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packages/java.lang.reflect/src/jannotatedelement.ts

Description

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.

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.

The terms directly present, indirectly present,
present, and associated are used throughout this
interface to describe precisely which annotations are returned by
methods:

An annotation A is directly present on an
element E if E has a {@code
RuntimeVisibleAnnotations} or {@code
RuntimeVisibleParameterAnnotations} or {@code
RuntimeVisibleTypeAnnotations} attribute, and the attribute
contains A.
An annotation A is indirectly present on an
element E if E has a {@code RuntimeVisibleAnnotations} or
{@code RuntimeVisibleParameterAnnotations} or {@code RuntimeVisibleTypeAnnotations}
attribute, and A 's type is repeatable, and the attribute contains
exactly one annotation whose _value element contains A and whose
type is the containing annotation type of A 's type.
An annotation A is present on an element E if either:
- A is directly present on E; or
- No annotation of A 's type is directly present on
  E, and E is a class, and A 's type is
  inheritable, and A is present on the superclass of E.
An annotation A is associated with an element E
if either:
- A is directly or indirectly present on E; or
- No annotation of A 's type is directly or indirectly
  present on E, and E is a class, and A's type
  is inheritable, and A is associated with the superclass of
  E.

The table below summarizes which kind of annotation presence
different methods in this interface examine.

Overview of kind of presence detected by different AnnotatedElement methods
		Kind of Presence
Method		Directly Present	Indirectly Present	Present	Associated
{@code T}	{@link #getAnnotation(Class) getAnnotation(Class<T>)}			X
{@code Annotation[]}	{@link #getAnnotations getAnnotations()}			X
{@code T[]}	{@link #getAnnotationsByType(Class) getAnnotationsByType(Class<T>)}				X
{@code T}	{@link #getDeclaredAnnotation(Class) getDeclaredAnnotation(Class<T>)}	X
{@code Annotation[]}	{@link #getDeclaredAnnotations getDeclaredAnnotations()}	X
{@code T[]}	{@link #getDeclaredAnnotationsByType(Class) getDeclaredAnnotationsByType(Class<T>)}	X	X

For an invocation of {@code get[Declared]AnnotationsByType( Class <
T >)}, the order of annotations which are directly or indirectly
present on an element E is computed as if indirectly present
annotations on E are directly present on E in place
of their container annotation, in the order in which they appear in
the _value element of the container annotation.

There are several compatibility concerns to keep in mind if an
annotation type T is originally not repeatable and
later modified to be repeatable.

The containing annotation type for T is TC.

Modifying T to be repeatable is source and binary
compatible with existing uses of T and with existing uses
of TC.

That is, for source compatibility, source code with annotations of
type T or of type TC will still compile. For binary
compatibility, class files with annotations of type T or of
type TC (or with other kinds of uses of type T or of
type TC) will link against the modified version of T
if they linked against the earlier version.

(An annotation type TC may informally serve as an acting
containing annotation type before T is modified to be
formally repeatable. Alternatively, when T is made
repeatable, TC can be introduced as a new type.)
If an annotation type TC is present on an element, and
T is modified to be repeatable with TC as its
containing annotation type then:
- The change to T is behaviorally compatible with respect
  to the {@code get[Declared]Annotation(Class)} (called with an
  argument of T or TC) and {@code
  get[Declared]Annotations()} methods because the results of the
  methods will not change due to TC becoming the containing
  annotation type for T.
- The change to T changes the results of the {@code
  get[Declared]AnnotationsByType(Class)} methods called with an
  argument of T, because those methods will now recognize an
  annotation of type TC as a container annotation for T
  and will "look through" it to expose annotations of type T.
If an annotation of type T is present on an
element and T is made repeatable and more annotations of
type T are added to the element:
- The addition of the annotations of type T is both
  source compatible and binary compatible.
- The addition of the annotations of type T changes the results
  of the {@code get[Declared]Annotation(Class)} 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 T.
- The addition of the annotations of type T changes the
  results of the {@code get[Declared]AnnotationsByType(Class)}
  methods, because their results will expose the additional
  annotations of type T whereas previously they exposed only a
  single annotation of type T.

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}.

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.

If an annotation type T is (meta-)annotated with an
{@code @Repeatable} annotation whose _value element indicates a type
TC, but TC does not declare a {@code _value()} method
with a return type of T{@code []}, then an exception of type
{@link java.lang.annotation.AnnotationFormatError} is thrown.

Finally, attempting to read a member whose definition has evolved
incompatibly will result in a {@link
java.lang.annotation.AnnotationTypeMismatchException} or an
{@link java.lang.annotation.IncompleteAnnotationException}.

export interface JAnnotatedElement {
  /**
   * 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
   */
  // getAnnotation(annotationClass: JClass<T>): T;

  /**
   * 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
   */
  // getAnnotations(): JArray<JAnnotation>

  /**
   * 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
   */
  // getAnnotationsByType(annotationClass: JClass<T>): Jarray<T>; // TODO see default implementation?

  /**
   * 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
   */
  // getDeclaredAnnotation(annotationClass: JClass<T>): T; // TODO see default implementation?

  /**
   * 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
   */
  // getDeclaredAnnotations(): JArray<JAnnotation>;


  /**
   * 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
   */
  // getDeclaredAnnotationsByType(annotationClass: JClass<T>): Jarray<T>; // TODO see implementation?
}

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