projects / unix-history / blame
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|---|---|---|
| c65fedcf KB |
1 | /*- |
| 2 | * LstDeQueue.c -- | |
| 3 | * Remove the node and return its datum from the head of the list | |
| 4 | * | |
| 5 | * Copyright (c) 1988 by University of California Regents | |
| 6 | * | |
| 7 | * Permission to use, copy, modify, and distribute this | |
| 8 | * software and its documentation for any purpose and without | |
| 9 | * fee is hereby granted, provided that the above copyright | |
| 10 | * notice appears in all copies. Neither the University of California nor | |
| 11 | * Adam de Boor makes any representations about the suitability of this | |
| 12 | * software for any purpose. It is provided "as is" without | |
| 13 | * express or implied warranty. | |
| 14 | */ | |
| 15 | #ifndef lint | |
| 16 | static char *rcsid = | |
| 17 | "$Id: lstDeQueue.c,v 1.5 88/11/17 20:52:11 adam Exp $ SPRITE (Berkeley)"; | |
| 18 | #endif lint | |
| 19 | ||
| 20 | #include "lstInt.h" | |
| 21 | ||
| 22 | /*- | |
| 23 | *----------------------------------------------------------------------- | |
| 24 | * Lst_DeQueue -- | |
| 25 | * Remove and return the datum at the head of the given list. | |
| 26 | * | |
| 27 | * Results: | |
| 28 | * The datum in the node at the head or (ick) NIL if the list | |
| 29 | * is empty. | |
| 30 | * | |
| 31 | * Side Effects: | |
| 32 | * The head node is removed from the list. | |
| 33 | * | |
| 34 | *----------------------------------------------------------------------- | |
| 35 | */ | |
| 36 | ClientData | |
| 37 | Lst_DeQueue (l) | |
| 38 | Lst l; | |
| 39 | { | |
| 40 | ClientData rd; | |
| 41 | register ListNode tln; | |
| 42 | ||
| 43 | tln = (ListNode) Lst_First (l); | |
| 44 | if (tln == NilListNode) { | |
| 45 | return ((ClientData) NIL); | |
| 46 | } | |
| 47 | ||
| 48 | rd = tln->datum; | |
| 49 | if (Lst_Remove (l, (LstNode)tln) == FAILURE) { | |
| 50 | return ((ClientData) NIL); | |
| 51 | } else { | |
| 52 | return (rd); | |
| 53 | } | |
| 54 | } | |
| 55 |