LoopQueue 快速实现

#include "gtest/gtest.h"
#include "Util/LoopQueue/LoopQueue.h"

struct LoopQueueTest : testing::Test
{
protected:
    LoopQueue loopQueue;
};

TEST_F(LoopQueueTest, should_return_n_when_n_less_than_MAX_LOOP_QUEUE_LEN)
{
    loopQueue.add(1);
    loopQueue.add(2);
    loopQueue.add(3);
    loopQueue.add(4);
    loopQueue.add(5);

    ASSERT_EQ(5, loopQueue.getLatest());
}

TEST_F(LoopQueueTest, should_return_n_when_n_equals_MAX_LOOP_QUEUE_LEN)
{
    loopQueue.add(1);
    loopQueue.add(2);
    loopQueue.add(3);
    loopQueue.add(4);
    loopQueue.add(5);
    loopQueue.add(6);

    ASSERT_EQ(6, loopQueue.getLatest());
}

TEST_F(LoopQueueTest, should_return_n_when_n_more_than_MAX_LOOP_QUEUE_LEN)
{
    loopQueue.add(1);
    loopQueue.add(2);
    loopQueue.add(3);
    loopQueue.add(4);
    loopQueue.add(5);
    loopQueue.add(6);
    loopQueue.add(7);
    loopQueue.add(8);
    loopQueue.add(9);

    ASSERT_EQ(9, loopQueue.getLatest());
}

#ifndef _INCL_DESIGN_PATTERNS_LoopQueue_H
#define _INCL_DESIGN_PATTERNS_LoopQueue_H

struct LoopQueue
{
    LoopQueue();

    void add(const int&);
    
    void print() const;
    int getLatest() const;

private:
    int latestIndex;
    int len;

private:
    enum { MAX_LOOP_QUEUE_LEN = 6 };
    int elems[MAX_LOOP_QUEUE_LEN];
};

#endif 

#include "Util/LoopQueue/LoopQueue.h"
#include <iostream>

LoopQueue::LoopQueue() : latestIndex(0), len(0)
{
}

void LoopQueue::add(const int& elem)
{
    elems[latestIndex] = elem;
    latestIndex = (latestIndex + 1) % MAX_LOOP_QUEUE_LEN;

    if (len != MAX_LOOP_QUEUE_LEN)
    {
        len++;
    }
    else
    {
        len = MAX_LOOP_QUEUE_LEN;
    }
}

int LoopQueue::getLatest() const
{
    return elems[latestIndex - 1];
}

void LoopQueue::print() const
{
    int cursor, gap; 

    for (int index = 0; index < len; ++index)
    {
        int gap = latestIndex - index - 1;
        int cursor = (gap < 0) ? (gap + len) : gap;

        std::cout << elems[cursor] << ",";
    }
}