# 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 and similar templates. --
---  
local mHatnote = require('Module:Hatnote')
local mHatlist = require('Module:Hatnote list')
local mArguments --initialize lazily
local yesno --initialize lazily
local p = {}  
-- Defaults global to this module
local defaults = {
label = 'See also', --Final fallback for label argument
labelForm = '%s: %s',
prefixes = {'label', 'label ', 'l'},
template = 'Module:Labelled list hatnote'
}  
-- Localizable message strings
local msg = {
errorSuffix = '#Errors',
noInputWarning = 'no page names specified',
noOutputWarning =
"**%s — no output: of the target pages exist.**"
}  
-- Helper function that pre-combines display parameters into page arguments.
-- Also compresses sparse arrays, as a desirable side-effect.
function p.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 = prefixes or defaults.prefixes
local indices = {}
local sparsePages = {}
for k, v in pairs(args) do
if type(k) == 'number' then
indices[#indices + 1] = k
local display
for i = 1, #prefixes do
display = args[prefixes[i] .. k]
if display then break end
end
sparsePages[k] = display and
string.format('%s|%s', string.gsub(v, '|.*$', ''), display) or v
end
end
table.sort(indices)
local pages = {}
for k, v in ipairs(indices) do pages[#pages + 1] = sparsePages[v] end
return pages
end  
--Helper function to get a page target from a processed page string
--e.g. "Page|Label" → "Page" or "Target" → "Target"
local function getTarget(pagename)
local pipe = string.find(pagename, '|')
return string.sub(pagename, 0, pipe and pipe - 1 or nil)
end  
-- Produces a labelled pages-list hatnote.
-- The main (template definition) takes 1 or 2 arguments, for a singular
-- and (optionally) plural label respectively:
-- *
-- The resulting template takes pagename & label parameters normally.
function p.labelledList
mArguments = require('Module:Arguments')
yesno = require('Module:Yesno')
local labels = {.args[1] or defaults.label}
labels[2] = .args[2] or labels[1]
labels[3] = .args[3] --no defaulting
labels[4] = .args[4] --no defaulting
local template = :getParent:getTitle
local args = mArguments.getArgs(, {parentOnly = true})
local pages = p.preprocessDisplays(args)
local options = {
category = yesno(args.category),
extraclasses = .args.extraclasses,
ifexists = yesno(.args.ifexists),
namespace = .args.namespace or args.namespace,
selfref = yesno(.args.selfref or args.selfref),
template = template
}
return p._labelledList(pages, labels, options)
end  
function p._labelledList (pages, labels, options)
if options.ifexists then
for k = #pages, 1, -1 do --iterate backwards to allow smooth removals
local v = pages[k]
local title = mw.title.new(getTarget(v), namespace)
if (v == '') or title == nil or not title.exists then
table.remove(pages, k)
end
end
end
labels = labels or {}
label = (#pages == 1 and labels[1] or labels[2]) or defaults.label
for k, v in pairs(pages) do
if mHatnote.findNamespaceId(v) ~= 0 then
label =
(
1. pages == 1 and
(labels[3] or labels[1] or defaults.label) or
(labels[4] or labels[2] or defaults.label)
) or defaults.label
end
end
if #pages == 0 then
if options.ifexists then
mw.addWarning(
string.format(
msg.noOutputWarning, options.template or defaults.template
return ''
else
return mHatnote.makeWikitextError(
msg.noInputWarning,
(options.template or defaults.template) .. msg.errorSuffix,
options.category
end
end
local text = string.format(
options.labelForm or defaults.labelForm,
label,
mHatlist.andList(pages, true)
local hnOptions = {
extraclasses = options.extraclasses,
selfref = options.selfref
}
return mHatnote._hatnote(text, hnOptions)
end  
return p