1 /*
2 * Copyright (c) 2005, 2019, 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.util;
27
28 import java.util.ArrayList;
29 import java.util.Collections;
30 import java.util.List;
31 import java.util.Map;
32 import java.util.Set;
33 import java.util.LinkedHashSet;
34 import java.util.Objects;
35
36 import javax.lang.model.AnnotatedConstruct;
37 import javax.lang.model.element.*;
38
39
40 /**
41 * Utility methods for operating on program elements.
42 *
43 * <p><b>Compatibility Note:</b> Methods may be added to this interface
44 * in future releases of the platform.
45 *
46 * @author Joseph D. Darcy
47 * @author Scott Seligman
48 * @author Peter von der Ahé
49 * @see javax.annotation.processing.ProcessingEnvironment#getElementUtils
50 * @since 1.6
51 */
52 public interface Elements {
53
54 /**
55 * Returns a package given its fully qualified name if the package is unique in the environment.
56 * If running with modules, all modules in the modules graph are searched for matching packages.
57 *
58 * @param name fully qualified package name, or an empty string for an unnamed package
59 * @return the specified package, or {@code null} if it cannot be uniquely found
60 */
61 PackageElement getPackageElement(CharSequence name);
62
63 /**
64 * Returns a package given its fully qualified name, as seen from the given module.
65 *
66 * @implSpec The default implementation of this method returns
67 * {@code null}.
68 *
69 * @param name fully qualified package name, or an empty string for an unnamed package
70 * @param module module relative to which the lookup should happen
71 * @return the specified package, or {@code null} if it cannot be found
72 * @see #getAllPackageElements
73 * @since 9
74 */
75 default PackageElement getPackageElement(ModuleElement module, CharSequence name) {
76 return null;
77 }
78
79 /**
80 * Returns all package elements with the given canonical name.
81 *
82 * There may be more than one package element with the same canonical
83 * name if the package elements are in different modules.
84 *
85 * @implSpec The default implementation of this method calls
86 * {@link #getAllModuleElements() getAllModuleElements} and stores
87 * the result. If the set of modules is empty, {@link
88 * #getPackageElement(CharSequence) getPackageElement(name)} is
89 * called passing through the name argument. If {@code
90 * getPackageElement(name)} is {@code null}, an empty set of
91 * package elements is returned; otherwise, a single-element set
92 * with the found package element is returned. If the set of
93 * modules is nonempty, the modules are iterated over and any
94 * non-{@code null} results of {@link
95 * #getPackageElement(ModuleElement, CharSequence)
96 * getPackageElement(module, name)} are accumulated into a
97 * set. The set is then returned.
98 *
99 * @param name the canonical name
100 * @return the package elements, or an empty set if no package with the name can be found
101 * @see #getPackageElement(ModuleElement, CharSequence)
102 * @since 9
103 */
104 default Set<? extends PackageElement> getAllPackageElements(CharSequence name) {
105 Set<? extends ModuleElement> modules = getAllModuleElements();
106 if (modules.isEmpty()) {
107 PackageElement packageElt = getPackageElement(name);
108 return (packageElt != null) ?
109 Collections.singleton(packageElt):
110 Collections.emptySet();
111 } else {
112 Set<PackageElement> result = new LinkedHashSet<>(1); // Usually expect at most 1 result
113 for (ModuleElement module: modules) {
114 PackageElement packageElt = getPackageElement(module, name);
115 if (packageElt != null)
116 result.add(packageElt);
117 }
118 return Collections.unmodifiableSet(result);
119 }
120 }
121
122 /**
123 * Returns a type element given its canonical name if the type element is unique in the environment.
124 * If running with modules, all modules in the modules graph are searched for matching
125 * type elements.
126 *
127 * @param name the canonical name
128 * @return the named type element, or {@code null} if it cannot be uniquely found
129 */
130 TypeElement getTypeElement(CharSequence name);
131
132 /**
133 * Returns a type element given its canonical name, as seen from the given module.
