/*
 
* Copyright (c) 2003, 2013, Oracle and/or its affiliates. All rights reserved.
 
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 
*
 
* This code is free software; you can redistribute it and/or modify it
 
* under the terms of the GNU General Public License version 2 only, as
 
* published by the Free Software Foundation.
  
Oracle designates this
 
* particular file as subject to the "Classpath" exception as provided
 
* by Oracle in the LICENSE file that accompanied this code.
 
*
 
* This code is distributed in the hope that it will be useful, but WITHOUT
 
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 
* FITNESS FOR A PARTICULAR PURPOSE.
  
See the GNU General Public License
 
* version 2 for more details (a copy is included in the LICENSE file that
 
* accompanied this code).
 
*
 
* You should have received a copy of the GNU General Public License version
 
* 2 along with this work; if not, write to the Free Software Foundation,
 
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 
*
 
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*/

package java.lang.reflect;

import java.lang.annotation.Annotation;
import java.lang.annotation.AnnotationFormatError;
import java.lang.annotation.Repeatable;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Objects;
import java.util.function.Function;
import java.util.stream.Collectors;
import sun.reflect.annotation.AnnotationSupport;
import sun.reflect.annotation.AnnotationType;

/**
 
* Represents an annotated element of the program currently running in this
 
* VM.
  
This interface allows annotations to be read reflectively.All
 
* annotations returned by methods in this interface are immutable and
 
* serializable. The arrays returned by methods of this interface may be modified
 
* by callers without affecting the arrays returned to other callers.
 
*
 
* <p>The {@link #getAnnotationsByType(Class)} and {@link
 
* #getDeclaredAnnotationsByType(Class)} methods support multiple
 
* annotations of the same type on an element. If the argument to
 
* either method is a repeatable annotation type (JLS 9.6), then the
 
* method will "look through" a container annotation (JLS 9.7), if
 
* present, and return any annotations inside the container. Container
 
* annotations may be generated at compile-time to wrap multiple
 
* annotations of the argument type.
 
*
 
* <p>The terms <em>directly present</em>, <em>indirectly present</em>,
 
* <em>present</em>, and <em>associated</em> are used throughout this
 
* interface to describe precisely which annotations are returned by
 
* methods:
 
*
 
* <ul>
 
*
 
* <li> An annotation <i>A</i> is <em>directly present</em> on an
 
* element <i>E</i> if <i>E</i> has a {@code
 
* RuntimeVisibleAnnotations} or {@code
 
* RuntimeVisibleParameterAnnotations} or {@code
 
* RuntimeVisibleTypeAnnotations} attribute, and the attribute
 
* contains <i>A</i>.
 
*
 
* <li>An annotation <i>A</i> is <em>indirectly present</em> on an
 
* element <i>E</i> if <i>E</i> has a {@code RuntimeVisibleAnnotations} or
 
* {@code RuntimeVisibleParameterAnnotations} or {@code RuntimeVisibleTypeAnnotations}
 
* attribute, and <i>A</i> 's type is repeatable, and the attribute contains
 
* exactly one annotation whose value element contains <i>A</i> and whose
 
* type is the containing annotation type of <i>A</i> 's type.
 
*
 
* <li>An annotation <i>A</i> is present on an element <i>E</i> if either:
 
*
 
* <ul>
 
*
 
* <li><i>A</i> is directly present on <i>E</i>; or
 
*
 
* <li>No annotation of <i>A</i> 's type is directly present on
 
* <i>E</i>, and <i>E</i> is a class, and <i>A</i> 's type is
 
* inheritable, and <i>A</i> is present on the superclass of <i>E</i>.
 
*
 
* </ul>
 
*
 
* <li>An annotation <i>A</i> is <em>associated</em> with an element <i>E</i>
 
* if either:
 
*
 
* <ul>
 
*
 
* <li><i>A</i> is directly or indirectly present on <i>E</i>; or
 
*
 
* <li>No annotation of <i>A</i> 's type is directly or indirectly
 
* present on <i>E</i>, and <i>E</i> is a class, and <i>A</i>'s type
 
* is inheritable, and <i>A</i> is associated with the superclass of
 
* <i>E</i>.
 
*
 
* </ul>
 
*
 
* </ul>
 
*
 
* <p>The table below summarizes which kind of annotation presence
 
* different methods in this interface examine.
 
