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GraphHopper is a fast and memory efficient Java road routing engine working seamlessly with OpenStreetMap data.

There is a newer version: 10.0

/*
 *  Licensed to GraphHopper GmbH under one or more contributor
 *  license agreements. See the NOTICE file distributed with this work for
 *  additional information regarding copyright ownership.
 *
 *  GraphHopper GmbH licenses this file to you under the Apache License,
 *  Version 2.0 (the "License"); you may not use this file except in
 *  compliance with the License. You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */
package com.graphhopper.util;

import java.util.Arrays;

/**
 * push to end, pop from beginning
 * 
 *
 * @author Peter Karich
 */
public class SimpleIntDeque {
    private int[] arr;
    private float growFactor;
    private int frontIndex;
    private int endIndexPlusOne;

    public SimpleIntDeque() {
        this(100, 2);
    }

    public SimpleIntDeque(int initSize) {
        this(initSize, 2);
    }

    public SimpleIntDeque(int initSize, float growFactor) {
        if ((int) (initSize * growFactor) <= initSize) {
            throw new RuntimeException("initial size or increasing grow-factor too low!");
        }

        this.growFactor = growFactor;
        this.arr = new int[initSize];
    }

    int getCapacity() {
        return arr.length;
    }

    public void setGrowFactor(float factor) {
        this.growFactor = factor;
    }

    public boolean isEmpty() {
        return frontIndex >= endIndexPlusOne;
    }

    public int pop() {
        int tmp = arr[frontIndex];
        frontIndex++;

        // removing the empty space of the front if too much is unused        
        int smallerSize = (int) (arr.length / growFactor);
        if (frontIndex > smallerSize) {
            endIndexPlusOne = getSize();
            // ensure that there are at least 10 entries
            int[] newArr = new int[endIndexPlusOne + 10];
            System.arraycopy(arr, frontIndex, newArr, 0, endIndexPlusOne);
            arr = newArr;
            frontIndex = 0;
        }

        return tmp;
    }

    public int getSize() {
        return endIndexPlusOne - frontIndex;
    }

    public void push(int v) {
        if (endIndexPlusOne >= arr.length) {
            arr = Arrays.copyOf(arr, (int) (arr.length * growFactor));
        }

        arr[endIndexPlusOne] = v;
        endIndexPlusOne++;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        for (int i = frontIndex; i < endIndexPlusOne; i++) {
            if (i > frontIndex) {
                sb.append(", ");
            }
            sb.append(arr[i]);
        }
        return sb.toString();
    }
}