Module:TableTools: Difference between revisions

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--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--                               TableTools                                       --
--                                   TableTools                                   --
--                                                                                --
--                                                                                --
-- This module includes a number of functions for dealing with Lua tables.        --
-- This module includes a number of functions for dealing with Lua tables.        --
-- It is a meta-module, meant to be called from other Lua modules, and should     --
-- It is a meta-module, meant to be called from other Lua modules, and should not --
-- not be called directly from #invoke.                                           --
-- be called directly from #invoke.                                               --
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]


local libraryUtil = require('libraryUtil')
local libraryUtil = require('libraryUtil')
Line 19: Line 17:
local checkTypeMulti = libraryUtil.checkTypeMulti
local checkTypeMulti = libraryUtil.checkTypeMulti


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- isPositiveInteger
-- isPositiveInteger
Line 28: Line 25:
-- hash part of a table.
-- hash part of a table.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.isPositiveInteger(v)
function p.isPositiveInteger(v)
return type(v) == 'number' and v >= 1 and floor(v) == v and v < infinity
return type(v) == 'number' and v >= 1 and floor(v) == v and v < infinity
end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- isNan
-- isNan
--
--
-- This function returns true if the given number is a NaN value, and false
-- This function returns true if the given number is a NaN value, and false if
-- if not. Although it doesn't operate on tables, it is included here as it is
-- not. Although it doesn't operate on tables, it is included here as it is useful
-- useful for determining whether a value can be a valid table key. Lua will
-- for determining whether a value can be a valid table key. Lua will generate an
-- generate an error if a NaN is used as a table key.
-- error if a NaN is used as a table key.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.isNan(v)
function p.isNan(v)
return type(v) == 'number' and tostring(v) == '-nan'
return type(v) == 'number' and v ~= v
end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- shallowClone
-- shallowClone
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-- table will have no metatable of its own.
-- table will have no metatable of its own.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.shallowClone(t)
function p.shallowClone(t)
checkType('shallowClone', 1, t, 'table')
local ret = {}
local ret = {}
for k, v in pairs(t) do
for k, v in pairs(t) do
Line 64: Line 57:
end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- removeDuplicates
-- removeDuplicates
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-- removed, but otherwise the array order is unchanged.
-- removed, but otherwise the array order is unchanged.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.removeDuplicates(arr)
function p.removeDuplicates(t)
checkType('removeDuplicates', 1, arr, 'table')
checkType('removeDuplicates', 1, t, 'table')
local isNan = p.isNan
local isNan = p.isNan
local ret, exists = {}, {}
local ret, exists = {}, {}
for i, v in ipairs(t) do
for _, v in ipairs(arr) do
if isNan(v) then
if isNan(v) then
-- NaNs can't be table keys, and they are also unique, so we don't need to check existence.
-- NaNs can't be table keys, and they are also unique, so we don't need to check existence.
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exists[v] = true
exists[v] = true
end
end
end
end
end
end
return ret
return ret
end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- numKeys
-- numKeys
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-- keys that have non-nil values, sorted in numerical order.
-- keys that have non-nil values, sorted in numerical order.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.numKeys(t)
function p.numKeys(t)
checkType('numKeys', 1, t, 'table')
checkType('numKeys', 1, t, 'table')
local isPositiveInteger = p.isPositiveInteger
local isPositiveInteger = p.isPositiveInteger
local nums = {}
local nums = {}
for k, v in pairs(t) do
for k in pairs(t) do
if isPositiveInteger(k) then
if isPositiveInteger(k) then
nums[#nums + 1] = k
nums[#nums + 1] = k
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end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- affixNums
-- affixNums
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-- This takes a table and returns an array containing the numbers of keys with the
-- This takes a table and returns an array containing the numbers of keys with the
-- specified prefix and suffix. For example, for the table
-- specified prefix and suffix. For example, for the table
-- {a1 = 'foo', a3 = 'bar', a6 = 'baz'} and the prefix "a", affixNums will
-- {a1 = 'foo', a3 = 'bar', a6 = 'baz'} and the prefix "a", affixNums will return
-- return {1, 3, 6}.
-- {1, 3, 6}.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.affixNums(t, prefix, suffix)
function p.affixNums(t, prefix, suffix)
checkType('affixNums', 1, t, 'table')
checkType('affixNums', 1, t, 'table')
Line 139: Line 126:


