1 /*
2 * Copyright (c) 2005, 2016, 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.annotation.processing;
27
28 import javax.tools.JavaFileManager;
29 import javax.tools.*;
30 import javax.lang.model.element.Element;
31 import java.io.IOException;
32
33 /**
34 * This interface supports the creation of new files by an annotation
35 * processor. Files created in this way will be known to the
36 * annotation processing tool implementing this interface, better
37 * enabling the tool to manage them. Source and class files so
38 * created will be {@linkplain RoundEnvironment#getRootElements
39 * considered for processing} by the tool in a subsequent {@linkplain
40 * RoundEnvironment round of processing} after the {@code close}
41 * method has been called on the {@code Writer} or {@code
42 * OutputStream} used to write the contents of the file.
43 *
44 * Three kinds of files are distinguished: source files, class files,
45 * and auxiliary resource files.
46 *
47 * <p> There are two distinguished supported locations (subtrees
48 * within the logical file system) where newly created files are
49 * placed: one for {@linkplain
50 * javax.tools.StandardLocation#SOURCE_OUTPUT new source files}, and
51 * one for {@linkplain javax.tools.StandardLocation#CLASS_OUTPUT new
52 * class files}. (These might be specified on a tool's command line,
53 * for example, using flags such as {@code -s} and {@code -d}.) The
54 * actual locations for new source files and new class files may or
55 * may not be distinct on a particular run of the tool. Resource
56 * files may be created in either location. The methods for reading
57 * and writing resources take a relative name argument. A relative
58 * name is a non-null, non-empty sequence of path segments separated
59 * by {@code '/'}; {@code '.'} and {@code '..'} are invalid path
60 * segments. A valid relative name must match the
61 * "path-rootless" rule of <a
62 * href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986</a>, section
63 * 3.3.
64 *
65 * <p>The file creation methods take a variable number of arguments to
66 * allow the <em>originating elements</em> to be provided as hints to
67 * the tool infrastructure to better manage dependencies. The
68 * originating elements are the types or packages (representing {@code
69 * package-info} files) or modules (representing {@code
70 * module-info} files) which caused an annotation processor to
71 * attempt to create a new file. For example, if an annotation
72 * processor tries to create a source file, {@code
73 * GeneratedFromUserSource}, in response to processing
74 *
75 * <blockquote><pre>
76 * @Generate
77 * public class UserSource {}
78 * </pre></blockquote>
79 *
80 * the type element for {@code UserSource} should be passed as part of
81 * the creation method call as in:
82 *
83 * <blockquote><pre>
84 * filer.createSourceFile("GeneratedFromUserSource",
85 * eltUtils.getTypeElement("UserSource"));
86 * </pre></blockquote>
87 *
88 * If there are no originating elements, none need to be passed. This
89 * information may be used in an incremental environment to determine
90 * the need to rerun processors or remove generated files.
91 * Non-incremental environments may ignore the originating element
92 * information.
93 *
94 * <p> During each run of an annotation processing tool, a file with a
95 * given pathname may be created only once. If that file already
96 * exists before the first attempt to create it, the old contents will
97 * be deleted. Any subsequent attempt to create the same file during
98 * a run will throw a {@link FilerException}, as will attempting to
99 * create both a class file and source file for the same type name or
100 * same package name. The {@linkplain Processor initial inputs} to
101 * the tool are considered to be created by the zeroth round;
102 * therefore, attempting to create a source or class file
103 * corresponding to one of those inputs will result in a {@link
104 * FilerException}.
105 *
106 * <p> In general, processors must not knowingly attempt to overwrite
107 * existing files that were not generated by some processor. A {@code
108 * Filer} may reject attempts to open a file corresponding to an
109 * existing type, like {@code java.lang.Object}. Likewise, the
110 * invoker of the annotation processing tool must not knowingly
111 * configure the tool such that the discovered processors will attempt
112 * to overwrite existing files that were not generated.
113 *
114 * <p> Processors can indicate a source or class file is generated by
115 * including a {@code javax.annotation.Generated} annotation if the
116 * environment is configured so that that type is accessible.
