1 /*
2 * Copyright (c) 2005, 2017, 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 *
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20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24 */
25
26 package javax.lang.model.util;
27
28
29 import java.util.List;
30 import java.util.Map;
31
32 import javax.lang.model.AnnotatedConstruct;
33 import javax.lang.model.element.*;
34
35
36 /**
37 * Utility methods for operating on program elements.
38 *
39 * <p><b>Compatibility Note:</b> Methods may be added to this interface
40 * in future releases of the platform.
41 *
42 * @author Joseph D. Darcy
43 * @author Scott Seligman
44 * @author Peter von der Ahé
45 * @see javax.annotation.processing.ProcessingEnvironment#getElementUtils
46 * @since 1.6
47 */
48 public interface Elements {
49
50 /**
51 * Returns a package given its fully qualified name if the package is unique in the environment.
52 * If running with modules, all modules in the modules graph are searched for matching packages.
53 *
54 * @param name fully qualified package name, or an empty string for an unnamed package
55 * @return the specified package, or {@code null} if it cannot be uniquely found
56 */
57 PackageElement getPackageElement(CharSequence name);
58
59 /**
60 * Returns a package given its fully qualified name, as seen from the given module.
61 *
62 * @implSpec The default implementation of this method returns
63 * null.
64 *
65 * @param name fully qualified package name, or an empty string for an unnamed package
66 * @param module module relative to which the lookup should happen
67 * @return the specified package, or {@code null} if it cannot be found
68 * @since 9
69 */
70 default PackageElement getPackageElement(ModuleElement module, CharSequence name) {
71 return null;
72 }
73
74 /**
75 * Returns a type element given its canonical name if the type element is unique in the environment.
76 * If running with modules, all modules in the modules graph are searched for matching
77 * type elements.
78 *
79 * @param name the canonical name
80 * @return the named type element, or {@code null} if it cannot be uniquely found
81 */
82 TypeElement getTypeElement(CharSequence name);
83
84 /**
85 * Returns a type element given its canonical name, as seen from the given module.
86 *
87 * @implSpec The default implementation of this method returns
88 * null.
89 *
90 * @param name the canonical name
91 * @param module module relative to which the lookup should happen
92 * @return the named type element, or {@code null} if it cannot be found
93 * @since 9
94 */
95 default TypeElement getTypeElement(ModuleElement module, CharSequence name) {
96 return null;
97 }
98
99 /**
100 * Returns a module element given its fully qualified name.
101 * If the named module cannot be found, null is returned. One situation where a module
102 * cannot be found is if the environment does not include modules, such as
103 * an annotation processing environment configured for
104 * a {@linkplain
105 * javax.annotation.processing.ProcessingEnvironment#getSourceVersion
106 * source version} without modules.
107 *
108 * @implSpec The default implementation of this method returns
109 * null.
110 *
111 * @param name the name
112 * @return the named module element, or {@code null} if it cannot be found
113 * @since 9
114 */
115 default ModuleElement getModuleElement(CharSequence name) {
116 return null;
117 }
118
119 /**
120 * Returns the values of an annotation's elements, including defaults.
121 *
122 * @see AnnotationMirror#getElementValues()
123 * @param a annotation to examine
124 * @return the values of the annotation's elements, including defaults
125 */
126 Map<? extends ExecutableElement, ? extends AnnotationValue>
127 getElementValuesWithDefaults(AnnotationMirror a);
128
129 /**
130 * Returns the text of the documentation ("Javadoc")
131 * comment of an element.
132 *
133 * <p> A documentation comment of an element is a comment that
134 * begins with "{@code /**}" , ends with a separate
135 * "<code>*/</code>", and immediately precedes the element,
136 * ignoring white space. Therefore, a documentation comment
137 * contains at least three"{@code *}" characters. The text
138 * returned for the documentation comment is a processed form of
139 * the comment as it appears in source code. The leading "{@code
140 * /**}" and trailing "<code>*/</code>" are removed. For lines
141 * of the comment starting after the initial "{@code /**}",
142 * leading white space characters are discarded as are any
143 * consecutive "{@code *}" characters appearing after the white
144 * space or starting the line. The processed lines are then
145 * concatenated together (including line terminators) and
146 * returned.
