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*$')endlocal function isnotempty(s)return s and s:match('%S')endlocal function clean(text)-- Return text cleaned for display and truncated if too long.-- Strip markers are replaced with dummy text representing the original wikitext.local pos, truncatedlocal function truncate(text)if truncated thenreturn ''endif mw.ustring.len(text) > 25 thentruncated = truetext = mw.ustring.sub(text, 1, 25) .. '...'endreturn mw.text.nowiki(text)endlocal parts = {}for before, tag, remainder in text:gmatch('([^\127]*)\127[^\127]*%-(%l+)%-[^\127]*\127()') dopos = remaindertable.insert(parts, truncate(before) .. '&lt;' .. tag .. '&gt;...&lt;/' .. tag .. '&gt;')endtable.insert(parts, truncate(text:sub(pos or 1)))return table.concat(parts)endfunction p.check (frame)local args = frame.argslocal pargs = frame:getParent().argslocal ignoreblank = isnotempty(args['ignoreblank'])local showblankpos = isnotempty(args['showblankpositional'])local knownargs = {}local unknown = args['unknown'] or 'Found _VALUE_, 'local preview = args['preview']local values = {}local res = {}local regexps = {}-- create the list of known args, regular expressions, and the return stringfor k, v in pairs(args) doif type(k) == 'number' thenv = trim(v)knownargs[v] = 1elseif k:find('^regexp[1-9][0-9]*$') thentable.insert(regexps, '^' .. v .. '$')endend-- 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 _, regexp in ipairs(regexps) doif mw.ustring.match(k, regexp) thenknownflag = truebreakendendif not knownflag and ( not ignoreblank or isnotempty(v) )  thentable.insert(values, clean(k))endelseif type(k) == 'number' andknownargs[tostring(k)] == nil and( showblankpos or isnotempty(v) )thentable.insert(values, k .. ' = ' .. clean(v))endend-- add results to the output tablesif #values > 0 thenfor _, v in pairs(values) doif v == '' then-- Fix odd bug for | = which gets stripped to the empty string and-- breaks category linksv = ' 'end-- avoid error with v = 'example%2' ("invalid capture index")local r =  unknown:gsub('_VALUE_', {_VALUE_ = v})endendif isnotempty(preview) and r thenpreview = mw.addWarning('<div class="hatnote" style="color:red"><strong>Warning:</strong> ' .. r .. ' (this message is shown only in preview).</div>')elseif preview == nil thenpreview = unknownendlocal templatestyles = mw.getCurrentFrame():extensionTag{ name = 'templatestyles', args = { src = "Module:Hatnote/styles.css"} }return templatestyles .. table.concat(res)endreturn p