This Lua module is used in system messages, and onapproximately 8,750,000 pages, or roughly 14% of all pages. Changes to it can cause immediate changes to the Wikipedia user interface. To avoid major disruption and server load, any changes should be tested in the module's/sandbox or/testcases subpages, or in your ownmodule sandbox. The tested changes can be added to this page in a single edit. Please discuss changes on thetalk page before implementing them.
This module is rated asready for general use. It has reached a mature form and is thought to be relatively bug-free and ready for use wherever appropriate. It is ready to mention on help pages and other Wikipedia resources as an option for new users to learn. To reduce server load and bad output, it should be improved bysandbox testing rather than repeated trial-and-error editing.
This module issubject to page protection. It is ahighly visible module in use by a very large number of pages, or issubstituted very frequently. Because vandalism or mistakes would affect many pages, and even trivial editing might cause substantial load on the servers, it isprotected from editing.
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.
localTableTools=require('Module:TableTools')
isPositiveInteger
TableTools.isPositiveInteger(value)
Returnstrue ifvalue is a positive integer, andfalse 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)
Returnstrue ifvalue is aNaN value, andfalse 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 usemw.clone instead. If you want to make a new table with no shared subtables and without metatables transferred, usedeepCopy with thenoMetatable 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 firstnil value. (For arrays containingnil values, you can usecompressSparseArray 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{5,4,4,3,4,2,2,1}removeDuplicates will return{5,4,3,2,1}.
numKeys
TableTools.numKeys(t)
Takes a tablet 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{'foo',nil,'bar','baz',a='b'},numKeys will return{1,3,4}.
affixNums
TableTools.affixNums(t,prefix,suffix)
Takes a tablet and returns an array containing the numbers of keys with the optional prefixprefix and the optional suffixsuffix. For example, for the table{a1='foo',a3='bar',a6='baz'} and the prefix'a',affixNums will return{1,3,6}. All characters inprefix andsuffix are interpreted literally.
Given a table with keys like"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 withipairs.
compressSparseArray
TableTools.compressSparseArray(t)
Takes an arrayt with one or more nil values, and removes the nil values while preserving the order, so that the array can be safely traversed withipairs. Any keys that are not positive integers are removed. For example, for the table{1,nil,foo='bar',3,2},compressSparseArray will return{1,3,2}.
This is an iterator function for traversing a sparse arrayt. It is similar toipairs, but will continue to iterate until the highest numerical key, whereasipairs may stop after the firstnil value. Any keys that are not positive integers are ignored.
Note thatsparseIpairs uses thepairs 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 (associative array). For example, for{foo='foo',bar='bar'},size will return2. The function will also work on arrays, but for arrays it is more efficient to use the# operator. Note that to find the size, this function uses thepairs function to iterate through all of the keys.
keysToList
TableTools.keysToList(t,keySort,checked)
Returns a list of the keys in a table, sorted using either a default comparison function or a customkeySort function, which follows the same rules as thecomp function supplied totable.sort. IfkeySort isfalse, no sorting is done. Setchecked totrue to skip the internal type checking.
sortedPairs
TableTools.sortedPairs(t,keySort)
Iterates through a table, with the keys sorted using thekeysToList function. If there are only numerical keys,sparseIpairs is probably more efficient.
isArray
TableTools.isArray(value)
Returnstrue ifvalue is a table and all keys are consecutive integers starting at 1.
isArrayLike
TableTools.isArrayLike(value)
Returnstrue ifvalue is iterable and all keys are consecutive integers starting at 1.
invert
TableTools.invert(arr)
Transposes the keys and values in an array. For example,invert{"a","b","c"} yields{a=1,b=2,c=3}.
listToSet
TableTools.listToSet(arr)
Creates a set from the array part of the tablearr. Indexing the set by any of the values of the array returnstrue. For example,listToSet{"a","b","c"} yields{a=true,b=true,c=true}.
deepCopy
TableTools.deepCopy(orig,noMetatable,alreadySeen)
Creates a copy of the tableorig. As withmw.clone, all values that are not functions are duplicated and the identity of tables is preserved. IfnoMetatable istrue, then the metatable (if any) is not copied. Can copy tables loaded withmw.loadData.