local nums = {}
local nums = {}
for k, v in pairs(t) do
for k in pairs(t) do
if type(k) == 'string' then
if type(k) == 'string' then
local num = mw.ustring.match(k, pattern)
local num = mw.ustring.match(k, pattern)
if num then
if num then
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end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- numData
-- numData
--
--
-- Given a table with keys like ("foo1", "bar1", "foo2", "baz2"), returns a table
-- Given a table with keys like {"foo1", "bar1", "foo2", "baz2"}, returns a table
-- of subtables in the format  
-- of subtables in the format
-- { [1] = {foo = 'text', bar = 'text'}, [2] = {foo = 'text', baz = 'text'} }
-- {[1] = {foo = 'text', bar = 'text'}, [2] = {foo = 'text', baz = 'text'}}.
-- Keys that don't end with an integer are stored in a subtable named "other".
-- Keys that don't end with an integer are stored in a subtable named "other". The
-- The compress option compresses the table so that it can be iterated over with
-- compress option compresses the table so that it can be iterated over with
-- ipairs.
-- ipairs.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.numData(t, compress)
function p.numData(t, compress)
checkType('numData', 1, t, 'table')
checkType('numData', 1, t, 'table')
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end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- compressSparseArray
-- compressSparseArray
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-- ipairs.
-- ipairs.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.compressSparseArray(t)
function p.compressSparseArray(t)
checkType('compressSparseArray', 1, t, 'table')
checkType('compressSparseArray', 1, t, 'table')
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end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- sparseIpairs
-- sparseIpairs
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-- handle nil values.
-- handle nil values.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.sparseIpairs(t)
function p.sparseIpairs(t)
checkType('sparseIpairs', 1, t, 'table')
checkType('sparseIpairs', 1, t, 'table')
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end
end


--[[
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
-- size
-- size
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-- but for arrays it is more efficient to use the # operator.
-- but for arrays it is more efficient to use the # operator.
------------------------------------------------------------------------------------
------------------------------------------------------------------------------------
--]]
function p.size(t)
function p.size(t)
checkType('size', 1, t, 'table')
checkType('size', 1, t, 'table')
local i = 0
local i = 0
for k in pairs(t) do
for _ in pairs(t) do
i = i + 1
i = i + 1
end
end
return i
return i
end
end


local function defaultKeySort(item1, item2)
local function defaultKeySort(item1, item2)
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if type1 ~= type2 then
if type1 ~= type2 then
return type1 < type2
return type1 < type2
else -- This will fail with table, boolean, function.
elseif type1 == 'table' or type1 == 'boolean' or type1 == 'function' then
return tostring(item1) < tostring(item2)
else
return item1 < item2
return item1 < item2
end
end
end
end
 
------------------------------------------------------------------------------------
--[[
-- keysToList
Returns a list of the keys in a table, sorted using either a default
--
comparison function or a custom keySort function.
-- Returns an array of the keys in a table, sorted using either a default
]]
-- comparison function or a custom keySort function.
------------------------------------------------------------------------------------
function p.keysToList(t, keySort, checked)
function p.keysToList(t, keySort, checked)
if not checked then
if not checked then
checkType('keysToList', 1, t, 'table')
checkType('keysToList', 1, t, 'table')
checkTypeMulti('keysToList', 2, keySort, { 'function', 'boolean', 'nil' })
checkTypeMulti('keysToList', 2, keySort, {'function', 'boolean', 'nil'})
end
end
 
