com.vladsch.flexmark.util.collection.iteration.IndexedItemIterator Maven / Gradle / Ivy

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package com.vladsch.flexmark.util.collection.iteration;

import org.jetbrains.annotations.NotNull;

import java.util.ConcurrentModificationException;
import java.util.NoSuchElementException;
import java.util.function.Consumer;

public class IndexedItemIterator implements ReversibleIndexedIterator {
    final private Indexed items;
    final private boolean reversed;
    private int next;
    private int last;
    private int modificationCount;

    public IndexedItemIterator(@NotNull Indexed items) {
        this(items, false);
    }

    public IndexedItemIterator(@NotNull Indexed items, boolean isReversed) {
        this.items = items;
        reversed = isReversed;
        next = reversed ? items.size() - 1 : 0;

        // empty forward iterator has no next
        if (next >= items.size()) next = -1;

        last = -1;
        this.modificationCount = items.modificationCount();
    }

    @Override
    public boolean isReversed() {
        return reversed;
    }

    @Override
    public boolean hasNext() {
        return next != -1;
    }

    @Override
    public @NotNull R next() {
        if (modificationCount != items.modificationCount()) {
            throw new ConcurrentModificationException();
        }

        if (next == -1) {
            throw new NoSuchElementException();
        }

        last = next;
        next = reversed ? (next <= 0 ? -1 : next - 1) : next == items.size() - 1 ? -1 : next + 1;
        return items.get(last);
    }

    @Override
    public void remove() {
        if (last == -1) {
            throw new NoSuchElementException();
        }

        if (modificationCount != items.modificationCount()) {
            throw new ConcurrentModificationException();
        }

        items.removeAt(last);
        last = -1;
        modificationCount = items.modificationCount();
    }

    @Override
    public int getIndex() {
        if (last < 0) {
            throw new NoSuchElementException();
        }
        return last;
    }

    public void forEachRemaining(@NotNull Consumer consumer) {
        while (hasNext()) {
            consumer.accept(next());
        }
    }
}