#include "copyright.h"

/* $XConsortium: XPeekIfEv.c,v 11.11 88/09/06 16:09:33 jim Exp $ */
/* Copyright    Massachusetts Institute of Technology    1986	 */

#define NEED_EVENTS
#include "Xlibint.h"

extern _XQEvent *_qfree;

/*
 * return the next event in the queue that satisfies the predicate. BUT do
 * not remove it from the queue. If none found, flush, and then wait until
 * one satisfies the predicate.
 */

XPeekIfEvent (dpy, event, predicate, arg)
  register Display *dpy;
  register XEvent *event;
Bool (*predicate) ();
  char *arg;
{
  register _XQEvent *prev, *qelt;

  LockDisplay (dpy);
  prev = NULL;
  while (1) {
    for (qelt = prev ? prev->next : dpy->head;
	 qelt;
	 prev = qelt, qelt = qelt->next) {
      if ((*predicate) (dpy, &qelt->event, arg)) {
	*event = qelt->event;
	UnlockDisplay (dpy);
	return;
      }
    }
    _XReadEvents (dpy);
  }
}