1 /*
2 * Copyright (c) 2018, 2022, 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
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24 */
25 package java.lang.constant;
26
27 import java.lang.invoke.TypeDescriptor;
28 import java.util.stream.Stream;
29
30 import sun.invoke.util.Wrapper;
31
32 import static java.lang.constant.ConstantUtils.binaryToInternal;
33 import static java.lang.constant.ConstantUtils.dropLastChar;
34 import static java.lang.constant.ConstantUtils.internalToBinary;
35 import static java.lang.constant.ConstantUtils.validateMemberName;
36 import static java.util.Objects.requireNonNull;
37 import static java.util.stream.Collectors.joining;
38
39 /**
40 * A <a href="package-summary.html#nominal">nominal descriptor</a> for a
41 * {@link Class} constant.
42 *
43 * <p>For common system types, including all the primitive types, there are
44 * predefined {@linkplain ClassDesc} constants in {@link ConstantDescs}.
45 * (The {@code java.lang.constant} APIs consider {@code void} to be a primitive type.)
46 * To create a {@linkplain ClassDesc} for a class or interface type, use {@link #of} or
47 * {@link #ofDescriptor(String)}; to create a {@linkplain ClassDesc} for an array
48 * type, use {@link #ofDescriptor(String)}, or first obtain a
49 * {@linkplain ClassDesc} for the component type and then call the {@link #arrayType()}
50 * or {@link #arrayType(int)} methods.
51 *
52 * @see ConstantDescs
53 *
54 * @since 12
55 */
56 public sealed interface ClassDesc
57 extends ConstantDesc,
58 TypeDescriptor.OfField<ClassDesc>
59 permits PrimitiveClassDescImpl,
60 ReferenceClassDescImpl {
61
62 /**
63 * Returns a {@linkplain ClassDesc} for a class or interface type,
64 * given the name of the class or interface, such as {@code "java.lang.String"}.
65 * (To create a descriptor for an array type, either use {@link #ofDescriptor(String)}
66 * or {@link #arrayType()}; to create a descriptor for a primitive type, use
67 * {@link #ofDescriptor(String)} or use the predefined constants in
68 * {@link ConstantDescs}).
69 *
70 * @param name the fully qualified (dot-separated) binary class name
71 * @return a {@linkplain ClassDesc} describing the desired class
72 * @throws NullPointerException if the argument is {@code null}
73 * @throws IllegalArgumentException if the name string is not in the
74 * correct format
75 */
76 static ClassDesc of(String name) {
77 ConstantUtils.validateBinaryClassName(requireNonNull(name));
78 return ClassDesc.ofDescriptor("L" + binaryToInternal(name) + ";");
79 }
80
81 /**
82 * Returns a {@linkplain ClassDesc} for a class or interface type,
83 * given a package name and the unqualified (simple) name for the
84 * class or interface.
85 *
86 * @param packageName the package name (dot-separated); if the package
87 * name is the empty string, the class is considered to
88 * be in the unnamed package
89 * @param className the unqualified (simple) class name
90 * @return a {@linkplain ClassDesc} describing the desired class
91 * @throws NullPointerException if any argument is {@code null}
92 * @throws IllegalArgumentException if the package name or class name are
93 * not in the correct format
94 */
95 static ClassDesc of(String packageName, String className) {
96 ConstantUtils.validateBinaryClassName(requireNonNull(packageName));
97 if (packageName.isEmpty()) {
98 return of(className);
99 }
100 validateMemberName(requireNonNull(className), false);
101 return ofDescriptor("L" + binaryToInternal(packageName) +
102 "/" + className + ";");
103 }
104
105 /**
106 * Returns a {@linkplain ClassDesc} given a descriptor string for a class,
107 * interface, array, or primitive type.
108 *
109 * @apiNote
110 *
111 * A field type descriptor string for a non-array type is either
112 * a one-letter code corresponding to a primitive type
113 * ({@code "J", "I", "C", "S", "B", "D", "F", "Z", "V"}), or the letter {@code "L"}, followed
114 * by the fully qualified binary name of a class, followed by {@code ";"}.
115 * A field type descriptor for an array type is the character {@code "["}
116 * followed by the field descriptor for the component type. Examples of
117 * valid type descriptor strings include {@code "Ljava/lang/String;"}, {@code "I"},
118 * {@code "[I"}, {@code "V"}, {@code "[Ljava/lang/String;"}, etc.
