>Type</tt> objects representing the
99 * upper bound(s) of this type variable. Note that if no upper bound is
100 * explicitly declared, the upper bound is <tt>Object</tt>.
101 *
102 * <p>For each upper bound B:
103 * <ul>
104 * <li>if B is a parameterized type or a type variable, it is created,
105 * (see {@link #ParameterizedType} for the details of the creation
106 * process for parameterized types).
107 * <li>Otherwise, B is resolved.
108 * </ul>
109 *
110 * @throws <tt>TypeNotPresentException</tt> if any of the
111 * bounds refers to a non-existent type declaration
112 * @throws <tt>MalformedParameterizedTypeException</tt> if any of the
113 * bounds refer to a parameterized type that cannot be instantiated
114 * for any reason
115 * @return an array of Types representing the upper bound(s) of this
116 * type variable
117 */
118 public Type[] getBounds() {
119 // lazily initialize bounds if necessary
120 if (bounds == null) {
121 FieldTypeSignature[] fts = getBoundASTs(); // get AST
122 // allocate result array; note that
123 // keeping ts and bounds separate helps with threads
124 Type[] ts = new Type[fts.length];
125 // iterate over bound trees, reifying each in turn
126 for ( int j = 0; j < fts.length; j++) {
127 Reifier r = getReifier();
128 fts[j].accept(r);
129 ts[j] = r.getResult();
130 }
131 // cache result
132 bounds = ts;
133 // could throw away bound ASTs here; thread safety?
134 }
135 return bounds.clone(); // return cached bounds
136 }
137
138 /**
139 * Returns the <tt>GenericDeclaration</tt> object representing the
140 * generic declaration that declared this type variable.
141 *
142 * @return the generic declaration that declared this type variable.
143 *
144 * @since 1.5
145 */
146 public D getGenericDeclaration(){
147 return genericDeclaration;
148 }
149
150
151 /**
152 * Returns the name of this type variable, as it occurs in the source code.
153 *
154 * @return the name of this type variable, as it appears in the source code
155 */
156 public String getName() { return name; }
157
158 public String toString() {return getName();}
159
160 @Override
161 public boolean equals(Object o) {
162 if (o instanceof TypeVariable) {
163 TypeVariable<?> that = (TypeVariable<?>) o;
164
165 GenericDeclaration thatDecl = that.getGenericDeclaration();
166 String thatName = that.getName();
167
168 return
169 (genericDeclaration == null ?
170 thatDecl == null :
171 genericDeclaration.equals(thatDecl)) &&
172 (name == null ?
173 thatName == null :
174 name.equals(thatName));
175
176 } else
177 return false;
178 }
179
180 @Override
181 public int hashCode() {
182 return genericDeclaration.hashCode() ^ name.hashCode();
183 }
184
185 // Currently vacuous implementations of AnnotatedElement methods.
186 public boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
187 Objects.requireNonNull(annotationClass);
188 return false;
189 }
190
191 public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
192 Objects.requireNonNull(annotationClass);
193 return null;
194 }
195
196 public <T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass) {
197 Objects.requireNonNull(annotationClass);
198 return null;
199 }
200
201 @SuppressWarnings("unchecked")
202 public <T extends Annotation> T[] getAnnotations(Class<T> annotationClass) {
203 Objects.requireNonNull(annotationClass);
204 // safe because annotationClass is the class for T
205 return (T[])Array.newInstance(annotationClass, 0);
206 }
207
208 @SuppressWarnings("unchecked")
209 public <T extends Annotation> T[] getDeclaredAnnotations(Class<T> annotationClass) {
210 Objects.requireNonNull(annotationClass);
211 // safe because annotationClass is the class for T
212 return (T[])Array.newInstance(annotationClass, 0);
213 }
214
215 public Annotation[] getAnnotations() {
216 // Since zero-length, don't need defensive clone
217 return EMPTY_ANNOTATION_ARRAY;
218 }
219
220 public Annotation[] getDeclaredAnnotations() {
221 // Since zero-length, don't need defensive clone
222 return EMPTY_ANNOTATION_ARRAY;
223 }
224
225 private static final Annotation[] EMPTY_ANNOTATION_ARRAY = new Annotation[0];
226 }