Có thể viết tài liệu về mô đun này tại Mô đun:String2/tài liệu.

local p = {}


p.upper = function(frame)
	local s = mw.text.trim(frame.args[1] or "")
	return string.upper(s)
end

p.lower = function(frame)
	local s = mw.text.trim(frame.args[1] or "")
	return string.lower(s)
end

p.sentence = function (frame )
	frame.args[1] = string.lower(frame.args[1])
	return p.ucfirst(frame)
end

p.ucfirst = function (frame )
	local s =  mw.text.trim( frame.args[1] or "" )
	local s1 = ""
	-- if it's a list chop off and (store as s1) everything up to the first <li>
	local lipos = mw.ustring.find(s, "<li>" )
	if lipos then
		s1 = mw.ustring.sub(s, 1, lipos + 3)
		s = mw.ustring.sub(s, lipos + 4)
	end
	-- s1 is either "" or the first part of the list markup, so we can continue
	-- and prepend s1 to the returned string
	local letterpos
	if mw.ustring.find(s, "^%[%[[^|]+|[^%]]+%]%]") then
		-- this is a piped wikilink, so we capitalise the text, not the pipe
		local _
		_, letterpos = mw.ustring.find(s, "|%A*%a") -- find the first letter after the pipe
	else
		letterpos = mw.ustring.find(s, '%a')
	end
	if letterpos then
		local first = mw.ustring.sub(s, 1, letterpos - 1)
		local letter = mw.ustring.sub(s, letterpos, letterpos)
		local rest = mw.ustring.sub(s, letterpos + 1)
		return s1 .. first .. mw.ustring.upper(letter) .. rest
	else
		return s1 .. s
	end
end

p.title = function (frame )
	-- http://grammar.yourdictionary.com/capitalization/rules-for-capitalization-in-titles.html
	-- recommended by The U.S. Government Printing Office Style Manual:
	-- "Capitalize all words in titles of publications and documents,
	-- except a, an, the, at, by, for, in, of, on, to, up, and, as, but, or, and nor."
	local alwayslower = {['a'] = 1, ['an'] = 1, ['the'] = 1,
		['and'] = 1, ['but'] = 1, ['or'] = 1, ['for'] = 1,
		['nor'] = 1, ['on'] = 1, ['in'] = 1, ['at'] = 1, ['to'] = 1,
		['from'] = 1, ['by'] = 1, ['of'] = 1, ['up'] = 1 }
	local res = ''
	local s =  mw.text.trim( frame.args[1] or "" )
	local words = mw.text.split( s, " ")
	for i, s in ipairs(words) do
		s = string.lower( s )
		if( i > 1 and alwayslower[s] == 1) then
			-- leave in lowercase
		else
			s = mw.getContentLanguage():ucfirst(s)
		end
		words[i] = s
	end
	return table.concat(words, " ")
end

-- findlast finds the last item in a list
-- the first unnamed parameter is the list
-- the second, optional unnamed parameter is the list separator (default = comma space)
-- returns the whole list if separator not found
p.findlast = function(frame)
	local s =  mw.text.trim( frame.args[1] or "" )
	local sep = frame.args[2] or ""
	if sep == "" then sep = ", " end
	local pattern = ".*" .. sep .. "(.*)"
	a, b, last = s:find(pattern)
	if a then
		return last
	else
		return s
	end
end

-- stripZeros finds the first number and strips leading zeros (apart from units)
-- e.g "0940" -> "940"; "Year: 0023" -> "Year: 23"; "00.12" -> "0.12"
p.stripZeros = function(frame)
	local s = mw.text.trim(frame.args[1] or "")
	local n = tonumber( string.match( s, "%d+" ) ) or ""
	s = string.gsub( s, "%d+", n, 1 )
	return s
end

-- nowiki ensures that a string of text is treated by the MediaWiki software as just a string
-- it takes an unnamed parameter and trims whitespace, then removes any wikicode
p.nowiki = function(frame)
	local str = mw.text.trim(frame.args[1] or "")
	return mw.text.nowiki(str)
end

-- posnq (position, no quotes) returns the numerical start position of the first occurrence
-- of one piece of text ("match") inside another ("str").
-- It returns nil if no match is found, or if either parameter is blank.
-- It takes the text to be searched in as the first unnamed parameter, which is trimmed.
-- It takes the text to match as the second unnamed parameter, which is trimmed and
-- any double quotes " are stripped out.
p.posnq = function(frame)
	local str = mw.text.trim(frame.args[1] or "")
	local match = mw.text.trim(frame.args[2] or ""):gsub('"', '')
	if  str == "" or match == "" then return nil end
	-- just take the start position
	local pos = str:find(match, 1, true)
	return pos
end

-- split splits text at boundaries specified by separator
-- and returns the chunk for the index idx (starting at 1)
-- #invoke:String2 |split |text |separator |index |true/false
-- #invoke:String2 |split |txt=text |sep=separator |idx=index |plain=true/false
-- if plain is false/no/0 then separator is treated as a Lua pattern - defaults to plain=true
p.split = function(frame)
	local args = frame.args
	if not(args[1] or args.txt) then args = frame:getParent().args end
	local txt = args[1] or args.txt or ""
	if txt == "" then return nil end
	local sep = (args[2] or args.sep or ""):gsub('"', '')
	local idx = tonumber(args[3] or args.idx) or 1
	local plain = (args[4] or args.plain or "true"):sub(1,1)
	plain = (plain ~= "f" and plain ~= "n" and plain ~= "0")
	local splittbl = mw.text.split( txt, sep, plain )
	if idx < 0 then idx = #splittbl + idx + 1 end
	return splittbl[idx]
end

-- val2percent scans through a string, passed as either the first unnamed parameter or |txt=
-- it converts each number it finds into a percentage and returns the resultant string.
p.val2percent = function(frame)
	local args = frame.args
	if not(args[1] or args.txt) then args = frame:getParent().args end
	local txt = mw.text.trim(args[1] or args.txt or "")
	if txt == "" then return nil end
	local function v2p (x)
		x = (tonumber(x) or 0) * 100
		if x == math.floor(x) then x = math.floor(x) end
		return x .. "%"
	end
	txt = txt:gsub("%d[%d%.]*", v2p) -- store just the string
	return txt
end


return p