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src/share/classes/javax/lang/model/element/ElementVisitor.java@2eb010b6cb22 (annotated)

src/share/classes/javax/lang/model/element/ElementVisitor.java

Thu, 31 Aug 2017 15:17:03 +0800

author

aoqi

date

Thu, 31 Aug 2017 15:17:03 +0800

changeset 2525

2eb010b6cb22

parent 1522

09f65aad4759

parent 0

959103a6100f

permissions

-rw-r--r--

merge

aoqi@0	1	/*
aoqi@0	2	* Copyright (c) 2005, 2013, Oracle and/or its affiliates. All rights reserved.
aoqi@0	3	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0	4	*
aoqi@0	5	* This code is free software; you can redistribute it and/or modify it
aoqi@0	6	* under the terms of the GNU General Public License version 2 only, as
aoqi@0	7	* published by the Free Software Foundation. Oracle designates this
aoqi@0	8	* particular file as subject to the "Classpath" exception as provided
aoqi@0	9	* by Oracle in the LICENSE file that accompanied this code.
aoqi@0	10	*
aoqi@0	11	* This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0	12	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0	13	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
aoqi@0	14	* version 2 for more details (a copy is included in the LICENSE file that
aoqi@0	15	* accompanied this code).
aoqi@0	16	*
aoqi@0	17	* You should have received a copy of the GNU General Public License version
aoqi@0	18	* 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0	19	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0	20	*
aoqi@0	21	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0	22	* or visit www.oracle.com if you need additional information or have any
aoqi@0	23	* questions.
aoqi@0	24	*/
aoqi@0	25
aoqi@0	26	package javax.lang.model.element;
aoqi@0	27
aoqi@0	28	import javax.lang.model.util.*;
aoqi@0	29
aoqi@0	30	/**
aoqi@0	31	* A visitor of program elements, in the style of the visitor design
aoqi@0	32	* pattern. Classes implementing this interface are used to operate
aoqi@0	33	* on an element when the kind of element is unknown at compile time.
aoqi@0	34	* When a visitor is passed to an element's {@link Element#accept
aoqi@0	35	* accept} method, the <tt>visit<i>XYZ</i></tt> method most applicable
aoqi@0	36	* to that element is invoked.
aoqi@0	37	*
aoqi@0	38	* <p> Classes implementing this interface may or may not throw a
aoqi@0	39	* {@code NullPointerException} if the additional parameter {@code p}
aoqi@0	40	* is {@code null}; see documentation of the implementing class for
aoqi@0	41	* details.
aoqi@0	42	*
aoqi@0	43	* <p> <b>WARNING:</b> It is possible that methods will be added to
aoqi@0	44	* this interface to accommodate new, currently unknown, language
aoqi@0	45	* structures added to future versions of the Java&trade; programming
aoqi@0	46	* language. Therefore, visitor classes directly implementing this
aoqi@0	47	* interface may be source incompatible with future versions of the
aoqi@0	48	* platform. To avoid this source incompatibility, visitor
aoqi@0	49	* implementations are encouraged to instead extend the appropriate
aoqi@0	50	* abstract visitor class that implements this interface. However, an
aoqi@0	51	* API should generally use this visitor interface as the type for
aoqi@0	52	* parameters, return type, etc. rather than one of the abstract
aoqi@0	53	* classes.
aoqi@0	54	*
aoqi@0	55	* <p>Note that methods to accommodate new language constructs could
aoqi@0	56	* be added in a source <em>compatible</em> way if they were added as
aoqi@0	57	* <em>default methods</em>. However, default methods are only
