Module:form of

The following documentation is located at Module:form of/doc.^[edit]

Useful links: subpage list • links • transclusions • testcases • sandbox

---

local m_links = require("Module:links")
local m_table = require("Module:table")
local m_pos = mw.loadData("Module:form of/pos")
local m_functions = require("Module:form of/functions")

local ulen = mw.ustring.len
local rsubn = mw.ustring.gsub
local rmatch = mw.ustring.match
local rsplit = mw.text.split

local export = {}

--[=[

This module implements the underlying processing of {{form of}},
{{inflection of}} and specific variants such as {{past participle of}}
and {{alternative spelling of}}. Most of the logic in this file is to
handle tags in {{inflection of}}. Other related files:

* [[Module:form of/templates]] contains the majority of the logic that
  implements the templates themselves.
* [[Module:form of/data]] is a data-only file containing information on
  the more common inflection tags, listing the tags, their shortcuts,
  the category they belong to (tense-aspect, case, gender, voice-valence,
  etc.), the appropriate glossary link and the wikidata ID.
* [[Module:form of/data2]] is a data-only file containing information on
  the less common inflection tags, in the same format as
  [[Module:form of/data]].
* [[Module:form of/cats]] is a data-only file listing the
  language-specific categories that are added when the appropriate
  combinations of tags are seen for a given language.
* [[Module:form of/pos]] is a data-only file listing the recognized
  parts of speech and their abbreviations, used for categorization.
  FIXME: This should be unified with the parts of speech listed in
  [[Module:links]].
* [[Module:form of/functions]] contains functions for use with
  [[Module:form of/data]] and [[Module:form of/cats]]. They are
  contained in this module because data-only modules can't contain
  code. The functions in this file are of two types:

  (1) Display handlers allow for customization of the display of
      multipart tags (see below). Currently there is only one
	  such handler, for handling multipart person tags such as
	  '1//2//3'.
  (2) Cat functions allow for more complex categorization logic,
      and are referred to by name in [[Module:form of/cats]].
	  Currently no such functions exist.

The following terminology is used in conjunction with {{inflection of}}:

* A TAG is a single grammatical item, as specified in a single numbered
  parameter of {{inflection of}}. Examples are 'masculine', 'nominative',
  or 'first-person'. Tags may be abbreviated, e.g. 'm' for 'masculine',
  'nom' for 'nominative', or '1' for 'first-person'. Such abbreviations
  are called SHORTCUTS, and some tags have multiple equivalent shortcuts
  (e.g. 'p' or 'pl' for 'plural'). The full, non-abbreviated form of
  a tag is called its CANONICAL FORM.
* The DISPLAY FORM of a tag is the way it's displayed to the user. Usually
  the displayed text of the tag is the same as its canonical form, and it
  normally functions as a link to a glossary entry explaining the tag.
  Usually the link is to an entry in [[Appendix:Glossary]], but sometimes
  the tag is linked to an individual dictionary entry or to a Wikipedia
  entry. Occasionally, the display text differs from the canonical form of
  the tag. An example is the tag 'comparative case', which has the display
  text read as simply 'comparative'. Normally, tags referring to cases don't
  have the word "case" in them, but in this case the tag 'comparative' was
  already used as a shortcut for the tag 'comparative degree', so the tag was
  named 'comparative case' to avoid clashing. A similar situation occurs
  with 'adverbial case' vs. the grammar tag 'adverbial' (as in 'adverbial
  participle').
* A TAG SET is an ordered list of tags, which together express a single
  inflection, for example, '1|s|pres|ind', which can be expanded to
  canonical-form tags as 'first-person|singular|present|indicative'.
  Multiple tag sets can be specified in a single call to {{inflection of}}
  by separating the individual tag sets with a semicolon, e.g.
  '1|s|pres|ind|;|2|s|imp', which specifies two tag sets, '1|s|pres|ind'
  as above and '2|s|imp' (in canonical form,
  'second-person|singular|imperative').
* A MULTIPART TAG is a tag that embeds multiple tags within it, such as
  'f//n' or 'nom//acc//voc'. These are used in the case of [[syncretism]],
  when the same form applies to multiple inflections. Examples are the
  Spanish present subjunctive, where the first-person and third-person
  singular have the same form (e.g. [[siga]] from [[seguir]] "to follow"),
  or Latin third-declension adjectives, where the dative and ablative
  plural of all genders have the same form (e.g. [[omnibus]] from [[omnis]]
  "all"). These would be expressed respectively as '1//3|s|pres|sub'
  and 'dat//abl|m//f//n|p', where the use of the multipart tag compactly
  encodes the syncretism and avoids the need to individually list out
  all of the inflections. Multipart tags currently display as a list
  separated by "and", ''dative and ablative'' or
  ''masculine, feminine and neuter'' where each individual word is linked
  appropriately. As a special case, multipart tags involving persons display
  specially; for example, the multipart tag ''1//2//3'' displays as
  ''first-, second- and third-person'', with the word "person" occurring
  only once.
* A TWO-LEVEL MULTIPART TAG is a special type of multipart tag that
  joins two or more tag sets instead of joining individual tags. The tags
  within the tag set are joined by a colon, e.g. '1:s//3:p', which is
  displayed as ''first-person singular and third-person plural'', e.g.
  for use with the form [[μέλλον]] of the verb [[μέλλω]] "to intend",
  which uses the tag set '1:s//3:p|impf|actv|indc|unaugmented' to express
  the syncretism between the first singular and third plural forms of the
  imperfect active indicative unaugmented conjugation. Two-level multipart
  tags should be used sparingly; if in doubt, list out the inflections
  separately.
* A MULTIPART TAG SHORTCUT is a shortcut that expands into a multipart
  tag, for example '123', which expands to the multipart tag '1//2//3'.
  Only the most common such combinations exist as shortcuts.
* A LIST TAG SHORTCUT is a special type of shortcut that expands to a list
  of tags instead of a single tag. For example, the shortcut '1s' expands to
  '1|s' (first-person singular). Only the most common such combinations
  exist as shortcuts.

