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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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
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 *
 * 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).
 *
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package sun.reflect.annotation;

import java.lang.annotation.*;
import java.lang.reflect.*;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.Map;
import java.util.Objects;

import jdk.internal.misc.SharedSecrets;
import jdk.internal.misc.JavaLangAccess;
import jdk.internal.reflect.ReflectionFactory;

public final class AnnotationSupport {
    private static final JavaLangAccess LANG_ACCESS = SharedSecrets.getJavaLangAccess();

    
Finds and returns all annotations in annotations matching the given annoClass. Apart from annotations directly present in annotations this method searches for annotations inside containers i.e. indirectly present annotations. The order of the elements in the array returned depends on the iteration order of the provided map. Specifically, the directly present annotations come before the indirectly present annotations if and only if the directly present annotations come before the indirectly present annotations in the map. 
Params:
annotations – the Map in which to search for annotations
annoClass – the type of annotation to search for
Returns:
an array of instances of annoClass or an empty array if none were found/**
     * Finds and returns all annotations in {@code annotations} matching
     * the given {@code annoClass}.
     *
     * Apart from annotations directly present in {@code annotations} this
     * method searches for annotations inside containers i.e. indirectly
     * present annotations.
     *
     * The order of the elements in the array returned depends on the iteration
     * order of the provided map. Specifically, the directly present annotations
     * come before the indirectly present annotations if and only if the
     * directly present annotations come before the indirectly present
     * annotations in the map.
     *
     * @param annotations the {@code Map} in which to search for annotations
     * @param annoClass the type of annotation to search for
     *
     * @return an array of instances of {@code annoClass} or an empty
     *         array if none were found
     */
    public static <A extends Annotation> A[] getDirectlyAndIndirectlyPresent(
            Map<Class<? extends Annotation>, Annotation> annotations,
            Class<A> annoClass) {
        List<A> result = new ArrayList<>();

        @SuppressWarnings("unchecked")
        A direct = (A) annotations.get(annoClass);
        if (direct != null)
            result.add(direct);

        A[] indirect = getIndirectlyPresent(annotations, annoClass);
        if (indirect != null && indirect.length != 0) {
            boolean indirectFirst = direct == null ||
                                    containerBeforeContainee(annotations, annoClass);

            result.addAll((indirectFirst ? 0 : 1), Arrays.asList(indirect));
        }

        @SuppressWarnings("unchecked")
        A[] arr = (A[]) Array.newInstance(annoClass, result.size());
        return result.toArray(arr);
    }

    
Finds and returns all annotations matching the given annoClass indirectly present in annotations. 
Params:
annotations – annotations to search indexed by their types
annoClass – the type of annotation to search for
Returns:
an array of instances of annoClass or an empty array if no indirectly present annotations were found/**
     * Finds and returns all annotations matching the given {@code annoClass}
     * indirectly present in {@code annotations}.
     *
     * @param annotations annotations to search indexed by their types
     * @param annoClass the type of annotation to search for
     *
     * @return an array of instances of {@code annoClass} or an empty array if no
     *         indirectly present annotations were found
     */
    private static <A extends Annotation> A[] getIndirectlyPresent(
            Map<Class<? extends Annotation>, Annotation> annotations,
            Class<A> annoClass) {

        Repeatable repeatable = annoClass.getDeclaredAnnotation(Repeatable.class);
        if (repeatable == null)
            return null;  // Not repeatable -> no indirectly present annotations

        Class<? extends Annotation> containerClass = repeatable.value();

        Annotation container = annotations.get(containerClass);
        if (container == null)
            return null;

        // Unpack container
        A[] valueArray = getValueArray(container);
        checkTypes(valueArray, container, annoClass);

        return valueArray;
    }


    
Figures out if container class comes before containee class among the
keys of the given map.
Returns:
true if container class is found before containee class when
        iterating over annotations.keySet()./**
     * Figures out if container class comes before containee class among the
     * keys of the given map.
     *
     * @return true if container class is found before containee class when
     *         iterating over annotations.keySet().
     */
    private static <A extends Annotation> boolean containerBeforeContainee(
            Map<Class<? extends Annotation>, Annotation> annotations,
            Class<A> annoClass) {

        Class<? extends Annotation> containerClass =
                annoClass.getDeclaredAnnotation(Repeatable.class).value();

        for (Class<? extends Annotation> c : annotations.keySet()) {
            if (c == containerClass) return true;
            if (c == annoClass) return false;
        }

