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

Wed, 09 Jan 2013 20:02:53 -0800

author
darcy
date
Wed, 09 Jan 2013 20:02:53 -0800
changeset 1484
7612fe48be90
parent 1357
c75be5bc5283
child 1491
9f42a06a49c0
permissions
-rw-r--r--

8004730: Add language model support for parameter reflection
Reviewed-by: abuckley

duke@1 1 /*
darcy@1181 2 * Copyright (c) 2005, 2012, Oracle and/or its affiliates. All rights reserved.
duke@1 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@1 4 *
duke@1 5 * This code is free software; you can redistribute it and/or modify it
duke@1 6 * under the terms of the GNU General Public License version 2 only, as
ohair@554 7 * published by the Free Software Foundation. Oracle designates this
duke@1 8 * particular file as subject to the "Classpath" exception as provided
ohair@554 9 * by Oracle in the LICENSE file that accompanied this code.
duke@1 10 *
duke@1 11 * This code is distributed in the hope that it will be useful, but WITHOUT
duke@1 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@1 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@1 14 * version 2 for more details (a copy is included in the LICENSE file that
duke@1 15 * accompanied this code).
duke@1 16 *
duke@1 17 * You should have received a copy of the GNU General Public License version
duke@1 18 * 2 along with this work; if not, write to the Free Software Foundation,
duke@1 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@1 20 *
ohair@554 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
ohair@554 22 * or visit www.oracle.com if you need additional information or have any
ohair@554 23 * questions.
duke@1 24 */
duke@1 25
duke@1 26 package javax.lang.model.element;
duke@1 27
duke@1 28
duke@1 29 import java.lang.annotation.Annotation;
duke@1 30 import java.lang.annotation.AnnotationTypeMismatchException;
duke@1 31 import java.lang.annotation.IncompleteAnnotationException;
duke@1 32 import java.util.List;
duke@1 33 import java.util.Set;
duke@1 34
duke@1 35 import javax.lang.model.type.*;
duke@1 36 import javax.lang.model.util.*;
duke@1 37
duke@1 38
duke@1 39 /**
duke@1 40 * Represents a program element such as a package, class, or method.
duke@1 41 * Each element represents a static, language-level construct
duke@1 42 * (and not, for example, a runtime construct of the virtual machine).
duke@1 43 *
duke@1 44 * <p> Elements should be compared using the {@link #equals(Object)}
duke@1 45 * method. There is no guarantee that any particular element will
duke@1 46 * always be represented by the same object.
duke@1 47 *
duke@1 48 * <p> To implement operations based on the class of an {@code
duke@1 49 * Element} object, either use a {@linkplain ElementVisitor visitor} or
duke@1 50 * use the result of the {@link #getKind} method. Using {@code
duke@1 51 * instanceof} is <em>not</em> necessarily a reliable idiom for
duke@1 52 * determining the effective class of an object in this modeling
duke@1 53 * hierarchy since an implementation may choose to have a single object
duke@1 54 * implement multiple {@code Element} subinterfaces.
duke@1 55 *
duke@1 56 * @author Joseph D. Darcy
duke@1 57 * @author Scott Seligman
duke@1 58 * @author Peter von der Ah&eacute;
duke@1 59 * @see Elements
duke@1 60 * @see TypeMirror
duke@1 61 * @since 1.6
duke@1 62 */
duke@1 63 public interface Element {
duke@1 64
duke@1 65 /**
duke@1 66 * Returns the type defined by this element.
duke@1 67 *
duke@1 68 * <p> A generic element defines a family of types, not just one.
duke@1 69 * If this is a generic element, a <i>prototypical</i> type is
duke@1 70 * returned. This is the element's invocation on the
duke@1 71 * type variables corresponding to its own formal type parameters.
duke@1 72 * For example,
duke@1 73 * for the generic class element {@code C<N extends Number>},
duke@1 74 * the parameterized type {@code C<N>} is returned.
duke@1 75 * The {@link Types} utility interface has more general methods
duke@1 76 * for obtaining the full range of types defined by an element.
duke@1 77 *
duke@1 78 * @see Types
duke@1 79 *
duke@1 80 * @return the type defined by this element
duke@1 81 */
duke@1 82 TypeMirror asType();
duke@1 83
duke@1 84 /**
duke@1 85 * Returns the {@code kind} of this element.
duke@1 86 *
duke@1 87 * @return the kind of this element
duke@1 88 */
duke@1 89 ElementKind getKind();
duke@1 90
duke@1 91 /**
duke@1 92 * Returns the annotations that are directly present on this element.
duke@1 93 *
duke@1 94 * <p> To get inherited annotations as well, use
duke@1 95 * {@link Elements#getAllAnnotationMirrors(Element) getAllAnnotationMirrors}.
