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dlist.c
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C/C++ Source or Header
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1992-05-06
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3KB
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126 lines
/* The routines in this file are copyright (c) 1987 by Helene (Lee) Taran.
* Permission is granted for use and free distribution as long as the
* original author's name is included with the code.
*/
#include "dlist.h"
Init_List(list)
DLISTPTR list;
{
int *calloc();
list->next = list;
list->prev = list;
list->contents = calloc(1,sizeof(int));
*((int *)(list->contents)) = 0;
}
/* Inserts <element> before <position> in <list> */
Insert_Before(position, element, list)
DLISTPTR position, element, list;
{
*((int *)(list->contents)) = LENGTH(list) + 1;
element->next = position;
element->prev = position->prev;
position->prev->next = element;
position->prev = element;
}
/* Inserts <element> after <position> in <list> */
Insert_After(position,element,list)
DLISTPTR position, element, list;
{
*((int *)(list->contents)) = LENGTH(list) + 1;
element->prev = position;
element->next = position->next;
position->next->prev = element;
position->next = element;
}
/* Removes <element> from <list>. Assumes the <element> is currently
* a member of <list>. Does not deallocate <element>
*/
DLISTPTR Remove_Element(element,list)
DLISTPTR element,list;
{
if (ISEMPTY(list)) return(list);
*((int *)(list->contents)) = LENGTH(list) - 1;
element->prev->next = element->next;
element->next->prev = element->prev;
element->next = NULL;
element->prev = NULL;
return(element);
}
/* Member: Returns TRUE if element is a member of the list
*/
Member (element, list)
DLISTPTR element,list;
{
DLISTPTR tmp = list;
while ((tmp = tmp->next) != list)
if (tmp == element) return(TRUE);
return(FALSE);
}
/* Get_Member : returns the member of the list that contains <element>
* returns NULL if not a member of the list.
*/
DLISTPTR GET_MEMBER(element, list)
void *element;
DLISTPTR list;
{
DLISTPTR tmp = list;
while ((tmp = tmp->next) != list )
if (tmp->contents == element) return(tmp);
return(FALSE);
}
/* Find_Element: returns the member of the list that contains some element
* that satisfies the given test with respect to <element>. For example:
* you can define a function equal that returns true if two elements have
* the exact same fields.
* Returns FALSE if no member of the list satifies the test.
*/
DLISTPTR Find_Element(element,list,test)
void *element;
DLISTPTR list;
int (*test)();
{
DLISTPTR tmp = list;
while ((tmp = tmp->next) != list )
if ((*test)(tmp->contents,element)) return(tmp);
return(FALSE);
}
/* Apply : applies the given function to the contents of each list
* element.
*/
Apply(fn,list)
int (*fn)();
DLISTPTR list;
{
DLISTPTR tmp = list;
while ((tmp = tmp->next) != list) (*fn)(tmp->contents);
}
/* Removes and disposes of all elements in a list --- does not deallocate
* the head of the list. if <foo> is non-zero then deallocate the contents
* of each element.
*/
ClearList (list,foo)
DLISTPTR list;
int foo;
{
DLISTPTR doomed;
while ((doomed = Remove_Element(FIRST(list),list)) != list) {
if (foo) free(doomed->contents);
free(doomed);
}
}