134 *
135 * @implSpec The default implementation of this method returns
136 * {@code null}.
137 *
138 * @param name the canonical name
139 * @param module module relative to which the lookup should happen
140 * @return the named type element, or {@code null} if it cannot be found
141 * @see #getAllTypeElements
142 * @since 9
143 */
144 default TypeElement getTypeElement(ModuleElement module, CharSequence name) {
145 return null;
146 }
147
148 /**
149 * Returns all type elements with the given canonical name.
150 *
151 * There may be more than one type element with the same canonical
152 * name if the type elements are in different modules.
153 *
154 * @implSpec The default implementation of this method calls
155 * {@link #getAllModuleElements() getAllModuleElements} and stores
156 * the result. If the set of modules is empty, {@link
157 * #getTypeElement(CharSequence) getTypeElement(name)} is called
158 * passing through the name argument. If {@code
159 * getTypeElement(name)} is {@code null}, an empty set of type
160 * elements is returned; otherwise, a single-element set with the
161 * found type element is returned. If the set of modules is
162 * nonempty, the modules are iterated over and any non-{@code null}
163 * results of {@link #getTypeElement(ModuleElement,
164 * CharSequence) getTypeElement(module, name)} are accumulated
165 * into a set. The set is then returned.
166 *
167 * @param name the canonical name
168 * @return the type elements, or an empty set if no type with the name can be found
169 * @see #getTypeElement(ModuleElement, CharSequence)
170 * @since 9
171 */
172 default Set<? extends TypeElement> getAllTypeElements(CharSequence name) {
173 Set<? extends ModuleElement> modules = getAllModuleElements();
174 if (modules.isEmpty()) {
175 TypeElement typeElt = getTypeElement(name);
176 return (typeElt != null) ?
177 Collections.singleton(typeElt):
178 Collections.emptySet();
179 } else {
180 Set<TypeElement> result = new LinkedHashSet<>(1); // Usually expect at most 1 result
181 for (ModuleElement module: modules) {
182 TypeElement typeElt = getTypeElement(module, name);
183 if (typeElt != null)
184 result.add(typeElt);
185 }
186 return Collections.unmodifiableSet(result);
187 }
188 }
189
190 /**
191 * Returns a module element given its fully qualified name.
192 *
193 * If the requested module cannot be found, {@code null} is
194 * returned. One situation where a module cannot be found is if
195 * the environment does not include modules, such as an annotation
196 * processing environment configured for a {@linkplain
197 * javax.annotation.processing.ProcessingEnvironment#getSourceVersion
198 * source version} without modules.
199 *
200 * @implSpec The default implementation of this method returns
201 * {@code null}.
202 *
203 * @param name the name, or an empty string for an unnamed module
204 * @return the named module element, or {@code null} if it cannot be found
205 * @see #getAllModuleElements
206 * @since 9
207 * @spec JPMS
208 */
209 default ModuleElement getModuleElement(CharSequence name) {
210 return null;
211 }
212
213 /**
214 * Returns all module elements in the current environment.
215 *
216 * If no modules are present, an empty set is returned. One
217 * situation where no modules are present occurs when the
218 * environment does not include modules, such as an annotation
219 * processing environment configured for a {@linkplain
220 * javax.annotation.processing.ProcessingEnvironment#getSourceVersion
221 * source version} without modules.
222 *
223 * @implSpec The default implementation of this method returns
224 * an empty set.
225 *
226 * @return the known module elements, or an empty set if there are no modules
227 * @see #getModuleElement(CharSequence)
228 * @since 9
229 */
230 default Set<? extends ModuleElement> getAllModuleElements() {
231 return Collections.emptySet();
232 }
233
234 /**
235 * Returns the values of an annotation's elements, including defaults.
