Implement safe removal of elements of an intrusive list while looping over them....

diff --git a/qcsrc/lib/intrusivelist.qh b/qcsrc/lib/intrusivelist.qh
index 63a21565601085c4e34ce72c8aff021ae5fa70e6..7c4728a322e683845f1a4f296b309907d7debbf9 100644 (file)
--- a/qcsrc/lib/intrusivelist.qh
+++ b/qcsrc/lib/intrusivelist.qh
@@ -27,6 +27,7 @@ CLASS(IntrusiveList, Object)
        ATTRIB(IntrusiveList, il_tail, entity);
        ATTRIB(IntrusiveList, il_nextfld, .entity, nil);
        ATTRIB(IntrusiveList, il_prevfld, .entity, nil);
+       ATTRIB(IntrusiveList, il_loop_item, entity, nil);
        INIT(IntrusiveList) { IL_INIT(this); }
        DESTRUCTOR(IntrusiveList) { IL_DTOR(this); }
 ENDCLASS(IntrusiveList)
@@ -142,6 +143,8 @@ void IL_REMOVE(IntrusiveList this, entity it)
        next ? next.(il_prev) = prev : this.il_tail = prev;
        prev ? prev.(il_next) = next : this.il_head = next;
        LOG_DEBUGF("remove %i (%i :: %i), head: %i -> %i, tail: %i -> %i", it, it.(il_prev), it.(il_next), ohead, this.il_head, otail, this.il_tail);
+       if (this.il_loop_item == it)
+               this.il_loop_item = it.(il_next);
        it.(il_next) = it.(il_prev) = NULL;
 }
 
@@ -175,9 +178,15 @@ void IL_REMOVE(IntrusiveList this, entity it)
                for (entity _next, _it = _il.il_head; _it; (_it = _next, ++i)) \
                { \
                        const noref entity it = _it; \
+                       this.il_loop_item = it; \
                        _next = it.(il_next); \
                        if (cond) { LAMBDA(body) } \
+                       if (this.il_loop_item != it) /* current item removed? */ \
+                               _next = this.il_loop_item; \
+                       else \
+                               _next = it.(il_next); /* in case next item has changed */ \
                } \
+               this.il_loop_item = nil; \
        MACRO_END
 
 .int il_id;