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.
Loading the module
To use any of the functions, first you must load the module.
<source lang="lua"> local TableTools = require('Module:TableTools') </source>
isPositiveInteger
<source lang="lua"> TableTools.isPositiveInteger(value) </source>
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
<source lang="lua"> TableTools.isNan(value) </source>
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
<source lang="lua"> TableTools.shallowClone(t) </source>
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.
removeDuplicates
<source lang="lua"> TableTools.removeDuplicates(t) </source>
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. For example, for the table <syntaxhighlight lang="lua" enclose="none">{5, 4, 4, 3, 4, 2, 2, 1}</syntaxhighlight>
removeDuplicates will return <syntaxhighlight lang="lua" enclose="none">{5, 4, 3, 2, 1}</syntaxhighlight>
numKeys
<source lang="lua"> TableTools.numKeys(t) </source>
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. For example, for the table <syntaxhighlight lang="lua" enclose="none">{'foo', nil, 'bar', 'baz', a = 'b'}</syntaxhighlight>
, numKeys will return <syntaxhighlight lang="lua" enclose="none">{1, 3, 4}</syntaxhighlight>
.
affixNums
<source lang="lua"> TableTools.affixNums(t, prefix, suffix) </source>
Takes a table t
and returns an array containing the numbers of keys with the optional prefix prefix
and the optional suffix suffix
. For example, for the table <syntaxhighlight lang="lua" enclose="none">{a1 = 'foo', a3 = 'bar', a6 = 'baz'}</syntaxhighlight>
and the prefix 'a'
, affixNums will return <syntaxhighlight lang="lua" enclose="none">{1, 3, 6}</syntaxhighlight>
. All characters in prefix
and suffix
are interpreted literally.
numData
<source lang="lua"> TableTools.numData(t, compress) </source>
Given a table with keys like "foo1", "bar1", "foo2", and "baz2", returns a table of subtables in the format <syntaxhighlight lang="lua" enclose="none">{ [1] = {foo = 'text', bar = 'text'}, [2] = {foo = 'text', baz = 'text'} }</syntaxhighlight>
. 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
<source lang="lua"> TableTools.compressSparseArray(t) </source>
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. For example, for the table <syntaxhighlight lang="lua" enclose="none">{1, nil, foo = 'bar', 3, 2}</syntaxhighlight>
, compressSparseArray will return <syntaxhighlight lang="lua" enclose="none">{1, 3, 2}</syntaxhighlight>
.
sparseIpairs
<source lang="lua"> TableTools.sparseIpairs(t) </source>
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.
<source lang="lua"> for i, v in TableTools.sparseIpairs(t) do
-- code block
end </source>
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
<source lang="lua"> TableTools.size(t) </source>
Finds the size of a key/value pair table. For example, for the table <syntaxhighlight lang="lua" enclose="none">{foo = 'foo', bar = 'bar'}</syntaxhighlight>
, 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.
--[[ ------------------------------------------------------------------------------------ -- 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 --[[ ------------------------------------------------------------------------------------ -- 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 return p