]=]

-- version of rsubn() that discards all but the first return value
local function rsub(term, foo, bar)
	local retval = rsubn(term, foo, bar)
	return retval
end


function export.format_form_of(data)
	if type(data) ~= "table" then
		error("First argument must now be a table of arguments")
	end

	local text_classes = data.text_classes or "form-of-definition use-with-mention"
	local terminfo_classes = data.text_classes or "form-of-definition-link"
	local parts = {}
	table.insert(parts, "<span class='" .. text_classes .. "'>")
	table.insert(parts, data.text)
	if data.text ~= "" and data.terminfo then
		table.insert(parts, " ")
	end
	if data.terminfo then
		table.insert(parts, "<span class='" .. terminfo_classes .. "'>")
		if type(data.terminfo) == "string" then
			table.insert(parts, data.terminfo)
		else
			table.insert(parts, m_links.full_link(data.terminfo, data.terminfo_face, false))
		end
		table.insert(parts, "</span>")
	end
	if data.posttext then
		table.insert(parts, data.posttext)
	end
	table.insert(parts, "</span>")
	return table.concat(parts)
end


-- Add tracking category for PAGE when called from {{inflection of}} or
-- similar TEMPLATE. The tracking category linked to is
-- [[Template:tracking/inflection of/PAGE]].
local function infl_track(page)
	require("Module:debug").track("inflection of/" ..
		-- avoid including links in pages (may cause error)
		page:gsub("%[", "("):gsub("%]", ")"):gsub("|", "!"))
end


local function is_link_or_html(tag)
	return tag:find("[[", nil, true) or tag:find("|", nil, true) or
		tag:find("<", nil, true)
end


-- Look up a tag (either a shortcut of any sort of a canonical long-form tag)
-- and return its expansion. The expansion will be a string unless the
-- shortcut is a list-tag shortcut such as "1s"; in that case, the expansion
-- will be a list. The caller must handle both cases. Only one level of
-- expansion happens; hence, "acc" expands to "accusative", "1s" expands to
-- {"1", "s"} (not to {"first", "singular"}) and "123" expands to "1//2//3".
-- The expansion will be the same as the passed-in tag in the following
-- circumstances:
--
-- 1. The tag is ";" (this is special-cased, and no lookup is done).
-- 2. The tag is a multipart tag such as "nom//acc" (this is special-cased,
--    and no lookup is done).
-- 3. The tag contains a raw link (this is special-cased, and no lookup is
--    done).
-- 4. The tag contains HTML (this is special-cased, and no lookup is done).
-- 5. The tag is already a canonical long-form tag.
-- 6. The tag is unrecognized.
--
-- This function first looks up in [[Module:form of/data]] (which includes
-- more common tags) and then (only if the tag is not recognized as a
-- shortcut or canonical tag, and is not of types 1-4 above) in
-- [[Module:form of/data2]].
--
-- If the expansion is a string and is different from the tag, track it if
-- DO_TRACK is true.
function export.lookup_shortcut(tag, do_track)
	-- If there is HTML or a link in the tag, return it directly; don't try
	-- to look it up, which will fail.
	if tag == ";" or tag:find("//", nil, true) or is_link_or_html(tag) then
		return tag
	end
	local m_data = mw.loadData("Module:form of/data")
	-- If this is a canonical long-form tag, just return it, and don't
	-- check for shortcuts (which will cause [[Module:form of/data2]] to be
	-- loaded).
	if m_data.tags[tag] then
		return tag
	end
	local expansion = m_data.shortcuts[tag]
	if not expansion then
		local m_data2 = mw.loadData("Module:form of/data2")
		expansion = m_data2.shortcuts[tag]
	end
	if not expansion then
		return tag
	end
	-- Maybe track the expansion if it's not the same as the raw tag.
	if do_track and expansion ~= tag and type(expansion) == "string" then
		infl_track("tag/" .. tag)
	end
	return expansion
end


