Module:ForLoop

p = {}

local args

local function callTemplate(template, targs)

   return mw.getCurrentFrame():expandTemplate{title = template, args = targs}

end

local function getArgNums(prefix, suffix)

   -- Returns a table containing the numbers of the arguments that exist
   -- for the specified prefix and suffix.
   local nums = {}
   for k, v in pairs(args) do
       local num = tostring(k):match('^' .. prefix .. '([1-9]%d*)' .. suffix .. '$')
       if num then table.insert(nums, tonumber(num)) end
   end
   table.sort(nums)
   return nums

end

local function getConstants()

   local constantArgNums = getArgNums('pc', 'n')
   local constantArgs = {}
   for _, v in ipairs(constantArgNums) do
       local keyArgName = 'pc' .. tostring(v) .. 'n'
       local valArgName = 'pc' .. tostring(v) .. 'v'
       constantArgs[args[keyArgName]] = args[valArgName]
   end
   return constantArgs

end

local function getVariableVals()

   local variableVals = {}
   for i, v in ipairs(args) do
       if i ~= 1 then
           variableVals[i - 1] = v
       end
   end
   return variableVals

end

local function _main()

   local template = args['call'] or 'void'
   local variableParam = args.pv or 1
   local variableValPrefix = args.prefix or 
   local variableValPostfix = args.postfix or 
   local sep = args[1] or 
   local constantArgs = getConstants()
   local variableVals = getVariableVals()

   local result = 
   for i, v in ipairs(variableVals) do
       v = mw.text.trim(v) -- trim whitespace
       local targs = constantArgs
       targs[variableParam] = variableValPrefix .. v .. variableValPostfix
       result = result .. tostring(callTemplate(template, targs))
       if variableVals[i + 1] then
           result = result .. sep
       end
   end
   return result

end

function p.main(frame)

   -- If called via #invoke, use the args passed into the invoking template.
   -- Otherwise, for testing purposes, assume args are being passed directly in.
   if frame == mw.getCurrentFrame() then
       args = frame:getParent().args
       for k, v in pairs(frame.args) do
           args = frame.args
           break
       end
   else
       args = frame
   end
   return _main()

end

return p