php-src/dlist.c
1999-07-19 18:58:44 +00:00

419 lines
12 KiB
C

/****************************************************************************
*
* Copyright (C) 1991 Kendall Bennett.
* All rights reserved.
*
* Filename: $RCSfile$
* Version: $Revision$
*
* Language: ANSI C
* Environment: any
*
* Description: Module to implement doubly linked lists. Includes a routine
* to peform a mergesort on the doubly linked list.
*
* $Id$
*
* Revision History:
* -----------------
*
* $Log$
* Revision 1.2 1999/05/11 00:01:42 zeev
* * Get Apache to work. POST doesn't work yet.
* * There are now -I directives for the absolute path of php4, php4/libzend and the builddir for
* the Apache module, so we can #include any php/Zend header.
* * Rename config.h to php_config.h
*
* Revision 1.1 1999/04/21 23:11:20 ssb
* moved apache, com and hyperwave into ext/
*
* Revision 1.1.1.1 1999/04/07 21:03:31 zeev
* PHP 4.0
*
* Revision 1.1.1.1 1999/03/17 04:29:11 andi
* PHP4
*
* Revision 1.1.1.1 1998/12/21 07:56:22 andi
* Trying to start the zend CVS tree
*
* Revision 1.1 1998/08/12 09:29:16 steinm
* First version of Hyperwave module.
*
* Revision 1.5 91/12/31 19:39:49 kjb
* Modified include file directories.
*
* Revision 1.4 91/10/28 03:16:39 kjb
* Ported to the Iris.
*
* Revision 1.3 91/09/27 03:09:18 kjb
* Cosmetic change.
*
* Revision 1.2 91/09/03 18:27:42 ROOT_DOS
* Ported to UNIX.
*
* Revision 1.1 91/09/01 18:35:23 ROOT_DOS
* Initial revision
*
****************************************************************************/
#ifndef MSVC5
#include "php_config.h"
#endif
#include <stdio.h>
#include <malloc.h>
#include <signal.h>
#include "dlist.h"
#define PUBLIC
#define PRIVATE static
PUBLIC void *dlst_newnode(int size)
/****************************************************************************
*
* Function: dlst_newnode
* Parameters: size - Amount of memory to allocate for node
* Returns: Pointer to the allocated node's user space.
*
* Description: Allocates the memory required for a node, adding a small
* header at the start of the node. We return a reference to
* the user space of the node, as if it had been allocated via
* malloc().
*
****************************************************************************/
{
PHP_DLST_BUCKET *node;
if ( !(node = (PHP_DLST_BUCKET*)malloc(size + sizeof(PHP_DLST_BUCKET))) ) {
fprintf(stderr,"Not enough memory to allocate list node.\n");
/* raise(SIGABRT);*/
return NULL;
}
return PHP_DLST_USERSPACE(node); /* Return pointer to user space */
}
PUBLIC void dlst_freenode(void *node)
/****************************************************************************
*
* Function: dlst_freenode
* Parameters: node - Node to free.
*
* Description: Frees a node previously allocated with lst_newnode().
*
****************************************************************************/
{
free(PHP_DLST_HEADER(node));
}
PUBLIC DLIST *dlst_init(void)
/****************************************************************************
*
* Function: dlst_init
* Returns: Pointer to a newly created list.
*
* Description: Initialises a list and returns a pointer to it.