*
 
* <table border>
 
* <caption>Overview of kind of presence detected by different AnnotatedElement methods</caption>
 
* <tr><th colspan=2></th><th colspan=4>Kind of Presence</th>
 
* <tr><th colspan=2>Method</th><th>Directly Present</th><th>Indirectly Present</th><th>Present</th><th>Associated</th>
 
* <tr><td align=right>{@code T}</td><td>{@link #getAnnotation(Class) getAnnotation(Class&lt;T&gt;)}
 
* <td></td><td></td><td>X</td><td></td>
 
* </tr>
 
* <tr><td align=right>{@code Annotation[]}</td><td>{@link #getAnnotations getAnnotations()}
 
* <td></td><td></td><td>X</td><td></td>
 
* </tr>
 
* <tr><td align=right>{@code T[]}</td><td>{@link #getAnnotationsByType(Class) getAnnotationsByType(Class&lt;T&gt;)}
 
* <td></td><td></td><td></td><td>X</td>
 
* </tr>
 
* <tr><td align=right>{@code T}</td><td>{@link #getDeclaredAnnotation(Class) getDeclaredAnnotation(Class&lt;T&gt;)}
 
* <td>X</td><td></td><td></td><td></td>
 
* </tr>
 
* <tr><td align=right>{@code Annotation[]}</td><td>{@link #getDeclaredAnnotations getDeclaredAnnotations()}
 
* <td>X</td><td></td><td></td><td></td>
 
* </tr>
 
* <tr><td align=right>{@code T[]}</td><td>{@link #getDeclaredAnnotationsByType(Class) getDeclaredAnnotationsByType(Class&lt;T&gt;)}
 
* <td>X</td><td>X</td><td></td><td></td>
 
* </tr>
 
* </table>
 
*
 
* <p>For an invocation of {@code get[Declared]AnnotationsByType( Class <
 
* T >)}, the order of annotations which are directly or indirectly
 
* present on an element <i>E</i> is computed as if indirectly present
 
* annotations on <i>E</i> are directly present on <i>E</i> in place
 
* of their container annotation, in the order in which they appear in
 
* the value element of the container annotation.
 
*
 
* <p>There are several compatibility concerns to keep in mind if an
 
* annotation type <i>T</i> is originally <em>not</em> repeatable and
 
* later modified to be repeatable.
 
*
 
* The containing annotation type for <i>T</i> is <i>TC</i>.
 
*
 
* <ul>
 
*
 
* <li>Modifying <i>T</i> to be repeatable is source and binary
 
* compatible with existing uses of <i>T</i> and with existing uses
 
* of <i>TC</i>.
 
*
 
* That is, for source compatibility, source code with annotations of
 
* type <i>T</i> or of type <i>TC</i> will still compile. For binary
 
* compatibility, class files with annotations of type <i>T</i> or of
 
* type <i>TC</i> (or with other kinds of uses of type <i>T</i> or of
 
* type <i>TC</i>) will link against the modified version of <i>T</i>
 
* if they linked against the earlier version.
 
*
 
* (An annotation type <i>TC</i> may informally serve as an acting
 
* containing annotation type before <i>T</i> is modified to be
 
* formally repeatable. Alternatively, when <i>T</i> is made
 
* repeatable, <i>TC</i> can be introduced as a new type.)
 
*
 
* <li>If an annotation type <i>TC</i> is present on an element, and
 
* <i>T</i> is modified to be repeatable with <i>TC</i> as its
 
* containing annotation type then:
 
*
 
* <ul>
 
*
 
* <li>The change to <i>T</i> is behaviorally compatible with respect
 
* to the {@code get[Declared]Annotation(Class<T>)} (called with an
 
* argument of <i>T</i> or <i>TC</i>) and {@code
 
* get[Declared]Annotations()} methods because the results of the
 
* methods will not change due to <i>TC</i> becoming the containing
 
* annotation type for <i>T</i>.
 
*
 
* <li>The change to <i>T</i> changes the results of the {@code
 
* get[Declared]AnnotationsByType(Class<T>)} methods called with an
 
* argument of <i>T</i>, because those methods will now recognize an
 
* annotation of type <i>TC</i> as a container annotation for <i>T</i>
 
* and will "look through" it to expose annotations of type <i>T</i>.
 
*
 
* </ul>
 
*
 
* <li>If an annotation of type <i>T</i> is present on an
 
* element and <i>T</i> is made repeatable and more annotations of
 
* type <i>T</i> are added to the element:
 
*
 
* <ul>
 
*
 
* <li> The addition of the annotations of type <i>T</i> is both
 
* source compatible and binary compatible.
 
*
 
* <li>The addition of the annotations of type <i>T</i> changes the results
 
* of the {@code get[Declared]Annotation(Class<T>)} methods and {@code
 
* get[Declared]Annotations()} methods, because those methods will now
 
* only see a container annotation on the element and not see an
 
* annotation of type <i>T</i>.
 
*
 
* <li>The addition of the annotations of type <i>T</i> changes the
 
* results of the {@code get[Declared]AnnotationsByType(Class<T>)}
 
* methods, because their results will expose the additional
 
* annotations of type <i>T</i> whereas previously they exposed only a
 
* single annotation of type <i>T</i>.
 