117 *
118 * @apiNote Some of the effect of overwriting a file can be
119 * achieved by using a <i>decorator</i>-style pattern. Instead of
120 * modifying a class directly, the class is designed so that either
121 * its superclass is generated by annotation processing or subclasses
122 * of the class are generated by annotation processing. If the
123 * subclasses are generated, the parent class may be designed to use
124 * factories instead of public constructors so that only subclass
125 * instances would be presented to clients of the parent class.
126 *
127 * @author Joseph D. Darcy
128 * @author Scott Seligman
129 * @author Peter von der Ahé
130 * @since 1.6
131 */
132 public interface Filer {
133 /**
134 * Creates a new source file and returns an object to allow
135 * writing to it. A source file for a type, or a package can
136 * be created.
137 *
138 * The file's name and path (relative to the {@linkplain
139 * StandardLocation#SOURCE_OUTPUT root output location for source
140 * files}) are based on the name of the item to be declared in
141 * that file as well as the specified module for the item (if
142 * any).
143 *
144 * If more than one type is being declared in a single file (that
145 * is, a single compilation unit), the name of the file should
146 * correspond to the name of the principal top-level type (the
147 * public one, for example).
148 *
149 * <p>A source file can also be created to hold information about
150 * a package, including package annotations. To create a source
151 * file for a named package, have the {@code name} argument be the
152 * package's name followed by {@code ".package-info"}; to create a
153 * source file for an unnamed package, use {@code "package-info"}.
154 *
155 * <p>The optional module name is prefixed to the type name or
156 * package name and separated using a "{@code /}" character. For
157 * example, to create a source file for type {@code a.B} in module
158 * {@code foo}, use a {@code name} argument of {@code "foo/a.B"}.
159 *
160 * <p>Creating a source file in or for an unnamed package in a named
161 * module is <em>not</em> supported.
162 *
163 * @apiNote To use a particular {@linkplain
164 * java.nio.charset.Charset charset} to encode the contents of the
165 * file, an {@code OutputStreamWriter} with the chosen charset can
166 * be created from the {@code OutputStream} from the returned
167 * object. If the {@code Writer} from the returned object is
168 * directly used for writing, its charset is determined by the
169 * implementation. An annotation processing tool may have an
170 * {@code -encoding} flag or analogous option for specifying this;
171 * otherwise, it will typically be the platform's default
172 * encoding.
173 *
174 * <p>To avoid subsequent errors, the contents of the source file
175 * should be compatible with the {@linkplain
176 * ProcessingEnvironment#getSourceVersion source version} being used
177 * for this run.
178 *
179 * @param name canonical (fully qualified) name of the principal type
180 * being declared in this file or a package name followed by
181 * {@code ".package-info"} for a package information file
182 * @param originatingElements type or package or module elements causally
183 * associated with the creation of this file, may be elided or
184 * {@code null}
185 * @return a {@code JavaFileObject} to write the new source file
186 * @throws FilerException if the same pathname has already been
187 * created, the same type has already been created, or the name is
188 * otherwise not valid for the entity requested to being created
189 * @throws IOException if the file cannot be created
190 * @jls 7.3 Compilation Units
191 */
192 JavaFileObject createSourceFile(CharSequence name,
193 Element... originatingElements) throws IOException;
194
195 /**
196 * Creates a new class file, and returns an object to allow
197 * writing to it. A class file for a type, or a package can
198 * be created.
199 *
200 * The file's name and path (relative to the {@linkplain
201 * StandardLocation#CLASS_OUTPUT root output location for class
202 * files}) are based on the name of the item to be declared as
203 * well as the specified module for the item (if any).
204 *
205 * <p>A class file can also be created to hold information about a
206 * package, including package annotations. To create a class file
207 * for a named package, have the {@code name} argument be the
208 * package's name followed by {@code ".package-info"}; creating a
209 * class file for an unnamed package is not supported.
210 *
211 * <p>The optional module name is prefixed to the type name or
212 * package name and separated using a "{@code /}" character. For
213 * example, to create a class file for type {@code a.B} in module
214 * {@code foo}, use a {@code name} argument of {@code "foo/a.B"}.
215 *
216 * <p>Creating a class file in or for an unnamed package in a named
217 * module is <em>not</em> supported.
