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src/share/classes/javax/lang/model/type/TypeVisitor.java@2eb010b6cb22 (annotated)

src/share/classes/javax/lang/model/type/TypeVisitor.java

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

author

aoqi

date

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

changeset 2525

2eb010b6cb22

parent 1644

40adaf938847

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.type;
aoqi@0	27
aoqi@0	28	import javax.lang.model.element.*;
aoqi@0	29
aoqi@0	30	/**
aoqi@0	31	* A visitor of types, in the style of the
aoqi@0	32	* visitor design pattern. Classes implementing this
aoqi@0	33	* interface are used to operate on a type when the kind of
aoqi@0	34	* type is unknown at compile time. When a visitor is passed to a
aoqi@0	35	* type's {@link TypeMirror#accept accept} method, the <tt>visit<i>XYZ</i></tt>
aoqi@0	36	* method most applicable to that type 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	* @since 1.6
aoqi@0	77	*/
aoqi@0	78	public interface TypeVisitor<R, P> {
aoqi@0	79	/**
aoqi@0	80	* Visits a type.
aoqi@0	81	* @param t the type to visit
aoqi@0	82	* @param p a visitor-specified parameter
aoqi@0	83	* @return a visitor-specified result
aoqi@0	84	*/
aoqi@0	85	R visit(TypeMirror t, P p);
aoqi@0	86
aoqi@0	87	/**
aoqi@0	88	* A convenience method equivalent to {@code v.visit(t, null)}.
aoqi@0	89	* @param t the element to visit
aoqi@0	90	* @return a visitor-specified result
aoqi@0	91	*/
aoqi@0	92	R visit(TypeMirror t);
aoqi@0	93
aoqi@0	94	/**
aoqi@0	95	* Visits a primitive type.
aoqi@0	96	* @param t the type to visit
aoqi@0	97	* @param p a visitor-specified parameter
aoqi@0	98	* @return a visitor-specified result
aoqi@0	99	*/
aoqi@0	100	R visitPrimitive(PrimitiveType t, P p);
aoqi@0	101
aoqi@0	102	/**
aoqi@0	103	* Visits the null type.
aoqi@0	104	* @param t the type to visit
aoqi@0	105	* @param p a visitor-specified parameter
aoqi@0	106	* @return a visitor-specified result
aoqi@0	107	*/
aoqi@0	108	R visitNull(NullType t, P p);
aoqi@0	109
aoqi@0	110	/**
aoqi@0	111	* Visits an array type.
aoqi@0	112	* @param t the type to visit
aoqi@0	113	* @param p a visitor-specified parameter
aoqi@0	114	* @return a visitor-specified result
aoqi@0	115	*/
aoqi@0	116	R visitArray(ArrayType t, P p);
aoqi@0	117
aoqi@0	118	/**
aoqi@0	119	* Visits a declared type.
aoqi@0	120	* @param t the type to visit
aoqi@0	121	* @param p a visitor-specified parameter
aoqi@0	122	* @return a visitor-specified result
aoqi@0	123	*/
aoqi@0	124	R visitDeclared(DeclaredType t, P p);
aoqi@0	125
aoqi@0	126	/**
aoqi@0	127	* Visits an error type.
aoqi@0	128	* @param t the type to visit
aoqi@0	129	* @param p a visitor-specified parameter
aoqi@0	130	* @return a visitor-specified result
aoqi@0	131	*/
aoqi@0	132	R visitError(ErrorType t, P p);
aoqi@0	133
aoqi@0	134	/**
aoqi@0	135	* Visits a type variable.
aoqi@0	136	* @param t the type to visit
aoqi@0	137	* @param p a visitor-specified parameter
aoqi@0	138	* @return a visitor-specified result
aoqi@0	139	*/
aoqi@0	140	R visitTypeVariable(TypeVariable t, P p);
aoqi@0	141
aoqi@0	142	/**
aoqi@0	143	* Visits a wildcard type.
aoqi@0	144	* @param t the type to visit
aoqi@0	145	* @param p a visitor-specified parameter
aoqi@0	146	* @return a visitor-specified result
aoqi@0	147	*/
aoqi@0	148	R visitWildcard(WildcardType t, P p);
aoqi@0	149
aoqi@0	150	/**
aoqi@0	151	* Visits an executable type.
aoqi@0	152	* @param t the type to visit
aoqi@0	153	* @param p a visitor-specified parameter
aoqi@0	154	* @return a visitor-specified result
aoqi@0	155	*/
aoqi@0	156	R visitExecutable(ExecutableType t, P p);
aoqi@0	157
aoqi@0	158	/**
aoqi@0	159	* Visits a {@link NoType} instance.
aoqi@0	160	* @param t the type to visit
aoqi@0	161	* @param p a visitor-specified parameter
aoqi@0	162	* @return a visitor-specified result
aoqi@0	163	*/
aoqi@0	164	R visitNoType(NoType t, P p);
aoqi@0	165
aoqi@0	166	/**
aoqi@0	167	* Visits an unknown kind of type.
aoqi@0	168	* This can occur if the language evolves and new kinds
aoqi@0	169	* of types are added to the {@code TypeMirror} hierarchy.
aoqi@0	170	* @param t the type to visit
aoqi@0	171	* @param p a visitor-specified parameter
aoqi@0	172	* @return a visitor-specified result
aoqi@0	173	* @throws UnknownTypeException
aoqi@0	174	* a visitor implementation may optionally throw this exception
aoqi@0	175	*/
aoqi@0	176	R visitUnknown(TypeMirror t, P p);
aoqi@0	177
aoqi@0	178	/**
aoqi@0	179	* Visits a union type.
aoqi@0	180	*
aoqi@0	181	* @param t the type to visit
aoqi@0	182	* @param p a visitor-specified parameter
aoqi@0	183	* @return a visitor-specified result
aoqi@0	184	* @since 1.7
aoqi@0	185	*/
aoqi@0	186	R visitUnion(UnionType t, P p);
aoqi@0	187
aoqi@0	188	/**
aoqi@0	189	* Visits an intersection type.
aoqi@0	190	*
aoqi@0	191	* @param t the type to visit
aoqi@0	192	* @param p a visitor-specified parameter
aoqi@0	193	* @return a visitor-specified result
aoqi@0	194	* @since 1.8
aoqi@0	195	*/
aoqi@0	196	R visitIntersection(IntersectionType t, P p);
aoqi@0	197	}