local list = {}
local arr = {}
local index = 1
local index = 1
for key, value in pairs(t) do
for k in pairs(t) do
list[index] = key
arr[index] = k
index = index + 1
index = index + 1
end
end
 
if keySort ~= false then
if keySort ~= false then
keySort = type(keySort) == 'function' and keySort or defaultKeySort
keySort = type(keySort) == 'function' and keySort or defaultKeySort
table.sort(arr, keySort)
table.sort(list, keySort)
end
end
 
return list
return arr
end
end


--[[
------------------------------------------------------------------------------------
Iterates through a table, with the keys sorted using the keysToList function.
-- sortedPairs
If there are only numerical keys, sparseIpairs is probably more efficient.
--
]]
-- Iterates through a table, with the keys sorted using the keysToList function.
-- If there are only numerical keys, sparseIpairs is probably more efficient.
------------------------------------------------------------------------------------
function p.sortedPairs(t, keySort)
function p.sortedPairs(t, keySort)
checkType('sortedPairs', 1, t, 'table')
checkType('sortedPairs', 1, t, 'table')
checkType('sortedPairs', 2, keySort, 'function', true)
checkType('sortedPairs', 2, keySort, 'function', true)
 
local list = p.keysToList(t, keySort, true)
local arr = p.keysToList(t, keySort, true)
 
local i = 0
local i = 0
return function()
return function ()
i = i + 1
i = i + 1
local key = list[i]
local key = arr[i]
if key ~= nil then
if key ~= nil then
return key, t[key]
return key, t[key]
Line 312: Line 293:
end
end


--[[
------------------------------------------------------------------------------------
Returns true if all keys in the table are consecutive integers starting at 1.
-- isArray
--]]
--
function p.isArray(t)
-- Returns true if the given value is a table and all keys are consecutive
checkType("isArray", 1, t, "table")
-- integers starting at 1.
------------------------------------------------------------------------------------
function p.isArray(v)
if type(v) ~= 'table' then
return false
end
local i = 0
local i = 0
for k, v in pairs(t) do
for _ in pairs(v) do
i = i + 1
if v[i] == nil then
return false
end
end
return true
end
 
------------------------------------------------------------------------------------
-- isArrayLike
--
-- Returns true if the given value is iterable and all keys are consecutive
-- integers starting at 1.
------------------------------------------------------------------------------------
function p.isArrayLike(v)
if not pcall(pairs, v) then
return false
end
local i = 0
for _ in pairs(v) do
i = i + 1
i = i + 1
if t[i] == nil then
if v[i] == nil then
return false
return false
end
end
Line 328: Line 333:
end
end


-- { "a", "b", "c" } -> { a = 1, b = 2, c = 3 }
------------------------------------------------------------------------------------
function p.invert(array)
-- invert
checkType("invert", 1, array, "table")
--
-- Transposes the keys and values in an array. For example, {"a", "b", "c"} ->
-- {a = 1, b = 2, c = 3}. Duplicates are not supported (result values refer to
-- the index of the last duplicate) and NaN values are ignored.
------------------------------------------------------------------------------------
function p.invert(arr)
checkType("invert", 1, arr, "table")
local isNan = p.isNan
local map = {}
local map = {}
for i, v in ipairs(array) do
for i, v in ipairs(arr) do
map[v] = i
if not isNan(v) then
map[v] = i
end
end
end
 
return map
return map
end
end


--[[
------------------------------------------------------------------------------------
{ "a", "b", "c" } -> { ["a"] = true, ["b"] = true, ["c"] = true }
-- listToSet
--]]
--
function p.listToSet(t)
-- Creates a set from the array part of the table. Indexing the set by any of the
checkType("listToSet", 1, t, "table")
-- values of the array returns true. For example, {"a", "b", "c"} ->
-- {a = true, b = true, c = true}. NaN values are ignored as Lua considers them
-- never equal to any value (including other NaNs or even themselves).
------------------------------------------------------------------------------------
function p.listToSet(arr)
checkType("listToSet", 1, arr, "table")
local isNan = p.isNan
local set = {}
local set = {}
for _, item in ipairs(t) do
for _, v in ipairs(arr) do
set[item] = true
if not isNan(v) then
set[v] = true
end
end
end
 