-- Look up a normalized/canonicalized tag and return the data object
-- associated with it. If the tag isn't found, return nil. This first looks up
-- in [[Module:form of/data]] (which includes more common tags) and then in
-- [[Module:form of/data2]].
function export.lookup_tag(tag)
	local m_data = mw.loadData("Module:form of/data")
	local tagobj = m_data.tags[tag]
	if tagobj then
		return tagobj
	end
	local m_data2 = mw.loadData("Module:form of/data2")
	local tagobj2 = m_data2.tags[tag]
	if tagobj2 then
		return tagobj2
	end
	return nil
end


-- Normalize a single tag, which may be a shortcut but should not be a
-- multipart tag, a multipart-tag shortcut or a list-tag shortcut.
local function normalize_single_tag(tag, do_track)
	local expansion = export.lookup_shortcut(tag, do_track)
	if type(expansion) ~= "string" then
		error("Tag '" .. tag .. "' is a list-tag shortcut, which is not allowed here")
	end
	tag = expansion
	if not export.lookup_tag(tag) and do_track then
		-- If after all expansions and normalizations we don't recognize
		-- the canonical tag, track it.
		infl_track("unknown")
		infl_track("unknown/" .. tag)
	end
	return tag
end


-- Normalize a component of a multipart tag. This should not have any // in it,
-- but may join multiple individual tags with a colon, and may be a single
-- list-tag shortcut, which is treates as if colon-separated. If
-- RECOMBINE_TAGS isn't given, the return value may be a list of tags;
-- otherwise, it will always be a string, and multiple tags will be
-- represented as canonical-form tags joined by ":".
local function normalize_multipart_component(tag, recombine_tags, do_track)
	-- If there is HTML or a link in the tag, don't try to split on colon.
	-- A colon may legitimately occur in either one, and we don't want
	-- these things parsed. Note that we don't do this check before splitting
	-- on //, which we don't expect to occur in links or HTML; see comment
	-- in normalize_tag().
	if is_link_or_html(tag) then
		return tag
	end
	local components = rsplit(tag, ":", true)
	if #components == 1 then
		-- We allow list-tag shortcuts inside of multipart tags, e.g.
		-- '1s//3p'. Check for this now.
		tag = export.lookup_shortcut(tag, do_track)
		if type(tag) == "table" then
			-- We found a list-tag shortcut; treat as if colon-separated.
			components = tag
		else
			return normalize_single_tag(tag, do_track)
		end
	end
	local normtags = {}
	for _, component in ipairs(components) do
		if do_track then
			-- There are multiple components; track each of the individual
			-- raw tags.
			infl_track("tag/" .. component)
		end
		table.insert(normtags, normalize_single_tag(component, do_track))
	end

	if recombine_tags then
		return table.concat(normtags, ":")
	else
		return normtags
	end
end


-- Normalize a single tag. If RECOMBINE_TAGS isn't given, the return value
-- may be a list (in the case of multipart tags), which will contain nested
-- lists in the case of two-level multipart tags; otherwise, it will always
-- be a string, and multipart tags will be represented as canonical-form tags
-- joined by "//" and/or ":".
local function normalize_tag(tag, recombine_multitags, do_track)
	-- We don't check for links or HTML before splitting on //, which we
	-- don't expect to occur in links or HTML. Doing it this way allows for
	-- a tag like '{{lb|grc|Epic}}//{{lb|grc|Ionic}}' to function correctly
	-- (the template calls will be expanded before we process the tag, and
	-- will contain links and HTML). The only check we do is for a URL,
	-- which shouldn't normally occur, but might if the user tries to put
	-- an external link into the tag. URL's with // normally have the
	-- sequence ://, which should never normally occur when // and : are
	-- used in their normal ways.
	if tag:find("://", nil, true) then
		return tag
	end
	local split_tags = rsplit(tag, "//", true)
	if #split_tags == 1 then
		local retval = normalize_multipart_component(tag, recombine_multitags,
			do_track)
		if type(retval) == "table" then
			-- The user gave a tag like '1:s', i.e. with colon but without
			-- //. Allow this, but we need to return a nested list. Note,
			-- this will never happen when RECOMBINE_TAGS is given.
			return {retval}
		end
		return retval
	end
	local normtags = {}
	for _, single_tag in ipairs(split_tags) do
		if do_track then
			-- If the tag was a multipart tag, track each of individual raw tags.
			infl_track("tag/" .. single_tag)
		end
		table.insert(normtags, normalize_multipart_component(single_tag,
			recombine_multitags, do_track))
	end
	if recombine_multitags then
		return table.concat(normtags, "//")
	else
		return normtags
	end
end


