link2.h

using queue to solve traffic matter by C++ in linux environment

// FILE: link2.h
// PROVIDES: A toolkit of ten template functions for manipulating linked lists.
// Each node of the list contains a piece of data and a pointer to the next
// node, as shown in this template struct:
// 
//     template <class Item>        Item may be any of the C++ built-in types
//     struct Node                  (int, char, etc.), or a class with a default
//     {                            constructor, an assignment operator,
//         Item data;               and a test for equality (x == y).
//         Node *link;
//     };
//
// FUNCTIONS in the linked list toolkit:
//   template <class Item>
//   size_t list_length(Node<Item>* head_ptr)
//     Precondition: head_ptr is the head pointer of a linked list.
//     Postcondition: The value returned is the number of nodes in the linked
//     list. The list itself is unaltered.
//
//   template <class Item>
//   void list_head_insert(Node<Item>*& head_ptr, const Item& entry)
//     Precondition: head_ptr is the head pointer of a linked list.
//     Postcondition: A new node containing the given entry has been added at
//     the head of the linked list; head_ptr now points to the head of the new,
//     longer linked list.
//
//   template <class Item>
//   void list_insert(Node<Item>* previous_ptr, const Item& entry) 
//     Precondition: previous_ptr points to a node in a linked list.
//     Postcondition: A new node containing the given entry has been added
//     after the node that previous_ptr points to.
//
//   template <class Item>
//   Node<Item>* list_search(Node<Item>* head_ptr, const Item& target)
//     Precondition: head_ptr is the head pointer of a linked list.
//     Postcondition: The pointer returned points to the first node containing
//     the specified target in its data member. If there is no such node, the
//     null pointer is returned. The list itself is unaltered.
//
//   template <class Item, class SizeType>
//   Node<Item>* list_locate(Node<Item>* head_ptr, SizeType position)
//     Precondition: head_ptr is the head pointer of a list, and position > 0.
//     Postcondition: The pointer returned points to the node at the specified
//     position in the list. (The head node is position 1, the next node is
//     position 2, and so on). If there is no such position, then the null
//     pointer is returned. The list itself is unaltered.
//
//   template <class Item>
//   void list_head_remove(Node<Item>*& head_ptr)
//     Precondition: head_ptr is the head pointer of a linked list, with at
//     least one node.
//     Postcondition: The head node has been removed and returned to the heap;
//     head_ptr is now the head pointer of the new, shorter linked list.
//
//   template <class Item>
//   void list_remove(Node<Item>* previous_ptr)
//     Precondition: previous_ptr points to a node in a linked list, and this
//     is not the tail node of the list.
//     Postcondition: The node after previous_ptr has been removed.
//
//   template <class Item>
//   void list_clear(Node<Item>*& head_ptr)
//     Precondition: head_ptr is the head pointer of a linked list.
//     Postcondition: All nodes of the list have been returned to the heap,
//     and the head_ptr is now NULL.
//
//   template <class Item>
//   void list_copy
//     (Node<Item>* source_ptr, Node<Item>*& head_ptr, Node<Item>*& tail_ptr)
//     Precondition: source_ptr is the head pointer of a linked list.
//     Postcondition: head_ptr and tail_ptr are the head and tail pointers for
//     a new list that that contains the same items as the list pointed to by
//     source_ptr.
//
//   template <class Item>
//   void list_piece
//     (Node<Item>* source_ptr, Node<Item>* end_ptr,
//     Node<Item>*& head_ptr, Node<Item>*& tail_ptr)
//     Precondition: source_ptr and end_ptr are pointers to nodes on the same
//     linked list, with the source_ptr node at or before the end_ptr node.
//     Postcondition: head_ptr and tail_ptr are the head and tail pointers for
//     a new linked list that contains the items from source_ptr to end_ptr.
//     The original list is unaltered.

#ifndef LINK2_H
#define LINK2_H
#include <stdlib.h> // Provides size_t

    template <class Item>
    struct Node
    {
        Item data;
        Node *link;
    };

    // FUNCTIONS for the linked list toolkit
    template <class Item>
    size_t list_length(Node<Item>* head_ptr);

    template <class Item>
    void list_head_insert(Node<Item>*& head_ptr, const Item& entry); 

    template <class Item>
    void list_insert(Node<Item>* previous_ptr, const Item& entry);

    template <class Item>
    Node<Item>* list_search(Node<Item>* head_ptr, const Item& target);

    template <class Item, class SizeType>
    Node<Item>* list_locate(Node<Item>* head_ptr, SizeType position);

    template <class Item>
    void list_head_remove(Node<Item>*& head_ptr);

    template <class Item>
    void list_remove(Node<Item>* previous_ptr);

    template <class Item>
    void list_clear(Node<Item>*& head_ptr);

    template <class Item>
    void list_copy 
      (Node<Item>* source_ptr, Node<Item>*& head_ptr, Node<Item>*& tail_ptr);

    template <class Item>
    void list_piece
      (Node<Item>*  source_ptr, Node<Item>*  end_ptr,
       Node<Item>*& head_ptr,   Node<Item>*& tail_ptr);

#include "link2.template"  // Include the implementation
#endif