236 *
237 * @see AnnotationMirror#getElementValues()
238 * @param a annotation to examine
239 * @return the values of the annotation's elements, including defaults
240 */
241 Map<? extends ExecutableElement, ? extends AnnotationValue>
242 getElementValuesWithDefaults(AnnotationMirror a);
243
244 /**
245 * Returns the text of the documentation ("Javadoc")
246 * comment of an element.
247 *
248 * <p> A documentation comment of an element is a comment that
249 * begins with "{@code /**}" , ends with a separate
250 * "<code>*/</code>", and immediately precedes the element,
251 * ignoring white space. Therefore, a documentation comment
252 * contains at least three"{@code *}" characters. The text
253 * returned for the documentation comment is a processed form of
254 * the comment as it appears in source code. The leading "{@code
255 * /**}" and trailing "<code>*/</code>" are removed. For lines
256 * of the comment starting after the initial "{@code /**}",
257 * leading white space characters are discarded as are any
258 * consecutive "{@code *}" characters appearing after the white
259 * space or starting the line. The processed lines are then
260 * concatenated together (including line terminators) and
261 * returned.
262 *
263 * @param e the element being examined
264 * @return the documentation comment of the element, or {@code null}
265 * if there is none
266 * @jls 3.6 White Space
267 */
268 String getDocComment(Element e);
269
270 /**
271 * Returns {@code true} if the element is deprecated, {@code false} otherwise.
272 *
273 * @param e the element being examined
274 * @return {@code true} if the element is deprecated, {@code false} otherwise
275 */
276 boolean isDeprecated(Element e);
277
278 /**
279 * Returns the <em>origin</em> of the given element.
280 *
281 * <p>Note that if this method returns {@link Origin#EXPLICIT
282 * EXPLICIT} and the element was created from a class file, then
283 * the element may not, in fact, correspond to an explicitly
284 * declared construct in source code. This is due to limitations
285 * of the fidelity of the class file format in preserving
286 * information from source code. For example, at least some
287 * versions of the class file format do not preserve whether a
288 * constructor was explicitly declared by the programmer or was
289 * implicitly declared as the <em>default constructor</em>.
290 *
291 * @implSpec The default implementation of this method returns
292 * {@link Origin#EXPLICIT EXPLICIT}.
293 *
294 * @param e the element being examined
295 * @return the origin of the given element
296 * @since 9
297 */
298 default Origin getOrigin(Element e) {
299 return Origin.EXPLICIT;
300 }
301
302 /**
303 * Returns the <em>origin</em> of the given annotation mirror.
304 *
305 * An annotation mirror is {@linkplain Origin#MANDATED mandated}
306 * if it is an implicitly declared <em>container annotation</em>
307 * used to hold repeated annotations of a repeatable annotation
308 * type.
309 *
310 * <p>Note that if this method returns {@link Origin#EXPLICIT
311 * EXPLICIT} and the annotation mirror was created from a class
312 * file, then the element may not, in fact, correspond to an
313 * explicitly declared construct in source code. This is due to
314 * limitations of the fidelity of the class file format in
315 * preserving information from source code. For example, at least
316 * some versions of the class file format do not preserve whether
317 * an annotation was explicitly declared by the programmer or was
318 * implicitly declared as a <em>container annotation</em>.
319 *
320 * @implSpec The default implementation of this method returns
321 * {@link Origin#EXPLICIT EXPLICIT}.
322 *
323 * @param c the construct the annotation mirror modifies
324 * @param a the annotation mirror being examined
325 * @return the origin of the given annotation mirror
326 * @jls 9.6.3 Repeatable Annotation Types
327 * @jls 9.7.5 Multiple Annotations of the Same Type
328 * @since 9
329 */
330 default Origin getOrigin(AnnotatedConstruct c,
331 AnnotationMirror a) {
332 return Origin.EXPLICIT;
333 }
334
335 /**
336 * Returns the <em>origin</em> of the given module directive.