return set
return set
end
end


--[[
------------------------------------------------------------------------------------
Recursive deep copy function.
-- deepCopy
Preserves identities of subtables.
--
-- Recursive deep copy function. Preserves identities of subtables.
]]
------------------------------------------------------------------------------------
local function _deepCopy(orig, includeMetatable, already_seen)
local function _deepCopy(orig, includeMetatable, already_seen)
-- Stores copies of tables indexed by the original table.
-- Stores copies of tables indexed by the original table.
already_seen = already_seen or {}
already_seen = already_seen or {}
 
local copy = already_seen[orig]
local copy = already_seen[orig]
if copy ~= nil then
if copy ~= nil then
return copy
return copy
end
end
 
if type(orig) == 'table' then
if type(orig) == 'table' then
copy = {}
copy = {}
for orig_key, orig_value in pairs(orig) do
for orig_key, orig_value in pairs(orig) do
copy[deepcopy(orig_key, includeMetatable, already_seen)] = deepcopy(orig_value, includeMetatable, already_seen)
copy[_deepCopy(orig_key, includeMetatable, already_seen)] = _deepCopy(orig_value, includeMetatable, already_seen)
end
end
already_seen[orig] = copy
already_seen[orig] = copy
 
if includeMetatable then
if includeMetatable then
local mt = getmetatable(orig)
local mt = getmetatable(orig)
if mt ~= nil then
if mt ~= nil then
local mt_copy = deepcopy(mt, includeMetatable, already_seen)
local mt_copy = _deepCopy(mt, includeMetatable, already_seen)
setmetatable(copy, mt_copy)
setmetatable(copy, mt_copy)
already_seen[mt] = mt_copy
already_seen[mt] = mt_copy
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function p.deepCopy(orig, noMetatable, already_seen)
function p.deepCopy(orig, noMetatable, already_seen)
checkType("deepCopy", 3, already_seen, "table", true)
checkType("deepCopy", 3, already_seen, "table", true)
return _deepCopy(orig, not noMetatable, already_seen)
return _deepCopy(orig, not noMetatable, already_seen)
end
end


--[[
------------------------------------------------------------------------------------
Concatenates all values in the table that are indexed by a number, in order.
-- sparseConcat
sparseConcat{ a, nil, c, d }  =>  "acd"
--
sparseConcat{ nil, b, c, d }  =>  "bcd"
-- Concatenates all values in the table that are indexed by a number, in order.
]]
-- sparseConcat{a, nil, c, d}  =>  "acd"
-- sparseConcat{nil, b, c, d}  =>  "bcd"
------------------------------------------------------------------------------------
function p.sparseConcat(t, sep, i, j)
function p.sparseConcat(t, sep, i, j)
local list = {}
local arr = {}
 
local list_i = 0
local arr_i = 0
for _, v in p.sparseIpairs(t) do
for _, v in p.sparseIpairs(t) do
list_i = list_i + 1
arr_i = arr_i + 1
list[list_i] = v
arr[arr_i] = v
end
end
 
return table.concat(list, sep, i, j)
return table.concat(arr, sep, i, j)
end
end


--[[
------------------------------------------------------------------------------------
-- Finds the length of an array, or of a quasi-array with keys such
-- length
-- as "data1", "data2", etc., using an exponential search algorithm.  
--
-- It is similar to the operator #, but may return
-- Finds the length of an array, or of a quasi-array with keys such as "data1",
-- a different value when there are gaps in the array portion of the table.
-- "data2", etc., using an exponential search algorithm. It is similar to the
-- Intended to be used on data loaded with mw.loadData. For other tables, use #.
-- operator #, but may return a different value when there are gaps in the array
-- Note: #frame.args in frame object always be set to 0, regardless of  
-- portion of the table. Intended to be used on data loaded with mw.loadData. For
-- the number of unnamed template parameters, so use this function for
-- other tables, use #.
-- frame.args.
-- Note: #frame.args in frame object always be set to 0, regardless of the number
--]]
-- of unnamed template parameters, so use this function for frame.args.
 
