lib/core: Have `is_empty` work with `_bytelen` instead of `length` for speed

Signed-off-by: Lucas Bajolet <r4pass@hotmail.com>

diff --git a/lib/core/text/ropes.nit b/lib/core/text/ropes.nit
index 84afa5b..1a91e00 100644 (file)
--- a/lib/core/text/ropes.nit
+++ b/lib/core/text/ropes.nit
@@ -115,6 +115,8 @@ private class Concat
                _bytelen = l.bytelen + r.bytelen
        end
 
+       redef fun is_empty do return _bytelen == 0
+
        redef fun output do
                _left.output
                _right.output