-- Normalize a tag set (a list of tags) into a list of canonical-form tags
-- (which -- may be larger due to the possibility of list-tag shortcuts).
-- If RECOMBINE_TAGS isn't given, the return list may itself contains lists;
-- in particular, multipart tags will be represented as lists. Specifically,
-- the list will consist of the elements of the multipart tag, which will
-- either be canonical-form strings or (in the case of two-level multipart
-- tags) nested lists of canonical-form strings. For example, the multipart
-- tag ''nom//acc//voc'' will expand to
--   {"nominative", "accusative", "vocative"}
-- and the two-level multipart tag ''1:s//3:p'' will expand to
--   {{"first-person", "singular"}, {"third-person", "plural"}}.
-- If RECOMBINE_TAGS is given, multipart tags will be represented in string
-- form, i.e. as canonical-form tags joined by "//" and/or ":".
function export.normalize_tags(tags, recombine_multitags, do_track)
	-- We track usage of shortcuts, normalized forms and (in the case of
	-- multipart tags or list tags) intermediate forms. For example,
	-- if the tags 1s|mn|gen|indefinite are passed in, we track the following:
	-- [[Template:tracking/inflection of/tag/1s]]
	-- [[Template:tracking/inflection of/tag/1]]
	-- [[Template:tracking/inflection of/tag/s]]
	-- [[Template:tracking/inflection of/tag/first-person]]
	-- [[Template:tracking/inflection of/tag/singular]]
	-- [[Template:tracking/inflection of/tag/mn]]
	-- [[Template:tracking/inflection of/tag/m//n]]
	-- [[Template:tracking/inflection of/tag/m]]
	-- [[Template:tracking/inflection of/tag/n]]
	-- [[Template:tracking/inflection of/tag/masculine]]
	-- [[Template:tracking/inflection of/tag/neuter]]
	-- [[Template:tracking/inflection of/tag/gen]]
	-- [[Template:tracking/inflection of/tag/genitive]]
	-- [[Template:tracking/inflection of/tag/indefinite]]
	local ntags = {}
	for _, tag in ipairs(tags) do
		if do_track then
			-- Track the raw tag.
			infl_track("tag/" .. tag)
		end
		-- Expand the tag, which may generate a new tag (either a
		-- fully canonicalized tag, a multipart tag, or a list of tags).
		tag = export.lookup_shortcut(tag, do_track)
		if type(tag) == "table" then
			for _, t in ipairs(tag) do
				if do_track then
					-- If the tag expands to a list of raw tags, track each of
					-- those.
					infl_track("tag/" .. t)
				end
				table.insert(ntags, normalize_tag(t, recombine_multitags,
					do_track))
			end
		else
			table.insert(ntags, normalize_tag(tag, recombine_multitags,
				do_track))
		end
	end
	return ntags
end


