1 /*
   2  * Copyright (c) 2005, 2017, 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.element;
  27 
  28 
  29 import java.lang.annotation.Annotation;
  30 import java.lang.annotation.AnnotationTypeMismatchException;
  31 import java.lang.annotation.IncompleteAnnotationException;
  32 import java.util.List;
  33 import java.util.Set;
  34 
  35 import javax.lang.model.type.*;
  36 import javax.lang.model.util.*;
  37 
  38 
  39 /**
  40  * Represents a program element such as a module, package, class, or method.
  41  * Each element represents a static, language-level construct
  42  * (and not, for example, a runtime construct of the virtual machine).
  43  *
  44  * <p> Elements should be compared using the {@link #equals(Object)}
  45  * method.  There is no guarantee that any particular element will
  46  * always be represented by the same object.
  47  *
  48  * <p> To implement operations based on the class of an {@code
  49  * Element} object, either use a {@linkplain ElementVisitor visitor} or
  50  * use the result of the {@link #getKind} method.  Using {@code
  51  * instanceof} is <em>not</em> necessarily a reliable idiom for
  52  * determining the effective class of an object in this modeling
  53  * hierarchy since an implementation may choose to have a single object
  54  * implement multiple {@code Element} subinterfaces.
  55  *
  56  * @author Joseph D. Darcy
  57  * @author Scott Seligman
  58  * @author Peter von der Ah&eacute;
  59  * @see Elements
  60  * @see TypeMirror
  61  * @since 1.6
  62  */
  63 public interface Element extends javax.lang.model.AnnotatedConstruct {
  64     /**
  65      * Returns the type defined by this element.
  66      *
  67      * <p> A generic element defines a family of types, not just one.
  68      * If this is a generic element, a <i>prototypical</i> type is
  69      * returned.  This is the element's invocation on the
  70      * type variables corresponding to its own formal type parameters.
  71      * For example,
  72      * for the generic class element {@code C<N extends Number>},
  73      * the parameterized type {@code C<N>} is returned.
  74      * The {@link Types} utility interface has more general methods
  75      * for obtaining the full range of types defined by an element.
  76      *
  77      * @see Types
  78      *
  79      * @return the type defined by this element
  80      */
  81     TypeMirror asType();
  82 
  83     /**
  84      * Returns the {@code kind} of this element.
  85      *
  86      * @return the kind of this element
  87      */
  88     ElementKind getKind();
  89 
  90     /**
  91      * Returns the modifiers of this element, excluding annotations.
  92      * Implicit modifiers, such as the {@code public} and {@code static}
  93      * modifiers of interface members, are included.
  94      *
  95      * @return the modifiers of this element, or an empty set if there are none
  96      */
  97     Set<Modifier> getModifiers();
  98 
  99     /**
 100      * Returns the simple (unqualified) name of this element.  The
 101      * name of a generic type does not include any reference to its
 102      * formal type parameters.
 103      *
 104      * For example, the simple name of the type element {@code
 105      * java.util.Set<E>} is {@code "Set"}.
 106      *
 107      * If this element represents an unnamed {@linkplain
 108      * PackageElement#getSimpleName package} or unnamed {@linkplain
 109      * ModuleElement#getSimpleName module}, an empty name is returned.
 110      *
 111      * If it represents a {@linkplain ExecutableElement#getSimpleName
 112      * constructor}, the name "{@code <init>}" is returned.  If it
 113      * represents a {@linkplain ExecutableElement#getSimpleName static
 114      * initializer}, the name "{@code <clinit>}" is returned.
 115      *
 116      * If it represents an {@linkplain TypeElement#getSimpleName
 117      * anonymous class} or {@linkplain ExecutableElement#getSimpleName
 118      * instance initializer}, an empty name is returned.
 119      *
 120      * @return the simple name of this element
 121      * @see PackageElement#getSimpleName
 122      * @see ExecutableElement#getSimpleName
 123      * @see TypeElement#getSimpleName
 124      * @see VariableElement#getSimpleName
 125      * @see ModuleElement#getSimpleName
 126      */
 127     Name getSimpleName();
 128 
 129     /**
 130      * Returns the innermost element
 131      * within which this element is, loosely speaking, enclosed.
 132      * <ul>
 133      * <li> If this element is one whose declaration is lexically enclosed
 134      * immediately within the declaration of another element, that other
 135      * element is returned.
