1 /*
2 * Copyright (c) 2005, 2020, 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 javax.lang.model;
27
28 import java.util.Collections;
29 import java.util.Set;
30 import java.util.HashSet;
31
32 /**
33 * Source versions of the Java™ programming language.
34 *
35 * See the appropriate edition of
36 * <cite>The Java™ Language Specification</cite>
37 * for information about a particular source version.
38 *
39 * <p>Note that additional source version constants will be added to
40 * model future releases of the language.
41 *
42 * @author Joseph D. Darcy
43 * @author Scott Seligman
44 * @author Peter von der Ahé
45 * @since 1.6
46 */
47 public enum SourceVersion {
48 /*
49 * Summary of language evolution
50 * 1.1: nested classes
51 * 1.2: strictfp
52 * 1.3: no changes
53 * 1.4: assert
54 * 1.5: annotations, generics, autoboxing, var-args...
55 * 1.6: no changes
56 * 1.7: diamond syntax, try-with-resources, etc.
57 * 1.8: lambda expressions and default methods
58 * 9: modules, small cleanups to 1.7 and 1.8 changes
59 * 10: local-variable type inference (var)
60 * 11: local-variable syntax for lambda parameters
61 * 12: no changes (switch expressions in preview)
62 * 13: no changes (switch expressions and text blocks in preview)
63 * 14: switch expressions (pattern matching and records in
64 * preview, text blocks in preview again)
65 * 15: text blocks (records and pattern matching in preview again)
66 */
67
68 /**
69 * The original version.
70 *
71 * The language described in
72 * <cite>The Java™ Language Specification, First Edition</cite>.
73 */
74 RELEASE_0,
75
76 /**
77 * The version recognized by the Java Platform 1.1.
78 *
79 * The language is {@code RELEASE_0} augmented with nested classes as described in the 1.1 update to
80 * <cite>The Java™ Language Specification, First Edition</cite>.
81 */
82 RELEASE_1,
83
84 /**
85 * The version recognized by the Java 2 Platform, Standard Edition,
86 * v 1.2.
87 *
88 * The language described in
89 * <cite>The Java™ Language Specification,
90 * Second Edition</cite>, which includes the {@code
91 * strictfp} modifier.
92 */
93 RELEASE_2,
94
95 /**
96 * The version recognized by the Java 2 Platform, Standard Edition,
97 * v 1.3.
98 *
99 * No major changes from {@code RELEASE_2}.
100 */
101 RELEASE_3,
102
103 /**
104 * The version recognized by the Java 2 Platform, Standard Edition,
105 * v 1.4.
106 *
107 * Added a simple assertion facility.
108 */
109 RELEASE_4,
110
111 /**
112 * The version recognized by the Java 2 Platform, Standard
113 * Edition 5.0.
114 *
115 * The language described in
116 * <cite>The Java™ Language Specification,
117 * Third Edition</cite>. First release to support
118 * generics, annotations, autoboxing, var-args, enhanced {@code
119 * for} loop, and hexadecimal floating-point literals.
120 */
121 RELEASE_5,
122
123 /**
124 * The version recognized by the Java Platform, Standard Edition
125 * 6.
126 *
127 * No major changes from {@code RELEASE_5}.
128 */
129 RELEASE_6,
130
131 /**
132 * The version recognized by the Java Platform, Standard Edition
133 * 7.
134 *
135 * Additions in this release include, diamond syntax for
136 * constructors, {@code try}-with-resources, strings in switch,
137 * binary literals, and multi-catch.
138 * @since 1.7
139 */
140 RELEASE_7,
141
142 /**
143 * The version recognized by the Java Platform, Standard Edition
144 * 8.
145 *
146 * Additions in this release include lambda expressions and default methods.
147 * @since 1.8
148 */
149 RELEASE_8,
150
151 /**
152 * The version recognized by the Java Platform, Standard Edition
153 * 9.
154 *
155 * Additions in this release include modules and removal of a
156 * single underscore from the set of legal identifier names.
157 *
158 * @since 9
159 */
160 RELEASE_9,
161
162 /**
163 * The version recognized by the Java Platform, Standard Edition
164 * 10.
165 *
166 * Additions in this release include local-variable type inference
167 * ({@code var}).
168 *
169 * @since 10
170 */
171 RELEASE_10,
172
173 /**
174 * The version recognized by the Java Platform, Standard Edition
175 * 11.
176 *
177 * Additions in this release include local-variable syntax for
178 * lambda parameters.