Similar tomw.clone, butmw.clone cannot copy tables loaded withmw.loadData and does not allow metatablesnot to be copied.
sparseConcat
TableTools.sparseConcat(t,sep,i,j)
Concatenates all values in the table that are indexed by a positive integer, in order. For example,sparseConcat{"a",nil,"c","d"} yields"acd" andsparseConcat{nil,"b","c","d"} yields"bcd".
length
TableTools.length(t,prefix)
Finds the length of an array or of a quasi-array with keys with an optionalprefix such as "data1", "data2", etc. It uses anexponential search algorithm to find the length, so as to use as few table lookups as possible.
This algorithm is useful for arrays that use metatables (e.g.frame.args) and for quasi-arrays. For normal arrays, just use the# operator, as it is implemented inC and will be quicker.
Returnstrue ifsearchElement is a member of the arrayarray, andfalse otherwise. Equivalent to the javascriptArray.prototype.includes() function, except fromIndex is 1-indexed instead of zero-indexed.
fromIndex
fromIndex is the optional 1-based index at which to start searching. IffromIndex is not present, all values in the array will be searched and the array will be treated as a table/associative array (it will be iterated over usingpairs()).
IffromIndex is present and an integer, the array is assumed to be a conventional array/sequence/list (indexed with consecutive integer keys starting at1, and interated over usingipairs()). Only the values whose index isfromIndex or higher will be searched.
In the following examples,#array represents the length of the integer-keyed portion of the array.
IffromIndex < 0 it will count back from the end of the array, e.g. a value of-1 will only search the last integer-keyed element in the array. IffromIndex <= (-1 * #array), the entire integer-keyed portion of the array will be searched.
IffromIndex = 0 it will be treated as a1 and the entire integer-keyed portion of the array will be searched.
IffromIndex > #array, the array is not searched andfalse is returned.
merge
TableTools.merge(...)
Given the arrays, returns an array containing the elements of each input array in sequence.
extend
TableTools.extend(arr1,arr2)
Extends the first array in place by appending all elements from the second array.
-------------------------------------------------------------------------------------- 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. --------------------------------------------------------------------------------------locallibraryUtil=require('libraryUtil')localp={}-- Define often-used variables and functions.localfloor=math.floorlocalinfinity=math.hugelocalcheckType=libraryUtil.checkTypelocalcheckTypeMulti=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.------------------------------------------------------------------------------------functionp.isPositiveInteger(v)returntype(v)=='number'andv>=1andfloor(v)==vandv<infinityend-------------------------------------------------------------------------------------- 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.------------------------------------------------------------------------------------functionp.isNan(v)returntype(v)=='number'andv~=vend-------------------------------------------------------------------------------------- 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.------------------------------------------------------------------------------------functionp.shallowClone(t)checkType('shallowClone',1,t,'table')localret={}fork,vinpairs(t)doret[k]=vendreturnretend-------------------------------------------------------------------------------------- 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.------------------------------------------------------------------------------------functionp.removeDuplicates(arr)checkType('removeDuplicates',1,arr,'table')localisNan=p.isNanlocalret,exists={},{}for_,vinipairs(arr)doifisNan(v)then-- NaNs can't be table keys, and they are also unique, so we don't need to check existence.ret[#ret+1]=velseifnotexists[v]thenret[#ret+1]=vexists[v]=trueendendreturnretend-------------------------------------------------------------------------------------- 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.------------------------------------------------------------------------------------functionp.numKeys(t)checkType('numKeys',1,t,'table')localisPositiveInteger=p.isPositiveIntegerlocalnums={}forkinpairs(t)doifisPositiveInteger(k)thennums[#nums+1]=kendendtable.sort(nums)returnnumsend-------------------------------------------------------------------------------------- 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}.