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 * @see ClassDesc#ofDescriptor(String)
76 * @see ClassDesc#ofInternalName(String)
77 */
78 static ClassDesc of(String name) {
79 ConstantUtils.validateBinaryClassName(requireNonNull(name));
80 return ClassDesc.ofDescriptor("L" + binaryToInternal(name) + ";");
81 }
82
83 /**
84 * Returns a {@linkplain ClassDesc} for a class or interface type,
85 * given the name of the class or interface in internal form,
86 * such as {@code "java/lang/String"}.
87 *
88 * @apiNote
89 * To create a descriptor for an array type, either use {@link #ofDescriptor(String)}
90 * or {@link #arrayType()}; to create a descriptor for a primitive type, use
91 * {@link #ofDescriptor(String)} or use the predefined constants in
92 * {@link ConstantDescs}.
93 *
94 * @param name the fully qualified class name, in internal (slash-separated) form
95 * @return a {@linkplain ClassDesc} describing the desired class
96 * @throws NullPointerException if the argument is {@code null}
97 * @throws IllegalArgumentException if the name string is not in the
98 * correct format
99 * @jvms 4.2.1 Binary Class and Interface Names
100 * @see ClassDesc#of(String)
101 * @see ClassDesc#ofDescriptor(String)
102 */
103 static ClassDesc ofInternalName(String name) {
104 ConstantUtils.validateInternalClassName(requireNonNull(name));
105 return ClassDesc.ofDescriptor("L" + name + ";");
106 }
107
108 /**
109 * Returns a {@linkplain ClassDesc} for a class or interface type,
110 * given a package name and the unqualified (simple) name for the
111 * class or interface.
112 *
113 * @param packageName the package name (dot-separated); if the package
114 * name is the empty string, the class is considered to
115 * be in the unnamed package
116 * @param className the unqualified (simple) class name
117 * @return a {@linkplain ClassDesc} describing the desired class
118 * @throws NullPointerException if any argument is {@code null}
119 * @throws IllegalArgumentException if the package name or class name are
120 * not in the correct format
121 */
122 static ClassDesc of(String packageName, String className) {
123 ConstantUtils.validateBinaryClassName(requireNonNull(packageName));
124 if (packageName.isEmpty()) {
125 return of(className);
126 }
127 validateMemberName(requireNonNull(className), false);
128 return ofDescriptor("L" + binaryToInternal(packageName) +
129 "/" + className + ";");
130 }
131
132 /**
133 * Returns a {@linkplain ClassDesc} given a descriptor string for a class,
134 * interface, array, or primitive type.
135 *
136 * @apiNote
137 *
138 * A field type descriptor string for a non-array type is either
139 * a one-letter code corresponding to a primitive type
140 * ({@code "J", "I", "C", "S", "B", "D", "F", "Z", "V"}), or the letter {@code "L"}, followed
141 * by the fully qualified binary name of a class, followed by {@code ";"}.
142 * A field type descriptor for an array type is the character {@code "["}
143 * followed by the field descriptor for the component type. Examples of
144 * valid type descriptor strings include {@code "Ljava/lang/String;"}, {@code "I"},
145 * {@code "[I"}, {@code "V"}, {@code "[Ljava/lang/String;"}, etc.
146 * See JVMS {@jvms 4.3.2 }("Field Descriptors") for more detail.
147 *
148 * @param descriptor a field descriptor string
149 * @return a {@linkplain ClassDesc} describing the desired class
150 * @throws NullPointerException if the argument is {@code null}
151 * @throws IllegalArgumentException if the name string is not in the
152 * correct format
153 * @jvms 4.3.2 Field Descriptors
154 * @jvms 4.4.1 The CONSTANT_Class_info Structure
155 * @see ClassDesc#of(String)
156 * @see ClassDesc#ofInternalName(String)
157 */
158 static ClassDesc ofDescriptor(String descriptor) {
159 requireNonNull(descriptor);
160 if (descriptor.isEmpty()) {
161 throw new IllegalArgumentException(
162 "not a valid reference type descriptor: " + descriptor);
163 }
164 int depth = ConstantUtils.arrayDepth(descriptor);
165 if (depth > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
166 throw new IllegalArgumentException(
167 "Cannot create an array type descriptor with more than " +
168 ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
169 }
170 return (descriptor.length() == 1)
171 ? new PrimitiveClassDescImpl(descriptor)
172 : new ReferenceClassDescImpl(descriptor);
173 }
174
175 /**
176 * Returns a {@linkplain ClassDesc} for an array type whose component type
177 * is described by this {@linkplain ClassDesc}.
