queued.h

Code

/*
    queued.h
    CIS 250
    Dave Klick
    2008-03-24
   
    This program implements a templated queue class.
*/
#ifndef __QUEUED_H_
#define __QUEUED_H_
#include <cstdlib>

template <class T>
class queued {
private:
    struct Node {
        T data;
        Node* next;
    };
    Node* head;
public:
    queued();
    queued(const queued& q);
    ~queued();
    bool isEmpty() const;
    bool isFull() const;
    bool add(const T data);
    bool remove(T& data);
    queued& operator=(const queued& q);
};

template <class T>
queued<T>::queued() { head = NULL; }

template <class T>
queued<T>::queued(const queued& q) {
    Node* p = q.head;
    Node* prev = NULL;
    while (p != NULL) {
        // create new node
        Node* n = new Node();
        if (n == NULL) return; // unrecoverable error
        n->data = p->data;
        n->next = NULL;
        // set up pointers
        if (prev == NULL) head = n; // first node in stack/list
        else prev->next = n;
        // get ready for next pass
        prev = n;
        p = p->next;
    }
}

template <class T>
queued<T>& queued<T>::operator=(const queued<T>& q) {
    if (this == &q) return *this;
    T tmp;
    while (!isEmpty()) remove(tmp);
    Node* p = q.head;
    Node* prev = NULL;
    while (p != NULL) {
        // create new node
        Node* n = new Node();
        if (n == NULL) return *this; // unrecoverable error
        n->data = p->data;
        n->next = NULL;
        // set up pointers
        if (prev == NULL) head = n; // first node in stack/list
        else prev->next = n;
        // get ready for next pass
        prev = n;
        p = p->next;
    }
    return *this;
}

template <class T>
queued<T>::~queued() {
    T tmp;
    while (!isEmpty()) remove(tmp);
}

template <typename T>
bool queued<T>::isEmpty() const { return head==NULL; }

template <class T>
bool queued<T>::add(const T data) {
    Node* n = new Node();
    if (n==NULL) return false;
    n->data = data;
    n->next = NULL;
    if (head == NULL) head = n;
    else {
        Node* p = head;
        while (p->next != NULL) p = p->next;
        p->next = n;
    }
    return true;
}

template <class T>
bool queued<T>::remove(T& data) {
    if (isEmpty()) return false;
    Node* tmp = head;
    data = head->data;
    head = head->next;
    delete tmp;
    return true;
}

#endif