*
****************************************************************************/
{
DLIST *l;
if ((l = (DLIST*)malloc(sizeof(DLIST))) != NULL) {
l->count = 0;
l->head = &(l->hz[0]);
l->z = &(l->hz[1]);
l->head->next = l->z->next = l->z;
l->z->prev = l->head->prev = l->head;
}
else {
fprintf(stderr,"Insufficient memory to allocate list\n");
/*raise(SIGABRT);*/
return NULL;
}
return l;
}
PUBLIC void dlst_kill(DLIST *l,void (*freeNode)(void *node))
/****************************************************************************
*
* Function: dlst_kill
* Parameters: l - List to kill
* freeNode - Pointer to user routine to free a node
*
* Description: Kills the list l, by deleting all of the elements contained
* within the list one by one and then deleting the list
* itself. Note that we call the user supplied routine
* (*freeNode)() to free each list node. This allows the user
* program to perform any extra processing needed to kill each
* node (if each node contains pointers to other items on the
* heap for example). If no extra processing is required, just
* pass the address of dlst_freenode(), ie:
*
* dlst_kill(myList,dlst_freenode);
*
****************************************************************************/
{
PHP_DLST_BUCKET *n,*p;
n = l->head->next;
while (n != l->z) { /* Free all nodes in list */
p = n;
n = n->next;
(*freeNode)(PHP_DLST_USERSPACE(p));
}
free(l); /* Free the list itself */
}
PUBLIC void dlst_insertafter(DLIST *l,void *node,void *after)
/****************************************************************************
*
* Function: lst_insertafter
* Parameters: l - List to insert node into
* node - Pointer to user space of node to insert
* after - Pointer to user space of node to insert node after
*
* Description: Inserts a new node into the list after the node 'after'. To
* insert a new node at the beginning of the list, user the
* macro PHP_DLST_HEAD in place of 'after'. ie:
*
* dlst_insertafter(mylist,node,PHP_DLST_HEAD(mylist));
*
****************************************************************************/
{
PHP_DLST_BUCKET *n = PHP_DLST_HEADER(node),*a = PHP_DLST_HEADER(after);
n->next = a->next;
a->next = n;
n->prev = a;
n->next->prev = n;
l->count++;
}
PUBLIC void *dlst_deletenext(DLIST *l,void *node)
/****************************************************************************
*
* Function: lst_deletenext
* Parameters: l - List to delete node from.
* node - Node to delete the next node from
* Returns: Pointer to the deleted node's userspace.
*
* Description: Removes the node AFTER 'node' from the list l.
*
****************************************************************************/
{
PHP_DLST_BUCKET *n = PHP_DLST_HEADER(node);
node = PHP_DLST_USERSPACE(n->next);
n->next->next->prev = n;
n->next = n->next->next;
l->count--;
return node;
}
PUBLIC void *dlst_first(DLIST *l)
/****************************************************************************
*
* Function: dlst_first
* Parameters: l - List to obtain first node from
* Returns: Pointer to first node in list, NULL if list is empty.
*
* Description: Returns a pointer to the user space of the first node in
* the list. If the list is empty, we return NULL.
*
****************************************************************************/
{
PHP_DLST_BUCKET *n;
n = l->head->next;
return (n == l->z ? NULL : PHP_DLST_USERSPACE(n));
}
PUBLIC void *dlst_last(DLIST *l)
/****************************************************************************
*
* Function: dlst_last
* Parameters: l - List to obtain last node from
* Returns: Pointer to last node in list, NULL if list is empty.
*
* Description: Returns a pointer to the user space of the last node in
* the list. If the list is empty, we return NULL.
*
****************************************************************************/
{
PHP_DLST_BUCKET *n;
n = l->z->prev;
return (n == l->head ? NULL : PHP_DLST_USERSPACE(n));
}
PUBLIC void *dlst_next(void *prev)
/****************************************************************************
*
* Function: dlst_next
* Parameters: prev - Previous node in list to obtain next node from
* Returns: Pointer to the next node in the list, NULL at end of list.
*
* Description: Returns a pointer to the user space of the next node in the
* list given a pointer to the user space of the previous node.
* If we have reached the end of the list, we return NULL. The
* end of the list is detected when the next pointer of a node
* points back to itself, as does the dummy last node's next
* pointer. This enables us to detect the end of the list
* without needed access to the list data structure itself.
*
* NOTE: We do no checking to ensure that 'prev' is NOT a
* NULL pointer.
*
****************************************************************************/
{
PHP_DLST_BUCKET *n = PHP_DLST_HEADER(prev);
n = n->next;
return (n == n->next ? NULL : PHP_DLST_USERSPACE(n));
}
PUBLIC void *dlst_prev(void *next)
/****************************************************************************
*
* Function: dlst_prev
* Parameters: next - Next node in list to obtain previous node from
* Returns: Pointer to the previous node in the list, NULL at start list.
