001: /*
002: * Copyright 2005-2006 Sun Microsystems, Inc. All Rights Reserved.
003: * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004: *
005: * This code is free software; you can redistribute it and/or modify it
006: * under the terms of the GNU General Public License version 2 only, as
007: * published by the Free Software Foundation. Sun designates this
008: * particular file as subject to the "Classpath" exception as provided
009: * by Sun in the LICENSE file that accompanied this code.
010: *
011: * This code is distributed in the hope that it will be useful, but WITHOUT
012: * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013: * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014: * version 2 for more details (a copy is included in the LICENSE file that
015: * accompanied this code).
016: *
017: * You should have received a copy of the GNU General Public License version
018: * 2 along with this work; if not, write to the Free Software Foundation,
019: * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020: *
021: * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022: * CA 95054 USA or visit www.sun.com if you need additional information or
023: * have any questions.
024: */
025:
026: package javax.annotation.processing;
027:
028: import javax.tools.JavaFileManager;
029: import javax.tools.*;
030: import javax.lang.model.element.Element;
031: import java.io.IOException;
032:
033: /**
034: * This interface supports the creation of new files by an annotation
035: * processor. Files created in this way will be known to the
036: * annotation processing tool implementing this interface, better
037: * enabling the tool to manage them. Source and class files so
038: * created will be considered for processing by the tool after the
039: * {@code close} method has been called on the {@code Writer} or
040: * {@code OutputStream} used to write the contents of the file.
041: *
042: * Three kinds of files are distinguished: source files, class files,
043: * and auxiliary resource files.
044: *
045: * <p> There are two distinguished supported locations (subtrees
046: * within the logical file system) where newly created files are
047: * placed: one for {@linkplain
048: * javax.tools.StandardLocation#SOURCE_OUTPUT new source files}, and
049: * one for {@linkplain javax.tools.StandardLocation#CLASS_OUTPUT new
050: * class files}. (These might be specified on a tool's command line,
051: * for example, using flags such as {@code -s} and {@code -d}.) The
052: * actual locations for new source files and new class files may or
053: * may not be distinct on a particular run of the tool. Resource
054: * files may be created in either location. The methods for reading
055: * and writing resources take a relative name argument. A relative
056: * name is a non-null, non-empty sequence of path segments separated
057: * by {@code '/'}; {@code '.'} and {@code '..'} are invalid path
058: * segments. A valid relative name must match the
059: * "path-rootless" rule of <a
060: * href="http://www.ietf.org/rfc/rfc3986.txt">RFC 3986</a>, section
061: * 3.3.
062: *
063: * <p>The file creation methods take a variable number of arguments to
064: * allow the <em>originating elements</em> to be provided as hints to
065: * the tool infrastructure to better manage dependencies. The
066: * originating elements are the types or packages (representing {@code
067: * package-info} files) which caused an annotation processor to
068: * attempt to create a new file. For example, if an annotation
069: * processor tries to create a source file, {@code
070: * GeneratedFromUserSource}, in response to processing
071: *
072: * <blockquote><pre>
073: * @Generate
074: * public class UserSource {}
075: * </pre></blockquote>
076: *
077: * the type element for {@code UserSource} should be passed as part of
078: * the creation method call as in:
079: *
080: * <blockquote><pre>
081: * filer.createSourceFile("GeneratedFromUserSource",
082: * eltUtils.getTypeElement("UserSource"));
083: * </pre></blockquote>
084: *
085: * If there are no originating elements, none need to be passed. This
086: * information may be used in an incremental environment to determine
087: * the need to rerun processors or remove generated files.
088: * Non-incremental environments may ignore the originating element
089: * information.
090: *
091: * <p> During each run of an annotation processing tool, a file with a
092: * given pathname may be created only once. If that file already
093: * exists before the first attempt to create it, the old contents will
094: * be deleted. Any subsequent attempt to create the same file during
095: * a run will throw a {@link FilerException}, as will attempting to
096: * create both a class file and source file for the same type name or
097: * same package name. The {@linkplain Processor initial inputs} to
098: * the tool are considered to be created by the zeroth round;
099: * 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: * @version 1.16 07/05/05
128: * @since 1.6
129: */
130: public interface Filer {
131: /**
132: * Creates a new source file and returns an object to allow
133: * writing to it. The file's name and path (relative to the
134: * {@linkplain StandardLocation#SOURCE_OUTPUT root output location
135: * for source files}) are based on the type to be declared in that
136: * file. If more than one type is being declared, the name of the
137: * principal top-level type (the public one, for example) should
138: * be used. A source file can also be created to hold information
139: * about a package, including package annotations. To create a
140: * source file for a named package, have {@code name} be the
141: * package's name followed by {@code ".package-info"}; to create a
142: * source file for an unnamed package, use {@code "package-info"}.