337 *
338 * <p>Note that if this method returns {@link Origin#EXPLICIT
339 * EXPLICIT} and the module directive was created from a class
340 * file, then the module directive may not, in fact, correspond to
341 * an explicitly declared construct in source code. This is due to
342 * limitations of the fidelity of the class file format in
343 * preserving information from source code. For example, at least
344 * some versions of the class file format do not preserve whether
345 * a {@code uses} directive was explicitly declared by the
346 * programmer or was added as a synthetic construct.
347 *
348 * <p>Note that an implementation may not be able to reliably
349 * determine the origin status of the directive if the directive
350 * is created from a class file due to limitations of the fidelity
351 * of the class file format in preserving information from source
352 * code.
353 *
354 * @implSpec The default implementation of this method returns
355 * {@link Origin#EXPLICIT EXPLICIT}.
356 *
357 * @param m the module of the directive
358 * @param directive the module directive being examined
359 * @return the origin of the given directive
360 * @since 9
361 */
362 default Origin getOrigin(ModuleElement m,
363 ModuleElement.Directive directive) {
364 return Origin.EXPLICIT;
365 }
366
367 /**
368 * The <em>origin</em> of an element or other language model
369 * item. The origin of an element or item models how a construct
370 * in a program is declared in the source code, explicitly,
371 * implicitly, etc.
372 *
373 * <p>Note that it is possible additional kinds of origin values
374 * will be added in future versions of the platform.
375 *
376 * @jls 13.1 The Form of a Binary
377 * @since 9
378 */
379 public enum Origin {
380 /**
381 * Describes a construct explicitly declared in source code.
382 */
383 EXPLICIT,
384
385 /**
386 * A mandated construct is one that is not explicitly declared
387 * in the source code, but whose presence is mandated by the
388 * specification. Such a construct is said to be implicitly
389 * declared.
390 *
391 * One example of a mandated element is a <em>default
392 * constructor</em> in a class that contains no explicit
393 * constructor declarations.
394 *
395 * Another example of a mandated construct is an implicitly
396 * declared <em>container annotation</em> used to hold
397 * multiple annotations of a repeatable annotation type.
398 *
399 * @jls 8.8.9 Default Constructor
400 * @jls 8.9.3 Enum Members
401 * @jls 9.6.3 Repeatable Annotation Types
402 * @jls 9.7.5 Multiple Annotations of the Same Type
403 */
404 MANDATED,
405
406 /**
407 * A synthetic construct is one that is neither implicitly nor
408 * explicitly declared in the source code. Such a construct is
409 * typically a translation artifact created by a compiler.
410 */
411 SYNTHETIC;
412
413 /**
414 * Returns {@code true} for values corresponding to constructs
415 * that are implicitly or explicitly declared, {@code false}
416 * otherwise.
417 * @return {@code true} for {@link EXPLICIT} and {@link
418 * MANDATED}, {@code false} otherwise.
419 */
420 public boolean isDeclared() {
421 return this != SYNTHETIC;
422 }
423 }
424
425 /**
426 * Returns {@code true} if the executable element is a bridge
427 * method, {@code false} otherwise.
428 *
429 * @implSpec The default implementation of this method returns {@code false}.
430 *
431 * @param e the executable being examined
432 * @return {@code true} if the executable element is a bridge
433 * method, {@code false} otherwise
434 * @since 9
435 */
436 default boolean isBridge(ExecutableElement e) {
437 return false;
438 }
439
440 /**
441 * Returns the <i>binary name</i> of a type element.
442 *
443 * @param type the type element being examined
444 * @return the binary name
445 *
446 * @see TypeElement#getQualifiedName
447 * @jls 13.1 The Form of a Binary
448 */
449 Name getBinaryName(TypeElement type);
450
451
452 /**
453 * Returns the package of an element. The package of a package is
454 * itself.
455 * The package of a module is {@code null}.
456 *
457 * The package of a top-level type is its {@linkplain
458 * TypeElement#getEnclosingElement enclosing package}. Otherwise,
459 * the package of an element is equal to the package of the
460 * {@linkplain Element#getEnclosingElement enclosing element}.
