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lib/src/list/queue.cpp

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+#include <cstdlib>
+#include <cassert>
+#include "queue.h"
+
+
+DoublyListNode *newDoublyListNode(void *data) {
+    DoublyListNode *node = (DoublyListNode *) malloc(sizeof(DoublyListNode));
+    node->val = data;
+    node->next = NULL;
+    node->prev = NULL;
+    return node;
+}
+
+/* 析构函数 */
+void delDoublyListNode(DoublyListNode *node) {
+    free(node);
+}
+
+
+/* 构造函数 */
+LinkedListDeque *newLinkedListDeque() {
+    LinkedListDeque *deque = (LinkedListDeque *) malloc(sizeof(LinkedListDeque));
+    deque->front = NULL;
+    deque->rear = NULL;
+    deque->queSize = 0;
+    return deque;
+}
+
+/* 析构函数 */
+void delLinkedListdeque(LinkedListDeque *deque) {
+    // 释放所有节点
+    for (int i = 0; i < deque->queSize && deque->front != NULL; i++) {
+        DoublyListNode *tmp = deque->front;
+        deque->front = deque->front->next;
+        free(tmp);
+    }
+    // 释放 deque 结构体
+    free(deque);
+}
+
+/* 获取队列的长度 */
+int queue_size(LinkedListDeque *deque) {
+    return deque->queSize;
+}
+
+/* 判断队列是否为空 */
+bool queue_is_empty(LinkedListDeque *deque) {
+    return (queue_size(deque) == 0);
+}
+
+/* 入队 */
+void push(LinkedListDeque *deque, void *data, bool isFront) {
+    DoublyListNode *node = newDoublyListNode(data);
+    // 若链表为空，则令 front 和 rear 都指向node
+    if (queue_is_empty(deque)) {
+        deque->front = deque->rear = node;
+    }
+        // 队首入队操作
+    else if (isFront) {
+        // 将 node 添加至链表头部
+        deque->front->prev = node;
+        node->next = deque->front;
+        deque->front = node; // 更新头节点
+    }
+        // 队尾入队操作
+    else {
+        // 将 node 添加至链表尾部
+        deque->rear->next = node;
+        node->prev = deque->rear;
+        deque->rear = node;
+    }
+    deque->queSize++; // 更新队列长度
+}
+
+/* 队首入队 */
+void pushFirst(LinkedListDeque *deque, void *data) {
+    push(deque, data, true);
+}
+
+/* 队尾入队 */
+void pushLast(LinkedListDeque *deque, void *data) {
+    push(deque, data, false);
+}
+
+/* 访问队首元素 */
+void *peekFirst(LinkedListDeque *deque) {
+    assert(queue_size(deque) && deque->front);
+    return deque->front->val;
+}
+
+/* 访问队尾元素 */
+void *peekLast(LinkedListDeque *deque) {
+    assert(queue_size(deque) && deque->rear);
+    return deque->rear->val;
+}
+
+/* 出队 */
+void *pop(LinkedListDeque *deque, bool isFront) {
+    if (queue_is_empty(deque))
+        return nullptr;
+    void *val;
+    // 队首出队操作
+    if (isFront) {
+        val = peekFirst(deque); // 暂存头节点值
+        DoublyListNode *fNext = deque->front->next;
+        if (fNext) {
+            fNext->prev = NULL;
+            deque->front->next = NULL;
+        }
+        delDoublyListNode(deque->front);
+        deque->front = fNext; // 更新头节点
+    }
+        // 队尾出队操作
+    else {
+        val = peekLast(deque); // 暂存尾节点值
+        DoublyListNode *rPrev = deque->rear->prev;
+        if (rPrev) {
+            rPrev->next = NULL;
+            deque->rear->prev = NULL;
+        }
+        delDoublyListNode(deque->rear);
+        deque->rear = rPrev; // 更新尾节点
+    }
+    deque->queSize--; // 更新队列长度
+    return val;
+}
+
+/* 队首出队 */
+void *popFirst(LinkedListDeque *deque) {
+    return pop(deque, true);
+}
+
+/* 队尾出队 */
+void *popLast(LinkedListDeque *deque) {
+    return pop(deque, false);
+}