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 *
17 * You should have received a copy of the GNU General Public License version
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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
26 package javax.annotation.processing;
27
28 import javax.tools.JavaFileManager;
29 import javax.tools.*;
30 import javax.lang.model.element.Element;
31 import javax.lang.model.util.Elements;
32 import java.io.IOException;
33
34 /**
35 * This interface supports the creation of new files by an annotation
36 * processor. Files created in this way will be known to the
37 * annotation processing tool implementing this interface, better
38 * enabling the tool to manage them. Source and class files so
39 * created will be {@linkplain RoundEnvironment#getRootElements
40 * considered for processing} by the tool in a subsequent {@linkplain
41 * RoundEnvironment round of processing} after the {@code close}
42 * method has been called on the {@code Writer} or {@code
43 * OutputStream} used to write the contents of the file.
44 *
45 * Three kinds of files are distinguished: source files, class files,
46 * and auxiliary resource files.
47 *
48 * <p> There are two distinguished supported locations (subtrees
49 * within the logical file system) where newly created files are
50 * placed: one for {@linkplain
51 * javax.tools.StandardLocation#SOURCE_OUTPUT new source files}, and
52 * one for {@linkplain javax.tools.StandardLocation#CLASS_OUTPUT new
53 * class files}. (These might be specified on a tool's command line,
54 * for example, using flags such as {@code -s} and {@code -d}.) The
55 * actual locations for new source files and new class files may or
56 * may not be distinct on a particular run of the tool. Resource
57 * files may be created in either location. The methods for reading
58 * and writing resources take a relative name argument. A relative
59 * name is a non-null, non-empty sequence of path segments separated
60 * by {@code '/'}; {@code '.'} and {@code '..'} are invalid path
61 * segments. A valid relative name must match the
62 * "path-rootless" rule of <a
63 * href="http://www.ietf.org/html/rfc3986.txt">RFC 3986</a>, section
64 * 3.3.
65 *
66 * <p>The file creation methods take a variable number of arguments to
67 * allow the <em>originating elements</em> to be provided as hints to
68 * the tool infrastructure to better manage dependencies. The
69 * originating elements are the types or packages (representing {@code
70 * package-info} files) or modules (representing {@code
71 * module-info} files) which caused an annotation processor to
72 * attempt to create a new file. For example, if an annotation
73 * processor tries to create a source file, {@code
74 * GeneratedFromUserSource}, in response to processing
75 *
76 * <blockquote><pre>
77 * @Generate
78 * public class UserSource {}
79 * </pre></blockquote>
80 *
81 * the type element for {@code UserSource} should be passed as part of
82 * the creation method call as in:
83 *
84 * <blockquote><pre>
85 * filer.createSourceFile("GeneratedFromUserSource",
86 * eltUtils.getTypeElement("UserSource"));
87 * </pre></blockquote>
88 *
89 * If there are no originating elements, none need to be passed. This
90 * information may be used in an incremental environment to determine
91 * the need to rerun processors or remove generated files.
92 * Non-incremental environments may ignore the originating element
93 * information.
94 *
95 * <p> During each run of an annotation processing tool, a file with a
96 * given pathname may be created only once. If that file already
97 * exists before the first attempt to create it, the old contents will
98 * be deleted. Any subsequent attempt to create the same file during
99 * a run will throw a {@link FilerException}, as will attempting to
100 * create both a class file and source file for the same type name or
101 * same package name. The {@linkplain Processor initial inputs} to
102 * the tool are considered to be created by the zeroth round;
103 * therefore, attempting to create a source or class file
104 * corresponding to one of those inputs will result in a {@link
105 * FilerException}.
106 *
107 * <p> In general, processors must not knowingly attempt to overwrite
108 * existing files that were not generated by some processor. A {@code
109 * Filer} may reject attempts to open a file corresponding to an
110 * existing type, like {@code java.lang.Object}. Likewise, the
111 * invoker of the annotation processing tool must not knowingly
112 * configure the tool such that the discovered processors will attempt
113 * to overwrite existing files that were not generated.
114 *
115 * <p> Processors can indicate a source or class file is generated by
116 * including a {@code javax.annotation.Generated} annotation if the
117 * environment is configured so that that type is accessible.