461 *
462 * @param e the element being examined
463 * @return the package of an element
464 */
465 PackageElement getPackageOf(Element e);
466
467 /**
468 * Returns the module of an element. The module of a module is
469 * itself.
470 *
471 * If a package has a module as its {@linkplain
472 * PackageElement#getEnclosingElement enclosing element}, that
473 * module is the module of the package. If the enclosing element
474 * of a package is {@code null}, {@code null} is returned for the
475 * package's module.
476 *
477 * (One situation where a package may have a {@code null} module
478 * is if the environment does not include modules, such as an
479 * annotation processing environment configured for a {@linkplain
480 * javax.annotation.processing.ProcessingEnvironment#getSourceVersion
481 * source version} without modules.)
482 *
483 * Otherwise, the module of an element is equal to the module
484 * {@linkplain #getPackageOf(Element) of the package} of the
485 * element.
486 *
487 * @implSpec The default implementation of this method returns
488 * {@code null}.
489 *
490 * @param e the element being examined
491 * @return the module of an element
492 * @since 9
493 * @spec JPMS
494 */
495 default ModuleElement getModuleOf(Element e) {
496 return null;
497 }
498
499 /**
500 * Returns all members of a type element, whether inherited or
501 * declared directly. For a class the result also includes its
502 * constructors, but not local or anonymous classes.
503 *
504 * @apiNote Elements of certain kinds can be isolated using
505 * methods in {@link ElementFilter}.
506 *
507 * @param type the type being examined
508 * @return all members of the type
509 * @see Element#getEnclosedElements
510 */
511 List<? extends Element> getAllMembers(TypeElement type);
512
513 /**
514 * Returns all annotations <i>present</i> on an element, whether
515 * directly present or present via inheritance.
516 *
517 * <p>Note that any annotations returned by this method are
518 * declaration annotations.
519 *
520 * @param e the element being examined
521 * @return all annotations of the element
522 * @see Element#getAnnotationMirrors
523 * @see javax.lang.model.AnnotatedConstruct
524 */
525 List<? extends AnnotationMirror> getAllAnnotationMirrors(Element e);
526
527 /**
528 * Tests whether one type, method, or field hides another.
529 *
530 * @param hider the first element
531 * @param hidden the second element
532 * @return {@code true} if and only if the first element hides
533 * the second
534 * @jls 8.4.8 Inheritance, Overriding, and Hiding
535 */
536 boolean hides(Element hider, Element hidden);
537
538 /**
539 * Tests whether one method, as a member of a given type,
540 * overrides another method.
541 * When a non-abstract method overrides an abstract one, the
542 * former is also said to <i>implement</i> the latter.
543 *
544 * <p> In the simplest and most typical usage, the value of the
545 * {@code type} parameter will simply be the class or interface
546 * directly enclosing {@code overrider} (the possibly-overriding
547 * method). For example, suppose {@code m1} represents the method
548 * {@code String.hashCode} and {@code m2} represents {@code
549 * Object.hashCode}. We can then ask whether {@code m1} overrides
550 * {@code m2} within the class {@code String} (it does):
551 *
552 * <blockquote>
553 * {@code assert elements.overrides(m1, m2,
554 * elements.getTypeElement("java.lang.String")); }
555 * </blockquote>
556 *
557 * A more interesting case can be illustrated by the following example
558 * in which a method in type {@code A} does not override a
559 * like-named method in type {@code B}:
560 *
561 * <blockquote>
562 * {@code class A { public void m() {} } }<br>
563 * {@code interface B { void m(); } }<br>
564 * ...<br>
565 * {@code m1 = ...; // A.m }<br>
566 * {@code m2 = ...; // B.m }<br>
567 * {@code assert ! elements.overrides(m1, m2,
568 * elements.getTypeElement("A")); }
569 * </blockquote>
570 *
571 * When viewed as a member of a third type {@code C}, however,
572 * the method in {@code A} does override the one in {@code B}:
573 *
574 * <blockquote>
575 * {@code class C extends A implements B {} }<br>
576 * ...<br>
577 * {@code assert elements.overrides(m1, m2,
578 * elements.getTypeElement("C")); }
579 * </blockquote>
580 *
581 * @param overrider the first method, possible overrider
582 * @param overridden the second method, possibly being overridden
583 * @param type the type of which the first method is a member
584 * @return {@code true} if and only if the first method overrides
585 * the second
586 * @jls 8.4.8 Inheritance, Overriding, and Hiding
587 * @jls 9.4.1 Inheritance and Overriding
588 */
589 boolean overrides(ExecutableElement overrider, ExecutableElement overridden,
590 TypeElement type);
591
592 /**
593 * Returns the text of a <i>constant expression</i> representing a
594 * primitive value or a string.