147 *
148 * @param e the element being examined
149 * @return the documentation comment of the element, or {@code null}
150 * if there is none
151 * @jls 3.6 White Space
152 */
153 String getDocComment(Element e);
154
155 /**
156 * Returns {@code true} if the element is deprecated, {@code false} otherwise.
157 *
158 * @param e the element being examined
159 * @return {@code true} if the element is deprecated, {@code false} otherwise
160 */
161 boolean isDeprecated(Element e);
162
163 /**
164 * Returns the <em>origin</em> of the given element.
165 *
166 * <p>Note that if this method returns {@link Origin#EXPLICIT
167 * EXPLICIT} and the element was created from a class file, then
168 * the element may not, in fact, correspond to an explicitly
169 * declared construct in source code. This is due to limitations
170 * of the fidelity of the class file format in preserving
171 * information from source code. For example, at least some
172 * versions of the class file format do not preserve whether a
173 * constructor was explicitly declared by the programmer or was
174 * implicitly declared as the <em>default constructor</em>.
175 *
176 * @implSpec The default implementation of this method returns
177 * {@link Origin#EXPLICIT EXPLICIT}.
178 *
179 * @param e the element being examined
180 * @return the origin of the given element
181 * @since 9
182 */
183 default Origin getOrigin(Element e) {
184 return Origin.EXPLICIT;
185 }
186
187 /**
188 * Returns the <em>origin</em> of the given annotation mirror.
189 *
190 * An annotation mirror is {@linkplain Origin#MANDATED mandated}
191 * if it is an implicitly declared <em>container annotation</em>
192 * used to hold repeated annotations of a repeatable annotation
193 * type.
194 *
195 * <p>Note that if this method returns {@link Origin#EXPLICIT
196 * EXPLICIT} and the annotation mirror was created from a class
197 * file, then the element may not, in fact, correspond to an
198 * explicitly declared construct in source code. This is due to
199 * limitations of the fidelity of the class file format in
200 * preserving information from source code. For example, at least
201 * some versions of the class file format do not preserve whether
202 * an annotation was explicitly declared by the programmer or was
203 * implicitly declared as a <em>container annotation</em>.
204 *
205 * @implSpec The default implementation of this method returns
206 * {@link Origin#EXPLICIT EXPLICIT}.
207 *
208 * @param c the construct the annotation mirror modifies
209 * @param a the annotation mirror being examined
210 * @return the origin of the given annotation mirror
211 * @jls 9.6.3 Repeatable Annotation Types
212 * @jls 9.7.5 Multiple Annotations of the Same Type
213 * @since 9
214 */
215 default Origin getOrigin(AnnotatedConstruct c,
216 AnnotationMirror a) {
217 return Origin.EXPLICIT;
218 }
219
220 /**
221 * Returns the <em>origin</em> of the given module directive.
222 *
223 * <p>Note that if this method returns {@link Origin#EXPLICIT
224 * EXPLICIT} and the module directive was created from a class
225 * file, then the module directive may not, in fact, correspond to
226 * an explicitly declared construct in source code. This is due to
227 * limitations of the fidelity of the class file format in
228 * preserving information from source code. For example, at least
229 * some versions of the class file format do not preserve whether
230 * a {@code uses} directive was explicitly declared by the
231 * programmer or was added as a synthetic construct.
232 *
233 * <p>Note that an implementation may not be able to reliably
234 * determine the origin status of the directive if the directive
235 * is created from a class file due to limitations of the fidelity
236 * of the class file format in preserving information from source
237 * code.
238 *
239 * @implSpec The default implementation of this method returns
240 * {@link Origin#EXPLICIT EXPLICIT}.
241 *
242 * @param m the module of the directive
243 * @param directive the module directive being examined
244 * @return the origin of the given directive
245 * @since 9
246 */
247 default Origin getOrigin(ModuleElement m,
248 ModuleElement.Directive directive) {
249 return Origin.EXPLICIT;
250 }
251
252 /**
253 * The <em>origin</em> of an element or other language model
254 * item. The origin of an element or item models how a construct
255 * in a program is declared in the source code, explicitly,
256 * implicitly, etc.
