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// https://github.com/compuphase/pawn/tree/main/examples/queue.p
/* Priority queue (for simple text strings) */
#include <string>
@start()
{
var msg[.text{40}, .priority]
/* insert a few items (read from console input) */
printf "Please insert a few messages and their priorities; " ...
"end with an empty string\n"
for ( ;; )
{
printf "Message: "
getstring msg.text, .pack = true
if (strlen(msg.text) == 0)
break
printf "Priority: "
msg.priority = getvalue()
if (!insert(msg))
{
printf "Queue is full, cannot insert more items\n"
break
}
}
/* now print the messages extracted from the queue */
printf "\nContents of the queue:\n"
while (extract(msg))
printf "[%d] %s\n", msg.priority, msg.text
}
const queuesize = 10
var queue[queuesize][.text{40}, .priority]
var queueitems = 0
insert(const item[.text{40}, .priority])
{
/* check if the queue can hold one more message */
if (queueitems == queuesize)
return false /* queue is full */
/* find the position to insert it to */
var pos = queueitems /* start at the bottom */
while (pos > 0 && item.priority > queue[pos-1].priority)
--pos /* higher priority: move up a slot */
/* make place for the item at the insertion spot */
for (var i = queueitems; i > pos; --i)
queue[i] = queue[i-1]
/* add the message to the correct slot */
queue[pos] = item
queueitems++
return true
}
extract(item[.text{40}, .priority])
{
/* check whether the queue has one more message */
if (queueitems == 0)
return false
/* queue is empty */
/* copy the topmost item */
item = queue[0]
--queueitems
/* move the queue one position up */
for (var i = 0; i < queueitems; ++i)
queue[i] = queue[i+1]
return true
}
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