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package jdk.javadoc.internal.doclets.formats.html;

import jdk.javadoc.internal.doclets.formats.html.SearchIndexItem.Category;
import jdk.javadoc.internal.doclets.toolkit.util.Utils;

import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.TreeSet;
import java.util.stream.Stream;

A container for organizing search items by category. 
This is NOT part of any supported API.
 If you write code that depends on this, you do so at your own risk.
 This code and its internal interfaces are subject to change or
 deletion without notice.
/**
 * A container for organizing {@linkplain SearchIndexItem search items}
 * by {@linkplain Category category}.
 *
 *  <p><b>This is NOT part of any supported API.
 *  If you write code that depends on this, you do so at your own risk.
 *  This code and its internal interfaces are subject to change or
 *  deletion without notice.</b>
 */
public final class SearchIndexItems {

    private final Map<Category, Set<SearchIndexItem>> items = new HashMap<>();
    private final Utils utils;

    public SearchIndexItems(Utils utils) {
        this.utils = Objects.requireNonNull(utils);
    }

    
Adds the specified item to this container.
Params:
item – 
        the item to add/**
     * Adds the specified item to this container.
     *
     * @param item
     *         the item to add
     */
    public void add(SearchIndexItem item) {
        Objects.requireNonNull(item);
        items.computeIfAbsent(item.getCategory(), this::newSetForCategory)
                .add(item);
    }

    private Set<SearchIndexItem> newSetForCategory(Category category) {
        final Comparator<SearchIndexItem> cmp;
        if (category == Category.TYPES) {
            cmp = utils.comparators.makeTypeSearchIndexComparator();
        } else {
            cmp = utils.comparators.makeGenericSearchIndexComparator();
        }
        return new TreeSet<>(cmp);
    }

    
Checks if there are items of any of the specified categories
in this container.
 Iff there exists an item i for which there is a category c from the specified categories such that i.getCategory().equals(c), then true is returned. 
Params:
firstCategory – 
        the first category
otherCategories – 
        other categories (optional)
Throws:
NullPointerException –  if there are null categories
Returns:
true if there are items of any of the specified categories, false otherwise/**
     * Checks if there are items of any of the specified categories
     * in this container.
     *
     * <p> Iff there exists an item {@code i} for which there is a category
     * {@code c} from the specified categories such that
     * {@code i.getCategory().equals(c)}, then {@code true} is returned.
     *
     * @param firstCategory
     *         the first category
     * @param otherCategories
     *         other categories (optional)
     *
     * @return {@code true} if there are items of any of the specified categories,
     *         {@code false} otherwise
     *
     * @throws NullPointerException
     *         if there are {@code null} categories
     */
    public boolean containsAnyOfCategories(Category firstCategory,
                                           Category... otherCategories)
    {
        return itemsOfCategories(firstCategory, otherCategories)
                .findAny()
                .isPresent();
    }

    
Returns a stream of items of any of the specified categories
from this container.
 The returned stream consists of all items i for which there is a category c from the specified categories such that i.getCategory().equals(c). The stream may be empty. 
Params:
firstCategory – 
        the first category
otherCategories – 
        other categories (optional)
Throws:
NullPointerException –  if there are null categories
Returns:
a stream of items of the specified categories/**
     * Returns a stream of items of any of the specified categories
     * from this container.
     *
     * <p> The returned stream consists of all items {@code i} for which there
     * is a category {@code c} from the specified categories such that
     * {@code i.getCategory().equals(c)}. The stream may be empty.
     *
     * @param firstCategory
     *         the first category
     * @param otherCategories
     *         other categories (optional)
     *
     * @return a stream of items of the specified categories
     *
     * @throws NullPointerException
     *         if there are {@code null} categories
     */
    public Stream<SearchIndexItem> itemsOfCategories(Category firstCategory,
                                                     Category... otherCategories)
    {
        return concatenatedStreamOf(firstCategory, otherCategories)
                .distinct()
                .flatMap(this::itemsOf);
    }

    private Stream<SearchIndexItem> itemsOf(Category cat) {
        Objects.requireNonNull(cat);
        return items.getOrDefault(cat, Set.of()).stream();
    }

    
Returns a concatenated stream of elements.
 The elements of the returned stream are encountered in the following order: first, remaining[0], remaining[1], ..., remaining[remaining.length - 1]. 
Params:
first – 
        the first element
remaining – 
        the remaining elements, if any
Type parameters:
<T> – 
        the type of elements
Throws:
NullPointerException –  if remaining is null
Returns:
the stream of elements/**
     * Returns a concatenated stream of elements.
     *
     * <p> The elements of the returned stream are encountered in the following order:
     * {@code first, remaining[0], remaining[1], ..., remaining[remaining.length - 1]}.
     *
     * @param first
     *         the first element
     * @param remaining
     *         the remaining elements, if any
     * @param <T>
     *         the type of elements
     *
     * @return the stream of elements
     *
     * @throws NullPointerException
     *         if {@code remaining} is {@code null}
     */
    private static <T> Stream<T> concatenatedStreamOf(T first, T[] remaining) {
        return Stream.concat(Stream.of(first), Stream.of(remaining));
    }
}