 136      *
 137      * <li> If this is a {@linkplain TypeElement#getEnclosingElement
 138      * top-level type}, its package is returned.
 139      *
 140      * <li> If this is a {@linkplain
 141      * PackageElement#getEnclosingElement package}, its module is
 142      * returned if such a module exists. Otherwise, {@code null} is returned.
 143      *
 144      * <li> If this is a {@linkplain
 145      * TypeParameterElement#getEnclosingElement type parameter},
 146      * {@linkplain TypeParameterElement#getGenericElement the
 147      * generic element} of the type parameter is returned.
 148      *
 149      * <li> If this is a {@linkplain
 150      * VariableElement#getEnclosingElement method or constructor
 151      * parameter}, {@linkplain ExecutableElement the executable
 152      * element} which declares the parameter is returned.
 153      *
 154      * <li> If this is a {@linkplain ModuleElement#getEnclosingElement
 155      * module}, {@code null} is returned.
 156      *
 157      * </ul>
 158      *
 159      * @return the enclosing element, or {@code null} if there is none
 160      * @see Elements#getPackageOf
 161      */
 162     Element getEnclosingElement();
 163 
 164     /**
 165      * Returns the elements that are, loosely speaking, directly
 166      * enclosed by this element.
 167      *
 168      * A {@linkplain TypeElement#getEnclosedElements class or
 169      * interface} is considered to enclose the fields, methods,
 170      * constructors, and member types that it directly declares.
 171      *
 172      * A {@linkplain PackageElement#getEnclosedElements package}
 173      * encloses the top-level classes and interfaces within it, but is
 174      * not considered to enclose subpackages.
 175      *
 176      * A {@linkplain ModuleElement#getEnclosedElements module}
 177      * encloses packages within it.
 178      *
 179      * Other kinds of elements are not currently considered to enclose
 180      * any elements; however, that may change as this API or the
 181      * programming language evolves.
 182      *
 183      * @apiNote Elements of certain kinds can be isolated using
 184      * methods in {@link ElementFilter}.
 185      *
 186      * @return the enclosed elements, or an empty list if none
 187      * @see TypeElement#getEnclosedElements
 188      * @see PackageElement#getEnclosedElements
 189      * @see ModuleElement#getEnclosedElements
 190      * @see Elements#getAllMembers
 191      * @jls 8.8.9 Default Constructor
 192      * @jls 8.9 Enums
 193      */
 194     List<? extends Element> getEnclosedElements();
 195 
 196     /**
 197      * Returns {@code true} if the argument represents the same
 198      * element as {@code this}, or {@code false} otherwise.
 199      *
 200      * @apiNote The identity of an element involves implicit state
 201      * not directly accessible from the element's methods, including
 202      * state about the presence of unrelated types.  Element objects
 203      * created by different implementations of these interfaces should
 204      * <i>not</i> be expected to be equal even if &quot;the same&quot;
 205      * element is being modeled; this is analogous to the inequality
 206      * of {@code Class} objects for the same class file loaded through
 207      * different class loaders.
 208      *
 209      * @param obj  the object to be compared with this element
 210      * @return {@code true} if the specified object represents the same
 211      *          element as this
 212      */
 213     @Override
 214     boolean equals(Object obj);
 215 
 216     /**
 217      * Obeys the general contract of {@link Object#hashCode Object.hashCode}.
 218      *
 219      * @see #equals
 220      */
 221     @Override
 222     int hashCode();
 223 
 224 
 225     /**
 226      * {@inheritDoc}
 227      *
 228      * <p> To get inherited annotations as well, use {@link
 229      * Elements#getAllAnnotationMirrors(Element)
 230      * getAllAnnotationMirrors}.
 231      *
 232      * @since 1.6
 233      */
 234     @Override
 235     List<? extends AnnotationMirror> getAnnotationMirrors();
 236 
 237     /**
 238      * {@inheritDoc}
 239      * @since 1.6
 240      */
 241     @Override
 242     <A extends Annotation> A getAnnotation(Class<A> annotationType);
 243 
 244     /**
 245      * Applies a visitor to this element.
 246      *
 247      * @param <R> the return type of the visitor's methods
 248      * @param <P> the type of the additional parameter to the visitor's methods
 249      * @param v   the visitor operating on this element
 250      * @param p   additional parameter to the visitor
 251      * @return a visitor-specified result
 252      */
 253     <R, P> R accept(ElementVisitor<R, P> v, P p);
 254 }