143: *
144: * <p> Note that to use a particular {@linkplain
145: * java.nio.charset.Charset charset} to encode the contents of the
146: * file, an {@code OutputStreamWriter} with the chosen charset can
147: * be created from the {@code OutputStream} from the returned
148: * object. If the {@code Writer} from the returned object is
149: * directly used for writing, its charset is determined by the
150: * implementation. An annotation processing tool may have an
151: * {@code -encoding} flag or analogous option for specifying this;
152: * otherwise, it will typically be the platform's default
153: * encoding.
154: *
155: * <p>To avoid subsequent errors, the contents of the source file
156: * should be compatible with the {@linkplain
157: * ProcessingEnvironment#getSourceVersion source version} being used
158: * for this run.
159: *
160: * @param name canonical (fully qualified) name of the principal type
161: * being declared in this file or a package name followed by
162: * {@code ".package-info"} for a package information file
163: * @param originatingElements type or package elements causally
164: * associated with the creation of this file, may be elided or
165: * {@code null}
166: * @return a {@code JavaFileObject} to write the new source file
167: * @throws FilerException if the same pathname has already been
168: * created, the same type has already been created, or the name is
169: * not valid for a type
170: * @throws IOException if the file cannot be created
171: */
172: JavaFileObject createSourceFile(CharSequence name,
173: Element... originatingElements) throws IOException;
174:
175: /**
176: * Creates a new class file, and returns an object to allow
177: * writing to it. The file's name and path (relative to the
178: * {@linkplain StandardLocation#CLASS_OUTPUT root output location
179: * for class files}) are based on the name of the type being
180: * written. A class file can also be created to hold information
181: * about a package, including package annotations. To create a
182: * class file for a named package, have {@code name} be the
183: * package's name followed by {@code ".package-info"}; creating a
184: * class file for an unnamed package is not supported.
185: *
186: * <p>To avoid subsequent errors, the contents of the class file
187: * should be compatible with the {@linkplain
188: * ProcessingEnvironment#getSourceVersion source version} being used
189: * for this run.
190: *
191: * @param name binary name of the type being written or a package name followed by
192: * {@code ".package-info"} for a package information file
193: * @param originatingElements type or package elements causally
194: * associated with the creation of this file, may be elided or
195: * {@code null}
196: * @return a {@code JavaFileObject} to write the new class file
197: * @throws FilerException if the same pathname has already been
198: * created, the same type has already been created, or the name is
199: * not valid for a type
200: * @throws IOException if the file cannot be created
201: */
202: JavaFileObject createClassFile(CharSequence name,
203: Element... originatingElements) throws IOException;
204:
205: /**
206: * Creates a new auxiliary resource file for writing and returns a
207: * file object for it. The file may be located along with the
208: * newly created source files, newly created binary files, or
209: * other supported location. The locations {@link
210: * StandardLocation#CLASS_OUTPUT CLASS_OUTPUT} and {@link
211: * StandardLocation#SOURCE_OUTPUT SOURCE_OUTPUT} must be
212: * supported. The resource may be named relative to some package
213: * (as are source and class files), and from there by a relative
214: * pathname. In a loose sense, the full pathname of the new file
215: * will be the concatenation of {@code location}, {@code pkg}, and
216: * {@code relativeName}.
217: *
218: * <p>Files created via this method are not registered for
219: * annotation processing, even if the full pathname of the file
220: * would correspond to the full pathname of a new source file
221: * or new class file.
222: *
223: * @param location location of the new file
224: * @param pkg package relative to which the file should be named,
225: * or the empty string if none
226: * @param relativeName final pathname components of the file
227: * @param originatingElements type or package elements causally
228: * associated with the creation of this file, may be elided or
229: * {@code null}
230: * @return a {@code FileObject} to write the new resource
231: * @throws IOException if the file cannot be created
232: * @throws FilerException if the same pathname has already been
233: * created
234: * @throws IllegalArgumentException for an unsupported location
235: * @throws IllegalArgumentException if {@code relativeName} is not relative
236: */
237: FileObject createResource(JavaFileManager.Location location,
238: CharSequence pkg, 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, CharSequence relativeName)
260: throws IOException;
261: }
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