From 2d138a421a2093ac4d31527e3963db09d0e5dd6d Mon Sep 17 00:00:00 2001
From: validark <validarkness@gmail.com>
Date: Wed, 21 Aug 2019 00:06:31 -0500
Subject: [PATCH] utf8 dev

---
 lib/libs/utf8.lua | 134 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 lib/libs/utf8.lua

diff --git a/lib/libs/utf8.lua b/lib/libs/utf8.lua
new file mode 100644
index 0000000..e8f6847
--- /dev/null
+++ b/lib/libs/utf8.lua
@@ -0,0 +1,134 @@
+local function castToNumber(argNum, value, r1, r2)
+	local num = tonumber(value)
+
+	if type(num) ~= "number" then
+		error("bad argument #" .. argNum .. " to 'char' (number expect, got " .. typeof(num) .. ")", 2)
+	end
+
+	if (r1 and not (r1 <= num)) or (r2 and not (num <= r2)) then
+		error("bad argument #" .. argNum .. " to 'char' (value out of range)", 2)
+	end
+
+	return num
+end
+
+local rbxUTF8 = {}
+rbxUTF8.charpattern = "[%z\1-\127\194-\244][\128-\191]*"
+
+-- works for every valid input
+rbxUTF8.char = function(...)
+	local results = {}
+	for i = 1, select("#", ...) do
+		local a = castToNumber(i, select(i, ...), 0, 1114111)
+
+		if a >= 128 then
+			local _1 = a % 64
+			local b = (a - _1) / 64
+
+			if a >= 2048 then
+				local _64 = b % 64
+				local c = (b - _64) / 64
+
+				if a >= 65536 then
+					local _4096 = c % 64
+					local d = (c - _4096) / 64
+					results[i] = string.char(d + 240, _4096 + 128, _64 + 128, _1 + 128)
+				else
+					results[i] = string.char(c + 224, _64 + 128, _1 + 128)
+				end
+			else
+				results[i] = string.char(b + 192, _1 + 128)
+			end
+		else
+			results[i] = string.char(a)
+		end
+	end
+	return table.concat(results)
+end
+
+rbxUTF8.graphemes = function(str, i, j)
+	return coroutine.wrap(function()
+		local a, b = string.find(str, rbxUTF8.charpattern)
+
+		while a do
+			local c, d = string.find(str, rbxUTF8.charpattern, b + 1)
+			if c then
+				-- FIXME: We need to lookahead here to see if a-b can be paired with c-d
+				coroutine.yield(a, b, c, d)
+			else
+				coroutine.yield(a, b)
+			end
+			a, b = c, d
+		end
+		coroutine.yield()
+	end)
+end
+
+-- not fully tested yet
+rbxUTF8.codes = function(_, i, j)
+	return coroutine.wrap(function(str)
+		local a, b = 0
+
+		while true do
+			a, b = string.find(str, rbxUTF8.charpattern, a + 1)
+			if a == nil then break end
+			local c = b - a
+
+			if c == 0 then
+				coroutine.yield(a, string.byte(str, a))
+			elseif c == 1 then
+				coroutine.yield(
+					a,
+					(string.byte(str, a) - 192) * 64 +
+					(string.byte(str, a + 1) - 128)
+				)
+			elseif c == 2 then
+				coroutine.yield(
+					a,
+					(string.byte(str, a) - 224) * 4096 +
+					(string.byte(str, a + 1) - 128) * 64 +
+					(string.byte(str, a + 2) - 128)
+				)
+			elseif c == 3 then
+				coroutine.yield(
+					a,
+					(string.byte(str, a) - 240) * 262144 +
+					(string.byte(str, a + 1) - 128) * 4096 +
+					(string.byte(str, a + 2) - 128) * 64 +
+					(string.byte(str, a + 3) - 128)
+				)
+			end
+		end
+		coroutine.yield()
+	end)
+end
+
+-- temp tests
+local valid = [[
+هذه هي بعض النصوص العربي
+Hello there!
+ᚠᛇᚻ᛫ᛒᛦᚦ᛫ᚠᚱᚩᚠᚢᚱ᛫ᚠᛁᚱᚪ᛫ᚷᛖᚻᚹᛦᛚᚳᚢᛗ
+Sîne klâwen durh die wolken sint geslagen,
+Τη γλώσσα μου έδωσαν ελληνική
+На берегу пустынных волн
+ვეპხის ტყაოსანი შოთა რუსთაველი
+யாமறிந்த மொழிகளிலே தமிழ்மொழி போல் இனிதாவது எங்கும் காணோம்,
+我能吞下玻璃而不伤身体
+나는 유리를 먹을 수 있어요. 그래도 아프지 않아요
+]]
+
+local a = utf8.graphemes(valid)
+local b = rbxUTF8.graphemes(valid)
+
+repeat
+	local t1 = {a()}
+	local t2 = {b()}
+	if (t1[1] ~= t2[1] or t1[2] ~= t2[2]) then
+		print(unpack(t1))
+		print(unpack(t2)) -- see FIXME above
+		error("problem!")
+	end
+until t1[1] == nil and t2[1] == nil
+-- Previous art?? https://github.com/luapower/utf8/blob/master/utf8.lua#L194
+
+return rbxUTF8