You can use std.uni.byGrapheme to iterate by graphemes:
http://dlang.org/phobos/std_uni.html#.byGrapheme
AFAIK, graphemes are not "self synchronizing", but codepoints
are. You can pop code units until you reach the beginning of a
new codepoint. From there, you can iterate by graphemes, though
your first grapheme might be off.
Maybe there is some idea how to just detect first code unit of
grapheme without overhead for using Grapheme struct? I just tried
to check if ch < 128 (for UTF-8). But this dont work. How to
check if byte is continuation of code for single code point or if
new sequence started?