        // Neither containee nor container present
        return false;
    }


    
Finds and returns all associated annotations matching the given class.
The order of the elements in the array returned depends on the iteration
order of the provided maps. Specifically, the directly present annotations
come before the indirectly present annotations if and only if the
directly present annotations come before the indirectly present
annotations in the relevant map.
Params:
declaredAnnotations – the declared annotations indexed by their types
decl – the class declaration on which to search for annotations
annoClass – the type of annotation to search for
Returns:
an array of instances of annoClass or an empty array if none were found./**
     * Finds and returns all associated annotations matching the given class.
     *
     * The order of the elements in the array returned depends on the iteration
     * order of the provided maps. Specifically, the directly present annotations
     * come before the indirectly present annotations if and only if the
     * directly present annotations come before the indirectly present
     * annotations in the relevant map.
     *
     * @param declaredAnnotations the declared annotations indexed by their types
     * @param decl the class declaration on which to search for annotations
     * @param annoClass the type of annotation to search for
     *
     * @return an array of instances of {@code annoClass} or an empty array if none were found.
     */
    public static <A extends Annotation> A[] getAssociatedAnnotations(
            Map<Class<? extends Annotation>, Annotation> declaredAnnotations,
            Class<?> decl,
            Class<A> annoClass) {
        Objects.requireNonNull(decl);

        // Search declared
        A[] result = getDirectlyAndIndirectlyPresent(declaredAnnotations, annoClass);

        // Search inherited
        if(AnnotationType.getInstance(annoClass).isInherited()) {
            Class<?> superDecl = decl.getSuperclass();
            while (result.length == 0 && superDecl != null) {
                result = getDirectlyAndIndirectlyPresent(LANG_ACCESS.getDeclaredAnnotationMap(superDecl), annoClass);
                superDecl = superDecl.getSuperclass();
            }
        }

        return result;
    }


    /* Reflectively invoke the values-method of the given annotation
     * (container), cast it to an array of annotations and return the result.
     */
    private static <A extends Annotation> A[] getValueArray(Annotation container) {
        try {
            // According to JLS the container must have an array-valued value
            // method. Get the AnnotationType, get the "value" method and invoke
            // it to get the content.

            Class<? extends Annotation> containerClass = container.annotationType();
            AnnotationType annoType = AnnotationType.getInstance(containerClass);
            if (annoType == null)
                throw invalidContainerException(container, null);
            Method m = annoType.members().get("value");
            if (m == null)
                throw invalidContainerException(container, null);

            if (Proxy.isProxyClass(container.getClass())) {
                // Invoke by invocation handler
                InvocationHandler handler = Proxy.getInvocationHandler(container);

                try {
                    // This will erase to (Annotation[]) but we do a runtime cast on the
                    // return-value in the method that call this method.
                    @SuppressWarnings("unchecked")
                    A[] values = (A[]) handler.invoke(container, m, null);
                    return values;
                } catch (Throwable t) { // from InvocationHandler::invoke
                    throw invalidContainerException(container, t);
                }
            } else {
                // In theory there might be instances of Annotations that are not
                // implemented using Proxies. Try to invoke the "value" element with
                // reflection.

                // Declaring class should be an annotation type
                Class<?> iface = m.getDeclaringClass();
                if (!iface.isAnnotation())
                    throw new UnsupportedOperationException("Unsupported container annotation type.");
                // Method must be public
                if (!Modifier.isPublic(m.getModifiers()))
                    throw new UnsupportedOperationException("Unsupported value member.");

                // Interface might not be public though
                final Method toInvoke;
                if (!Modifier.isPublic(iface.getModifiers())) {
                    if (System.getSecurityManager() != null) {
                        toInvoke = AccessController.doPrivileged(new PrivilegedAction<Method>() {
                            @Override
                            public Method run() {
                                Method res = ReflectionFactory.getReflectionFactory().leafCopyMethod(m);
                                res.setAccessible(true);
                                return res;
                            }
                        });
                    } else {
                        toInvoke = ReflectionFactory.getReflectionFactory().leafCopyMethod(m);
                        toInvoke.setAccessible(true);
                    }
                } else {
                    toInvoke = m;
                }

                // This will erase to (Annotation[]) but we do a runtime cast on the
                // return-value in the method that call this method.
                @SuppressWarnings("unchecked")
                A[] values = (A[]) toInvoke.invoke(container);

                return values;
            }
        } catch (IllegalAccessException    | // couldn't loosen security
                 IllegalArgumentException  | // parameters doesn't match
                 InvocationTargetException | // the value method threw an exception
                 ClassCastException e) {
            throw invalidContainerException(container, e);
        }
    }


    private static AnnotationFormatError invalidContainerException(Annotation anno,
                                                                   Throwable cause) {
        return new AnnotationFormatError(
                anno + " is an invalid container for repeating annotations",
                cause);
    }


    /* Sanity check type of all the annotation instances of type {@code annoClass}
     * from {@code container}.
     */
    private static <A extends Annotation> void checkTypes(A[] annotations,
                                                          Annotation container,
                                                          Class<A> annoClass) {
        for (A a : annotations) {
            if (!annoClass.isInstance(a)) {
                throw new AnnotationFormatError(
                        String.format("%s is an invalid container for " +
                                      "repeating annotations of type: %s",
                                      container, annoClass));
            }
        }
    }
}