From 1076427f843612a61d6190ab740d0bbd32053075 Mon Sep 17 00:00:00 2001
From: Shaun Reed <shaunrd0@gmail.com>
Date: Fri, 12 Jun 2020 00:21:59 -0400
Subject: [PATCH] Add RD of queue using linked list

---
 cpp/datastructs/queuelist/Makefile      |  23 +++
 cpp/datastructs/queuelist/driver.cpp    |  68 +++++++
 cpp/datastructs/queuelist/queuelist.cpp | 255 ++++++++++++++++++++++++
 cpp/datastructs/queuelist/queuelist.h   |  44 ++++
 4 files changed, 390 insertions(+)
 create mode 100644 cpp/datastructs/queuelist/Makefile
 create mode 100644 cpp/datastructs/queuelist/driver.cpp
 create mode 100644 cpp/datastructs/queuelist/queuelist.cpp
 create mode 100644 cpp/datastructs/queuelist/queuelist.h

diff --git a/cpp/datastructs/queuelist/Makefile b/cpp/datastructs/queuelist/Makefile
new file mode 100644
index 0000000..0197dd3
--- /dev/null
+++ b/cpp/datastructs/queuelist/Makefile
@@ -0,0 +1,23 @@
+CXX=g++
+CXXFLAGS=-g -Wall
+
+###############################################################################
+# Driver
+###############################################################################
+
+driver:	driver.cpp	queuelist.o
+	${CXX} ${CXXFLAGS} driver.cpp queuelist.o -o driver
+
+###############################################################################
+# QueueList
+###############################################################################
+
+queuelist.o:	queuelist.cpp queuelist.h
+	${CXX} ${CXXFLAGS} -c queuelist.cpp -o queuelist.o
+
+###############################################################################
+# Clean
+###############################################################################
+
+clean:
+	rm -f *.o driver
diff --git a/cpp/datastructs/queuelist/driver.cpp b/cpp/datastructs/queuelist/driver.cpp
new file mode 100644
index 0000000..508a05c
--- /dev/null
+++ b/cpp/datastructs/queuelist/driver.cpp
@@ -0,0 +1,68 @@
+/*#############################################################################
+## Author: Shaun Reed                                                        ##
+## Legal: All Content (c) 2020 Shaun Reed, all rights reserved               ##
+## About: A driver program to test a queue implementation using linked lists ##
+##                                                                           ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0  ##
+##############################################################################
+## driver.cpp
+*/
+
+#include "queuelist.h"
+#include <iostream>
+
+enum OPS {
+  EXIT, ENQUEUE, DEQUEUE, NEXT, PRINT, EMPTY
+};
+
+int main()
+{
+  std::cout << "Driver: \n";
+
+  QueueList testList;
+  bool exit = false;
+  int choice = -1;
+  int val;
+
+  while (!exit)
+  {
+    std::cout << "##### Queues Using Linked Lists Menu #####\n\t0. Exit"
+      << "\n\t1. Enqueue\n\t2. Dequeue\n\t3. Next\n\t4. Print"
+      << "\n\t5. Empty\n\t";
+    std::cin >> choice;
+    std::cin.clear();
+    switch (choice) {
+    case EXIT:
+      exit = true;
+      break;
+
+    case ENQUEUE:
+      std::cout << "Enter a value to add to the end of our queue: ";
+      std::cin >> val;
+      std::cin.clear();
+      testList.enqueue(val);
+      break;
+
+    case DEQUEUE:
+      testList.dequeue();
+      break;
+
+    case NEXT:
+      testList.next();
+      break;
+
+    case PRINT:
+      testList.print();
+      break;
+
+    case EMPTY:
+      testList.makeEmpty();
+      break;
+
+    default:
+      std::cout << "Invalid entry...\n";
+      break;
+    }
+  }
+}
+
diff --git a/cpp/datastructs/queuelist/queuelist.cpp b/cpp/datastructs/queuelist/queuelist.cpp
new file mode 100644
index 0000000..ee01580
--- /dev/null
+++ b/cpp/datastructs/queuelist/queuelist.cpp
@@ -0,0 +1,255 @@
+/*#############################################################################
+## Author: Shaun Reed                                                        ##
+## Legal: All Content (c) 2020 Shaun Reed, all rights reserved               ##
+## About: An example of a queue implementation using linked lists            ##
+##                                                                           ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0  ##
