lib/core: Added new `append_substring` service to avoid creating ephemeral instances

[nit.git] / lib / core / text / flat.nit

diff --git a/lib/core/text/flat.nit b/lib/core/text/flat.nit
index 45ad144..83cae37 100644 (file)
--- a/lib/core/text/flat.nit
+++ b/lib/core/text/flat.nit
@@ -411,7 +411,7 @@ abstract class FlatString
 
                if from < 0 then
                        count += from
-                       if count < 0 then return ""
+                       if count <= 0 then return ""
                        from = 0
                end
 
@@ -1054,6 +1054,21 @@ class FlatBuffer
                return new FlatBuffer.with_infos(r_items, byte_length, byte_length, count)
        end
 
+       redef fun append_substring_impl(s, from, length) do
+               if length <= 0 then return
+               if not s isa FlatText then
+                       super
+                       return
+               end
+               var bytest = s.char_to_byte_index(from)
+               var bytend = s.char_to_byte_index(from + length - 1)
+               var btln = bytend - bytest + 1
+               enlarge(btln + _bytelen)
+               s._items.copy_to(_items, btln, bytest, _bytelen)
+               _bytelen += btln
+               _length += length
+       end
+
        redef fun reverse
        do
                written = false