1 /*
2 * Copyright 2005-2006 Sun Microsystems, Inc. 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. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any 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 considered for processing by the tool after the
39 * {@code close} method has been called on the {@code Writer} or
40 * {@code OutputStream} used to write the contents of the file.
41 *
42 * Three kinds of files are distinguished: source files, class files,
43 * and auxiliary resource files.
44 *
45 * <p> There are two distinguished supported locations (subtrees
46 * within the logical file system) where newly created files are
47 * placed: one for {@linkplain
48 * javax.tools.StandardLocation#SOURCE_OUTPUT new source files}, and
49 * one for {@linkplain javax.tools.StandardLocation#CLASS_OUTPUT new
50 * class files}. (These might be specified on a tool's command line,
51 * for example, using flags such as {@code -s} and {@code -d}.) The
52 * actual locations for new source files and new class files may or
53 * may not be distinct on a particular run of the tool. Resource
54 * files may be created in either location. The methods for reading
55 * and writing resources take a relative name argument. A relative
56 * name is a non-null, non-empty sequence of path segments separated
57 * by {@code '/'}; {@code '.'} and {@code '..'} are invalid path
58 * segments. A valid relative name must match the
59 * "path-rootless" rule of <a
60 * href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986</a>, section
61 * 3.3.
62 *
63 * <p>The file creation methods take a variable number of arguments to
64 * allow the <em>originating elements</em> to be provided as hints to
65 * the tool infrastructure to better manage dependencies. The
66 * originating elements are the types or packages (representing {@code
67 * package-info} files) which caused an annotation processor to
68 * attempt to create a new file. For example, if an annotation
69 * processor tries to create a source file, {@code
70 * GeneratedFromUserSource}, in response to processing
71 *
72 * <blockquote><pre>
73 * @Generate
74 * public class UserSource {}
75 * </pre></blockquote>
76 *
77 * the type element for {@code UserSource} should be passed as part of
78 * the creation method call as in:
79 *
80 * <blockquote><pre>
81 * filer.createSourceFile("GeneratedFromUserSource",
82 * eltUtils.getTypeElement("UserSource"));
83 * </pre></blockquote>
84 *
85 * If there are no originating elements, none need to be passed. This
86 * information may be used in an incremental environment to determine
87 * the need to rerun processors or remove generated files.
88 * Non-incremental environments may ignore the originating element
89 * information.
90 *
91 * <p> During each run of an annotation processing tool, a file with a
92 * given pathname may be created only once. If that file already
93 * exists before the first attempt to create it, the old contents will
94 * be deleted. Any subsequent attempt to create the same file during
95 * a run will throw a {@link FilerException}, as will attempting to
96 * create both a class file and source file for the same type name or
97 * same package name. The {@linkplain Processor initial inputs} to
98 * the tool are considered to be created by the zeroth round;
99 * therefore, attempting to create a source or class file
100 * corresponding to one of those inputs will result in a {@link
101 * FilerException}.
102 *
103 * <p> In general, processors must not knowingly attempt to overwrite
104 * existing files that were not generated by some processor. A {@code
105 * Filer} may reject attempts to open a file corresponding to an
106 * existing type, like {@code java.lang.Object}. Likewise, the
107 * invoker of the annotation processing tool must not knowingly
108 * configure the tool such that the discovered processors will attempt
109 * to overwrite existing files that were not generated.
110 *
111 * <p> Processors can indicate a source or class file is generated by
112 * including an {@link javax.annotation.Generated @Generated}
113 * annotation.
114 *
115 * <p> Note that some of the effect of overwriting a file can be
116 * achieved by using a <i>decorator</i>-style pattern. Instead of
117 * modifying a class directly, the class is designed so that either
118 * its superclass is generated by annotation processing or subclasses
119 * of the class are generated by annotation processing. If the
120 * subclasses are generated, the parent class may be designed to use
121 * factories instead of public constructors so that only subclass
122 * instances would be presented to clients of the parent class.
123 *
124 * @author Joseph D. Darcy
125 * @author Scott Seligman
126 * @author Peter von der Ahé
127 * @since 1.6
128 */
129 public interface Filer {
130 /**
131 * Creates a new source file and returns an object to allow
132 * writing to it. The file's name and path (relative to the
133 * {@linkplain StandardLocation#SOURCE_OUTPUT root output location
134 * for source files}) are based on the type to be declared in that
135 * file. If more than one type is being declared, the name of the
136 * principal top-level type (the public one, for example) should
137 * be used. A source file can also be created to hold information
138 * about a package, including package annotations. To create a
139 * source file for a named package, have {@code name} be the
140 * package's name followed by {@code ".package-info"}; to create a
141 * source file for an unnamed package, use {@code "package-info"}.