118 *
119 * @apiNote Some of the effect of overwriting a file can be
120 * achieved by using a <i>decorator</i>-style pattern. Instead of
121 * modifying a class directly, the class is designed so that either
122 * its superclass is generated by annotation processing or subclasses
123 * of the class are generated by annotation processing. If the
124 * subclasses are generated, the parent class may be designed to use
125 * factories instead of public constructors so that only subclass
126 * instances would be presented to clients of the parent class.
127 *
128 * @author Joseph D. Darcy
129 * @author Scott Seligman
130 * @author Peter von der Ahé
131 * @since 1.6
132 */
133 public interface Filer {
134 /**
135 * Creates a new source file and returns an object to allow
136 * writing to it. A source file for a type, or a package can
137 * be created.
138 *
139 * The file's name and path (relative to the {@linkplain
140 * StandardLocation#SOURCE_OUTPUT root output location for source
141 * files}) are based on the name of the item to be declared in
142 * that file as well as the specified module for the item (if
143 * any).
144 *
145 * If more than one type is being declared in a single file (that
146 * is, a single compilation unit), the name of the file should
147 * correspond to the name of the principal top-level type (the
148 * public one, for example).
149 *
150 * <p>A source file can also be created to hold information about
151 * a package, including package annotations. To create a source
152 * file for a named package, have the {@code name} argument be the
153 * package's name followed by {@code ".package-info"}; to create a
154 * source file for an unnamed package, use {@code "package-info"}.
155 *
156 * <p>The optional module name is prefixed to the type name or
157 * package name and separated using a "{@code /}" character. For
158 * example, to create a source file for type {@code a.B} in module
159 * {@code foo}, use a {@code name} argument of {@code "foo/a.B"}.
160 *
161 * <p>If no explicit module prefix is given and modules are supported
162 * in the environment, a suitable module is inferred. If a suitable
163 * module cannot be inferred {@link FilerException} is thrown.
164 * An implementation may use information about the configuration of
165 * the annotation processing tool as part of the inference.
166 *
167 * <p>Creating a source file in or for an unnamed package in a named
168 * module is <em>not</em> supported.
169 *
170 * @apiNote To use a particular {@linkplain
171 * java.nio.charset.Charset charset} to encode the contents of the
172 * file, an {@code OutputStreamWriter} with the chosen charset can
173 * be created from the {@code OutputStream} from the returned
174 * object. If the {@code Writer} from the returned object is
175 * directly used for writing, its charset is determined by the
176 * implementation. An annotation processing tool may have an
177 * {@code -encoding} flag or analogous option for specifying this;
178 * otherwise, it will typically be the platform's default
179 * encoding.
180 *
181 * <p>To avoid subsequent errors, the contents of the source file
182 * should be compatible with the {@linkplain
183 * ProcessingEnvironment#getSourceVersion source version} being used
184 * for this run.
185 *
186 * @implNote In the reference implementation, if the annotation
187 * processing tool is processing a single module <i>M</i>,
188 * then <i>M</i> is used as the module for files created without
189 * an explicit module prefix. If the tool is processing multiple
190 * modules, and {@link
191 * Elements#getPackageElement(java.lang.CharSequence)
192 * Elements.getPackageElement(package-of(name))}
193 * returns a package, the module that owns the returned package is used
194 * as the target module. A separate option may be used to provide the target
195 * module if it cannot be determined using the above rules.
196 *
197 * @param name canonical (fully qualified) name of the principal type
198 * being declared in this file or a package name followed by
199 * {@code ".package-info"} for a package information file
200 * @param originatingElements type or package or module elements causally
201 * associated with the creation of this file, may be elided or
202 * {@code null}
203 * @return a {@code JavaFileObject} to write the new source file
204 * @throws FilerException if the same pathname has already been
205 * created, the same type has already been created, the name is
206 * otherwise not valid for the entity requested to being created,
207 * if the target module cannot be determined, if the target
208 * module is not writable, or a module is specified when the environment
209 * doesn't support modules.
210 * @throws IOException if the file cannot be created
211 * @jls 7.3 Compilation Units
212 */
213 JavaFileObject createSourceFile(CharSequence name,
214 Element... originatingElements) throws IOException;
215
216 /**
217 * Creates a new class file, and returns an object to allow
218 * writing to it. A class file for a type, or a package can
219 * be created.
