Module:Labelled list hatnote

 --------------------------------------------------------------------------------
 -- Labelled list --
 -- --
 -- This module does the core work of creating a hatnote composed of a list --
 -- prefixed by a colon-terminated label, i.e. "LABEL: [andList of pages]", --
 -- for {{see also}} and similar templates. --
 --------------------------------------------------------------------------------

 localmHatnote=require('Module:Hatnote')
 localmHatlist=require('Module:Hatnote list')
 localmArguments--initialize lazily
 localyesno--initialize lazily
 localp={}

 -- Defaults global to this module
 localdefaults={
 label='See also',--Final fallback for label argument
 labelForm='%s: %s',
 prefixes={'label','label ','l'},
 template='Module:Labelled list hatnote'
 }

 -- Localizable message strings
 localmsg={
 errorSuffix='#Errors',
 noInputWarning='no page names specified',
 noOutputWarning=
 "'''[[%s]] — no output: none of the target pages exist.'''"
 }

 -- Helper function that pre-combines display parameters into page arguments.
 -- Also compresses sparse arrays, as a desirable side-effect.
 functionp.preprocessDisplays(args,prefixes)
 -- Prefixes specify which parameters, in order, to check for display options
 -- They each have numbers auto-appended, e.g. 'label1', 'label 1', & 'l1'
 prefixes=prefixesordefaults.prefixes
 localindices={}
 localsparsePages={}
 fork,vinpairs(args)do
 iftype(k)=='number'then
 indices[#indices+1]=k
 localdisplay
 fori=1,#prefixesdo
 display=args[prefixes[i]..k]
 ifdisplaythenbreakend
 end
 sparsePages[k]=displayand
 string.format('%s|%s',string.gsub(v,'|.*$',''),display)orv
 end
 end
 table.sort(indices)
 localpages={}
 fork,vinipairs(indices)dopages[#pages+1]=sparsePages[v]end
 returnpages
 end

 --Helper function to get a page target from a processed page string
 --e.g. "Page|Label" → "Page" or "Target" → "Target"
 localfunctiongetTarget(pagename)
 localpipe=string.find(pagename,'|')
 returnstring.sub(pagename,0,pipeandpipe-1ornil)
 end

 -- Produces a labelled pages-list hatnote.
 -- The main frame (template definition) takes 1 or 2 arguments, for a singular
 -- and (optionally) plural label respectively:
 -- * {{#invoke:Labelled list hatnote|labelledList|Singular label|Plural label}}
 -- The resulting template takes pagename & label parameters normally.
 functionp.labelledList(frame)
 mArguments=require('Module:Arguments')
 yesno=require('Module:Yesno')
 locallabels={frame.args[1]ordefaults.label}
 labels[2]=frame.args[2]orlabels[1]
 labels[3]=frame.args[3]--no defaulting
 labels[4]=frame.args[4]--no defaulting
 localtemplate=frame:getParent():getTitle()
 localargs=mArguments.getArgs(frame,{parentOnly=true})
 localpages=p.preprocessDisplays(args)
 localoptions={
 category=yesno(args.category),
 extraclasses=frame.args.extraclasses,
 ifexists=yesno(frame.args.ifexists),
 namespace=frame.args.namespaceorargs.namespace,
 selfref=yesno(frame.args.selfreforargs.selfref),
 template=template
 }
 returnp._labelledList(pages,labels,options)
 end
 localfunctionexists(title)
 localsuccess,result=pcall(function()returntitle.existsend)
 ifsuccessthen
 returnresult
 else
 returntrue
 end
 end

 functionp._labelledList(pages,labels,options)
 localremovednonexist=false
 ifoptions.ifexiststhen
 fork=#pages,1,-1do--iterate backwards to allow smooth removals
 localv=pages[k]
 ifmw.ustring.sub(mw.text.trim(v),1,1)~="#"then
 localtitle=mw.title.new(getTarget(v),namespace)
 if(v=='')or(title==nil)ornotexists(title)then
 table.remove(pages,k)
 removednonexist=true
 end
 end
 end
 end
 labels=labelsor{}
 label=(#pages==1andlabels[1]orlabels[2])ordefaults.label
 fork,vinpairs(pages)do
 ifmHatnote.findNamespaceId(v)~=0then
 label=
 (
 #pages==1and
 (labels[3]orlabels[1]ordefaults.label)or
 (labels[4]orlabels[2]ordefaults.label)
 )ordefaults.label
 end
 end
 if#pages==0then
 ifremovednonexistthen
 mw.addWarning(
 string.format(
 msg.noOutputWarning,options.templateordefaults.template
 )
 )
 return''
 else
 returnmHatnote.makeWikitextError(
 msg.noInputWarning,
 (options.templateordefaults.template)..msg.errorSuffix,
 options.category
 )
 end
 end
 localtext=string.format(
 options.labelFormordefaults.labelForm,
 label,
 mHatlist.andList(pages,true)
 )
 localhnOptions={
 extraclasses=options.extraclasses,
 selfref=options.selfref
 }
 returnmHatnote._hatnote(text,hnOptions)
 end

 returnp