119 * See JVMS {@jvms 4.3.2 }("Field Descriptors") for more detail.
120 *
121 * @param descriptor a field descriptor string
122 * @return a {@linkplain ClassDesc} describing the desired class
123 * @throws NullPointerException if the argument is {@code null}
124 * @throws IllegalArgumentException if the name string is not in the
125 * correct format
126 * @jvms 4.3.2 Field Descriptors
127 * @jvms 4.4.1 The CONSTANT_Class_info Structure
128 */
129 static ClassDesc ofDescriptor(String descriptor) {
130 requireNonNull(descriptor);
131 if (descriptor.isEmpty()) {
132 throw new IllegalArgumentException(
133 "not a valid reference type descriptor: " + descriptor);
134 }
135 int depth = ConstantUtils.arrayDepth(descriptor);
136 if (depth > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
137 throw new IllegalArgumentException(
138 "Cannot create an array type descriptor with more than " +
139 ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
140 }
141 return (descriptor.length() == 1)
142 ? new PrimitiveClassDescImpl(descriptor)
143 : new ReferenceClassDescImpl(descriptor);
144 }
145
146 /**
147 * Returns a {@linkplain ClassDesc} for an array type whose component type
148 * is described by this {@linkplain ClassDesc}.
149 *
150 * @return a {@linkplain ClassDesc} describing the array type
151 * @throws IllegalStateException if the resulting {@linkplain
152 * ClassDesc} would have an array rank of greater than 255
153 * @jvms 4.4.1 The CONSTANT_Class_info Structure
154 */
155 default ClassDesc arrayType() {
156 int depth = ConstantUtils.arrayDepth(descriptorString());
157 if (depth >= ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
158 throw new IllegalStateException(
159 "Cannot create an array type descriptor with more than " +
160 ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
161 }
162 return arrayType(1);
163 }
164
165 /**
166 * Returns a {@linkplain ClassDesc} for an array type of the specified rank,
167 * whose component type is described by this {@linkplain ClassDesc}.
168 *
169 * @param rank the rank of the array
170 * @return a {@linkplain ClassDesc} describing the array type
171 * @throws IllegalArgumentException if the rank is less than or
172 * equal to zero or if the rank of the resulting array type is
173 * greater than 255
174 * @jvms 4.4.1 The CONSTANT_Class_info Structure
175 */
176 default ClassDesc arrayType(int rank) {
177 int netRank;
178 if (rank <= 0) {
179 throw new IllegalArgumentException("rank " + rank + " is not a positive value");
180 }
181 try {
182 int currentDepth = ConstantUtils.arrayDepth(descriptorString());
183 netRank = Math.addExact(currentDepth, rank);
184 if (netRank > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
185 throw new IllegalArgumentException("rank: " + netRank +
186 " exceeds maximum supported dimension of " +
187 ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS);
188 }
189 } catch (ArithmeticException ae) {
190 throw new IllegalArgumentException("Integer overflow in rank computation");
191 }
192 return ClassDesc.ofDescriptor("[".repeat(rank) + descriptorString());
193 }
194
195 /**
196 * Returns a {@linkplain ClassDesc} for a nested class of the class or
197 * interface type described by this {@linkplain ClassDesc}.
198 *
199 * @apiNote
200 *
201 * Example: If descriptor {@code d} describes the class {@code java.util.Map}, a
202 * descriptor for the class {@code java.util.Map.Entry} could be obtained
203 * by {@code d.nested("Entry")}.
204 *
205 * @param nestedName the unqualified name of the nested class
206 * @return a {@linkplain ClassDesc} describing the nested class
207 * @throws NullPointerException if the argument is {@code null}
208 * @throws IllegalStateException if this {@linkplain ClassDesc} does not
209 * describe a class or interface type
210 * @throws IllegalArgumentException if the nested class name is invalid
211 */
212 default ClassDesc nested(String nestedName) {
213 validateMemberName(nestedName, false);
214 if (!isClassOrInterface())
215 throw new IllegalStateException("Outer class is not a class or interface type");
216 return ClassDesc.ofDescriptor(dropLastChar(descriptorString()) + "$" + nestedName + ";");
217 }
218
219 /**
220 * Returns a {@linkplain ClassDesc} for a nested class of the class or
221 * interface type described by this {@linkplain ClassDesc}.