-- Split a tag set containing two-level multipart tags into one or more tag sets not containing such tags.
-- Single-level multipart tags are left alone. (If we need to, a slight modification of the following code
-- will also split single-level multipart tags.) This assumes that multipart tags are represented as lists
-- and two-level multipart tags are represented as lists of lists, as is output by normalize_tags().
-- NOTE: We have to be careful to properly handle imbalanced two-level multipart tags such as
-- <code>def:s//p</code> (or the reverse, <code>s//def:p</code>).
function export.split_two_level_multipart_tag_set(tag_set)
	-- This would be a whole lot easier in Python, with built-in support for
	-- slicing and array concatenation.
	for i, tag in ipairs(tag_set) do
		if type(tag) == "table" then
			-- We saw a multipart tag. Check if any of the parts are two-level.
			local saw_two_level_tag = false
			for _, first_level_tag in ipairs(tag) do
				if type(first_level_tag) == "table" then
					saw_two_level_tag = true
					break
				end
			end
			if saw_two_level_tag then
				-- We found a two-level multipart tag.
				-- (1) Extract the preceding tags.
				local pre_tags = {}
				for j=1,i-1 do
					table.insert(pre_tags, tag_set[j])
				end
				-- (2) Extract the following tags.
				local post_tags = {}
				for j=i+1,#tag_set do
					table.insert(post_tags, tag_set[j])
				end
				-- (3) Loop over each tag set alternant in the two-level multipart tag.
				-- For each alternant, form the tag set consisting of pre_tags + alternant + post_tags,
				-- and recursively split that tag set.
				local resulting_tag_sets = {}
				for _, first_level_tag_set in ipairs(tag) do
					local expanded_tag_set = {}
					for _, pre_tag in ipairs(pre_tags) do
						table.insert(expanded_tag_set, pre_tag)
					end
					-- The second level may have a string or a list.
					if type(first_level_tag_set) == "table" then
						for _, second_level_tag in ipairs(first_level_tag_set) do
							table.insert(expanded_tag_set, second_level_tag)
						end
					else
						table.insert(expanded_tag_set, first_level_tag_set)
					end
					for _, post_tag in ipairs(post_tags) do
						table.insert(expanded_tag_set, post_tag)
					end
					for _, split_tag_set in ipairs(export.split_two_level_multipart_tag_set(expanded_tag_set)) do
						table.insert(resulting_tag_sets, split_tag_set)
					end
				end
				return resulting_tag_sets
			end
		end
	end

	return {tag_set}
end


-- Given a list of tags, split into tag sets (separated by semicolons in the initial list of tags).
function export.split_tags_into_tag_sets(tags)
	local tag_set_group = {}
	local cur_tag_set = {}
	for _, tag in ipairs(tags) do
		if tag == ";" then
			if #cur_tag_set > 0 then
				table.insert(tag_set_group, cur_tag_set)
			end
			cur_tag_set = {}
		else
			table.insert(cur_tag_set, tag)
		end
	end
	if #cur_tag_set > 0 then
		table.insert(tag_set_group, cur_tag_set)
	end
	return tag_set_group
end


-- Given a list of tags, split into tag sets (separated by semicolons in the initial list of tags).
-- Then, potentially split each tag set into multiple tag sets if there are any two-level multipart
-- tags in those tag sets.
function export.split_tags_into_tag_sets_and_expand_two_level_multipart_tags(tags)
	-- First, split into tag sets.
	local tag_sets = export.split_tags_into_tag_sets(tags)
	-- Now split any two-level multipart tags.
	local resulting_tag_sets = {}
	for _, tag_set in ipairs(tag_sets) do
		for _, resulting_tag_set in ipairs(export.split_two_level_multipart_tag_set(tag_set)) do
			table.insert(resulting_tag_sets, resulting_tag_set)
		end
	end
	return resulting_tag_sets
end


function export.normalize_pos(pos)
	return m_pos[pos] or pos
end


-- Return the display form of a single canonical-form tag. The value
-- passed in must be a string (i.e. it cannot be a list describing a
-- multipart tag). To handle multipart tags, use get_tag_display_form().
local function get_single_tag_display_form(normtag)
	local data = export.lookup_tag(normtag)

	-- If the tag has a special display form, use it
	if data and data.display then
		normtag = data.display
	end

	-- If there is a nonempty glossary index, then show a link to it
	if data and data.glossary then
		if data.glossary_type == "wikt" then
			normtag = "[[" .. data.glossary .. "|" .. normtag .. "]]"
		elseif data.glossary_type == "wp" then
			normtag = "[[w:" .. data.glossary .. "|" .. normtag .. "]]"
		else
			normtag = "[[Appendix:Glossary#" .. mw.uri.anchorEncode(data.glossary) .. "|" .. normtag .. "]]"
		end
	end
	return normtag
end