*
* Description: Returns a pointer to the user space of the prev node in the
* list given a pointer to the user space of the next node.
* If we have reached the start of the list, we return NULL. The
* start of the list is detected when the prev pointer of a node
* points back to itself, as does the dummy head node's prev
* pointer. This enables us to detect the start of the list
* without needed access to the list data structure itself.
*
* NOTE: We do no checking to ensure that 'next' is NOT a
* NULL pointer.
*
****************************************************************************/
{
PHP_DLST_BUCKET *n = PHP_DLST_HEADER(next);
n = n->prev;
return (n == n->prev ? NULL : PHP_DLST_USERSPACE(n));
}
/* Static globals required by merge() */
static PHP_DLST_BUCKET *z;
static int (*cmp)(void*,void*);
PRIVATE PHP_DLST_BUCKET *merge(PHP_DLST_BUCKET *a,PHP_DLST_BUCKET *b,PHP_DLST_BUCKET **end)
/****************************************************************************
*
* Function: merge
* Parameters: a,b - Sublist's to merge
* Returns: Pointer to the merged sublists.
*
* Description: Merges two sorted lists of nodes together into a single
* sorted list.
*
****************************************************************************/
{
PHP_DLST_BUCKET *c;
/* Go through the lists, merging them together in sorted order */
c = z;
while (a != z && b != z) {
if ((*cmp)(PHP_DLST_USERSPACE(a),PHP_DLST_USERSPACE(b)) <= 0) {
c->next = a; c = a; a = a->next;
}
else {
c->next = b; c = b; b = b->next;
}
};
/* If one of the lists is not exhausted, then re-attach it to the end
* of the newly merged list
*/
if (a != z) c->next = a;
if (b != z) c->next = b;
/* Set *end to point to the end of the newly merged list */
while (c->next != z) c = c->next;
*end = c;
/* Determine the start of the merged lists, and reset z to point to
* itself
*/
c = z->next; z->next = z;
return c;
}
PUBLIC void dlst_mergesort(DLIST *l,int (*cmp_func)(void*,void*))
/****************************************************************************
*
* Function: dlst_mergesort
* Parameters: l - List to merge sort
* cmp_func - Function to compare two user spaces
*
* Description: Mergesort's all the nodes in the list. 'cmp' must point to
* a comparison function that can compare the user spaces of
* two different nodes. 'cmp' should work the same as
* strcmp(), in terms of the values it returns. Rather than
* waste processing time keeping the previous pointers up to
* date while performing the mergesort, we simply run through
* the list at the end of the sort to fix the previous pointers.
*
****************************************************************************/
{
int i,N;
PHP_DLST_BUCKET *a,*b; /* Pointers to sublists to merge */
PHP_DLST_BUCKET *c; /* Pointer to end of sorted sublists */
PHP_DLST_BUCKET *head; /* Pointer to dummy head node for list */
PHP_DLST_BUCKET *todo; /* Pointer to sublists yet to be sorted */
PHP_DLST_BUCKET *t; /* Temporary */
/* Set up globals required by merge() and pointer to head */
z = l->z; cmp = cmp_func; head = l->head;
for (N = 1,a = z; a != head->next; N = N + N) {
todo = head->next; c = head;
while (todo != z) {
/* Build first sublist to be merged, and splice from main list
*/
a = t = todo;
for (i = 1; i < N; i++) t = t->next;
b = t->next; t->next = z; t = b;
/* Build second sublist to be merged and splice from main list
*/
for (i = 1; i < N; i++) t = t->next;
todo = t->next; t->next = z;
/* Merge the two sublists created, and set 'c' to point to the
* end of the newly merged sublists.
*/
c->next = merge(a,b,&t); c = t;
}
}
/* Fix the previous pointers for the list */
a = b = l->head;
b = b->next;
while (1) {
b->prev = a;
if (b == z)
break;
a = a->next;
b = b->next;
}
}