aoqi@0	58	* available on Java SE 8 and higher releases and the {@code
aoqi@0	59	* javax.lang.model.*} packages bundled in Java SE 8 are required to
aoqi@0	60	* also be runnable on Java SE 7. Therefore, default methods
aoqi@0	61	* <em>cannot</em> be used when extending {@code javax.lang.model.*}
aoqi@0	62	* to cover Java SE 8 language features. However, default methods may
aoqi@0	63	* be used in subsequent revisions of the {@code javax.lang.model.*}
aoqi@0	64	* packages that are only required to run on Java SE 8 and higher
aoqi@0	65	* platform versions.
aoqi@0	66	*
aoqi@0	67	* @param <R> the return type of this visitor's methods. Use {@link
aoqi@0	68	* Void} for visitors that do not need to return results.
aoqi@0	69	* @param <P> the type of the additional parameter to this visitor's
aoqi@0	70	* methods. Use {@code Void} for visitors that do not need an
aoqi@0	71	* additional parameter.
aoqi@0	72	*
aoqi@0	73	* @author Joseph D. Darcy
aoqi@0	74	* @author Scott Seligman
aoqi@0	75	* @author Peter von der Ah&eacute;
aoqi@0	76	* @see AbstractElementVisitor6
aoqi@0	77	* @see AbstractElementVisitor7
aoqi@0	78	* @since 1.6
aoqi@0	79	*/
aoqi@0	80	public interface ElementVisitor<R, P> {
aoqi@0	81	/**
aoqi@0	82	* Visits an element.
aoqi@0	83	* @param e the element to visit
aoqi@0	84	* @param p a visitor-specified parameter
aoqi@0	85	* @return a visitor-specified result
aoqi@0	86	*/
aoqi@0	87	R visit(Element e, P p);
aoqi@0	88
aoqi@0	89	/**
aoqi@0	90	* A convenience method equivalent to {@code v.visit(e, null)}.
aoqi@0	91	* @param e the element to visit
aoqi@0	92	* @return a visitor-specified result
aoqi@0	93	*/
aoqi@0	94	R visit(Element e);
aoqi@0	95
aoqi@0	96	/**
aoqi@0	97	* Visits a package element.
aoqi@0	98	* @param e the element to visit
aoqi@0	99	* @param p a visitor-specified parameter
aoqi@0	100	* @return a visitor-specified result
aoqi@0	101	*/
aoqi@0	102	R visitPackage(PackageElement e, P p);
aoqi@0	103
aoqi@0	104	/**
aoqi@0	105	* Visits a type element.
aoqi@0	106	* @param e the element to visit
aoqi@0	107	* @param p a visitor-specified parameter
aoqi@0	108	* @return a visitor-specified result
aoqi@0	109	*/
aoqi@0	110	R visitType(TypeElement e, P p);
aoqi@0	111
aoqi@0	112	/**
aoqi@0	113	* Visits a variable element.
aoqi@0	114	* @param e the element to visit
aoqi@0	115	* @param p a visitor-specified parameter
aoqi@0	116	* @return a visitor-specified result
aoqi@0	117	*/
aoqi@0	118	R visitVariable(VariableElement e, P p);
aoqi@0	119
aoqi@0	120	/**
aoqi@0	121	* Visits an executable element.
aoqi@0	122	* @param e the element to visit
aoqi@0	123	* @param p a visitor-specified parameter
aoqi@0	124	* @return a visitor-specified result
aoqi@0	125	*/
aoqi@0	126	R visitExecutable(ExecutableElement e, P p);
aoqi@0	127
aoqi@0	128	/**
aoqi@0	129	* Visits a type parameter element.
aoqi@0	130	* @param e the element to visit
aoqi@0	131	* @param p a visitor-specified parameter
aoqi@0	132	* @return a visitor-specified result
aoqi@0	133	*/
aoqi@0	134	R visitTypeParameter(TypeParameterElement e, P p);
aoqi@0	135
aoqi@0	136	/**
aoqi@0	137	* Visits an unknown kind of element.
aoqi@0	138	* This can occur if the language evolves and new kinds
aoqi@0	139	* of elements are added to the {@code Element} hierarchy.
aoqi@0	140	*
aoqi@0	141	* @param e the element to visit
aoqi@0	142	* @param p a visitor-specified parameter
aoqi@0	143	* @return a visitor-specified result
aoqi@0	144	* @throws UnknownElementException
aoqi@0	145	* a visitor implementation may optionally throw this exception
aoqi@0	146	*/
aoqi@0	147	R visitUnknown(Element e, P p);
aoqi@0	148	}