179 *
180 * @since 11
181 */
182 RELEASE_11,
183
184 /**
185 * The version recognized by the Java Platform, Standard Edition
186 * 12.
187 *
188 * @since 12
189 */
190 RELEASE_12,
191
192 /**
193 * The version recognized by the Java Platform, Standard Edition
194 * 13.
195 *
196 * @since 13
197 */
198 RELEASE_13,
199
200 /**
201 * The version recognized by the Java Platform, Standard Edition
202 * 14.
203 *
204 * Additions in this release include switch expressions.
205 *
206 * @since 14
207 */
208 RELEASE_14,
209
210 /**
211 * The version recognized by the Java Platform, Standard Edition
212 * 15.
213 *
214 * Additions in this release include text blocks.
215 *
216 * @since 15
217 */
218 RELEASE_15;
219
220 // Note that when adding constants for newer releases, the
221 // behavior of latest() and latestSupported() must be updated too.
222
223 /**
224 * Returns the latest source version that can be modeled.
225 *
226 * @return the latest source version that can be modeled
227 */
228 public static SourceVersion latest() {
229 return RELEASE_15;
230 }
231
232 private static final SourceVersion latestSupported = getLatestSupported();
233
234 /*
235 * The integer version to enum constant mapping implemented by
236 * this method assumes the JEP 322: "Time-Based Release
237 * Versioning" scheme is in effect. This scheme began in JDK
238 * 10. If the JDK versioning scheme is revised, this method may
239 * need to be updated accordingly.
240 */
241 private static SourceVersion getLatestSupported() {
242 int intVersion = Runtime.version().feature();
243 return (intVersion >= 11) ?
244 valueOf("RELEASE_" + Math.min(15, intVersion)):
245 RELEASE_10;
246 }
247
248 /**
249 * Returns the latest source version fully supported by the
250 * current execution environment. {@code RELEASE_9} or later must
251 * be returned.
252 *
253 * @apiNote This method is included alongside {@link latest} to
254 * allow identification of situations where the language model API
255 * is running on a platform version different than the latest
256 * version modeled by the API. One way that sort of situation can
257 * occur is if an IDE or similar tool is using the API to model
258 * source version <i>N</i> while running on platform version
259 * (<i>N</i> - 1). Running in this configuration is
260 * supported by the API. Running an API on platform versions
261 * earlier than (<i>N</i> - 1) or later than <i>N</i>
262 * may or may not work as an implementation detail. If an
263 * annotation processor was generating code to run under the
264 * current execution environment, the processor should only use
265 * platform features up to the {@code latestSupported} release,
266 * which may be earlier than the {@code latest} release.
267 *
268 * @return the latest source version that is fully supported
269 */
270 public static SourceVersion latestSupported() {
271 return latestSupported;
272 }
273
274 /**
275 * Returns whether or not {@code name} is a syntactically valid
276 * identifier (simple name) or keyword in the latest source
277 * version. The method returns {@code true} if the name consists
278 * of an initial character for which {@link
279 * Character#isJavaIdentifierStart(int)} returns {@code true},
280 * followed only by characters for which {@link
281 * Character#isJavaIdentifierPart(int)} returns {@code true}.
282 * This pattern matches regular identifiers, keywords, restricted
283 * keywords, restricted identifiers and the literals {@code "true"},
284 * {@code "false"}, {@code "null"}.
285 *
286 * The method returns {@code false} for all other strings.
287 *
288 * @param name the string to check
289 * @return {@code true} if this string is a
290 * syntactically valid identifier or keyword, {@code false}
291 * otherwise.
292 *
293 * @jls 3.8 Identifiers
294 */
295 public static boolean isIdentifier(CharSequence name) {
296 String id = name.toString();
297
298 if (id.length() == 0) {
299 return false;
300 }
301 int cp = id.codePointAt(0);
302 if (!Character.isJavaIdentifierStart(cp)) {
303 return false;
304 }
305 for (int i = Character.charCount(cp);
306 i < id.length();
307 i += Character.charCount(cp)) {
308 cp = id.codePointAt(i);
309 if (!Character.isJavaIdentifierPart(cp)) {
310 return false;
311 }
312 }
313 return true;
314 }
315
316 /**
317 * Returns whether or not {@code name} is a syntactically valid
318 * qualified name in the latest source version.
319 *
320 * Syntactically, a qualified name is a sequence of identifiers
321 * separated by period characters ("{@code .}"). This method
322 * splits the input string into period-separated segments and
323 * applies checks to each segment in turn.