------------------------------------------------------------------------------------
function p.length(t, prefix)
function p.length(t, prefix)
-- requiring module inline so that [[Module:Exponential search]]
-- requiring module inline so that [[Module:Exponential search]] which is
-- which is only needed by this one function
-- only needed by this one function doesn't get millions of transclusions
-- doesn't get millions of transclusions
local expSearch = require("Module:Exponential search")
local expSearch = require("Module:Exponential search")
checkType('length', 1, t, 'table')
checkType('length', 1, t, 'table')
checkType('length', 2, prefix, 'string', true)
checkType('length', 2, prefix, 'string', true)
return expSearch(function(i)
return expSearch(function (i)
local key
local key
if prefix then
if prefix then
Line 440: Line 460:
end) or 0
end) or 0
end
end
------------------------------------------------------------------------------------
-- inArray
--
-- Returns true if valueToFind is a member of the array, and false otherwise.
------------------------------------------------------------------------------------
function p.inArray(arr, valueToFind)
function p.inArray(arr, valueToFind)
checkType("inArray", 1, arr, "table")
checkType("inArray", 1, arr, "table")
-- if valueToFind is nil, error?
-- if valueToFind is nil, error?
 
for _, v in ipairs(arr) do
for _, v in ipairs(arr) do
if v == valueToFind then
if v == valueToFind then
Line 450: Line 475:
end
end
end
end
return false
return false
end
end


return p
return p

Latest revision as of 19:48, 24 April 2023

Documentation for this module may be created at Module:TableTools/doc

------------------------------------------------------------------------------------
--                                   TableTools                                   --
--                                                                                --
-- This module includes a number of functions for dealing with Lua tables.        --
-- It is a meta-module, meant to be called from other Lua modules, and should not --
-- be called directly from #invoke.                                               --
------------------------------------------------------------------------------------

local libraryUtil = require('libraryUtil')

local p = {}

-- Define often-used variables and functions.
local floor = math.floor
local infinity = math.huge
local checkType = libraryUtil.checkType
local checkTypeMulti = libraryUtil.checkTypeMulti

------------------------------------------------------------------------------------
-- isPositiveInteger
--
-- This function returns true if the given value is a positive integer, and false
-- if not. Although it doesn't operate on tables, it is included here as it is
-- useful for determining whether a given table key is in the array part or the
-- hash part of a table.
------------------------------------------------------------------------------------
function p.isPositiveInteger(v)
	return type(v) == 'number' and v >= 1 and floor(v) == v and v < infinity
end

------------------------------------------------------------------------------------
-- isNan
--
-- This function returns true if the given number is a NaN value, and false if
-- not. Although it doesn't operate on tables, it is included here as it is useful
-- for determining whether a value can be a valid table key. Lua will generate an
-- error if a NaN is used as a table key.
------------------------------------------------------------------------------------
function p.isNan(v)
	return type(v) == 'number' and v ~= v
end

------------------------------------------------------------------------------------
-- shallowClone
--
-- This returns a clone of a table. The value returned is a new table, but all
-- subtables and functions are shared. Metamethods are respected, but the returned
-- table will have no metatable of its own.
------------------------------------------------------------------------------------
function p.shallowClone(t)
	checkType('shallowClone', 1, t, 'table')
	local ret = {}
	for k, v in pairs(t) do
		ret[k] = v
	end
	return ret
end

