Module:TableTools
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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.
Module Quality
Loading the module
To use any of the functions, first you must load the module.
local TableTools = require('Module:TableTools')
Functions
isPositiveInteger
TableTools.isPositiveInteger(value)
Returns true if 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.
isNan
TableTools.isNan(value)
Returns true if value 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 value is used as a table key.)
shallowClone
TableTools.shallowClone(t)
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.
If you want to make a new table with no shared subtables and with metatables transferred, you can use mw.clone instead.
If you want to make a new table with no shared subtables and without metatables transferred, use deepCopy with the noMetatable option.
removeDuplicates
TableTools.removeDuplicates(t)
Removes duplicate values from an array.
This function is only designed to work with standard arrays: keys that are not positive integers are ignored, as are all values after the first nil value.
(For arrays containing nil values, you can use compressSparseArray first.) The function tries to preserve the order of the array: the earliest non-unique value is kept, and all subsequent duplicate values are removed.
{5, 4, 4, 3, 4, 2, 2, 1}
removeDuplicates will return {5, 4, 3, 2, 1}
numKeys
TableTools.numKeys(t)
Takes a table t and returns an array containing the numbers of any positive integer keys that have non-nil values, sorted in numerical order.
{'foo', nil, 'bar', 'baz', a = 'b'}
numKeys will return {1, 3, 4}
affixNums
TableTools.affixNums(t, prefix, suffix)
Takes a table t and returns an array containing the numbers of keys with the optional prefix prefix and the optional suffix suffix.
{a1 = 'foo', a3 = 'bar', a6 = 'baz'}
'a', affixNums will return {1, 3, 6}
All characters in prefix and suffix are interpreted literally.
numData
TableTools.numData(t, compress)
"foo1", "bar1", "foo2", and "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.
compressSparseArray
TableTools.compressSparseArray(t)
Takes an array t 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.
Any keys that are not positive integers are removed.
{1, nil, foo = 'bar', 3, 2}
compressSparseArray will return {1, 3, 2}
sparseIpairs
TableTools.sparseIpairs(t)
This is an iterator function for traversing a sparse array t.
It is similar to ipairs, but will continue to iterate until the highest numerical key, whereas ipairs may stop after the first nil value.
Any keys that are not positive integers are ignored.
Usually sparseIpairs is used in a generic for loop.
for i, v in TableTools.sparseIpairs(t) do
-- code block
end
Note that sparseIpairs uses the pairs function in its implementation.
Although some table keys appear to be ignored, all table keys are accessed when it is run.
size
TableTools.size(t)
Finds the size of a key/value pair table.
For example, for the table{foo = 'foo', bar = 'bar'}
size will return 2.
The function will also work on arrays, but for arrays it is more efficient to use the # operator.
Note that to find the table size, this function uses the pairs function to iterate through all of the table keys.
keysToList
TableTools.keysToList(t, keySort)
Returns a list of the keys in a table, sorted using either a default comparison function or a custom keySort function, which follows the same rules as the comp function supplied to table.sort.
sortedPairs
TableTools.sortedPairs(t, keySort)
Iterates through a table, with the keys sorted using the keysToList function.
If there are only numerical keys, sparseIpairs is probably more efficient.
isArray
TableTools.isArray(t)
Returns true if all keys in the table are consecutive integers starting at 1.
listToSet
TableTools.listToSet(arr)
Creates a set from the array part of the table arr.
Indexing the set by any of the values in arr returns true.
local set = TableTools.listToSet { "a", "b", "c" }
assert(set["a"] === true)
invert
TableTools.invert(t)
Transposes the keys and values in an array.
For example, invert{ "a", "b", "c" } yields { a = 1, b = 2, c = 3 }.
deepCopy
TableTools.deepCopy(orig, noMetatable, alreadySeen)
Creates a copy of the table orig.
As with mw.clone, all values that are not functions are duplicated and the identity of tables is preserved.
If noMetatable is true, then the metatable (if any) is not copied.
Can copy tables loaded with mw.loadData.
Similar to mw.clone, but mw.clone cannot copy tables loaded with mw.loadData and does not allow metatables not to be copied.
sparseConcat
TableTools.sparseConcat(t, sep)
Concatenates all values in the table that are indexed by a positive integer, in order.
length
TableTools.length(t)
Returns the length of a table, or the first integer key n counting from 0 such that t[n + 1] is nil.
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 and on frame.args.
Both use a metatable such that #mw.loadData("module:...") and #frame.args don't work correctly.
For other tables, use #.
inArray
TableTools.inArray(arr, valueToFind)
Returns true if valueToFind is a member of the array arr, and false otherwise.
--[[
------------------------------------------------------------------------------------
-- 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)
if type(v) == 'number' and v >= 1 and floor(v) == v and v < infinity then
return true
else
return false
end
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)
if type(v) == 'number' and tostring(v) == '-nan' then
return true
else
return false
end
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)
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(t)
checkType('removeDuplicates', 1, t, 'table')
local isNan = p.isNan
local ret, exists = {}, {}
for i, v in ipairs(t) 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, v 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.
s = s:gsub('([%(%)%%%.%[%]%*%+%-%?%^%$])', '%%%1')
return s
end
prefix = prefix or ''
suffix = suffix or ''
prefix = cleanPattern(prefix)
suffix = cleanPattern(suffix)
local pattern = '^' .. prefix .. '([1-9]%d*)' .. suffix .. '$'
local nums = {}
for k, v 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 k 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
else -- This will fail with table, boolean, function.
return item1 < item2
end
end
--[[
Returns a list 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 list = {}
local index = 1
for key, value in pairs(t) do
list[index] = key
index = index + 1
end
if keySort ~= false then
keySort = type(keySort) == 'function' and keySort or defaultKeySort
table.sort(list, keySort)
end
return list
end
--[[
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 list = p.keysToList(t, keySort, true)
local i = 0
return function()
i = i + 1
local key = list[i]
if key ~= nil then
return key, t[key]
else
return nil, nil
end
end
end
--[[
Returns true if all keys in the table are consecutive integers starting at 1.
--]]
function p.isArray(t)
checkType("isArray", 1, t, "table")
local i = 0
for k, v in pairs(t) do
i = i + 1
if t[i] == nil then
return false
end
end
return true
end
-- { "a", "b", "c" } -> { a = 1, b = 2, c = 3 }
function p.invert(array)
checkType("invert", 1, array, "table")
local map = {}
for i, v in ipairs(array) do
map[v] = i
end
return map
end
--[[
{ "a", "b", "c" } -> { ["a"] = true, ["b"] = true, ["c"] = true }
--]]
function p.listToSet(t)
checkType("listToSet", 1, t, "table")
local set = {}
for _, item in ipairs(t) do
set[item] = true
end
return set
end
--[[
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
--[[
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 list = {}
local list_i = 0
for _, v in p.sparseIpairs(t) do
list_i = list_i + 1
list[list_i] = v
end
return table.concat(list, sep, i, j)
end
--[[
-- This returns the length of a table, or the first integer key n counting from
-- 1 such that t[n + 1] is nil. 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)
local i = 1
while t[i] ~= nil do
i = i + 1
end
return i - 1
end
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