222 *
223 * @param firstNestedName the unqualified name of the first level of nested class
224 * @param moreNestedNames the unqualified name(s) of the remaining levels of
225 * nested class
226 * @return a {@linkplain ClassDesc} describing the nested class
227 * @throws NullPointerException if any argument or its contents is {@code null}
228 * @throws IllegalStateException if this {@linkplain ClassDesc} does not
229 * describe a class or interface type
230 * @throws IllegalArgumentException if the nested class name is invalid
231 */
232 default ClassDesc nested(String firstNestedName, String... moreNestedNames) {
233 if (!isClassOrInterface())
234 throw new IllegalStateException("Outer class is not a class or interface type");
235 validateMemberName(firstNestedName, false);
236 requireNonNull(moreNestedNames);
237 for (String addNestedNames : moreNestedNames) {
238 validateMemberName(addNestedNames, false);
239 }
240 return moreNestedNames.length == 0
241 ? nested(firstNestedName)
242 : nested(firstNestedName + Stream.of(moreNestedNames).collect(joining("$", "$", "")));
243 }
244
245 /**
246 * Returns whether this {@linkplain ClassDesc} describes an array type.
247 *
248 * @return whether this {@linkplain ClassDesc} describes an array type
249 */
250 default boolean isArray() {
251 return descriptorString().startsWith("[");
252 }
253
254 /**
255 * Returns whether this {@linkplain ClassDesc} describes a primitive type.
256 *
257 * @return whether this {@linkplain ClassDesc} describes a primitive type
258 */
259 default boolean isPrimitive() {
260 return descriptorString().length() == 1;
261 }
262
263 /**
264 * Returns whether this {@linkplain ClassDesc} describes a class or interface type.
265 *
266 * @return whether this {@linkplain ClassDesc} describes a class or interface type
267 */
268 default boolean isClassOrInterface() {
269 return descriptorString().startsWith("L");
270 }
271
272 /**
273 * Returns the component type of this {@linkplain ClassDesc}, if it describes
274 * an array type, or {@code null} otherwise.
275 *
276 * @return a {@linkplain ClassDesc} describing the component type, or {@code null}
277 * if this descriptor does not describe an array type
278 */
279 default ClassDesc componentType() {
280 return isArray() ? ClassDesc.ofDescriptor(descriptorString().substring(1)) : null;
281 }
282
283 /**
284 * Returns the package name of this {@linkplain ClassDesc}, if it describes
285 * a class or interface type.
286 *
287 * @return the package name, or the empty string if the class is in the
288 * default package, or this {@linkplain ClassDesc} does not describe a class or interface type
289 */
290 default String packageName() {
291 if (!isClassOrInterface())
292 return "";
293 String className = internalToBinary(ConstantUtils.dropFirstAndLastChar(descriptorString()));
294 int index = className.lastIndexOf('.');
295 return (index == -1) ? "" : className.substring(0, index);
296 }
297
298 /**
299 * Returns a human-readable name for the type described by this descriptor.
300 *
301 * @implSpec
302 * <p>The default implementation returns the simple name
303 * (e.g., {@code int}) for primitive types, the unqualified class name
304 * for class or interface types, or the display name of the component type
305 * suffixed with the appropriate number of {@code []} pairs for array types.
306 *
307 * @return the human-readable name
308 */
309 default String displayName() {
310 if (isPrimitive())
311 return Wrapper.forBasicType(descriptorString().charAt(0)).primitiveSimpleName();
312 else if (isClassOrInterface()) {
313 return descriptorString().substring(Math.max(1, descriptorString().lastIndexOf('/') + 1),
314 descriptorString().length() - 1);
315 }
316 else if (isArray()) {
317 int depth = ConstantUtils.arrayDepth(descriptorString());
318 ClassDesc c = this;
319 for (int i=0; i<depth; i++)
320 c = c.componentType();
321 return c.displayName() + "[]".repeat(depth);
322 }
323 else
324 throw new IllegalStateException(descriptorString());
325 }
326
327 /**
328 * Returns a field type descriptor string for this type
329 *
330 * @return the descriptor string
331 * @jvms 4.3.2 Field Descriptors
332 */
333 String descriptorString();
334
335 /**
336 * Compare the specified object with this descriptor for equality. Returns
337 * {@code true} if and only if the specified object is also a
338 * {@linkplain ClassDesc} and both describe the same type.
339 *
340 * @param o the other object
341 * @return whether this descriptor is equal to the other object
342 */
343 boolean equals(Object o);
344 }