257 *
258 * <p>Note that it is possible additional kinds of origin values
259 * will be added in future versions of the platform.
260 *
261 * @jls 13.1 The Form of a Binary
262 * @since 9
263 */
264 public enum Origin {
265 /**
266 * Describes a construct explicitly declared in source code.
267 */
268 EXPLICIT,
269
270 /**
271 * A mandated construct is one that is not explicitly declared
272 * in the source code, but whose presence is mandated by the
273 * specification. Such a construct is said to be implicitly
274 * declared.
275 *
276 * One example of a mandated element is a <em>default
277 * constructor</em> in a class that contains no explicit
278 * constructor declarations.
279 *
280 * Another example of a mandated construct is an implicitly
281 * declared <em>container annotation</em> used to hold
282 * multiple annotations of a repeatable annotation type.
283 *
284 * @jls 8.8.9 Default Constructor
285 * @jls 9.6.3 Repeatable Annotation Types
286 * @jls 9.7.5 Multiple Annotations of the Same Type
287 */
288 MANDATED,
289
290 /**
291 * A synthetic construct is one that is neither implicitly nor
292 * explicitly declared in the source code. Such a construct is
293 * typically a translation artifact created by a compiler.
294 */
295 SYNTHETIC;
296
297 /**
298 * Returns {@code true} for values corresponding to constructs
299 * that are implicitly or explicitly declared, {@code false}
300 * otherwise.
301 * @return {@code true} for {@link EXPLICIT} and {@link
302 * MANDATED}, {@code false} otherwise.
303 */
304 public boolean isDeclared() {
305 return this != SYNTHETIC;
306 }
307 }
308
309 /**
310 * Returns {@code true} if the executable element is a bridge
311 * method, {@code false} otherwise.
312 *
313 * @implSpec The default implementation of this method returns {@code false}.
314 *
315 * @param e the executable being examined
316 * @return {@code true} if the executable element is a bridge
317 * method, {@code false} otherwise
318 * @since 9
319 */
320 default boolean isBridge(ExecutableElement e) {
321 return false;
322 }
323
324 /**
325 * Returns the <i>binary name</i> of a type element.
326 *
327 * @param type the type element being examined
328 * @return the binary name
329 *
330 * @see TypeElement#getQualifiedName
331 * @jls 13.1 The Form of a Binary
332 */
333 Name getBinaryName(TypeElement type);
334
335
336 /**
337 * Returns the package of an element. The package of a package is
338 * itself.
339 *
340 * @param type the element being examined
341 * @return the package of an element
342 */
343 PackageElement getPackageOf(Element type);
344
345 /**
346 * Returns the module of an element. The module of a module is
347 * itself.
348 * If there is no module for the element, null is returned. One situation where there is
349 * no module for an element is if the environment does not include modules, such as
350 * an annotation processing environment configured for
351 * a {@linkplain
352 * javax.annotation.processing.ProcessingEnvironment#getSourceVersion
353 * source version} without modules.
354 *
355 * @implSpec The default implementation of this method returns
356 * null.
357 *
358 * @param type the element being examined
359 * @return the module of an element
360 * @since 9
361 */
362 default ModuleElement getModuleOf(Element type) {
363 return null;
364 }
365
366 /**
367 * Returns all members of a type element, whether inherited or
368 * declared directly. For a class the result also includes its
369 * constructors, but not local or anonymous classes.
370 *
371 * @apiNote Elements of certain kinds can be isolated using
372 * methods in {@link ElementFilter}.
373 *
374 * @param type the type being examined
375 * @return all members of the type
376 * @see Element#getEnclosedElements
377 */
378 List<? extends Element> getAllMembers(TypeElement type);
379
380 /**
381 * Returns all annotations <i>present</i> on an element, whether
382 * directly present or present via inheritance.
