125 lines
3.5 KiB
C
125 lines
3.5 KiB
C
/*
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pqueue.h
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Priority Queues
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Copyright (C) 2021 Bill Currie <bill@taniwha.org>
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Author: Bill Currie <bill@taniwha.org>
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Date: 2021/08/02
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to:
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Free Software Foundation, Inc.
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59 Temple Place - Suite 330
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Boston, MA 02111-1307, USA
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*/
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#ifndef __QF_pqueue_h
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#define __QF_pqueue_h
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#include <stdlib.h>
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#include "QF/heapsort.h"
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#include "QF/sys.h"
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/** \defgroup pqueue Priority Queues
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\ingroup utils
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Priority queue management
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*/
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///@{
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/** The structure def for a priority queue with elements of the given type.
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This is just the def of a struct delcaration: it is useless on its own.
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The intended usage is something like:
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typedef struct priority_queue_s PQUEUE_TYPE (int) priority_queue_t;
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This allows full flexibility in just how the actual type is used.
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The \a size field is the number of elements currently in the queue, and
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the \a maxSize field is the number of elements the queue can hold. The
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priority queue functions will never resize the array. However, with a
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little glue logic, priority queues can be used with dynamic arrays.
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\param T The type to use for the element array, which is accessed
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by the \a a field.
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*/
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#define PQUEUE_TYPE(T) \
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{ \
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size_t size; \
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size_t maxSize; \
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T *a; \
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int (*compare) (const T *a, const T *b, void *data); \
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void *data; \
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}
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#define PQUEUE_IS_EMPTY(queue) ((queue)->size == 0)
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#define PQUEUE_IS_FULL(queue) \
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({ \
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__auto_type q_f = (queue); \
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q_f->size == q_f->maxSize; \
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})
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#define PQUEUE_PEEK(queue) ((queue)->a[0])
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#define PQUEUE_INSERT(queue, value) \
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do { \
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__auto_type q = (queue); \
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if (PQUEUE_IS_FULL (q)) { \
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Sys_Error ("Priority queue full"); \
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} \
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q->a[q->size++] = (value); \
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heap_swim_r (q->a, q->size - 1, q->size, sizeof (q->a[0]), \
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(__compar_d_fn_t) q->compare, q->data); \
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} while (0)
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#define PQUEUE_REMOVE(queue) \
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({ \
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__auto_type q = (queue); \
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if (PQUEUE_IS_EMPTY (q)) { \
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Sys_Error ("Priority queue empty"); \
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} \
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__auto_type value = q->a[0]; \
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q->a[0] = q->a[--q->size]; \
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heap_sink_r (q->a, 0, q->size, sizeof (q->a[0]), \
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(__compar_d_fn_t) q->compare, q->data); \
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value; \
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})
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#define PQUEUE_ADJUST(queue, index) \
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do { \
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__auto_type q = (queue); \
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size_t ind = (index); \
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if (ind >= q->size) { \
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Sys_Error ("Priority queue index error"); \
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} \
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if (ind>0 && q->compare(q->a + ind, q->a + (ind-1)/2, q->data)>0) { \
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heap_swim_r (q->a, ind, q->size, sizeof (q->a[0]), \
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(__compar_d_fn_t) q->compare, q->data); \
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} else { \
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heap_sink_r (q->a, ind, q->size, sizeof (q->a[0]), \
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(__compar_d_fn_t) q->compare, q->data); \
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} \
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} while (0)
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///@}
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#endif//__QF_pqueue_h
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