142 *
143 * <p> Note that to use a particular {@linkplain
144 * java.nio.charset.Charset charset} to encode the contents of the
145 * file, an {@code OutputStreamWriter} with the chosen charset can
146 * be created from the {@code OutputStream} from the returned
147 * object. If the {@code Writer} from the returned object is
148 * directly used for writing, its charset is determined by the
149 * implementation. An annotation processing tool may have an
150 * {@code -encoding} flag or analogous option for specifying this;
151 * otherwise, it will typically be the platform's default
152 * encoding.
153 *
154 * <p>To avoid subsequent errors, the contents of the source file
155 * should be compatible with the {@linkplain
156 * ProcessingEnvironment#getSourceVersion source version} being used
157 * for this run.
158 *
159 * @param name canonical (fully qualified) name of the principal type
160 * being declared in this file or a package name followed by
161 * {@code ".package-info"} for a package information file
162 * @param originatingElements type or package elements causally
163 * associated with the creation of this file, may be elided or
164 * {@code null}
165 * @return a {@code JavaFileObject} to write the new source file
166 * @throws FilerException if the same pathname has already been
167 * created, the same type has already been created, or the name is
168 * not valid for a type
169 * @throws IOException if the file cannot be created
170 */
171 JavaFileObject createSourceFile(CharSequence name,
172 Element... originatingElements) throws IOException;
173
174 /**
175 * Creates a new class file, and returns an object to allow
176 * writing to it. The file's name and path (relative to the
177 * {@linkplain StandardLocation#CLASS_OUTPUT root output location
178 * for class files}) are based on the name of the type being
179 * written. A class file can also be created to hold information
180 * about a package, including package annotations. To create a
181 * class file for a named package, have {@code name} be the
182 * package's name followed by {@code ".package-info"}; creating a
183 * class file for an unnamed package is not supported.
184 *
185 * <p>To avoid subsequent errors, the contents of the class file
186 * should be compatible with the {@linkplain
187 * ProcessingEnvironment#getSourceVersion source version} being used
188 * for this run.
189 *
190 * @param name binary name of the type being written or a package name followed by
191 * {@code ".package-info"} for a package information file
192 * @param originatingElements type or package elements causally
193 * associated with the creation of this file, may be elided or
194 * {@code null}
195 * @return a {@code JavaFileObject} to write the new class file
196 * @throws FilerException if the same pathname has already been
197 * created, the same type has already been created, or the name is
198 * not valid for a type
199 * @throws IOException if the file cannot be created
200 */
201 JavaFileObject createClassFile(CharSequence name,
202 Element... originatingElements) throws IOException;
203
204 /**
205 * Creates a new auxiliary resource file for writing and returns a
206 * file object for it. The file may be located along with the
207 * newly created source files, newly created binary files, or
208 * other supported location. The locations {@link
209 * StandardLocation#CLASS_OUTPUT CLASS_OUTPUT} and {@link
210 * StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must be
211 * supported. The resource may be named relative to some package
212 * (as are source and class files), and from there by a relative
213 * pathname. In a loose sense, the full pathname of the new file
214 * will be the concatenation of {@code location}, {@code pkg}, and
215 * {@code relativeName}.
216 *
217 * <p>Files created via this method are not registered for
218 * annotation processing, even if the full pathname of the file
219 * would correspond to the full pathname of a new source file
220 * or new class file.
221 *
222 * @param location location of the new file
223 * @param pkg package relative to which the file should be named,
224 * or the empty string if none
225 * @param relativeName final pathname components of the file
226 * @param originatingElements type or package elements causally
227 * associated with the creation of this file, may be elided or
228 * {@code null}
229 * @return a {@code FileObject} to write the new resource
230 * @throws IOException if the file cannot be created
231 * @throws FilerException if the same pathname has already been
232 * created
233 * @throws IllegalArgumentException for an unsupported location
234 * @throws IllegalArgumentException if {@code relativeName} is not relative
235 */
236 FileObject createResource(JavaFileManager.Location location,
237 CharSequence pkg,
238 CharSequence relativeName,
239 Element... originatingElements) throws IOException;
240
241 /**
242 * Returns an object for reading an existing resource. The
243 * locations {@link StandardLocation#CLASS_OUTPUT CLASS_OUTPUT}
244 * and {@link StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must
245 * be supported.
246 *
247 * @param location location of the file
248 * @param pkg package relative to which the file should be searched,
249 * or the empty string if none
250 * @param relativeName final pathname components of the file
251 * @return an object to read the file
252 * @throws FilerException if the same pathname has already been
253 * opened for writing
254 * @throws IOException if the file cannot be opened
255 * @throws IllegalArgumentException for an unsupported location
256 * @throws IllegalArgumentException if {@code relativeName} is not relative
257 */
258 FileObject getResource(JavaFileManager.Location location,
259 CharSequence pkg,
260 CharSequence relativeName) throws IOException;
261 }