383 *
384 * @param e the element being examined
385 * @return all annotations of the element
386 * @see Element#getAnnotationMirrors
387 * @see javax.lang.model.AnnotatedConstruct
388 */
389 List<? extends AnnotationMirror> getAllAnnotationMirrors(Element e);
390
391 /**
392 * Tests whether one type, method, or field hides another.
393 *
394 * @param hider the first element
395 * @param hidden the second element
396 * @return {@code true} if and only if the first element hides
397 * the second
398 */
399 boolean hides(Element hider, Element hidden);
400
401 /**
402 * Tests whether one method, as a member of a given type,
403 * overrides another method.
404 * When a non-abstract method overrides an abstract one, the
405 * former is also said to <i>implement</i> the latter.
406 *
407 * <p> In the simplest and most typical usage, the value of the
408 * {@code type} parameter will simply be the class or interface
409 * directly enclosing {@code overrider} (the possibly-overriding
410 * method). For example, suppose {@code m1} represents the method
411 * {@code String.hashCode} and {@code m2} represents {@code
412 * Object.hashCode}. We can then ask whether {@code m1} overrides
413 * {@code m2} within the class {@code String} (it does):
414 *
415 * <blockquote>
416 * {@code assert elements.overrides(m1, m2,
417 * elements.getTypeElement("java.lang.String")); }
418 * </blockquote>
419 *
420 * A more interesting case can be illustrated by the following example
421 * in which a method in type {@code A} does not override a
422 * like-named method in type {@code B}:
423 *
424 * <blockquote>
425 * {@code class A { public void m() {} } }<br>
426 * {@code interface B { void m(); } }<br>
427 * ...<br>
428 * {@code m1 = ...; // A.m }<br>
429 * {@code m2 = ...; // B.m }<br>
430 * {@code assert ! elements.overrides(m1, m2,
431 * elements.getTypeElement("A")); }
432 * </blockquote>
433 *
434 * When viewed as a member of a third type {@code C}, however,
435 * the method in {@code A} does override the one in {@code B}:
436 *
437 * <blockquote>
438 * {@code class C extends A implements B {} }<br>
439 * ...<br>
440 * {@code assert elements.overrides(m1, m2,
441 * elements.getTypeElement("C")); }
442 * </blockquote>
443 *
444 * @param overrider the first method, possible overrider
445 * @param overridden the second method, possibly being overridden
446 * @param type the type of which the first method is a member
447 * @return {@code true} if and only if the first method overrides
448 * the second
449 * @jls 8.4.8 Inheritance, Overriding, and Hiding
450 * @jls 9.4.1 Inheritance and Overriding
451 */
452 boolean overrides(ExecutableElement overrider, ExecutableElement overridden,
453 TypeElement type);
454
455 /**
456 * Returns the text of a <i>constant expression</i> representing a
457 * primitive value or a string.
458 * The text returned is in a form suitable for representing the value
459 * in source code.
460 *
461 * @param value a primitive value or string
462 * @return the text of a constant expression
463 * @throws IllegalArgumentException if the argument is not a primitive
464 * value or string
465 *
466 * @see VariableElement#getConstantValue()
467 */
468 String getConstantExpression(Object value);
469
470 /**
471 * Prints a representation of the elements to the given writer in
472 * the specified order. The main purpose of this method is for
473 * diagnostics. The exact format of the output is <em>not</em>
474 * specified and is subject to change.
475 *
476 * @param w the writer to print the output to
477 * @param elements the elements to print
478 */
479 void printElements(java.io.Writer w, Element... elements);
480
481 /**
482 * Return a name with the same sequence of characters as the
483 * argument.
484 *
485 * @param cs the character sequence to return as a name
486 * @return a name with the same sequence of characters as the argument
487 */
488 Name getName(CharSequence cs);
489
490 /**
491 * Returns {@code true} if the type element is a functional interface, {@code false} otherwise.
492 *
493 * @param type the type element being examined
494 * @return {@code true} if the element is a functional interface, {@code false} otherwise
495 * @jls 9.8 Functional Interfaces
496 * @since 1.8
497 */
498 boolean isFunctionalInterface(TypeElement type);
499 }