SciTE - UTF8BOM only for au3 files

[BugFix]

If you have set the property 

NewFileEncoding=UTF8BOM

each file, that will created in SciTE, get this encoding.

If you work only with au3-files, it's OK. But if you also use e.g. lua-files, the BOM must removed.

Therefore I've made another solution:

-- TIME_STAMP   2021-04-15 14:02:19


--[[
After a file was saved, the event OnSave will fired.
Now will checked:
- needs this file typ the BOM?
- If Yes: Has this file already the BOM?
-		  If No: Write the BOM sequence at the beginning of the file


If you want register other types as "au3" for set BOM use this property in SciTEUser.properties:

#~ File types, that needs byte order mark
#~ "au3" is predefined and does not need to be set here
BOM.File.Types=extension_1 extension_2
]]


CheckBOM = EventClass:new(Common)

CheckBOM.OnSave = function(self, _file)
	if not self:NeedsBOM(props['FileExt']) then return nil end
	if not self:StartsWithBOM(_file) then scite.MenuCommand(153) end
	return nil
end

CheckBOM.StartsWithBOM = function(self, _file)
	local ToHex = function(_s)
		if _s == nil then return "DEAD" end
		return (_s:gsub('.', function(_c) return ('%02X'):format(_c:byte()) end))
	end
	local fh = io.open(_file, "rb")
	local read = fh:read(3)
	fh:close()
	return (ToHex(read) == "EFBBBF")
end

CheckBOM.NeedsBOM = function(self, _ext)
	local extensions = props['BOM.File.Types']:lower()..' au3'
	if extensions:find(_ext:lower()) then return true else return false end
end

Load the "CheckBOM.lua" with your "SciTEStartup.lua" and, if required, create the property "BOM.File.Types" to add other file types for using BOM.

CheckBOM.lua