Class IntStack

core/src/main/java/io/questdb/std/IntStack.java:29–161

import java.util.Arrays;

public class IntStack implements Mutable {
    private static final int DEFAULT_INITIAL_CAPACITY = 16;
    private static final int MIN_INITIAL_CAPACITY = 8;
    private static final int NO_ENTRY_VALUE = -1;
    private int bottom;
    private int[] elements;
    private int head;
    private int mask;
    private int tail;

    public IntStack() {
        this(DEFAULT_INITIAL_CAPACITY);
    }

    public IntStack(int initialCapacity) {
        allocateElements(initialCapacity);
    }

    public int bottom() {
        return bottom;
    }

    public void clear() {
        if (head != tail) {
            head = tail = 0;
            Arrays.fill(elements, NO_ENTRY_VALUE);
            bottom = 0;
        }
    }

    public boolean notEmpty() {
        return size() > 0;
    }

    public int peek() {
        return peek(0);
    }

    public int peek(int n) {
        return n < size() ? elements[(head + n) & mask] : NO_ENTRY_VALUE;
    }

    public int pollLast() {
        if (bottom != 0) {
            throw new IllegalStateException("pollLast() called while bottom != 0");
        }
        final int[] elems = elements;
        int newTail = tail;
        if (head != newTail && --newTail < 0) {
            newTail = mask;
        }
        final int elem = elems[newTail];
        tail = newTail;
        elems[newTail] = NO_ENTRY_VALUE;
        return elem;
    }

    public int pop() {