------------------------------------------------------------------------------------functionp.affixNums(t,prefix,suffix)checkType('affixNums',1,t,'table')checkType('affixNums',2,prefix,'string',true)checkType('affixNums',3,suffix,'string',true)localfunctioncleanPattern(s)-- Cleans a pattern so that the magic characters ()%.[]*+-?^$ are interpreted literally.returns:gsub('([%(%)%%%.%[%]%*%+%-%?%^%$])','%%%1')endprefix=prefixor''suffix=suffixor''prefix=cleanPattern(prefix)suffix=cleanPattern(suffix)localpattern='^'..prefix..'([1-9]%d*)'..suffix..'$'localnums={}forkinpairs(t)doiftype(k)=='string'thenlocalnum=mw.ustring.match(k,pattern)ifnumthennums[#nums+1]=tonumber(num)endendendtable.sort(nums)returnnumsend-------------------------------------------------------------------------------------- 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.------------------------------------------------------------------------------------functionp.numData(t,compress)checkType('numData',1,t,'table')checkType('numData',2,compress,'boolean',true)localret={}fork,vinpairs(t)dolocalprefix,num=mw.ustring.match(tostring(k),'^([^0-9]*)([1-9][0-9]*)$')ifnumthennum=tonumber(num)localsubtable=ret[num]or{}ifprefix==''then-- Positional parameters match the blank string; put them at the start of the subtable instead.prefix=1endsubtable[prefix]=vret[num]=subtableelselocalsubtable=ret.otheror{}subtable[k]=vret.other=subtableendendifcompressthenlocalother=ret.otherret=p.compressSparseArray(ret)ret.other=otherendreturnretend-------------------------------------------------------------------------------------- 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.------------------------------------------------------------------------------------functionp.compressSparseArray(t)checkType('compressSparseArray',1,t,'table')localret={}localnums=p.numKeys(t)for_,numinipairs(nums)doret[#ret+1]=t[num]endreturnretend-------------------------------------------------------------------------------------- sparseIpairs---- This is an iterator for sparse arrays. It can be used like ipairs, but can-- handle nil values.------------------------------------------------------------------------------------functionp.sparseIpairs(t)checkType('sparseIpairs',1,t,'table')localnums=p.numKeys(t)locali=0locallim=#numsreturnfunction()i=i+1ifi<=limthenlocalkey=nums[i]returnkey,t[key]elsereturnnil,nilendendend-------------------------------------------------------------------------------------- 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.------------------------------------------------------------------------------------functionp.size(t)checkType('size',1,t,'table')locali=0for_inpairs(t)doi=i+1endreturniendlocalfunctiondefaultKeySort(item1,item2)-- "number" < "string", so numbers will be sorted before strings.localtype1,type2=type(item1),type(item2)iftype1~=type2thenreturntype1<type2elseiftype1=='table'ortype1=='boolean'ortype1=='function'thenreturntostring(item1)<tostring(item2)elsereturnitem1<item2endend-------------------------------------------------------------------------------------- keysToList---- Returns an array of the keys in a table, sorted using either a default-- comparison function or a custom keySort function.------------------------------------------------------------------------------------functionp.keysToList(t,keySort,checked)ifnotcheckedthencheckType('keysToList',1,t,'table')checkTypeMulti('keysToList',2,keySort,{'function','boolean','nil'})endlocalarr={}localindex=1forkinpairs(t)doarr[index]=kindex=index+1endifkeySort~=falsethenkeySort=type(keySort)=='function'andkeySortordefaultKeySorttable.sort(arr,keySort)endreturnarrend-------------------------------------------------------------------------------------- sortedPairs---- Iterates through a table, with the keys sorted using the keysToList function.-- If there are only numerical keys, sparseIpairs is probably more efficient.------------------------------------------------------------------------------------functionp.sortedPairs(t,keySort)checkType('sortedPairs',1,t,'table')checkType('sortedPairs',2,keySort,'function',true)localarr=p.keysToList(t,keySort,true)locali=0returnfunction()i=i+1localkey=arr[i]ifkey~=nilthenreturnkey,t[key]elsereturnnil,nilendendend-------------------------------------------------------------------------------------- isArray---- Returns true if the given value is a table and all keys are consecutive-- integers starting at 1.