gamnit: make SpriteSet behave more like a Set

Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>

diff --git a/lib/gamnit/flat.nit b/lib/gamnit/flat.nit
index 7c2db7e..d5cb28e 100644 (file)
--- a/lib/gamnit/flat.nit
+++ b/lib/gamnit/flat.nit
@@ -654,6 +654,7 @@ private class SpriteSet
 
        redef fun add(e)
        do
+               if contexts_items.has(e.context) then return
                map_sprite e
                super
        end
@@ -664,6 +665,12 @@ private class SpriteSet
                if e isa Sprite then unmap_sprite e
        end
 
+       redef fun remove_all(e)
+       do
+               if not has(e) then return
+               remove e
+       end
+
        redef fun clear
        do
                super