duke@1 96 *
duke@1 97 * @see ElementFilter
duke@1 98 *
duke@1 99 * @return the annotations directly present on this element;
duke@1 100 * an empty list if there are none
duke@1 101 */
duke@1 102 List<? extends AnnotationMirror> getAnnotationMirrors();
duke@1 103
duke@1 104 /**
duke@1 105 * Returns this element's annotation for the specified type if
duke@1 106 * such an annotation is present, else {@code null}. The
duke@1 107 * annotation may be either inherited or directly present on this
duke@1 108 * element.
duke@1 109 *
duke@1 110 * <p> The annotation returned by this method could contain an element
duke@1 111 * whose value is of type {@code Class}.
duke@1 112 * This value cannot be returned directly: information necessary to
duke@1 113 * locate and load a class (such as the class loader to use) is
duke@1 114 * not available, and the class might not be loadable at all.
duke@1 115 * Attempting to read a {@code Class} object by invoking the relevant
duke@1 116 * method on the returned annotation
duke@1 117 * will result in a {@link MirroredTypeException},
duke@1 118 * from which the corresponding {@link TypeMirror} may be extracted.
duke@1 119 * Similarly, attempting to read a {@code Class[]}-valued element
duke@1 120 * will result in a {@link MirroredTypesException}.
duke@1 121 *
duke@1 122 * <blockquote>
duke@1 123 * <i>Note:</i> This method is unlike others in this and related
duke@1 124 * interfaces. It operates on runtime reflective information &mdash;
duke@1 125 * representations of annotation types currently loaded into the
duke@1 126 * VM &mdash; rather than on the representations defined by and used
duke@1 127 * throughout these interfaces. Consequently, calling methods on
duke@1 128 * the returned annotation object can throw many of the exceptions
duke@1 129 * that can be thrown when calling methods on an annotation object
duke@1 130 * returned by core reflection. This method is intended for
duke@1 131 * callers that are written to operate on a known, fixed set of
duke@1 132 * annotation types.
duke@1 133 * </blockquote>
duke@1 134 *
duke@1 135 * @param <A> the annotation type
duke@1 136 * @param annotationType the {@code Class} object corresponding to
duke@1 137 * the annotation type
duke@1 138 * @return this element's annotation for the specified annotation
duke@1 139 * type if present on this element, else {@code null}
duke@1 140 *
duke@1 141 * @see #getAnnotationMirrors()
duke@1 142 * @see java.lang.reflect.AnnotatedElement#getAnnotation
duke@1 143 * @see EnumConstantNotPresentException
duke@1 144 * @see AnnotationTypeMismatchException
duke@1 145 * @see IncompleteAnnotationException
duke@1 146 * @see MirroredTypeException
duke@1 147 * @see MirroredTypesException
duke@1 148 */
duke@1 149 <A extends Annotation> A getAnnotation(Class<A> annotationType);
duke@1 150
duke@1 151 /**
duke@1 152 * Returns the modifiers of this element, excluding annotations.
duke@1 153 * Implicit modifiers, such as the {@code public} and {@code static}
duke@1 154 * modifiers of interface members, are included.
duke@1 155 *
duke@1 156 * @return the modifiers of this element, or an empty set if there are none
duke@1 157 */
duke@1 158 Set<Modifier> getModifiers();
duke@1 159
duke@1 160 /**
darcy@849 161 * Returns the simple (unqualified) name of this element. The
darcy@849 162 * name of a generic type does not include any reference to its
darcy@849 163 * formal type parameters.
darcy@849 164 *
darcy@849 165 * For example, the simple name of the type element {@code
darcy@849 166 * java.util.Set<E>} is {@code "Set"}.
darcy@849 167 *
darcy@849 168 * If this element represents an unnamed {@linkplain
darcy@849 169 * PackageElement#getSimpleName package}, an empty name is
duke@1 170 * returned.
duke@1 171 *
darcy@849 172 * If it represents a {@linkplain ExecutableElement#getSimpleName
darcy@849 173 * constructor}, the name "{@code <init>}" is returned. If it
darcy@849 174 * represents a {@linkplain ExecutableElement#getSimpleName static
darcy@849 175 * initializer}, the name "{@code <clinit>}" is returned.
darcy@849 176 *
darcy@849 177 * If it represents an {@linkplain TypeElement#getSimpleName
darcy@849 178 * anonymous class} or {@linkplain ExecutableElement#getSimpleName
darcy@849 179 * instance initializer}, an empty name is returned.
darcy@849 180 *
duke@1 181 * @return the simple name of this element
darcy@1484 182 * @see PackageElement#getSimpleName
darcy@1484 183 * @see ExecutableElement#getSimpleName
darcy@1484 184 * @see TypeElement#getSimpleName
