stdlib/strings: Added cache for efficency when calling to_cstring on FlatTexts.

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

diff --git a/lib/standard/string.nit b/lib/standard/string.nit
index 11dece3..ecf7cf1 100644 (file)
--- a/lib/standard/string.nit
+++ b/lib/standard/string.nit
@@ -470,6 +470,9 @@ abstract class FlatText
 
        private var items: NativeString
 
+       # Real items, used as cache for to_cstring is called
+       private var real_items: nullable NativeString = null
+
        redef var length: Int
 
        init do end
@@ -733,10 +736,12 @@ class FlatString
        # Return a null terminated char *
        redef fun to_cstring: NativeString
        do
+               if real_items != null then return real_items.as(not null)
                if index_from > 0 or index_to != items.cstring_length - 1 then
                        var newItems = calloc_string(length + 1)
                        self.items.copy_to(newItems, length, index_from, 0)
                        newItems[length] = '\0'
+                       self.real_items = newItems
                        return newItems
                end
                return items
@@ -1043,10 +1048,13 @@ class FlatBuffer
 
        redef fun to_cstring
        do
-               var new_native = calloc_string(length + 1)
-               new_native[length] = '\0'
-               items.copy_to(new_native, length, 0, 0)
-               return new_native
+               if real_items == null then
+                       var new_native = calloc_string(length + 1)
+                       new_native[length] = '\0'
+                       items.copy_to(new_native, length, 0, 0)
+                       real_items = new_native
+               end
+               return real_items.as(not null)
        end
 
        # Create a new empty string.