------------------------------------------------------------------------------------functionp.isArray(v)iftype(v)~='table'thenreturnfalseendlocali=0for_inpairs(v)doi=i+1ifv[i]==nilthenreturnfalseendendreturntrueend-------------------------------------------------------------------------------------- isArrayLike---- Returns true if the given value is iterable and all keys are consecutive-- integers starting at 1.------------------------------------------------------------------------------------functionp.isArrayLike(v)ifnotpcall(pairs,v)thenreturnfalseendlocali=0for_inpairs(v)doi=i+1ifv[i]==nilthenreturnfalseendendreturntrueend-------------------------------------------------------------------------------------- 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.------------------------------------------------------------------------------------functionp.invert(arr)checkType("invert",1,arr,"table")localisNan=p.isNanlocalmap={}fori,vinipairs(arr)doifnotisNan(v)thenmap[v]=iendendreturnmapend-------------------------------------------------------------------------------------- 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).------------------------------------------------------------------------------------functionp.listToSet(arr)checkType("listToSet",1,arr,"table")localisNan=p.isNanlocalset={}for_,vinipairs(arr)doifnotisNan(v)thenset[v]=trueendendreturnsetend-------------------------------------------------------------------------------------- deepCopy---- Recursive deep copy function. Preserves identities of subtables.------------------------------------------------------------------------------------localfunction_deepCopy(orig,includeMetatable,already_seen)iftype(orig)~="table"thenreturnorigend-- already_seen stores copies of tables indexed by the original table.localcopy=already_seen[orig]ifcopy~=nilthenreturncopyendcopy={}already_seen[orig]=copy-- memoize before any recursion, to avoid infinite loopsfororig_key,orig_valueinpairs(orig)docopy[_deepCopy(orig_key,includeMetatable,already_seen)]=_deepCopy(orig_value,includeMetatable,already_seen)endifincludeMetatablethenlocalmt=getmetatable(orig)ifmt~=nilthensetmetatable(copy,_deepCopy(mt,true,already_seen))endendreturncopyendfunctionp.deepCopy(orig,noMetatable,already_seen)checkType("deepCopy",3,already_seen,"table",true)return_deepCopy(orig,notnoMetatable,already_seenor{})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"------------------------------------------------------------------------------------functionp.sparseConcat(t,sep,i,j)localarr={}localarr_i=0for_,vinp.sparseIpairs(t)doarr_i=arr_i+1arr[arr_i]=vendreturntable.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.------------------------------------------------------------------------------------functionp.length(t,prefix)-- requiring module inline so that [[Module:Exponential search]] which is-- only needed by this one function doesn't get millions of transclusionslocalexpSearch=require("Module:Exponential search")checkType('length',1,t,'table')checkType('length',2,prefix,'string',true)returnexpSearch(function(i)localkeyifprefixthenkey=prefix..tostring(i)elsekey=iendreturnt[key]~=nilend)or0end-------------------------------------------------------------------------------------- inArray---- Returns true if searchElement is a member of the array, and false otherwise.-- Equivalent to JavaScript array.includes(searchElement) or-- array.includes(searchElement, fromIndex), except fromIndex is 1 indexed------------------------------------------------------------------------------------functionp.inArray(array,searchElement,fromIndex)checkType("inArray",1,array,"table")-- if searchElement is nil, error?fromIndex=tonumber(fromIndex)iffromIndexthenif(fromIndex<0)thenfromIndex=#array+fromIndex+1endiffromIndex<1thenfromIndex=1endfor_,vinipairs({unpack(array,fromIndex)})doifv==searchElementthenreturntrueendendelsefor_,vinpairs(array)doifv==searchElementthenreturntrueendendendreturnfalseend-------------------------------------------------------------------------------------- merge---- Given the arrays, returns an array containing the elements of each input array-- in sequence.------------------------------------------------------------------------------------functionp.merge(...)localarrays={...}localret={}fori,arrinipairs(arrays)docheckType('merge',i,arr,'table')for_,vinipairs(arr)doret[#ret+1]=vendendreturnretend-------------------------------------------------------------------------------------- extend---- Extends the first array in place by appending all elements from the second-- array.------------------------------------------------------------------------------------functionp.extend(arr1,arr2)checkType('extend',1,arr1,'table')checkType('extend',2,arr2,'table')for_,vinipairs(arr2)doarr1[#arr1+1]=vendendreturnp