------------------------------------------------------------------------------------
-- removeDuplicates
--
-- This removes duplicate values from an array. Non-positive-integer keys are
-- ignored. The earliest value is kept, and all subsequent duplicate values are
-- removed, but otherwise the array order is unchanged.
------------------------------------------------------------------------------------
function p.removeDuplicates(arr)
	checkType('removeDuplicates', 1, arr, 'table')
	local isNan = p.isNan
	local ret, exists = {}, {}
	for _, v in ipairs(arr) do
		if isNan(v) then
			-- NaNs can't be table keys, and they are also unique, so we don't need to check existence.
			ret[#ret + 1] = v
		else
			if not exists[v] then
				ret[#ret + 1] = v
				exists[v] = true
			end
		end
	end
	return ret
end

------------------------------------------------------------------------------------
-- numKeys
--
-- This takes a table and returns an array containing the numbers of any numerical
-- keys that have non-nil values, sorted in numerical order.
------------------------------------------------------------------------------------
function p.numKeys(t)
	checkType('numKeys', 1, t, 'table')
	local isPositiveInteger = p.isPositiveInteger
	local nums = {}
	for k in pairs(t) do
		if isPositiveInteger(k) then
			nums[#nums + 1] = k
		end
	end
	table.sort(nums)
	return nums
end

------------------------------------------------------------------------------------
-- affixNums
--
-- This takes a table and returns an array containing the numbers of keys with the
-- specified prefix and suffix. For example, for the table
-- {a1 = 'foo', a3 = 'bar', a6 = 'baz'} and the prefix "a", affixNums will return
-- {1, 3, 6}.
------------------------------------------------------------------------------------
function p.affixNums(t, prefix, suffix)
	checkType('affixNums', 1, t, 'table')
	checkType('affixNums', 2, prefix, 'string', true)
	checkType('affixNums', 3, suffix, 'string', true)

	local function cleanPattern(s)
		-- Cleans a pattern so that the magic characters ()%.[]*+-?^$ are interpreted literally.
		return s:gsub('([%(%)%%%.%[%]%*%+%-%?%^%$])', '%%%1')
	end

	prefix = prefix or ''
	suffix = suffix or ''
	prefix = cleanPattern(prefix)
	suffix = cleanPattern(suffix)
	local pattern = '^' .. prefix .. '([1-9]%d*)' .. suffix .. '$'

	local nums = {}
	for k in pairs(t) do
		if type(k) == 'string' then
			local num = mw.ustring.match(k, pattern)
			if num then
				nums[#nums + 1] = tonumber(num)
			end
		end
	end
	table.sort(nums)
	return nums
end

------------------------------------------------------------------------------------
-- numData
--
-- Given a table with keys like {"foo1", "bar1", "foo2", "baz2"}, returns a table
-- of subtables in the format
-- {[1] = {foo = 'text', bar = 'text'}, [2] = {foo = 'text', baz = 'text'}}.
-- Keys that don't end with an integer are stored in a subtable named "other". The
-- compress option compresses the table so that it can be iterated over with
-- ipairs.
------------------------------------------------------------------------------------
function p.numData(t, compress)
	checkType('numData', 1, t, 'table')
	checkType('numData', 2, compress, 'boolean', true)
	local ret = {}
	for k, v in pairs(t) do
		local prefix, num = mw.ustring.match(tostring(k), '^([^0-9]*)([1-9][0-9]*)$')
		if num then
			num = tonumber(num)
			local subtable = ret[num] or {}
			if prefix == '' then
				-- Positional parameters match the blank string; put them at the start of the subtable instead.
				prefix = 1
			end
			subtable[prefix] = v
			ret[num] = subtable
		else
			local subtable = ret.other or {}
			subtable[k] = v
			ret.other = subtable
		end
	end
	if compress then
		local other = ret.other
		ret = p.compressSparseArray(ret)
		ret.other = other
	end
	return ret
end

------------------------------------------------------------------------------------
-- compressSparseArray
--
-- This takes an array with one or more nil values, and removes the nil values
-- while preserving the order, so that the array can be safely traversed with
-- ipairs.
------------------------------------------------------------------------------------
function p.compressSparseArray(t)
	checkType('compressSparseArray', 1, t, 'table')
	local ret = {}
	local nums = p.numKeys(t)
	for _, num in ipairs(nums) do
		ret[#ret + 1] = t[num]
	end
	return ret
end