178 *
179 * @return a {@linkplain ClassDesc} describing the array type
180 * @throws IllegalStateException if the resulting {@linkplain
181 * ClassDesc} would have an array rank of greater than 255
182 * @jvms 4.4.1 The CONSTANT_Class_info Structure
183 */
184 default ClassDesc arrayType() {
185 int depth = ConstantUtils.arrayDepth(descriptorString());
186 if (depth >= ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
187 throw new IllegalStateException(
188 "Cannot create an array type descriptor with more than " +
189 ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS + " dimensions");
190 }
191 return arrayType(1);
192 }
193
194 /**
195 * Returns a {@linkplain ClassDesc} for an array type of the specified rank,
196 * whose component type is described by this {@linkplain ClassDesc}.
197 *
198 * @param rank the rank of the array
199 * @return a {@linkplain ClassDesc} describing the array type
200 * @throws IllegalArgumentException if the rank is less than or
201 * equal to zero or if the rank of the resulting array type is
202 * greater than 255
203 * @jvms 4.4.1 The CONSTANT_Class_info Structure
204 */
205 default ClassDesc arrayType(int rank) {
206 int netRank;
207 if (rank <= 0) {
208 throw new IllegalArgumentException("rank " + rank + " is not a positive value");
209 }
210 try {
211 int currentDepth = ConstantUtils.arrayDepth(descriptorString());
212 netRank = Math.addExact(currentDepth, rank);
213 if (netRank > ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS) {
214 throw new IllegalArgumentException("rank: " + netRank +
215 " exceeds maximum supported dimension of " +
216 ConstantUtils.MAX_ARRAY_TYPE_DESC_DIMENSIONS);
217 }
218 } catch (ArithmeticException ae) {
219 throw new IllegalArgumentException("Integer overflow in rank computation");
220 }
221 return ClassDesc.ofDescriptor("[".repeat(rank) + descriptorString());
222 }
223
224 /**
225 * Returns a {@linkplain ClassDesc} for a nested class of the class or
226 * interface type described by this {@linkplain ClassDesc}.
227 *
228 * @apiNote
229 *
230 * Example: If descriptor {@code d} describes the class {@code java.util.Map}, a
231 * descriptor for the class {@code java.util.Map.Entry} could be obtained
232 * by {@code d.nested("Entry")}.
233 *
234 * @param nestedName the unqualified name of the nested class
235 * @return a {@linkplain ClassDesc} describing the nested class
236 * @throws NullPointerException if the argument is {@code null}
237 * @throws IllegalStateException if this {@linkplain ClassDesc} does not
238 * describe a class or interface type
239 * @throws IllegalArgumentException if the nested class name is invalid
240 */
241 default ClassDesc nested(String nestedName) {
242 validateMemberName(nestedName, false);
243 if (!isClassOrInterface())
244 throw new IllegalStateException("Outer class is not a class or interface type");
245 return ClassDesc.ofDescriptor(dropLastChar(descriptorString()) + "$" + nestedName + ";");
246 }
247
248 /**
249 * Returns a {@linkplain ClassDesc} for a nested class of the class or
250 * interface type described by this {@linkplain ClassDesc}.