*
 
* </ul>
 
*
 
* </ul>
 
*
 
* <p>If an annotation returned by a method in this interface contains
 
* (directly or indirectly) a {@link Class}-valued member referring to
 
* a class that is not accessible in this VM, attempting to read the class
 
* by calling the relevant Class-returning method on the returned annotation
 
* will result in a {@link TypeNotPresentException}.
 
*
 
* <p>Similarly, attempting to read an enum-valued member will result in
 
* a {@link EnumConstantNotPresentException} if the enum constant in the
 
* annotation is no longer present in the enum type.
 
*
 
* <p>If an annotation type <i>T</i> is (meta-)annotated with an
 
* {@code @Repeatable} annotation whose value element indicates a type
 
* <i>TC</i>, but <i>TC</i> does not declare a {@code value()} method
 
* with a return type of <i>T</i>{@code []}, then an exception of type
 
*
 
is thrown.
 
*
 
* <p>Finally, attempting to read a member whose definition has evolved
 
* incompatibly will result in a {@link
 
* java.lang.annotation.AnnotationTypeMismatchException} or an
 
* .
 
*
 
*
 
*
 
* @see AnnotationFormatError
 
*
 
*
 
* @since 1.5
 
* @author Josh Bloch
 
*/

public interface AnnotatedElement {
    
/**
     
* Returns true if an annotation for the specified type
     
* is <em>present</em> on this element, else false.
  
This method
     
* is designed primarily for convenient access to marker annotations.
     
*
     
* <p>The truth value returned by this method is equivalent to:
     
* {@code getAnnotation(annotationClass) != null}
     
*
     
* <p>The body of the default method is specified to be the code
     
* above.
     
*
     
* @param annotationClass the Class object corresponding to the
     
*
        
annotation type
     
* @return true if an annotation for the specified annotation
     
*type is present on this element, else false
     
* @throws NullPointerException if the given annotation class is null
     
* @since 1.5
     
*/

    
default boolean isAnnotationPresent(Class<? extends Annotation> annotationClass) {
        
return getAnnotation(annotationClass) != null;
    
}

   
/**
     
* Returns this element's annotation for the specified type if
     
* such an annotation is <em>present</em>, else null.
     
*
     
* @param <T> the type of the annotation to query for and return if present
     
* @param annotationClass the Class object corresponding to the
     
*
        
annotation type
     
* @return this element's annotation for the specified annotation type if
     
*present on this element, else null
     
* @throws NullPointerException if the given annotation class is null
     
* @since 1.5
     
*/

    
<T extends Annotation> T getAnnotation(Class<T> annotationClass);

    
/**
     
* Returns annotations that are <em>present</em> on this element.
     
*
     
* If there are no annotations <em>present</em> on this element, the return
     
* value is an array of length 0.
     
*
     
* The caller of this method is free to modify the returned array; it will
     
* have no effect on the arrays returned to other callers.
     
*
     
* @return annotations present on this element
     
* @since 1.5
     
*/

    
Annotation[] getAnnotations();

    
/**
     
* Returns annotations that are <em>associated</em> with this element.
     
*
     
* If there are no annotations <em>associated</em> with this element, the return
     
* value is an array of length 0.
     
*
     
* The difference between this method and {@link #getAnnotation(Class)}
     
* is that this method detects if its argument is a <em>repeatable
     
* annotation type</em> (JLS 9.6), and if so, attempts to find one or
     
* more annotations of that type by "looking through" a container
     
* annotation.
     
*
     
* The caller of this method is free to modify the returned array; it will
     
* have no effect on the arrays returned to other callers.
     
*
     
* @implSpec The default implementation first calls {@link
     
* #getDeclaredAnnotationsByType(Class)} passing {@code
     
* annotationClass} as the argument. If the returned array has
     
* length greater than zero, the array is returned. If the returned
     
* array is zero-length and this {@code AnnotatedElement} is a
     
* class and the argument type is an inheritable annotation type,
     
* and the superclass of this {@code AnnotatedElement} is non-null,
     
* then the returned result is the result of calling {@link
     
* #getAnnotationsByType(Class)} on the superclass with {@code
     
* annotationClass} as the argument. Otherwise, a zero-length
     
* array is returned.
     
*
     
* @param <T> the type of the annotation to query for and return if present
     
* @param annotationClass the Class object corresponding to the
     
*
        
annotation type
     
* @return all this element's annotations for the specified annotation type if
     
*associated with this element, else an array of length zero
     
* @throws NullPointerException if the given annotation class is null
     
* @since 1.8
     
*/

    
default <T extends Annotation> T[] getAnnotationsByType(Class<T> annotationClass) {
         
/*
          
* Definition of associated: directly or indirectly present OR
          
* neither directly nor indirectly present AND the element is
          
* a Class, the annotation type is inheritable, and the
          
* annotation type is associated with the superclass of the
          
* element.
          
