lib/standard: Added services on NativeString and Char for the support of UTF-8

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

diff --git a/lib/standard/text/flat.nit b/lib/standard/text/flat.nit
index 04fabc9..66e7734 100644 (file)
--- a/lib/standard/text/flat.nit
+++ b/lib/standard/text/flat.nit
@@ -869,6 +869,38 @@ redef class NativeString
                str.real_items = new_self
                return str
        end
+
+       # Sets the next bytes at position `pos` to the value of `c`, encoded in UTF-8
+       #
+       # Very unsafe, make sure to have room for this char prior to calling this function.
+       private fun set_char_at(pos: Int, c: Char) do
+               var ln = c.u8char_len
+               native_set_char(pos, c, ln)
+       end
+
+       private fun native_set_char(pos: Int, c: Char, ln: Int) `{
+               char* dst = self + pos;
+               switch(ln){
+                       case 1:
+                               dst[0] = c;
+                               break;
+                       case 2:
+                               dst[0] = 0xC0 | ((c & 0x7C0) >> 6);
+                               dst[1] = 0x80 | (c & 0x3F);
+                               break;
+                       case 3:
+                               dst[0] = 0xE0 | ((c & 0xF000) >> 12);
+                               dst[1] = 0x80 | ((c & 0xFC0) >> 6);
+                               dst[2] = 0x80 | (c & 0x3F);
+                               break;
+                       case 4:
+                               dst[0] = 0xF0 | ((c & 0x1C0000) >> 18);
+                               dst[1] = 0x80 | ((c & 0x3F000) >> 12);
+                               dst[2] = 0x80 | ((c & 0xFC0) >> 6);
+                               dst[3] = 0x80 | (c & 0x3F);
+                               break;
+               }
+       `}
 end
 
 redef class Int