From c3ccbbc4ff3352877ed39b6d4fa430affea0e9a4 Mon Sep 17 00:00:00 2001
From: Rob Landley <rob@landley.net>
Date: Wed, 10 Jul 2019 01:53:23 -0500
Subject: Add dlist_lpop() to remove last entry (use dlist as stack).

---
 lib/lib.h   |  1 +
 lib/llist.c | 16 ++++++++++++++++
 2 files changed, 17 insertions(+)

(limited to 'lib')

diff --git a/lib/lib.h b/lib/lib.h
index 0da3d9d6..b74cfbff 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -45,6 +45,7 @@ void llist_free_double(void *node);
 void llist_traverse(void *list, void (*using)(void *node));
 void *llist_pop(void *list);  // actually void **list
 void *dlist_pop(void *list);  // actually struct double_list **list
+void *dlist_lpop(void *list); // also struct double_list **list
 void dlist_add_nomalloc(struct double_list **list, struct double_list *new);
 struct double_list *dlist_add(struct double_list **list, char *data);
 void *dlist_terminate(void *list);
diff --git a/lib/llist.c b/lib/llist.c
index 2969102d..e1e6a564 100644
--- a/lib/llist.c
+++ b/lib/llist.c
@@ -51,6 +51,7 @@ void *llist_pop(void *list)
   return (void *)next;
 }
 
+// Remove first item from &list and return it
 void *dlist_pop(void *list)
 {
   struct double_list **pdlist = (struct double_list **)list, *dlist = *pdlist;
@@ -66,6 +67,21 @@ void *dlist_pop(void *list)
   return dlist;
 }
 
+// remove last item from &list and return it (stack pop)
+void *dlist_lpop(void *list)
+{
+  struct double_list *dl = *(struct double_list **)list;
+  void *v = 0;
+
+  if (dl) {
+    dl = dl->prev;
+    v = dlist_pop(&dl);
+    if (!dl) *(void **)list = 0;
+  }
+
+  return v;
+}
+
 void dlist_add_nomalloc(struct double_list **list, struct double_list *new)
 {
   if (*list) {
-- 
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