netsurf/utils/ring.h

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/*
* Copyright 2006, 2007 Daniel Silverstone <dsilvers@digital-scurf.org>
*
* This file is part of NetSurf, http://www.netsurf-browser.org/
*
* NetSurf is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License.
*
* NetSurf is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/** \file
* Ring list structure.
*
* Rings are structures which have an r_next pointer and an r_prev
* pointer which are always initialised and always point at the next
* or previous element respectively.
*
* The degenerate case of a single element in the ring simply points
* at itself in both directions. A zero element ring is NULL.
*
* Some of the ring functions are specific to the fetcher but may be
* of use to others and are thus included here.
*/
#ifndef _NETSURF_UTILS_RING_H_
#define _NETSURF_UTILS_RING_H_
/** Insert the given item into the specified ring.
* Assumes that the element is zeroed as appropriate.
*/
#define RING_INSERT(ring,element) \
/*LOG(("RING_INSERT(%s, %p(%s))", #ring, element, element->host));*/ \
if (ring) { \
element->r_next = ring; \
element->r_prev = ring->r_prev; \
ring->r_prev = element; \
element->r_prev->r_next = element; \
} else \
ring = element->r_prev = element->r_next = element
/** Remove the given element from the specified ring.
* Will zero the element as needed
*/
#define RING_REMOVE(ring, element) \
/*LOG(("RING_REMOVE(%s, %p(%s)", #ring, element, element->host));*/ \
if (element->r_next != element ) { \
/* Not the only thing in the ring */ \
element->r_next->r_prev = element->r_prev; \
element->r_prev->r_next = element->r_next; \
if (ring == element) ring = element->r_next; \
} else { \
/* Only thing in the ring */ \
ring = 0; \
} \
element->r_next = element->r_prev = 0
/** Find the element (by hostname) in the given ring, leave it in the
* provided element variable
*/
#define RING_FINDBYHOST(ring, element, hostname) \
/*LOG(("RING_FINDBYHOST(%s, %s)", #ring, hostname));*/ \
if (ring) { \
bool found = false; \
element = ring; \
do { \
if (strcasecmp(element->host, hostname) == 0) { \
found = true; \
break; \
} \
element = element->r_next; \
} while (element != ring); \
if (!found) element = 0; \
} else element = 0
/** Measure the size of a ring and put it in the supplied variable */
#define RING_GETSIZE(ringtype, ring, sizevar) \
/*LOG(("RING_GETSIZE(%s)", #ring));*/ \
if (ring) { \
ringtype *p = ring; \
sizevar = 0; \
do { \
sizevar++; \
p = p->r_next; \
} while (p != ring); \
} else sizevar = 0
/** Count the number of elements in the ring which match the provided hostname */
#define RING_COUNTBYHOST(ringtype, ring, sizevar, hostname) \
/*LOG(("RING_COUNTBYHOST(%s, %s)", #ring, hostname));*/ \
if (ring) { \
ringtype *p = ring; \
sizevar = 0; \
do { \
if (strcasecmp(p->host, hostname) == 0) \
sizevar++; \
p = p->r_next; \
} while (p != ring); \
} else sizevar = 0
/*
* Ring iteration works as follows:
*
* RING_ITERATE_START(ringtype, ring, iteratorptr) {
* code_using(iteratorptr);
* } RING_ITERATE_END(ring, iteratorptr);
*
* If you want to stop iterating (e.g. you found your answer)
* RING_ITERATE_STOP(ring, iteratorptr);
* You *MUST* abort the iteration if you do something to modify
* the ring such as deleting or adding an element.
*/
#define RING_ITERATE_START(ringtype, ring, iteratorptr) \
if (ring != NULL) { \
ringtype *iteratorptr = ring; \
do { \
do { \
#define RING_ITERATE_STOP(ring, iteratorptr) \
goto iteration_end_##ring##_##iteratorptr
#define RING_ITERATE_END(ring, iteratorptr) \
} while (false); \
iteratorptr = iteratorptr->r_next; \
} while (iteratorptr != ring); \
} \
iteration_end_##ring##_##iteratorptr:
#endif