Tèngghu sombher Modul:If not given or empty

-- This module's check_parameter function checks whether a parameter is given, empty, or nonempty in a template call.
-- It is intended to be called from templates only, as {{#invoke:If not given or empty|check_parameter|parameter name|before|after|when=NG EM NE|notgiven=|empty=|notempty=}}
-- This is similar to {{If then show|{{{parameter name|}}}|...|before|after}}, but also checks if the parameter is *present* in the template call. 
-- before and after are added only for cases in which when= contains the codes NG (for not given), EM (given but empty), NE (given and not empty)
local p = {}

function p.check_parameter(frame)
  local m_args = frame.args
  local t_args = frame:getParent().args

  local check_param = m_args[1] and mw.text.trim(m_args[1])  or  ''
  
  if (check_param ~= '') then
    local s, c
    if not t_args[check_param] then
      s = m_args.notgiven or ''
      c = 'NG'  
    elseif t_args[check_param] == '' then
      s = m_args.empty or ''
      c = 'EM'
    else
      s = m_args.notempty or ''
      c = 'NE'
    end

    local before = ''
    local after  = ''
    local when = m_args.when or ''
    if when:find(c) then
      before = m_args[2]
      after  = m_args[3]
    end
    return before .. s .. after
  end
  error("Function called without template's parameter name")
end

return p