------------------------------------------------------------------------------------
-- sparseIpairs
--
-- This is an iterator for sparse arrays. It can be used like ipairs, but can
-- handle nil values.
------------------------------------------------------------------------------------
function p.sparseIpairs(t)
	checkType('sparseIpairs', 1, t, 'table')
	local nums = p.numKeys(t)
	local i = 0
	local lim = #nums
	return function ()
		i = i + 1
		if i <= lim then
			local key = nums[i]
			return key, t[key]
		else
			return nil, nil
		end
	end
end

------------------------------------------------------------------------------------
-- size
--
-- This returns the size of a key/value pair table. It will also work on arrays,
-- but for arrays it is more efficient to use the # operator.
------------------------------------------------------------------------------------
function p.size(t)
	checkType('size', 1, t, 'table')
	local i = 0
	for _ in pairs(t) do
		i = i + 1
	end
	return i
end

local function defaultKeySort(item1, item2)
	-- "number" < "string", so numbers will be sorted before strings.
	local type1, type2 = type(item1), type(item2)
	if type1 ~= type2 then
		return type1 < type2
	elseif type1 == 'table' or type1 == 'boolean' or type1 == 'function' then
		return tostring(item1) < tostring(item2)
	else
		return item1 < item2
	end
end
------------------------------------------------------------------------------------
-- keysToList
--
-- Returns an array of the keys in a table, sorted using either a default
-- comparison function or a custom keySort function.
------------------------------------------------------------------------------------
function p.keysToList(t, keySort, checked)
	if not checked then
		checkType('keysToList', 1, t, 'table')
		checkTypeMulti('keysToList', 2, keySort, {'function', 'boolean', 'nil'})
	end

	local arr = {}
	local index = 1
	for k in pairs(t) do
		arr[index] = k
		index = index + 1
	end

	if keySort ~= false then
		keySort = type(keySort) == 'function' and keySort or defaultKeySort
		table.sort(arr, keySort)
	end

	return arr
end

------------------------------------------------------------------------------------
-- sortedPairs
--
-- Iterates through a table, with the keys sorted using the keysToList function.
-- If there are only numerical keys, sparseIpairs is probably more efficient.
------------------------------------------------------------------------------------
function p.sortedPairs(t, keySort)
	checkType('sortedPairs', 1, t, 'table')
	checkType('sortedPairs', 2, keySort, 'function', true)

	local arr = p.keysToList(t, keySort, true)

	local i = 0
	return function ()
		i = i + 1
		local key = arr[i]
		if key ~= nil then
			return key, t[key]
		else
			return nil, nil
		end
	end
end

------------------------------------------------------------------------------------
-- isArray
--
-- Returns true if the given value is a table and all keys are consecutive
-- integers starting at 1.
------------------------------------------------------------------------------------
function p.isArray(v)
	if type(v) ~= 'table' then
		return false
	end
	local i = 0
	for _ in pairs(v) do
		i = i + 1
		if v[i] == nil then
			return false
		end
	end
	return true
end

------------------------------------------------------------------------------------
-- isArrayLike
--
-- Returns true if the given value is iterable and all keys are consecutive
-- integers starting at 1.
------------------------------------------------------------------------------------
function p.isArrayLike(v)
	if not pcall(pairs, v) then
		return false
	end
	local i = 0
	for _ in pairs(v) do
		i = i + 1
		if v[i] == nil then
			return false
		end
	end
	return true
end