220 *
221 * The file's name and path (relative to the {@linkplain
222 * StandardLocation#CLASS_OUTPUT root output location for class
223 * files}) are based on the name of the item to be declared as
224 * well as the specified module for the item (if any).
225 *
226 * <p>A class file can also be created to hold information about a
227 * package, including package annotations. To create a class file
228 * for a named package, have the {@code name} argument be the
229 * package's name followed by {@code ".package-info"}; creating a
230 * class file for an unnamed package is not supported.
231 *
232 * <p>The optional module name is prefixed to the type name or
233 * package name and separated using a "{@code /}" character. For
234 * example, to create a class file for type {@code a.B} in module
235 * {@code foo}, use a {@code name} argument of {@code "foo/a.B"}.
236 *
237 * <p>If no explicit module prefix is given and modules are supported
238 * in the environment, a suitable module is inferred. If a suitable
239 * module cannot be inferred {@link FilerException} is thrown.
240 * An implementation may use information about the configuration of
241 * the annotation processing tool as part of the inference.
242 *
243 * <p>Creating a class file in or for an unnamed package in a named
244 * module is <em>not</em> supported.
245 *
246 * @apiNote To avoid subsequent errors, the contents of the class
247 * file should be compatible with the {@linkplain
248 * ProcessingEnvironment#getSourceVersion source version} being
249 * used for this run.
250 *
251 * @implNote In the reference implementation, if the annotation
252 * processing tool is processing a single module <i>M</i>,
253 * then <i>M</i> is used as the module for files created without
254 * an explicit module prefix. If the tool is processing multiple
255 * modules, and {@link
256 * Elements#getPackageElement(java.lang.CharSequence)
257 * Elements.getPackageElement(package-of(name))}
258 * returns a package, the module that owns the returned package is used
259 * as the target module. A separate option may be used to provide the target
260 * module if it cannot be determined using the above rules.
261 *
262 * @param name binary name of the type being written or a package name followed by
263 * {@code ".package-info"} for a package information file
264 * @param originatingElements type or package or module elements causally
265 * associated with the creation of this file, may be elided or
266 * {@code null}
267 * @return a {@code JavaFileObject} to write the new class file
268 * @throws FilerException if the same pathname has already been
269 * created, the same type has already been created, the name is
270 * not valid for a type, if the target module cannot be determined,
271 * if the target module is not writable, or a module is specified when
272 * the environment doesn't support modules.
273 * @throws IOException if the file cannot be created
274 */
275 JavaFileObject createClassFile(CharSequence name,
276 Element... originatingElements) throws IOException;
277
278 /**
279 * Creates a new auxiliary resource file for writing and returns a
280 * file object for it. The file may be located along with the
281 * newly created source files, newly created binary files, or
282 * other supported location. The locations {@link
283 * StandardLocation#CLASS_OUTPUT CLASS_OUTPUT} and {@link
284 * StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must be
285 * supported. The resource may be named relative to some module
286 * and/or package (as are source and class files), and from there
287 * by a relative pathname. In a loose sense, the full pathname of
288 * the new file will be the concatenation of {@code location},
289 * {@code moduleAndPkg}, and {@code relativeName}.
290 *
291 * If {@code moduleAndPkg} contains a "{@code /}" character, the
292 * prefix before the "{@code /}" character is the module name and
293 * the suffix after the "{@code /}" character is the package
294 * name. The package suffix may be empty. If {@code moduleAndPkg}
295 * does not contain a "{@code /}" character, the entire argument
296 * is interpreted as a package name.
297 *
298 * <p>If the given location is neither a {@linkplain
299 * JavaFileManager.Location#isModuleOrientedLocation()
300 * module oriented location}, nor an {@linkplain
301 * JavaFileManager.Location#isOutputLocation()
302 * output location containing multiple modules}, and the explicit
303 * module prefix is given, {@link FilerException} is thrown.
304 *
305 * <p>If the given location is either a module oriented location,
306 * or an output location containing multiple modules, and no explicit
307 * modules prefix is given, a suitable module is
308 * inferred. If a suitable module cannot be inferred {@link
309 * FilerException} is thrown. An implementation may use information
310 * about the configuration of the annotation processing tool
311 * as part of the inference.
312 *
313 * <p>Files created via this method are <em>not</em> registered for
314 * annotation processing, even if the full pathname of the file
315 * would correspond to the full pathname of a new source file
316 * or new class file.