-- Turn a canonicalized tag spec (which describes a single, possibly
-- multipart tag) into the displayed form. The tag spec may be a string
-- (a canonical-form tag), or a list of canonical-form tags (in the
-- case of a simple multipart tag), or a list of mixed canonical-form
-- tags and lists of such tags (in the case of a two-level multipart tag).
-- JOINER indicates how to join the parts of a multipart tag, and can
-- be either "and" ("foo and bar", or "foo, bar and baz" for 3 or more),
-- "slash" ("foo/bar"), "en-dash" ("foo–bar") or nil, which uses the
-- global default found in multipart_join_strategy() in
-- [[Module:form of/functions]].
function export.get_tag_display_form(tagspec, joiner)
	if type(tagspec) == "string" then
		return get_single_tag_display_form(tagspec)
	end
	-- We have a multipart tag. See if there's a display handler to
	-- display them specially.
	for _, handler in ipairs(m_functions.display_handlers) do
		local displayval = handler(tagspec, joiner)
		if displayval then
			return displayval
		end
	end
	-- No display handler.
	local displayed_tags = {}
	for _, first_level_tag in ipairs(tagspec) do
		if type(first_level_tag) == "string" then
			table.insert(displayed_tags, get_single_tag_display_form(first_level_tag))
		else
			-- A first-level element of a two-level multipart tag.
			-- Currently we just separate the individual components
			-- with spaces, but other ways are possible, e.g. using
			-- an underscore, colon, parens or braces.
			local components = {}
			for _, component in ipairs(first_level_tag) do
				table.insert(components, get_single_tag_display_form(component))
			end
			table.insert(displayed_tags, table.concat(components, " "))
		end
	end
	return m_functions.join_multiparts(displayed_tags, joiner)
end


-- Return true if the list `tags1`, treated as a set, is a subset of the list `tags2`, also
-- treated as a set.
local function is_subset(tags1, tags2)
	tags1 = m_table.listToSet(tags1)
	tags2 = m_table.listToSet(tags2)
	for tag, _ in pairs(tags1) do
		if not tags2[tag] then
			return false
		end
	end
	return true
end


-- Compute and return the appropriate categories for the tags in `tags` (user-specified tags,
-- which may consist of multiple tag sets separated by semicolons) and the language in `lang`.
-- This checks both language-specific and language-agnostic category specs in [[Module:form of/cats]].
-- `POS` is the user-specified part of speech, if any, and `terminfo` is currently unused.
function export.fetch_lang_categories(lang, tags, terminfo, POS)
	local m_cats = mw.loadData("Module:form of/cats")

	local categories = {}

	local normalized_tags = export.normalize_tags(tags)
	local split_tag_sets = export.split_tags_into_tag_sets_and_expand_two_level_multipart_tags(normalized_tags)
	POS = export.normalize_pos(POS)

	-- Loop over each tag set and compute categories for each one.
	for _, tag_set in ipairs(split_tag_sets) do
		local function make_function_table()
			return {
				lang=lang,
				tags=normalized_tags,
				term=term,
				p=POS
			}
		end

		-- Given a tag from the current tag set (which may be a list in case of a multipart tag),
		-- and a tag from a categorization spec, check that the two match.
		-- (1) If both are strings, we just check for equality.
		-- (2) If the spec tag is a string and the tag set tag is a list (i.e. it originates from a
		-- multipart tag), we check that the spec tag is in the list. This is because we want to treat
		-- multipart tags in user-specified tag sets as if the user had specified multiple tag sets.
		-- For example, if the user said "1//3|s|pres|ind" and the categorization spec says {"has", "1"},
		-- we want this to match, because "1//3|s|pres|ind" should be treated equivalently to two tag
		-- sets "1|s|pres|ind" and "3|s|pres|ind", and the former matches the categorization spec.
		-- (3) If the spec tag is a list (i.e. it originates from a multipart tag), we check that the
		-- tag set tag is also a list and is a superset of the spec tag. For example, if the categorization
		-- spec says {"has", "1//3"}, then the tag set tag must be a multipart tag that has both "1" and "3"
		-- in it. "1//3" works, as does "1//2//3".
		local function tag_set_tag_matches_spec_tag(tag_set_tag, spec_tag)
			if type(spec_tag) == "table" then
				if type(tag_set_tag) == "table" and is_subset(spec_tag, tag_set_tag) then
					return true
				end
			elseif type(tag_set_tag) == "table" then
				if m_table.contains(tag_set_tag, spec_tag) then
					return true
				end
			elseif tag_set_tag == spec_tag then
				return true
			end
			return false
		end

		-- Check that the current tag set matches the given spec tag. This means that any of the tags
		-- in the current tag set match, according to tag_set_tag_matches_spec_tag(); see above. If the
		-- current tag set contains only string tags (i.e. no multipart tags), and the spec tag is a
		-- string (i.e. not a multipart tag), this boils down to list containment, but it gets more
		-- complex when multipart tags are present.
		local function tag_set_matches_spec_tag(spec_tag)
			spec_tag = normalize_tag(spec_tag)
			for _, tag_set_tag in ipairs(tag_set) do
				if tag_set_tag_matches_spec_tag(tag_set_tag, spec_tag) then
					return true
				end
			end
			return false
		end