darcy@1484 185 * @see VariableElement#getSimpleName
duke@1 186 */
duke@1 187 Name getSimpleName();
duke@1 188
duke@1 189 /**
duke@1 190 * Returns the innermost element
duke@1 191 * within which this element is, loosely speaking, enclosed.
duke@1 192 * <ul>
duke@1 193 * <li> If this element is one whose declaration is lexically enclosed
duke@1 194 * immediately within the declaration of another element, that other
duke@1 195 * element is returned.
darcy@849 196 *
darcy@849 197 * <li> If this is a {@linkplain TypeElement#getEnclosingElement
darcy@849 198 * top-level type}, its package is returned.
darcy@849 199 *
darcy@849 200 * <li> If this is a {@linkplain
darcy@849 201 * PackageElement#getEnclosingElement package}, {@code null} is
darcy@849 202 * returned.
darcy@926 203 *
darcy@849 204 * <li> If this is a {@linkplain
darcy@849 205 * TypeParameterElement#getEnclosingElement type parameter},
darcy@926 206 * {@linkplain TypeParameterElement#getGenericElement the
darcy@926 207 * generic element} of the type parameter is returned.
darcy@926 208 *
darcy@1484 209 * <li> If this is a {@linkplain
darcy@1484 210 * VariableElement#getEnclosingElement method or constructor
darcy@1484 211 * parameter}, {@linkplain ExecutableElement the executable
darcy@1484 212 * element} which declares the parameter is returned.
darcy@1484 213 *
duke@1 214 * </ul>
duke@1 215 *
duke@1 216 * @return the enclosing element, or {@code null} if there is none
duke@1 217 * @see Elements#getPackageOf
duke@1 218 */
duke@1 219 Element getEnclosingElement();
duke@1 220
duke@1 221 /**
duke@1 222 * Returns the elements that are, loosely speaking, directly
duke@1 223 * enclosed by this element.
duke@1 224 *
darcy@1181 225 * A {@linkplain TypeElement#getEnclosedElements class or
darcy@1181 226 * interface} is considered to enclose the fields, methods,
darcy@1181 227 * constructors, and member types that it directly declares.
duke@1 228 *
darcy@1181 229 * A {@linkplain PackageElement#getEnclosedElements package}
darcy@1181 230 * encloses the top-level classes and interfaces within it, but is
darcy@1181 231 * not considered to enclose subpackages.
duke@1 232 *
duke@1 233 * Other kinds of elements are not currently considered to enclose
duke@1 234 * any elements; however, that may change as this API or the
duke@1 235 * programming language evolves.
duke@1 236 *
duke@1 237 * <p>Note that elements of certain kinds can be isolated using
duke@1 238 * methods in {@link ElementFilter}.
duke@1 239 *
duke@1 240 * @return the enclosed elements, or an empty list if none
darcy@1181 241 * @see PackageElement#getEnclosedElements
darcy@1181 242 * @see TypeElement#getEnclosedElements
duke@1 243 * @see Elements#getAllMembers
jjh@972 244 * @jls 8.8.9 Default Constructor
jjh@972 245 * @jls 8.9 Enums
duke@1 246 */
duke@1 247 List<? extends Element> getEnclosedElements();
duke@1 248
duke@1 249 /**
duke@1 250 * Returns {@code true} if the argument represents the same
duke@1 251 * element as {@code this}, or {@code false} otherwise.
duke@1 252 *
duke@1 253 * <p>Note that the identity of an element involves implicit state
duke@1 254 * not directly accessible from the element's methods, including
duke@1 255 * state about the presence of unrelated types. Element objects
duke@1 256 * created by different implementations of these interfaces should
duke@1 257 * <i>not</i> be expected to be equal even if &quot;the same&quot;
duke@1 258 * element is being modeled; this is analogous to the inequality
duke@1 259 * of {@code Class} objects for the same class file loaded through
duke@1 260 * different class loaders.
duke@1 261 *
duke@1 262 * @param obj the object to be compared with this element
duke@1 263 * @return {@code true} if the specified object represents the same
duke@1 264 * element as this
duke@1 265 */
duke@1 266 boolean equals(Object obj);
duke@1 267
duke@1 268 /**
duke@1 269 * Obeys the general contract of {@link Object#hashCode Object.hashCode}.
duke@1 270 *
duke@1 271 * @see #equals
duke@1 272 */
duke@1 273 int hashCode();
duke@1 274
duke@1 275 /**
duke@1 276 * Applies a visitor to this element.
duke@1 277 *
duke@1 278 * @param <R> the return type of the visitor's methods
duke@1 279 * @param <P> the type of the additional parameter to the visitor's methods
duke@1 280 * @param v the visitor operating on this element
duke@1 281 * @param p additional parameter to the visitor
duke@1 282 * @return a visitor-specified result
duke@1 283 */
duke@1 284 <R, P> R accept(ElementVisitor<R, P> v, P p);
duke@1 285 }

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