Fix Player Name Size Limit not working with UTF-8.

reframework/autorun/MHR_Overlay/Misc/unicode_helpers.lua

@@ -0,0 +1,112 @@
+local unicode_helpers = {};
+
+-- https://github.com/blitmap/lua-utf8-simple/blob/master/utf8_simple.lua
+
+-- ABNF from RFC 3629
+--
+-- UTF8-octets = *( UTF8-char )
+-- UTF8-char = UTF8-1 / UTF8-2 / UTF8-3 / UTF8-4
+-- UTF8-1 = %x00-7F
+-- UTF8-2 = %xC2-DF UTF8-tail
+-- UTF8-3 = %xE0 %xA0-BF UTF8-tail / %xE1-EC 2( UTF8-tail ) /
+-- %xED %x80-9F UTF8-tail / %xEE-EF 2( UTF8-tail )
+-- UTF8-4 = %xF0 %x90-BF 2( UTF8-tail ) / %xF1-F3 3( UTF8-tail ) /
+-- %xF4 %x80-8F 2( UTF8-tail )
+-- UTF8-tail = %x80-BF
+
+-- 0xxxxxxx                            | 007F   (127)
+-- 110xxxxx	10xxxxxx                   | 07FF   (2047)
+-- 1110xxxx	10xxxxxx 10xxxxxx          | FFFF   (65535)
+-- 11110xxx	10xxxxxx 10xxxxxx 10xxxxxx | 10FFFF (1114111)
+
+local pattern = '[%z\1-\127\194-\244][\128-\191]*';
+
+-- helper function
+function unicode_helpers.relative_position(position, length)
+	if position < 0 then
+		position = length + position + 1;
+	end
+	return position;
+end
+
+-- THE MEAT
+
+-- maps f over s's utf8 characters f can accept args: (visual_index, utf8_character, byte_index)
+function unicode_helpers.map(s, f, no_subs)
+	local i = 0;
+
+	if no_subs then
+		for b, e in s:gmatch('()' .. pattern .. '()') do
+			i = i + 1;
+			local c = e - b;
+			f(i, c, b)
+		end
+	else
+		for b, c in s:gmatch('()(' .. pattern .. ')') do
+			i = i + 1;
+			f(i, c, b);
+		end
+	end
+end
+
+-- THE REST
+
+-- generator for the above -- to iterate over all utf8 chars
+function unicode_helpers.chars(s, no_subs)
+	return coroutine.wrap(function ()
+		return unicode_helpers.map(s, coroutine.yield, no_subs);
+	end);
+end
+
+-- like string.sub() but i, j are utf8 strings
+-- a utf8-safe string.sub()
+function unicode_helpers.sub(string, i, j)
+		local l = utf8.len(string);
+
+		i =       unicode_helpers.relative_position(i, l);
+		j = j and unicode_helpers.relative_position(j, l) or l;
+
+		if i < 1 then
+			i = 1;
+		end
+
+		if j > l then
+			j = l;
+		end
+
+		if i > j then
+			return '';
+		end
+
+		local diff = j - i;
+		local iterator = unicode_helpers.chars(string, true);
+
+		-- advance up to i
+		for _ = 1, i - 1 do
+			iterator();
+		end
+
+		local c, b = select(2, iterator());
+
+		-- i and j are the same, single-charaacter sub
+		if diff == 0 then
+			return string.sub(string, b, b + c - 1);
+		end
+
+		i = b;
+
+		-- advance up to j
+		for _ = 1, diff - 1 do
+			iterator();
+		end
+
+		c, b = select(2, iterator());
+
+		return string.sub(string, i, b + c - 1);
+	end
+
+
+function unicode_helpers.init_module()
+end
+
+return unicode_helpers;