595 * The text returned is in a form suitable for representing the value
596 * in source code.
597 *
598 * @param value a primitive value or string
599 * @return the text of a constant expression
600 * @throws IllegalArgumentException if the argument is not a primitive
601 * value or string
602 *
603 * @see VariableElement#getConstantValue()
604 */
605 String getConstantExpression(Object value);
606
607 /**
608 * Prints a representation of the elements to the given writer in
609 * the specified order. The main purpose of this method is for
610 * diagnostics. The exact format of the output is <em>not</em>
611 * specified and is subject to change.
612 *
613 * @param w the writer to print the output to
614 * @param elements the elements to print
615 */
616 void printElements(java.io.Writer w, Element... elements);
617
618 /**
619 * Return a name with the same sequence of characters as the
620 * argument.
621 *
622 * @param cs the character sequence to return as a name
623 * @return a name with the same sequence of characters as the argument
624 */
625 Name getName(CharSequence cs);
626
627 /**
628 * Returns {@code true} if the type element is a functional interface, {@code false} otherwise.
629 *
630 * @param type the type element being examined
631 * @return {@code true} if the element is a functional interface, {@code false} otherwise
632 * @jls 9.8 Functional Interfaces
633 * @since 1.8
634 */
635 boolean isFunctionalInterface(TypeElement type);
636
637 /**
638 * {@preview Associated with records, a preview feature of the Java language.
639 *
640 * This method is associated with <i>records</i>, a preview
641 * feature of the Java language. Preview features
642 * may be removed in a future release, or upgraded to permanent
643 * features of the Java language.}
644 *
645 * Returns the record component for the given accessor. Returns null if the
646 * given method is not a record component accessor.
647 *
648 * @implSpec The default implementation of this method checks if the element
649 * enclosing the accessor has kind {@link ElementKind#RECORD RECORD} if that is
650 * the case, then all the record components on the accessor's enclosing element
651 * are retrieved by invoking {@link ElementFilter#recordComponentsIn(Iterable)}.
652 * If the accessor of at least one of the record components retrieved happen to
653 * be equal to the accessor passed as a parameter to this method, then that
654 * record component is returned, in any other case {@code null} is returned.
655 *
656 * @param accessor the method for which the record component should be found.
657 * @return the record component, or null if the given method is not an record
658 * component accessor
659 * @since 14
660 */
661 @jdk.internal.PreviewFeature(feature=jdk.internal.PreviewFeature.Feature.RECORDS,
662 essentialAPI=false)
663 @SuppressWarnings("preview")
664 default RecordComponentElement recordComponentFor(ExecutableElement accessor) {
665 if (accessor.getEnclosingElement().getKind() == ElementKind.RECORD) {
666 for (RecordComponentElement rec : ElementFilter.recordComponentsIn(accessor.getEnclosingElement().getEnclosedElements())) {
667 if (Objects.equals(rec.getAccessor(), accessor)) {
668 return rec;
669 }
670 }
671 }
672 return null;
673 }
674 }