Postgres95 1.01 Distribution - Virgin SourcesPG95-1_01

1 files changed, 204 insertions, 0 deletions

diff --git a/src/backend/lib/dllist.c b/src/backend/lib/dllist.c
new file mode 100644
index 00000000000..92526632c9f
--- /dev/null
+++ b/src/backend/lib/dllist.c
@@ -0,0 +1,204 @@
+/*-------------------------------------------------------------------------
+ *
+ * dllist.c--
+ *    this is a simple doubly linked list implementation
+ *    replaces the old simplelists stuff
+ *    the elements of the lists are void*
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/lib/dllist.c,v 1.1.1.1 1996/07/09 06:21:28 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "c.h"
+#include "lib/dllist.h"
+
+Dllist*
+DLNewList()
+{
+  Dllist* l;
+
+  l = malloc(sizeof(Dllist));
+  l->dll_head = 0;
+  l->dll_tail = 0;
+
+  return l;
+}
+
+ /* free up a list and all the nodes in it*/
+void
+DLFreeList(Dllist* l)
+{
+  Dlelem* curr;
+
+  while ( (curr = DLRemHead(l)) != 0)
+      free(curr);
+
+  free(l);
+}
+
+Dlelem* 
+DLNewElem(void* val)
+{
+ Dlelem* e;
+ e = malloc(sizeof(Dlelem));
+ e->dle_next = 0;
+ e->dle_prev = 0;
+ e->dle_val = val;
+ e->dle_list = 0;
+ return e;
+}
+
+void
+DLFreeElem(Dlelem* e)
+{
+  free(e);
+}
+
+Dlelem*
+DLGetHead(Dllist* l)
+{
+  return (l ? l->dll_head : 0);
+}
+
+/* get the value stored in the first element */
+void*
+DLGetHeadVal(Dllist* l)
+{
+  Dlelem* e = DLGetHead(l);
+  
+  return (e ? e->dle_val : 0);
+}
+
+Dlelem* 
+DLGetTail(Dllist* l)
+{
+  return (l ? l->dll_tail : 0);
+}
+
+/* get the value stored in the first element */
+void*
+DLGetTailVal(Dllist* l)
+{
+  Dlelem* e = DLGetTail(l);
+  
+  return (e ? e->dle_val : 0);
+}
+
+
+Dlelem* 
+DLGetPred(Dlelem* e) /* get predecessor */
+{
+  return (e ? e->dle_prev : 0);
+}
+
+Dlelem* 
+DLGetSucc(Dlelem* e) /* get successor */
+{
+    return (e ? e->dle_next : 0);
+}
+
+void
+DLRemove(Dlelem* e)
+{
+  Dllist* l;
+
+  if (e->dle_prev)
+    e->dle_prev->dle_next = e->dle_next;
+  if (e->dle_next)
+    e->dle_next->dle_prev = e->dle_prev;
+
+  /* check to see if we're removing the head or tail */
+  l = e->dle_list;
+  if (e == l->dll_head)
+    DLRemHead(l);
+  if (e == l->dll_tail)
+    DLRemTail(l);
+
+}
+
+void    
+DLAddHead(Dllist* l, Dlelem* e)
+{
+  e->dle_list = l;
+
+  if (l->dll_head)  {
+    l->dll_head->dle_prev = e;
+    e->dle_next = l->dll_head;
+  }
+  e->dle_prev = 0;
+  l->dll_head = e;
+
+  if (l->dll_tail == 0) /* if this is first element added */
+    l->dll_tail = l->dll_head;
+}
+
+void
+DLAddTail(Dllist* l, Dlelem* e)
+{
+  e->dle_list = l;
+
+  if (l->dll_tail)   {
+    l->dll_tail->dle_next = e;
+    e->dle_prev = l->dll_tail;
+  }
+  e->dle_next = 0;
+  l->dll_tail = e;
+
+  if (l->dll_head == 0) /* if this is first element added */
+    l->dll_head = l->dll_tail;
+}
+
+Dlelem* 
+DLRemHead(Dllist* l) 
+{
+ /* remove and return the head */
+  Dlelem* result;
+
+  if (l->dll_head == 0)
+    return 0;
+
+  result = l->dll_head;
+  if (l->dll_head->dle_next) {
+    l->dll_head->dle_next->dle_prev = 0;
+  }
+
+  l->dll_head = l->dll_head->dle_next;
+
+  result->dle_next = 0;
+  result->dle_list = 0;
+    
+  if (result == l->dll_tail) /* if the head is also the tail */
+    l->dll_tail = 0;
+
+  return result;
+}
+
+Dlelem* 
+DLRemTail(Dllist* l)
+{
+ /* remove and return the tail */
+  Dlelem* result;
+
+  if (l->dll_tail == 0 )
+    return 0;
+
+  result = l->dll_tail;
+  if (l->dll_tail->dle_prev) {
+    l->dll_tail->dle_prev->dle_next = 0;
+  }
+    l->dll_tail = l->dll_tail->dle_prev;
+
+  result->dle_prev = 0;
+  result->dle_list = 0;
+
+  if (result == l->dll_head) /* if the tail is also the head */
+    l->dll_head = 0;
+
+  return result;
+}
+