		-- Check whether the given spec matches the current tag set. Two values are returned:
		-- (1) whether the spec matches the tag set; (2) the index of the category to add if
		-- the spec matches.
		local function check_condition(spec)
			if type(spec) == "boolean" then
				return spec
			elseif type(spec) ~= "table" then
				error("Wrong type of condition " .. spec .. ": " .. type(spec))
			end
			local predicate = spec[1]
			if predicate == "has" then
				return tag_set_matches_spec_tag(spec[2]), 3
			elseif predicate == "hasall" then
				for _, tag in ipairs(spec[2]) do
					if not tag_set_matches_spec_tag(tag) then
						return false, 3
					end
				end
				return true, 3
			elseif predicate == "hasany" then
				for _, tag in ipairs(spec[2]) do
					if tag_set_matches_spec_tag(tag) then
						return true, 3
					end
				end
				return false, 3
			elseif predicate == "tags=" then
				local normalized_spec_tags = export.normalize_tags(spec[2])
				-- Allow tags to be in different orders, and multipart tags to
				-- be in different orders. To handle this, we first check that
				-- both tag set tags and spec tags have the same length. If so,
				-- we sort the multipart tags in the tag set tags and spec tags,
				-- and then check that all tags in the spec tags are in the
				-- tag set tags.
				if #tag_set ~= #normalized_spec_tags then
					return false, 3
				end
				local tag_set_tags = m_table.deepcopy(tag_set)
				for i=1,#tag_set_tags do
					if type(tag_set_tags[i]) == "table" then
						table.sort(tag_set_tags[i])
					end
					if type(normalized_spec_tags[i]) == "table" then
						table.sort(normalized_spec_tags[i])
					end
				end
				for i=1,#tag_set_tags do
					if not m_table.contains(tag_set_tags, normalized_spec_tags[i], "deepCompare") then
						return false, 3
					end
				end
				return true, 3
			elseif predicate == "p=" then
				return POS == export.normalize_pos(spec[2]), 3
			elseif predicate == "pany" then
				for _, specpos in ipairs(spec[2]) do
					if POS == export.normalize_pos(specpos) then
						return true, 3
					end
				end
				return false, 3
			elseif predicate == "pexists" then
				return POS ~= nil, 2
			elseif predicate == "not" then
				local condval = check_condition(spec[2])
				return not condval, 3
			elseif predicate == "and" then
				local condval = check_condition(spec[2])
				if condval then
					condval = check_condition(spec[3])
				end
				return condval, 4
			elseif predicate == "or" then
				local condval = check_condition(spec[2])
				if not condval then
					condval = check_condition(spec[3])
				end
				return condval, 4
			elseif predication == "call" then
				local fn = m_functions.cat_functions[spec[2]]
				if not fn then
					error("No condition function named '" .. spec[2] .. "'")
				end
				return fn(make_function_table()), 3
			else
				error("Unrecognized predicate: " .. predicate)
			end
		end

		-- Process a given spec. This checks any conditions in the spec against the
		-- tag set, and insert any resulting categories into `categories`. Return value
		-- is true if the outermost condition evaluated to true and a category was inserted
		-- (this is used in {"cond" ...} conditions, which stop when a subcondition evaluates
		-- to true).
		local function process_spec(spec)
			if not spec then
				return false
			elseif type(spec) == "string" then
				-- Substitute POS request with user-specified part of speech
				-- or default
				spec = rsub(spec, "<<p=(.-)>>", function(default)
					return POS or export.normalize_pos(default)
				end)
				table.insert(categories, lang:getCanonicalName() .. " " .. spec)
				return true
			elseif type(spec) ~= "table" then
				error("Wrong type of specification " .. spec .. ": " .. type(spec))
			end
			local predicate = spec[1]
			if predicate == "multi" then
				-- WARNING! #spec doesn't work for objects loaded from loadData()
				for i, sp in ipairs(spec) do
					if i > 1 then
						process_spec(sp)
					end
				end
				return true
			elseif predicate == "cond" then
				-- WARNING! #spec doesn't work for objects loaded from loadData()
				for i, sp in ipairs(spec) do
					if i > 1 and process_spec(sp) then
						return true
					end
				end
				return false
			elseif predicate == "call" then
				local fn = m_functions.cat_functions[spec[2]]
				if not fn then
					error("No spec function named '" .. spec[2] .. "'")
				end
				return process_spec(fn(make_function_table()))
			else
				local condval, ifspec = check_condition(spec)
				if condval then
					process_spec(spec[ifspec])
					return true
				else
					process_spec(spec[ifspec + 1])
					-- FIXME: Are we sure this is correct?
					return false
				end
			end
		end

