Module:Detect singular

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Lua to determine whether a string is singular or plural. Designed for use in infoboxes, to determine whether labels should be singular or plural based on the corresponding data, e.g.

{{#invoke:Detect singular|pluralize|Wynken, Blynken, and Nod||singular|plural}} →

• See Template:Detect singular for main() usage. Test cases here.
• See Template:Pluralize from text for pluralize() usage (a wrapper around main()). Test cases here.

The above documentation is transcluded from Module:Detect singular/doc. (edit | history)
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local p = {}
local getArgs = require('Module:Arguments').getArgs
local yesNo = require('Module:Yesno')

local function plainFind(s, sub)
	return mw.ustring.find(s, sub, 1, true)
end

local function countMatches(s, pattern)
	local dbg, count = mw.ustring.gsub(s, pattern, 'ASTERISK')
	mw.log(dbg)
	return count
end

function p._main(args)
	local checkComma = not yesNo(args.no_comma,true)
	local checkBullets = yesNo(args.bullets,true)
	local s = args[1]  -- the input string
	if not s then
		return nil -- empty input returns nil
	end
	s = tostring(s)
	s = mw.ustring.gsub(s,'%b[]','WIKILINK') -- replace all wikilinks with string
	if plainFind(s,'forcedetectsingular') then -- magic data string to return true
		return true
	end
	if plainFind(s,'forcedetectplural') then -- magic data string to return false
		return false
	end
	local hasComma = checkComma and mw.ustring.find(s, '%a,%s') 
	local hasMultipleListElements = countMatches(s,'<%s*li') > 1
	local hasAnd = mw.ustring.find(s,'%Aand%A')
	local hasBreak = mw.ustring.find(s,'<%s*br')
	local hasBullets = checkBullets and countMatches(s,'%*+') > 1
	local multipleQids = mw.ustring.find(s,'Q%d+[%p%s]+Q%d+') -- has multiple QIDs in a row
	return not (hasComma or hasMultipleListElements or hasAnd or hasBreak or hasBullets or multipleQids)
end

function p.main(frame)
	local args = getArgs(frame)
	if p._main(args) then
		return 1
	end
	return ""
end

return p