218 *
219 * @apiNote To avoid subsequent errors, the contents of the class
220 * file should be compatible with the {@linkplain
221 * ProcessingEnvironment#getSourceVersion source version} being
222 * used for this run.
223 *
224 * @param name binary name of the type being written or a package name followed by
225 * {@code ".package-info"} for a package information file
226 * @param originatingElements type or package or module elements causally
227 * associated with the creation of this file, may be elided or
228 * {@code null}
229 * @return a {@code JavaFileObject} to write the new class file
230 * @throws FilerException if the same pathname has already been
231 * created, the same type has already been created, or the name is
232 * not valid for a type
233 * @throws IOException if the file cannot be created
234 */
235 JavaFileObject createClassFile(CharSequence name,
236 Element... originatingElements) throws IOException;
237
238 /**
239 * Creates a new auxiliary resource file for writing and returns a
240 * file object for it. The file may be located along with the
241 * newly created source files, newly created binary files, or
242 * other supported location. The locations {@link
243 * StandardLocation#CLASS_OUTPUT CLASS_OUTPUT} and {@link
244 * StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must be
245 * supported. The resource may be named relative to some module
246 * and/or package (as are source and class files), and from there
247 * by a relative pathname. In a loose sense, the full pathname of
248 * the new file will be the concatenation of {@code location},
249 * {@code moduleAndPkg}, and {@code relativeName}.
250 *
251 * If {@code moduleAndPkg} contains a "{@code /}" character, the
252 * prefix before the "{@code /}" character is the module name and
253 * the suffix after the "{@code /}" character is the package
254 * name. The package suffix may be empty. If {@code moduleAndPkg}
255 * does not contain a "{@code /}" character, the entire argument
256 * is interpreted as a package name.
257 *
258 * <p>Files created via this method are <em>not</em> registered for
259 * annotation processing, even if the full pathname of the file
260 * would correspond to the full pathname of a new source file
261 * or new class file.
262 *
263 * @param location location of the new file
264 * @param moduleAndPkg module and/or package relative to which the file
265 * should be named, or the empty string if none
266 * @param relativeName final pathname components of the file
267 * @param originatingElements type or package elements causally
268 * associated with the creation of this file, may be elided or
269 * {@code null}
270 * @return a {@code FileObject} to write the new resource
271 * @throws IOException if the file cannot be created
272 * @throws FilerException if the same pathname has already been
273 * created
274 * @throws IllegalArgumentException for an unsupported location
275 * @throws IllegalArgumentException if {@code moduleAndPkg} is ill-formed
276 * @throws IllegalArgumentException if {@code relativeName} is not relative
277 */
278 FileObject createResource(JavaFileManager.Location location,
279 CharSequence moduleAndPkg,
280 CharSequence relativeName,
281 Element... originatingElements) throws IOException;
282
283 /**
284 * Returns an object for reading an existing resource. The
285 * locations {@link StandardLocation#CLASS_OUTPUT CLASS_OUTPUT}
286 * and {@link StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must
287 * be supported.
288 *
289 * <p>If {@code moduleAndPkg} contains a "{@code /}" character, the
290 * prefix before the "{@code /}" character is the module name and
291 * the suffix after the "{@code /}" character is the package
292 * name. The package suffix may be empty; however, if a module
293 * name is present, it must be nonempty. If {@code moduleAndPkg}
294 * does not contain a "{@code /}" character, the entire argument
295 * is interpreted as a package name.
296 *
297 * @param location location of the file
298 * @param moduleAndPkg module and/or package relative to which the file
299 * should be searched for, or the empty string if none
300 * @param relativeName final pathname components of the file
301 * @return an object to read the file
302 * @throws FilerException if the same pathname has already been
303 * opened for writing
304 * @throws IOException if the file cannot be opened
305 * @throws IllegalArgumentException for an unsupported location
306 * @throws IllegalArgumentException if {@code moduleAndPkg} is ill-formed
307 * @throws IllegalArgumentException if {@code relativeName} is not relative
308 */
309 FileObject getResource(JavaFileManager.Location location,
310 CharSequence moduleAndPkg,
311 CharSequence relativeName) throws IOException;
312 }