+##############################################################################
+## queuelist.cpp
+*/
+
+#include "queuelist.h"
+
+
+/******************************************************************************
+ * Constructors, Destructors, Operators
+ *****************************************************************************/
+
+/** copy constructor
+ * @brief Construct a new QueueList::QueueList object from an existing one
+ *        Creates a new deep copy of a given QueueList
+ *
+ * @param rhs QueueList object
+ */
+QueueList::QueueList(const QueueList& rhs)
+{
+  Node *cp = rhs.head;
+  Node *tempHead;
+  // If we are copying from an empty queue, create a new QueueList with a NULL head
+  if (cp == NULL) head = NULL;
+  else {
+    // If the queue has data, initialize a new queue with the head data
+    head = new Node(cp->data);
+    // Keep a temporary head node so we can return to it later
+    tempHead = head;
+    while (cp->next != NULL) {
+      // Until we hit an end, create new nodes with the next node data
+      cp = cp->next;
+      head->next = new Node(cp->data);
+      head = head->next;
+    }
+    tail = head;
+    head = tempHead;
+  }
+}
+
+/** operator=
+ * @brief Assign two QueueList objects equal using copy constr and class destr
+ *        Pass the rhs by value to create local copy, swap its contents
+ *        Destructor called on previous QueueList data at the end of this scope
+ *
+ * @param rhs QueueList object passed by value
+ * @return QueueList A deep copy of the rhs QueueList object
+ */
+QueueList QueueList::operator=(QueueList rhs)
+{
+  if (this == &rhs) return *this;
+  // Swap the pointers, moving the previous head data to the local variable rhs 
+  std::swap(head, rhs.head);
+  return *this;
+}
+
+/** destructor
+ * @brief Destroy the QueueList::QueueList object
+ */
+QueueList::~QueueList()
+{
+  makeEmpty(head);
+}
+
+
+/******************************************************************************
+ * Public Member Functions
+ *****************************************************************************/
+
+/** enqueue
+ * @brief Queue a value to the tail of our linked list
+ *
+ * @param x The value to be inserted into the queue
+ */
+bool QueueList::enqueue(int val)
+{
+  bool inserted = enqueue(val, tail);
+  if (inserted)
+    std::cout << "[" << val << "] was inserted into the queue\n";
+  else std::cout << "[" << val << "] could not be inserted into the queue\n";
+  return inserted;
+}
+
+/** dequeue
+ * @brief returns the value at the QueueList::head and moves head to the next in queue
+ *
+ * @return int The value held at the Node pointed to by QueueList::head
+ */
+int QueueList::dequeue()
+{
+  if (!isEmpty())
+    std::cout << "[" << dequeue(head) << "] has been removed from our queue\n";
+  else std::cout << "Nothing to dequeue, our queue is empty...\n";
+  // If the queue has data we return it, otherwise we return the smallest possible int (error)
+  return (!isEmpty()) ? head->data : INT32_MIN;
+}
+
+/** next
+ * @brief returns the value at the QueueList::head
+ *
+ * @return int The value held at the Node pointed to by QueueList::head
+ */
+int QueueList::next() const
+{
+  if (!isEmpty())
+    std::cout << "[" << head->data << "] is next in queue\n";
+  else std::cout << "Our queue is empty...\n";
+  // If the queue has data we return it, otherwise we return the smallest possible int (error)
+  return (!isEmpty()) ? head->data : INT32_MIN;
+}
+
+/** isEmpty
+ * @brief Determine if the QueueList is empty
+ *
+ * @return true If the QueueList::head is NULL
+ * @return false If the QueueList::head contains data
+ */
+bool QueueList::isEmpty() const
+{
+  return head == NULL;
+}
+
+/** print
+ * @brief Output the data held by the QueueList object
+ *        Calls to the private print()
+ */
+void QueueList::print() const
+{
+  if(!isEmpty()) print(head);
+  else std::cout << "Nothing to print, our queue is empty...\n";
+}
+
+/** makeEmpty
+ * @brief Empty this QueueList object, deleting all associated Nodes
+ */
+void QueueList::makeEmpty()
+{
+  Node *nextNode, *temp;
+
+  if (head == NULL) std::cout << "Our queue is empty...\n";
+  else {
+    nextNode = head->next;
+    delete head;