		local langspecs = m_cats[lang:getCode()]
		if langspecs then
			for _, spec in ipairs(langspecs) do
				process_spec(spec)
			end
		end
		if lang:getCode() ~= "und" then
			local langspecs = m_cats["und"]
			if langspecs then
				for _, spec in ipairs(langspecs) do
					process_spec(spec)
				end
			end
		end
	end

	return categories
end


function export.tagged_inflections(data, terminfo, notext, capfirst, posttext, joiner)
	data.tags = {"nominative"}
	
	if not data.tags then
		error("First argument must now be a table of arguments")
	end
	local cur_infl = {}
	local inflections = {}

	local ntags = export.normalize_tags(data.tags, nil, "do-track")

	for i, tagspec in ipairs(ntags) do
		if tagspec == ";" then
			if #cur_infl > 0 then
				table.insert(inflections, table.concat(cur_infl))
			end

			cur_infl = {}
		else
			local to_insert = export.get_tag_display_form(tagspec, data.joiner)
			-- Maybe insert a space before inserting the display form
			-- of the tag. We insert a space if
			-- (a) we're not the first tag; and
			-- (b) the tag we're about to insert doesn't have the
			--     "no_space_on_left" property; and
			-- (c) the preceding tag doesn't have the "no_space_on_right"
			--     property.
			-- NOTE: We depend here on the fact that
			-- (1) all tags with either of the above properties set have the
			--     same display form as canonical form, and
			-- (2) all tags with either of the above properties set are
			--     single-character tags.
			-- The second property is an optimization to avoid looking up
			-- display forms resulting from multipart tags, which won't be
			-- found and which will trigger loading of [[Module:form of/data2]].
			-- If multichar punctuation is added in the future, it's ok to
			-- change the == 1 below to <= 2 or <= 3.
			--
			-- If the first property above fails to hold in the future, we
			-- need to track the canonical form of each tag (including the
			-- previous one) as well as the display form. This would also
			-- avoid the need for the == 1 check.
			if #cur_infl > 0 then
				local most_recent_tagobj = ulen(cur_infl[#cur_infl]) == 1 and
					export.lookup_tag(cur_infl[#cur_infl])
				local to_insert_tagobj = ulen(to_insert) == 1 and
					export.lookup_tag(to_insert)
				if (
					(not most_recent_tagobj or
					 not most_recent_tagobj.no_space_on_right) and
					(not to_insert_tagobj or
					 not to_insert_tagobj.no_space_on_left)
				) then
					table.insert(cur_infl, " ")
				end
			end
			table.insert(cur_infl, to_insert)
		end
	end

	if #cur_infl > 0 then
		table.insert(inflections, table.concat(cur_infl))
	end

	local format_data = require("Module:table").shallowcopy(data)

	if #inflections == 1 then
		format_data.text =
			data.notext and "" or ((data.capfirst and require("Module:string utilities").ucfirst(inflections[1]) or inflections[1]) ..
				(data.terminfo and " of" or ""))
		return export.format_form_of(format_data)
	else
		format_data.text = data.notext and "" or ((data.capfirst and "Inflection" or "inflection") ..
			(data.terminfo and " of" or ""))
		format_data.posttext = (data.posttext or "") .. ":"
		local link = export.format_form_of(format_data)
		local text_classes = data.text_classes or "form-of-definition use-with-mention"
		return link .."\n## <span class='" .. text_classes .. "'>" ..
			table.concat(inflections, "</span>\n## <span class='" .. text_classes .. "'>") .. "</span>"
	end
end

function export.to_Wikidata_IDs(tags, skip_tags_without_ids)
	if type(tags) == "string" then
		tags = mw.text.split(tags, "|", true)
	end

	local ret = {}

	local function get_wikidata_id(tag)
		if tag == ";" and not skip_tags_without_ids then
			error("Semicolon is not supported for Wikidata IDs")
		else
			return nil
		end

		local data = export.lookup_tag(tag)

		if not data or not data.wikidata then
			if not skip_tags_without_ids then
				error("The tag \"" .. tag .. "\" does not have a Wikidata ID defined in [[Module:form of/data]]")
			else
				return nil
			end
		else
			return data.wikidata
		end
	end

	for i, tag in ipairs(export.normalize_tags(tags)) do
		if type(tag) == "table" then
			local ids = {}
			for _, onetag in ipairs(tag) do
				table.insert(ids, get_wikidata_id(onetag))
			end
			table.insert(ret, ids)
		else
			table.insert(ret, get_wikidata_id(tag))
		end
	end

	return ret
end


function export.dump_form_of_data(frame)
	local data = {
		data = require("Module:form of/data"),
		data2 = require("Module:form of/data2")
	}
	return require("Module:JSON").toJSON(data)
end


return export