Module:Check for unknown parameters

-- This module may be used to compare the arguments passed to the parent-- with a list of arguments, returning a specified result if an argument is-- not on the listlocal p = {}local function trim(s)return s:match('^%s*(.-)%s*$')endlocal function isnotempty(s)return s and trim(s) ~= ''endfunction p.check (frame)local args = frame.argslocal pargs = frame:getParent().argslocal ignoreblank = isnotempty(frame.args['ignoreblank'])local showblankpos = isnotempty(frame.args['showblankpositional'])local knownargs = {}local unknown = frame.args['unknown'] or 'Found _VALUE_, 'local preview = frame.args['preview']local values = {}local res = {}local regexps = {}-- create the list of known args, regular expressions, and the return stringfor k, v in pairs(args) doif type(k) == 'number' thenv = trim(v)knownargs[v] = 1elseif k:find('^regexp[1-9][0-9]*$') thentable.insert(regexps, '^' .. v .. '$')endendif isnotempty(preview) then preview = '<div class="hatnote" style="color:red"><strong>Warning:</strong> ' .. preview .. ' (this message is shown only in preview).</div>'elseif preview == nil thenpreview = unknownend-- loop over the parent args, and make sure they are on the listfor k, v in pairs(pargs) doif type(k) == 'string' and knownargs[k] == nil thenlocal knownflag = falsefor i, regexp in ipairs(regexps) doif mw.ustring.match(k, regexp) thenknownflag = truebreakendendif not knownflag and ( not ignoreblank or isnotempty(v) )  thenk = mw.ustring.gsub(k, '[^%w\-_ ]', '?')table.insert(values, k)endelseif type(k) == 'number' and knownargs[tostring(k)] == nil and( showblankpos or isnotempty(v) )thenlocal vlen = mw.ustring.len(v)v = mw.ustring.sub(v, 1, (vlen < 25) and vlen or 25) v = mw.ustring.gsub(v, '[^%w\-_ ]', '?')table.insert(values, k .. ' = ' .. v .. ((vlen >= 25) and ' ...' or ''))endend-- add resuls to the output tablesif #values > 0 thenif frame:preprocess( "{{REVISIONID}}" ) == "" thenunknown = previewendfor k, v in pairs(values) doif v == '' then-- Fix odd bug for | = which gets stripped to the empty string and-- breaks category linksv = ' 'endlocal r =  unknown:gsub('_VALUE_', v)table.insert(res, r)endendreturn table.concat(res)endreturn p