Module:Title monthname

--[[ v1.00
     Split the page title into words then test each of them against
     the list of months.
     Optionally, an alternative page name may be supplied as a parameter.
     Return the first word which matches a months name ...
     unless the "match=" parameter specifies a diffreent match.
     If there is no match, then return an empty string ... unles
     the "nomatch" parameter specifies something different
]]

local getArgs = require('Module:Arguments').getArgs
local p = {}

-- config
local nomatch = ""
local matchnum = 1

local monthList = {
 'January',
 'February',
 'March',
 'April',
 'May',
 'June',
 'July',
 'August',
 'September',
 'October',
 'November',
 'December'
}

-- splits a string into "words"
-- a "word" is a set of characters delineated at each end by one 
--    or more whitespace characters or punctaution charaters
function splitIntoWords(str)
 result = {}
 index = 1
 s = mw.ustring.gsub(str, "^[%s%p]+", "") -- strip leading whitespace or punctuation
 for s2 in mw.ustring.gmatch(s, "[^%s%p]+[%s%p]*") do
  s3 = mw.ustring.gsub(s2, "[%s%p]+$", "") -- strip trailing separators
  result[index] = s3
  index = index + 1
 end
return result
end

-- returns the first word is the pagename which matches the name of a month
-- ... or an empty string if there is no match
function checkPagename(pn)
 -- split the pagename into sparate words
 titleWords = splitIntoWords(pn)
 
 nMatches = 0
 myMatches ={}
 
 -- check each words in turn, to see if it matches a month
 for w, thisWord in ipairs(titleWords) do
  -- check agaist each month
  -- if there is a match, then return that monthname
  for i, thisMonth in ipairs(monthList) do
   if (thisMonth == thisWord) then
    nMatches = nMatches + 1
    myMatches[nMatches] = thisMonth
   end
  end
 end

 if (nMatches == 0) then
  -- none of the title words matches a whole month
  return nomatch
 end
 
 if ((matchnum >= 1) and (matchnum <= nMatches)) then
  return myMatches[matchnum]
 end

 if (matchnum < 0) then
  matchnum = matchnum + 1 -- so that -1 is the last match etc
  if ((matchnum + nMatches) >= 1) then
   return myMatches[matchnum + nMatches]
  end
 end
 
 -- if we get here, we have not found a match at the position specified by "matchnum"
 return nomatch
end

function p.main(frame)
 local args = getArgs(frame)
 return p._main(args)
end

function p._main(args)
 if (args['nomatch'] ~= nil) then
  nomatch = args['nomatch']
 end
 
 -- by default, we return the first match
 -- but the optional "C" paarmeter sets the "matchnum" variable, which
 -- * for a positive matchnum "n", returns the nth match if it exists
 -- * for a positive matchnum "n", returns (if it exists) the nth match
 --   counting backwards from the end.
 --   So "match=-1" returns the last match
 --   and "match=-3" returns the 3rd-last match
 if (args['match'] ~= nil) then
  matchnum = tonumber(args['match'])
  if ((matchnum == nil) or (matchnum == 0)) then
   matchnum = 1
  end
 end
 
 -- by default, we use the current page
 -- but if the "page=" parameters is supplied, we use that
 -- so we try the parameter first
 thispagename = nil
 if ((args['page'] ~= nil) and (args['page'] ~= "")) then
  -- we have a non-empty "page" parameter, so we use it
  thispagename = args['page']
 else
  -- get the page title
  thispage = mw.title.getCurrentTitle()
  thispagename = thispage.text;
 end
 
 -- now check the pagename to try to find a month ananme
 result = checkPagename(thispagename)
 if (result == "") then
  return nomatch
 end
 return result
end

return p