queue.h File Reference

generic first-in-first-out buffer (queue) More...

#include <assert.h>
#include <cgraph/alloc.h>
#include <stddef.h>
#include <string.h>

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Data Structures
struct	queue_t

Functions
static queue_t	queue_new (size_t hint)
static void	queue_push (queue_t *q, void *item)
static void *	queue_pop (queue_t *q)
static void	queue_free (queue_t *q)

Detailed Description

The header-only implementation below defines a queue with an optional initial capacity that expands on-demand if necessary. Expansions always succeed or exit on out-of-memory. A queue item is a generic pointer, void *.

Definition in file queue.h.

Function Documentation

queue_free()

static void queue_free ( queue_t *  q )

inlinestatic

deallocate backing memory and re-initialize a queue

Parameters

q	Queue to operate on

Definition at line 108 of file queue.h.

References queue_t::base, free(), and NULL.

Referenced by build_ranks(), init_rank(), setNStepsToCenter(), and travBFS().

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queue_new()

static queue_t queue_new ( size_t  hint )

inlinestatic

create a new queue

The hint should be a guess of the intended occupancy ceiling. If the guess is inaccurate, the queue expands on-demand anyway, so there are few consequences for getting it wrong. It is possible to pass 0 as the hint, but in this case you are better of using zero initialization for brevity.

Parameters

hint	Number of initial slots to allocate

Returns

An empty queue

Definition at line 39 of file queue.h.

References queue_t::base, and gv_calloc().

Referenced by init_rank().

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queue_pop()

static void * queue_pop ( queue_t *  q )

inlinestatic

remove an item from the head of a queue

Parameters

q	Queue to operate on

Returns

The popped entry on success or NULL if the queue was empty

Definition at line 90 of file queue.h.

References queue_t::base, queue_t::capacity, queue_t::head, NULL, and queue_t::size.

Referenced by build_ranks(), init_rank(), setNStepsToCenter(), and travBFS().

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queue_push()

static void queue_push ( queue_t *  q, void *  item  )

inlinestatic

insert a new item at the tail of a queue

It is possible to push NULL entries. But then you will be unable to distinguish popping this entry from the queue being empty.

Parameters

q	Queue to operate on
item	Entry to insert

Definition at line 52 of file queue.h.

References queue_t::base, queue_t::capacity, gv_recalloc(), queue_t::head, NULL, prefix, and queue_t::size.

Referenced by build_ranks(), enqueue_neighbors(), init_rank(), setNStepsToCenter(), and travBFS().

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