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 * Copyright 2024, Google LLC
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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package com.android.tools.smali.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Objects;
import java.util.function.Predicate;

public final class IteratorUtils {

    public static <T extends Object> T getLast(Iterator<T> iterator) {
        while (true) {
            T current = iterator.next();
            if (!iterator.hasNext()) {
                return current;
            }
        }
    }

    public static <T extends Object> AbstractIterator<T> filter(
            Iterable<T> unfiltered, Predicate<? super T> retainIfTrue) {
        return filter(unfiltered.iterator(), retainIfTrue);
    }

    public static <T extends Object> AbstractIterator<T> filter(
            Iterator<T> unfiltered, Predicate<? super T> retainIfTrue) {
        return new AbstractIterator<T>() {
            @Override
            protected T computeNext() {
                while (unfiltered.hasNext()) {
                    T next = unfiltered.next();
                    if (retainIfTrue.test(next)) {
                        return next;
                    }
                }
                return endOfData();
            }
        };
    }

    public static <T extends Object> List<T> toList(Iterable<T> iterable) {
        return toList(iterable.iterator());
    }

    public static <T extends Object> List<T> toList(Iterator<T> iterator) {
        ArrayList<T> list = new ArrayList<T>();
        while (iterator.hasNext()) {
            list.add(iterator.next());
        }
        return list;
    }

    public static <T extends Object> void addAll(Collection<T> collection, Iterator<T> iterator) {
        while (iterator.hasNext()) {
            collection.add(iterator.next());
        }
    }

    public static boolean elementsEqual(Iterator<?> iterator1, Iterator<?> iterator2) {
        while (iterator1.hasNext()) {
            if (!iterator2.hasNext()) {
                return false;
            }
            Object o1 = iterator1.next();
            Object o2 = iterator2.next();
            if (!Objects.equals(o1, o2)) {
                return false;
            }
        }
        return !iterator2.hasNext();
    }

    public static int size(Iterable<?> iterable) {
        Iterator<?> iterator = iterable.iterator();
        int count = 0;
        while (iterator.hasNext()) {
            count++;
            iterator.next();
        }
        return count;
    }
}