1 /*
2 * Copyright (c) 2005, 2020, 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.lang.model.type;
27
28 import java.lang.annotation.Annotation;
29 import java.util.List;
30 import javax.lang.model.element.*;
31 import javax.lang.model.util.Types;
32
33 /**
34 * Represents a type in the Java programming language.
35 * Types include primitive types, declared types (class and interface types),
36 * array types, type variables, and the null type.
37 * Also represented are wildcard type arguments, the signature and
38 * return types of executables, and pseudo-types corresponding to
39 * packages, modules, and the keyword {@code void}.
40 *
41 * <p> Types should be compared using the utility methods in {@link
42 * Types}. There is no guarantee that any particular type will always
43 * be represented by the same object.
44 *
45 * <p> To implement operations based on the class of an {@code
46 * TypeMirror} object, either use a {@linkplain TypeVisitor visitor}
47 * or use the result of the {@link #getKind} method. Using {@code
48 * instanceof} is <em>not</em> necessarily a reliable idiom for
49 * determining the effective class of an object in this modeling
50 * hierarchy since an implementation may choose to have a single
51 * object implement multiple {@code TypeMirror} subinterfaces.
52 *
53 * @author Joseph D. Darcy
54 * @author Scott Seligman
55 * @author Peter von der Ahé
56 * @see Element
57 * @see Types
58 * @since 1.6
59 */
60 public interface TypeMirror extends javax.lang.model.AnnotatedConstruct {
61
62 /**
63 * Returns the {@code kind} of this type.
64 *
65 * <ul>
66 *
67 * <li> The kind of a {@linkplain PrimitiveType primitive type} is
68 * one of the kinds for which {@link TypeKind#isPrimitive} returns
69 * {@code true}.
70 *
71 * <li> The kind of a {@linkplain NullType null type} is {@link
72 * TypeKind#NULL NULL}.
73 *
74 * <li> The kind of an {@linkplain ArrayType array type} is {@link
75 * TypeKind#ARRAY ARRAY}.
76 *
77 * <li> The kind of a {@linkplain DeclaredType declared type} is
78 * {@link TypeKind#DECLARED DECLARED}.
79 *
80 * <li> The kind of an {@linkplain ErrorType error type} is {@link
81 * TypeKind#ERROR ERROR}.
82 *
83 * <li> The kind of a {@linkplain TypeVariable type variable} is
84 * {@link TypeKind#TYPEVAR TYPEVAR}.
85 *
86 * <li> The kind of a {@linkplain WildcardType wildcard type} is
87 * {@link TypeKind#WILDCARD WILDCARD}.
88 *
89 * <li> The kind of an {@linkplain ExecutableType executable type}
90 * is {@link TypeKind#EXECUTABLE EXECUTABLE}.
91 *
92 * <li> The kind of a {@linkplain NoType pseudo-type} is one
93 * of {@link TypeKind#VOID VOID}, {@link TypeKind#PACKAGE
94 * PACKAGE}, {@link TypeKind#MODULE MODULE}, or {@link
95 * TypeKind#NONE NONE}.
96 *
97 * <li> The kind of a {@linkplain UnionType union type} is {@link
98 * TypeKind#UNION UNION}.
99 *
100 * <li> The kind of an {@linkplain IntersectionType intersection
101 * type} is {@link TypeKind#INTERSECTION INTERSECTION}.
102 *
103 * </ul>
104 *
105 * @return the kind of this type
106 */
107 TypeKind getKind();
108
109 /**
110 * Obeys the general contract of {@link Object#equals Object.equals}.
111 * This method does not, however, indicate whether two types represent
112 * the same type.
113 * Semantic comparisons of type equality should instead use
114 * {@link Types#isSameType(TypeMirror, TypeMirror)}.
115 * The results of {@code t1.equals(t2)} and
116 * {@code Types.isSameType(t1, t2)} may differ.
117 *
118 * @param obj the object to be compared with this type
119 * @return {@code true} if the specified object is equal to this one
120 */
121 boolean equals(Object obj);
122
123 /**
124 * Obeys the general contract of {@link Object#hashCode Object.hashCode}.
125 *
126 * @see #equals
127 */
128 int hashCode();
129
130 /**
131 * Returns an informative string representation of this type. If
132 * possible, the string should be of a form suitable for
133 * representing this type in source code. Any names embedded in
134 * the result are qualified if possible.
135 *
136 * @return a string representation of this type
137 */
138 String toString();
139
140 /**
141 * Applies a visitor to this type.
142 *
143 * @param <R> the return type of the visitor's methods
144 * @param <P> the type of the additional parameter to the visitor's methods
145 * @param v the visitor operating on this type
146 * @param p additional parameter to the visitor
147 * @return a visitor-specified result
148 */
149 <R, P> R accept(TypeVisitor<R, P> v, P p);
150 }