+    head = NULL;
+    tail = NULL;
+    while(nextNode != NULL) {
+      temp = nextNode;
+      nextNode = nextNode->next;
+      delete temp;
+      temp = NULL;
+    }
+
+  }
+}
+
+/******************************************************************************
+ * Private Member Functions
+ *****************************************************************************/
+
+/** queue
+ * @brief Private member to handle inserting value into the back of the queue
+ *
+ * @param val Value to be inserted
+ * @param tail The tail of the queue to insert into
+ * @return true If the value was inserted
+ * @return false If the value could not be inserted
+ */
+bool QueueList::enqueue(int val, Node *&tail)
+{
+  Node *newNode = new Node(val);
+  // If the queue is not empty, update next pointer to tail node
+  if (!isEmpty()) {
+    tail->next = newNode;
+  }
+  else head = newNode;
+  // Always set tail to our newNode
+  tail = newNode;
+  return true;
+}
+
+/** dequeue
+ * @brief Removes a node from the front of the queue
+ * 
+ * @param head The head of the queue to remove a node from
+ * @return int The value held at the node removed
+ */
+int QueueList::dequeue(Node *&head)
+{
+  // We already know the queue is not empty from public dequeue()
+  Node *temp = head;
+  // Store the data at the front of the queue before we delete the node
+  int data = head->data;
+
+  // If there is only one item in the queue 
+  if (temp == tail) {
+    tail = head = NULL;
+    delete temp;
+    return data;
+  }
+
+  // Move the front of the queue to the next node
+  head = head->next;
+  // tail->next = NULL;
+  // Delete the previous head node
+  delete temp;
+  return data;
+}
+
+/** print
+ * @brief Output the contents of a QueueList from the given Node to NULL
+ *
+ * @param start The Node to begin traversing output from
+ */
+void QueueList::print(Node *start) const
+{
+  Node *temp = start;
+  std::cout << "Queue Contents: ";
+  while (temp != NULL) {
+    std::cout << temp->data << " | ";
+    temp = temp->next;
+  }
+  std::cout << std::endl;
+}
+
+/** makeEmpty
+ * @brief Private member to empty this QueueList object, deletes all Nodes in the queue
+ *        Does not print any output. Avoids destructors printing to cout
+ * 
+ * @param head The head of the queue to be deleted
+ * 
+ */
+void QueueList::makeEmpty(Node *&head)
+{
+  Node *nextNode, *temp;
+
+  if (head == NULL) return;
+  else {
+    nextNode = head->next;
+    delete head;
+    head = NULL;
+    tail = NULL;
+    while(nextNode != NULL) {
+      temp = nextNode;
+      nextNode = nextNode->next;
+      delete temp;
+      temp = NULL;
+    }
+
+  }
+}
diff --git a/cpp/datastructs/queuelist/queuelist.h b/cpp/datastructs/queuelist/queuelist.h
new file mode 100644
index 0000000..ecaa243
--- /dev/null
+++ b/cpp/datastructs/queuelist/queuelist.h
@@ -0,0 +1,44 @@
+/*#############################################################################
+## Author: Shaun Reed                                                        ##
+## Legal: All Content (c) 2020 Shaun Reed, all rights reserved               ##
+## About: An example of a queue implementation using linked lists            ##
+##                                                                           ##
+## Contact: shaunrd0@gmail.com  | URL: www.shaunreed.com | GitHub: shaunrd0  ##
+##############################################################################
+## queuelist.h
+*/
+
+#ifndef QUEUELIST_H
+#define QUEUELIST_H
+
+#include <iostream>
+
+class QueueList {
+  public:
+    QueueList() : head(NULL), tail(NULL){};
+    QueueList(const QueueList& rhs);
+    QueueList operator=(QueueList rhs);
+    ~QueueList();
+    bool enqueue(int val);
+    int dequeue();
+    int next() const;
+    bool isEmpty() const;
+    void print() const;
+    void makeEmpty();
+
+  private:
+    struct Node {
+      int data;
+      Node *next;
+      Node(): data(), next(NULL) {};
+      Node(int val): data(val), next(NULL) {};
+    };
+    Node *head, *tail;
+    bool enqueue(int val, Node *&head);
+    int dequeue(Node *&tail);
+    void print(Node *start) const;
+    void makeEmpty(Node *&head);
+    
+};
+
+#endif