fix a typo in previous commit

[lcore.git] / blinklist.pas

diff --git a/blinklist.pas b/blinklist.pas
index 27232f41ef6687148ac947825dd56899d88d6697..5c3391d890a9a82ad4966e3c56d5e2bc6d4b9380 100755 (executable)
--- a/blinklist.pas
+++ b/blinklist.pas
@@ -54,11 +54,14 @@ var
   linklistdebug:integer;\r
 \r
 implementation\r
+
+uses sysutils;
 \r
 procedure linklistadd(var baseptr:tlinklist;newptr:tlinklist);\r
 var\r
   p:tlinklist;\r
 begin\r
+  if (newptr=baseptr) or assigned(newptr.prev) then raise exception.create('linklist double insertion detected');
   p := baseptr;\r
   baseptr := newptr;\r
   baseptr.prev := nil;\r
@@ -70,13 +73,16 @@ procedure linklistdel(var baseptr:tlinklist;item:tlinklist);
 begin\r
   if item = baseptr then baseptr := item.next;\r
   if item.prev <> nil then item.prev.next := item.next;\r
-  if item.next <> nil then item.next.prev := item.prev;\r
+  if item.next <> nil then item.next.prev := item.prev;
+  item.prev := nil;
+  item.next := nil;\r
 end;\r
 \r
 procedure linklist2add(var baseptr,newptr:tlinklist2);\r
 var\r
   p:tlinklist2;\r
 begin\r
+  if (newptr=baseptr) or assigned(newptr.prev2) then raise exception.create('linklist2 double insertion detected');
   p := baseptr;\r
   baseptr := newptr;\r
   baseptr.prev2 := nil;\r
@@ -88,7 +94,9 @@ procedure linklist2del(var baseptr:tlinklist2;item:tlinklist2);
 begin\r
   if item = baseptr then baseptr := item.next2;\r
   if item.prev2 <> nil then item.prev2.next2 := item.next2;\r
-  if item.next2 <> nil then item.next2.prev2 := item.prev2;\r
+  if item.next2 <> nil then item.next2.prev2 := item.prev2;
+  item.prev2 := nil;
+  item.next2 := nil;\r
 end;\r
 \r
 constructor tlinklist.create;\r