www.pudn.com > commutil.zip > LIST.CPP
// ******************************************************************** //
// //
// LIST.CPP //
// Copyright (c) 1993, Michael Holmes and Bob Flanders //
// C++ Communication Utilities //
// //
// Chapter 7: Receiving a FAX //
// Last changed in chapter 3 //
// //
// This file contains the definition and interface for //
// the List class. The List class implements a simple //
// double-linked list with a single string item stored //
// in the object. //
// //
// ******************************************************************** //
/* ******************************************************************** *
*
* List class definition
*
* ******************************************************************** */
class List
{
public:
List(void); // build a list header
List(char *s, // create a single entry
char *d); // ..with string and data
List(List *l, // add to end of list
char *s, // ..string name
char *d); // ..and data
List(char *s, // put at the head of list
char *d, // ..string and data
List *l); // ..list to chain to
char *Find(char *s); // find string name
~List(); // destructor
private:
void EntryInit(char *s, // initialize a entry
char *d); // ..with string and data
char *string_name, // string name
*data; // ..and data
List *prev, // pervious item pointer
*next; // next item pointer
};
/* ******************************************************************** *
*
* List -- build list header
*
* ******************************************************************** */
List::List(void)
{
EntryInit("", ""); // initialize new instance
}
/* ******************************************************************** *
*
* List -- build a single list entry
*
* ******************************************************************** */
List::List(char *s, // string name
char *d) // ..and data
{
EntryInit(s, d); // initialize new instance
}
/* ******************************************************************** *
*
* List -- add an entry to the end of the list
*
* ******************************************************************** */
List::List(List *l, // list to chain to
char *s, // string name
char *d) // ..and data
{
EntryInit(s, d); // build base instance
while (l->next) // loop thru..
l = l->next; // ..to the end of the list
l->next = this; // put this at the end
this->prev = l; // ..and backward chain
}
/* ******************************************************************** *
*
* List -- put an entry at the head of the list
*
* ******************************************************************** */
List::List(char *s, // string name
char *d, // ..and data
List *l) // list to chain into
{
EntryInit(s, d); // build base instance
this->prev = l; // set up backward link
this->next = l->next; // ..and forward link
l->next = this; // update list anchor
if (this->next) // q. any more after us?
(this->next)->prev = this; // a. yes .. set up link
}
/* ******************************************************************** *
*
* EntryInit -- initialize list entry instance
*
* ******************************************************************** */
void List::EntryInit(char *s, // string name
char *d) // ..and data
{
string_name = data = (char *) 0; // init string pointers
prev = next = 0; // ..and list pointers
if (*s) // q. string name given?
{
string_name = new char[strlen(s) + 1]; // a. yes .. get memory and
strcpy(string_name, s); // ..copy for this instance
}
if (*d) // q. data given
{
data = new char[strlen(d) + 1]; // a. yes .. get memory and
strcpy(data, d); // ..copy for this instance
}
}
/* ******************************************************************** *
*
* Find -- find a list entry by the string name
*
* ******************************************************************** */
char *List::Find(char *s) // string name to search on
{
List *l = this; // work pointer
for (;;) // loop thru the list
{
if (l->string_name && // q. string available?
NOT stricmp(s, l->string_name)) // ..and find the entry?
return(l->data); // a. yes .. quit here
if ((l = l->next) == 0) // q. end of list?
break; // a. yes .. exit loop
}
return(0); // else return empty-handed
}
/* ******************************************************************** *
*
* ~List -- object destructor
*
* ******************************************************************** */
List::~List()
{
if (string_name) // q. string name given?
delete string_name; // a. yes .. de-alloc space
if (data) // q. data string available?
delete data; // a. yes .. de-alloc space
if (this->next) // q. anything after this?
(this->next)->prev = this->prev; // a. yes .. de-chain prev
if (this->prev) // q. anything before this?
(this->prev)->next = this->next; // a. yes .. de-chain next
}