317 *
318 * @implNote In the reference implementation, if the annotation
319 * processing tool is processing a single module <i>M</i>,
320 * then <i>M</i> is used as the module for files created without
321 * an explicit module prefix. If the tool is processing multiple
322 * modules, and {@link
323 * Elements#getPackageElement(java.lang.CharSequence)
324 * Elements.getPackageElement(package-of(name))}
325 * returns a package, the module that owns the returned package is used
326 * as the target module. A separate option may be used to provide the target
327 * module if it cannot be determined using the above rules.
328 *
329 * @param location location of the new file
330 * @param moduleAndPkg module and/or package relative to which the file
331 * should be named, or the empty string if none
332 * @param relativeName final pathname components of the file
333 * @param originatingElements type or package or module elements causally
334 * associated with the creation of this file, may be elided or
335 * {@code null}
336 * @return a {@code FileObject} to write the new resource
337 * @throws IOException if the file cannot be created
338 * @throws FilerException if the same pathname has already been
339 * created, if the target module cannot be determined,
340 * or if the target module is not writable, or if an explicit
341 * target module is specified and the location does not support it.
342 * @throws IllegalArgumentException for an unsupported location
343 * @throws IllegalArgumentException if {@code moduleAndPkg} is ill-formed
344 * @throws IllegalArgumentException if {@code relativeName} is not relative
345 */
346 FileObject createResource(JavaFileManager.Location location,
347 CharSequence moduleAndPkg,
348 CharSequence relativeName,
349 Element... originatingElements) throws IOException;
350
351 /**
352 * Returns an object for reading an existing resource. The
353 * locations {@link StandardLocation#CLASS_OUTPUT CLASS_OUTPUT}
354 * and {@link StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must
355 * be supported.
356 *
357 * <p>If {@code moduleAndPkg} contains a "{@code /}" character, the
358 * prefix before the "{@code /}" character is the module name and
359 * the suffix after the "{@code /}" character is the package
360 * name. The package suffix may be empty; however, if a module
361 * name is present, it must be nonempty. If {@code moduleAndPkg}
362 * does not contain a "{@code /}" character, the entire argument
363 * is interpreted as a package name.
364 *
365 * <p>If the given location is neither a {@linkplain
366 * JavaFileManager.Location#isModuleOrientedLocation()
367 * module oriented location}, nor an {@linkplain
368 * JavaFileManager.Location#isOutputLocation()
369 * output location containing multiple modules}, and the explicit
370 * module prefix is given, {@link FilerException} is thrown.
371 *
372 * <p>If the given location is either a module oriented location,
373 * or an output location containing multiple modules, and no explicit
374 * modules prefix is given, a suitable module is
375 * inferred. If a suitable module cannot be inferred {@link
376 * FilerException} is thrown. An implementation may use information
377 * about the configuration of the annotation processing tool
378 * as part of the inference.
379 *
380 * @implNote In the reference implementation, if the annotation
381 * processing tool is processing a single module <i>M</i>,
382 * then <i>M</i> is used as the module for files read without
383 * an explicit module prefix. If the tool is processing multiple
384 * modules, and {@link
385 * Elements#getPackageElement(java.lang.CharSequence)
386 * Elements.getPackageElement(package-of(name))}
387 * returns a package, the module that owns the returned package is used
388 * as the source module. A separate option may be used to provide the target
389 * module if it cannot be determined using the above rules.
390 *
391 * @param location location of the file
392 * @param moduleAndPkg module and/or package relative to which the file
393 * should be searched for, or the empty string if none
394 * @param relativeName final pathname components of the file
395 * @return an object to read the file
396 * @throws FilerException if the same pathname has already been
397 * opened for writing, if the source module cannot be determined,
398 * or if the target module is not writable, or if an explicit target
399 * module is specified and the location does not support it.
400 * @throws IOException if the file cannot be opened
401 * @throws IllegalArgumentException for an unsupported location
402 * @throws IllegalArgumentException if {@code moduleAndPkg} is ill-formed
403 * @throws IllegalArgumentException if {@code relativeName} is not relative
404 */
405 FileObject getResource(JavaFileManager.Location location,
406 CharSequence moduleAndPkg,
407 CharSequence relativeName) throws IOException;
408 }