324 *
325 * Unlike {@link #isIdentifier isIdentifier}, this method returns
326 * {@code false} for keywords, boolean literals, and the null
327 * literal in any segment.
328 *
329 * This method returns {@code true} for <i>restricted
330 * keywords</i> and <i>restricted identifiers</i>.
331 *
332 * @param name the string to check
333 * @return {@code true} if this string is a
334 * syntactically valid name, {@code false} otherwise.
335 * @jls 3.9 Keywords
336 * @jls 6.2 Names and Identifiers
337 */
338 public static boolean isName(CharSequence name) {
339 return isName(name, latest());
340 }
341
342 /**
343 * Returns whether or not {@code name} is a syntactically valid
344 * qualified name in the given source version.
345 *
346 * Syntactically, a qualified name is a sequence of identifiers
347 * separated by period characters ("{@code .}"). This method
348 * splits the input string into period-separated segments and
349 * applies checks to each segment in turn.
350 *
351 * Unlike {@link #isIdentifier isIdentifier}, this method returns
352 * {@code false} for keywords, boolean literals, and the null
353 * literal in any segment.
354 *
355 * This method returns {@code true} for <i>restricted
356 * keywords</i> and <i>restricted identifiers</i>.
357 *
358 * @param name the string to check
359 * @param version the version to use
360 * @return {@code true} if this string is a
361 * syntactically valid name, {@code false} otherwise.
362 * @jls 3.9 Keywords
363 * @jls 6.2 Names and Identifiers
364 * @since 9
365 */
366 public static boolean isName(CharSequence name, SourceVersion version) {
367 String id = name.toString();
368
369 for(String s : id.split("\\.", -1)) {
370 if (!isIdentifier(s) || isKeyword(s, version))
371 return false;
372 }
373 return true;
374 }
375
376 /**
377 * Returns whether or not {@code s} is a keyword, boolean literal,
378 * or null literal in the latest source version.
379 * This method returns {@code false} for <i>restricted
380 * keywords</i> and <i>restricted identifiers</i>.
381 *
382 * @param s the string to check
383 * @return {@code true} if {@code s} is a keyword, or boolean
384 * literal, or null literal, {@code false} otherwise.
385 * @jls 3.9 Keywords
386 * @jls 3.10.3 Boolean Literals
387 * @jls 3.10.7 The Null Literal
388 */
389 public static boolean isKeyword(CharSequence s) {
390 return isKeyword(s, latest());
391 }
392
393 /**
394 * Returns whether or not {@code s} is a keyword, boolean literal,
395 * or null literal in the given source version.
396 * This method returns {@code false} for <i>restricted
397 * keywords</i> and <i>restricted identifiers</i>.
398 *
399 * @param s the string to check
400 * @param version the version to use
401 * @return {@code true} if {@code s} is a keyword, or boolean
402 * literal, or null literal, {@code false} otherwise.
403 * @jls 3.9 Keywords
404 * @jls 3.10.3 Boolean Literals
405 * @jls 3.10.7 The Null Literal
406 * @since 9
407 */
408 public static boolean isKeyword(CharSequence s, SourceVersion version) {
409 String id = s.toString();
410 switch(id) {
411 // A trip through history
412 case "strictfp":
413 return version.compareTo(RELEASE_2) >= 0;
414
415 case "assert":
416 return version.compareTo(RELEASE_4) >= 0;
417
418 case "enum":
419 return version.compareTo(RELEASE_5) >= 0;
420
421 case "_":
422 return version.compareTo(RELEASE_9) >= 0;
423
424 // Keywords common across versions
425
426 // Modifiers
427 case "public": case "protected": case "private":
428 case "abstract": case "static": case "final":
429 case "transient": case "volatile": case "synchronized":
430 case "native":
431
432 // Declarations
433 case "class": case "interface": case "extends":
434 case "package": case "throws": case "implements":
435
436 // Primitive types and void
437 case "boolean": case "byte": case "char":
438 case "short": case "int": case "long":
439 case "float": case "double":
440 case "void":
441
442 // Control flow
443 case "if": case "else":
444 case "try": case "catch": case "finally":
445 case "do": case "while":
446 case "for": case "continue":
447 case "switch": case "case": case "default":
448 case "break": case "throw": case "return":
449
450 // Other keywords
451 case "this": case "new": case "super":
452 case "import": case "instanceof":
453
454 // Forbidden!
455 case "goto": case "const":
456
457 // literals
458 case "null": case "true": case "false":
459 return true;
460
461 default:
462 return false;
463 }
464 }
465 }