c08p429b.txt

来自「Data Abstraction & Problem Solving with 」· 文本 代码 · 共 81 行

// *********************************************************
// Header file ListI.h for the ADT list.
// Implementation uses ListIterator.
// *********************************************************
#include "ListIterator.h"
#include "ListException.h"

class List
{
public:
// constructors and destructor:
   List();
   List(const List& aList);
   ~List();

// List operations:
   bool isEmpty() const; 
   int getLength() const;

   ListIterator insert(ListIterator iter, 
                       ListItemType newItem)
         throw(ListException);
   // Inserts an item into a list after the item 
   // specified by iter.  An iterator to the newly
   // added item is returned.
   // Precondition: Iterator iter specifies either an 
   // item in the list or the end of the list.
   // Postcondition:  If iter equals the value returned
   // by end(), newItem is placed at the end of the 
   // list. Returns an iterator to newItem within the list.
   // Exception: Throws ListException if the iterator is
   // not initialized properly for this list.

   void retrieve(ListIterator iter,
                 ListItemType& dataItem) const
         throw(ListException);
   // Retrieves an item in the list.
   // Precondition: Iterator iter specifies an item in
   // the list.
   // Postcondition: dataItem is the value of the 
   // desired item.
   // Exception: Throws ListException if the iterator is
   // not initialized properly for this list.
  ListIterator remove(ListIterator iter) throw(ListException);
   // Removes an item from the list and returns an
   // iterator to the item after the removed item.
   // Precondition: Iterator iter specifies an item in
   // the list.
   // Postcondition: The item specified by iter is 
   // removed from the list. Returns an iterator that
   // references the item after the one removed. If the last 
   // item in the list is removed, returns an iterator that
   // is equal to the result returned by end().
   // Exception: Throws ListException if the iterator is
   // not initialized properly for this list.

   ListIterator begin() const;
   // Returns an iterator that references the first item    // in the list.
   // Precondition: None.
   // Postcondition: Returns an iterator to the first 
   // item in the list. If the list is empty, returns an
  // iterator that is equal to the result returned by end().

   ListIterator end() const;
   // Returns an iterator value that can be used to 
   // determine whether an iterator has reached the end 
   // of the list.
   // Precondition: None.
   // Postcondition: None

private:
   int      size;   // number of items in the list
   ListNode *head;  // pointer to the linked list

   ListNode *findPrev(ListIterator iter);
   // Locates the node before the node specified by iter.
   // Precondition: The list is not empty (head != NULL).
   // Postcondition: Returns a pointer to the node 
   // before the node referenced by iter.  If iter == end(),
   // returns a pointer to the last node in the list.
};  // end class