251 *
252 * @param firstNestedName the unqualified name of the first level of nested class
253 * @param moreNestedNames the unqualified name(s) of the remaining levels of
254 * nested class
255 * @return a {@linkplain ClassDesc} describing the nested class
256 * @throws NullPointerException if any argument or its contents is {@code null}
257 * @throws IllegalStateException if this {@linkplain ClassDesc} does not
258 * describe a class or interface type
259 * @throws IllegalArgumentException if the nested class name is invalid
260 */
261 default ClassDesc nested(String firstNestedName, String... moreNestedNames) {
262 if (!isClassOrInterface())
263 throw new IllegalStateException("Outer class is not a class or interface type");
264 validateMemberName(firstNestedName, false);
265 requireNonNull(moreNestedNames);
266 for (String addNestedNames : moreNestedNames) {
267 validateMemberName(addNestedNames, false);
268 }
269 return moreNestedNames.length == 0
270 ? nested(firstNestedName)
271 : nested(firstNestedName + Stream.of(moreNestedNames).collect(joining("$", "$", "")));
272 }
273
274 /**
275 * Returns whether this {@linkplain ClassDesc} describes an array type.
276 *
277 * @return whether this {@linkplain ClassDesc} describes an array type
278 */
279 default boolean isArray() {
280 return descriptorString().startsWith("[");
281 }
282
283 /**
284 * Returns whether this {@linkplain ClassDesc} describes a primitive type.
285 *
286 * @return whether this {@linkplain ClassDesc} describes a primitive type
287 */
288 default boolean isPrimitive() {
289 return descriptorString().length() == 1;
290 }
291
292 /**
293 * Returns whether this {@linkplain ClassDesc} describes a class or interface type.
294 *
295 * @return whether this {@linkplain ClassDesc} describes a class or interface type
296 */
297 default boolean isClassOrInterface() {
298 return descriptorString().startsWith("L");
299 }
300
301 /**
302 * Returns the component type of this {@linkplain ClassDesc}, if it describes
303 * an array type, or {@code null} otherwise.
304 *
305 * @return a {@linkplain ClassDesc} describing the component type, or {@code null}
306 * if this descriptor does not describe an array type
307 */
308 default ClassDesc componentType() {
309 return isArray() ? ClassDesc.ofDescriptor(descriptorString().substring(1)) : null;
310 }
311
312 /**
313 * Returns the package name of this {@linkplain ClassDesc}, if it describes
314 * a class or interface type.
315 *
316 * @return the package name, or the empty string if the class is in the
317 * default package, or this {@linkplain ClassDesc} does not describe a class or interface type
318 */
319 default String packageName() {
320 if (!isClassOrInterface())
321 return "";
322 String className = internalToBinary(ConstantUtils.dropFirstAndLastChar(descriptorString()));
323 int index = className.lastIndexOf('.');
324 return (index == -1) ? "" : className.substring(0, index);
325 }
326
327 /**
328 * Returns a human-readable name for the type described by this descriptor.
329 *
330 * @implSpec
331 * <p>The default implementation returns the simple name
332 * (e.g., {@code int}) for primitive types, the unqualified class name
333 * for class or interface types, or the display name of the component type
334 * suffixed with the appropriate number of {@code []} pairs for array types.
335 *
336 * @return the human-readable name
337 */
338 default String displayName() {
339 if (isPrimitive())
340 return Wrapper.forBasicType(descriptorString().charAt(0)).primitiveSimpleName();
341 else if (isClassOrInterface()) {
342 return descriptorString().substring(Math.max(1, descriptorString().lastIndexOf('/') + 1),
343 descriptorString().length() - 1);
344 }
345 else if (isArray()) {
346 int depth = ConstantUtils.arrayDepth(descriptorString());
347 ClassDesc c = this;
348 for (int i=0; i<depth; i++)
349 c = c.componentType();
350 return c.displayName() + "[]".repeat(depth);
351 }
352 else
353 throw new IllegalStateException(descriptorString());
354 }
355
356 /**
357 * Returns a field type descriptor string for this type
358 *
359 * @return the descriptor string
360 * @jvms 4.3.2 Field Descriptors
361 */
362 String descriptorString();
363
364 /**
365 * Compare the specified object with this descriptor for equality. Returns
366 * {@code true} if and only if the specified object is also a
367 * {@linkplain ClassDesc} and both describe the same type.
368 *
369 * @param o the other object
370 * @return whether this descriptor is equal to the other object
371 */
372 boolean equals(Object o);
373 }