*/

         
T[] result = getDeclaredAnnotationsByType(annotationClass);

         
if (result.length == 0 && // Neither directly nor indirectly present
             
this instanceof Class && // the element is a class
             
AnnotationType.getInstance(annotationClass).isInherited()) { // Inheritable
             
Class<?> superClass = ((Class<?>) this).getSuperclass();
             
if (superClass != null) {
                 
// Determine if the annotation is associated with the
                 
// superclass
                 
result = superClass.getAnnotationsByType(annotationClass);
             
}
         
}

         
return result;
     
}

    
/**
     
* Returns this element's annotation for the specified type if
     
* such an annotation is <em>directly present</em>, else null.
     
*
     
* This method ignores inherited annotations. (Returns null if no
     
* annotations are directly present on this element.)
     
*
     
* @implSpec The default implementation first performs a null check
     
* and then loops over the results of {@link
     
* #getDeclaredAnnotations} returning the first annotation whose
     
* annotation type matches the argument type.
     
*
     
* @param <T> the type of the annotation to query for and return if directly present
     
* @param annotationClass the Class object corresponding to the
     
*
        
annotation type
     
* @return this element's annotation for the specified annotation type if
     
*directly present on this element, else null
     
* @throws NullPointerException if the given annotation class is null
     
* @since 1.8
     
*/

    
default <T extends Annotation> T getDeclaredAnnotation(Class<T> annotationClass) {
         
Objects.requireNonNull(annotationClass);
         
// Loop over all directly-present annotations looking for a matching one
         
for (Annotation annotation : getDeclaredAnnotations()) {
             
if (annotationClass.equals(annotation.annotationType())) {
                 
// More robust to do a dynamic cast at runtime instead
                 
// of compile-time only.
                 
return annotationClass.cast(annotation);
             
}
         
}
         
return null;
     
}

    
/**
     
* Returns this element's annotation(s) for the specified type if
     
* such annotations are either <em>directly present</em> or
     
* <em>indirectly present</em>. This method ignores inherited
     
* annotations.
     
*
     
* If there are no specified annotations directly or indirectly
     
* present on this element, the return value is an array of length
     
* 0.
     
*
     
* The difference between this method and {@link
     
* #getDeclaredAnnotation(Class)} is that this method detects if its
     
* argument is a <em>repeatable annotation type</em> (JLS 9.6), and if so,
     
* attempts to find one or more annotations of that type by "looking
     
* through" a container annotation if one is present.
     
*
     
* The caller of this method is free to modify the returned array; it will
     
* have no effect on the arrays returned to other callers.
     
*
     
* @implSpec The default implementation may call {@link
     
* #getDeclaredAnnotation(Class)} one or more times to find a
     
* directly present annotation and, if the annotation type is
     
* repeatable, to find a container annotation. If annotations of
     
* the annotation type {@code annotationClass} are found to be both
     
* directly and indirectly present, then {@link
     
* #getDeclaredAnnotations()} will get called to determine the
     
* order of the elements in the returned array.
     
*
     
* <p>Alternatively, the default implementation may call {@link
     
* #getDeclaredAnnotations()} a single time and the returned array
     
* examined for both directly and indirectly present
     
* annotations. The results of calling {@link
     
* #getDeclaredAnnotations()} are assumed to be consistent with the
     
* results of calling {@link #getDeclaredAnnotation(Class)}.
     
*
     
* @param <T> the type of the annotation to query for and return
     
* if directly or indirectly present
     
* @param annotationClass the Class object corresponding to the
     
*
        
annotation type
     
* @return all this element's annotations for the specified annotation type if
     
*directly or indirectly present on this element, else an array of length zero
     
* @throws NullPointerException if the given annotation class is null
     
* @since 1.8
     
*/

    
default <T extends Annotation> T[] getDeclaredAnnotationsByType(Class<T> annotationClass) {
        
Objects.requireNonNull(annotationClass);
        
return AnnotationSupport.
            
getDirectlyAndIndirectlyPresent
(Arrays.stream(getDeclaredAnnotations()).
                                            
collect(Collectors.toMap(Annotation::annotationType,
                                                                     
Function.identity(),
                                                                     
((first,second) -> first),
                                                                     
LinkedHashMap::new)),
                                            
annotationClass);
    
}

    
/**
     
* Returns annotations that are <em>directly present</em> on this element.
     
* This method ignores inherited annotations.
     
*
     
* If there are no annotations <em>directly present</em> on this element,
     
* the return value is an array of length 0.
     
*
     
* The caller of this method is free to modify the returned array; it will
     
* have no effect on the arrays returned to other callers.
     
*
     
* @return annotations directly present on this element
     
* @since 1.5
     
*/

    
Annotation[] getDeclaredAnnotations();
}