------------------------------------------------------------------------------------
-- invert
--
-- Transposes the keys and values in an array. For example, {"a", "b", "c"} ->
-- {a = 1, b = 2, c = 3}. Duplicates are not supported (result values refer to
-- the index of the last duplicate) and NaN values are ignored.
------------------------------------------------------------------------------------
function p.invert(arr)
	checkType("invert", 1, arr, "table")
	local isNan = p.isNan
	local map = {}
	for i, v in ipairs(arr) do
		if not isNan(v) then
			map[v] = i
		end
	end

	return map
end

------------------------------------------------------------------------------------
-- listToSet
--
-- Creates a set from the array part of the table. Indexing the set by any of the
-- values of the array returns true. For example, {"a", "b", "c"} ->
-- {a = true, b = true, c = true}. NaN values are ignored as Lua considers them
-- never equal to any value (including other NaNs or even themselves).
------------------------------------------------------------------------------------
function p.listToSet(arr)
	checkType("listToSet", 1, arr, "table")
	local isNan = p.isNan
	local set = {}
	for _, v in ipairs(arr) do
		if not isNan(v) then
			set[v] = true
		end
	end

	return set
end

------------------------------------------------------------------------------------
-- deepCopy
--
-- Recursive deep copy function. Preserves identities of subtables.
------------------------------------------------------------------------------------
local function _deepCopy(orig, includeMetatable, already_seen)
	-- Stores copies of tables indexed by the original table.
	already_seen = already_seen or {}

	local copy = already_seen[orig]
	if copy ~= nil then
		return copy
	end

	if type(orig) == 'table' then
		copy = {}
		for orig_key, orig_value in pairs(orig) do
			copy[_deepCopy(orig_key, includeMetatable, already_seen)] = _deepCopy(orig_value, includeMetatable, already_seen)
		end
		already_seen[orig] = copy

		if includeMetatable then
			local mt = getmetatable(orig)
			if mt ~= nil then
				local mt_copy = _deepCopy(mt, includeMetatable, already_seen)
				setmetatable(copy, mt_copy)
				already_seen[mt] = mt_copy
			end
		end
	else -- number, string, boolean, etc
		copy = orig
	end
	return copy
end

function p.deepCopy(orig, noMetatable, already_seen)
	checkType("deepCopy", 3, already_seen, "table", true)
	return _deepCopy(orig, not noMetatable, already_seen)
end

------------------------------------------------------------------------------------
-- sparseConcat
--
-- Concatenates all values in the table that are indexed by a number, in order.
-- sparseConcat{a, nil, c, d}  =>  "acd"
-- sparseConcat{nil, b, c, d}  =>  "bcd"
------------------------------------------------------------------------------------
function p.sparseConcat(t, sep, i, j)
	local arr = {}

	local arr_i = 0
	for _, v in p.sparseIpairs(t) do
		arr_i = arr_i + 1
		arr[arr_i] = v
	end

	return table.concat(arr, sep, i, j)
end

------------------------------------------------------------------------------------
-- length
--
-- Finds the length of an array, or of a quasi-array with keys such as "data1",
-- "data2", etc., using an exponential search algorithm. It is similar to the
-- operator #, but may return a different value when there are gaps in the array
-- portion of the table. Intended to be used on data loaded with mw.loadData. For
-- other tables, use #.
-- Note: #frame.args in frame object always be set to 0, regardless of  the number
-- of unnamed template parameters, so use this function for frame.args.
------------------------------------------------------------------------------------
function p.length(t, prefix)
	-- requiring module inline so that [[Module:Exponential search]] which is
	-- only needed by this one function doesn't get millions of transclusions
	local expSearch = require("Module:Exponential search")
	checkType('length', 1, t, 'table')
	checkType('length', 2, prefix, 'string', true)
	return expSearch(function (i)
		local key
		if prefix then
			key = prefix .. tostring(i)
		else
			key = i
		end
		return t[key] ~= nil
	end) or 0
end

------------------------------------------------------------------------------------
-- inArray
--
-- Returns true if valueToFind is a member of the array, and false otherwise.
------------------------------------------------------------------------------------
function p.inArray(arr, valueToFind)
	checkType("inArray", 1, arr, "table")
	-- if valueToFind is nil, error?

	for _, v in ipairs(arr) do
		if v == valueToFind then
			return true
		end
	end
	return false
end

return p