Module: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.

Loading the module

To use any of the functions, first you must load the module.

localTableTools=require('Module:TableTools')

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.

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. 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 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 {'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. For example, for the table {a1='foo',a3='bar',a6='baz'} and the prefix 'a', affixNums will return {1,3,6}. All characters in prefix and suffix are interpreted literally.

numData

TableTools.numData(t,compress)

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 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. For example, for the table {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.

fori,vinTableTools.sparseIpairs(t)do-- code blockend

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.

---

-------------------------------------------------------------------------------------- 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]=trueendendendreturnretend-------------------------------------------------------------------------------------- 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)-- Stores copies of tables indexed by the original table.already_seen=already_seenor{}localcopy=already_seen[orig]ifcopy~=nilthenreturncopyendiftype(orig)=='table'thencopy={}fororig_key,orig_valueinpairs(orig)docopy[_deepCopy(orig_key,includeMetatable,already_seen)]=_deepCopy(orig_value,includeMetatable,already_seen)endalready_seen[orig]=copyifincludeMetatablethenlocalmt=getmetatable(orig)ifmt~=nilthenlocalmt_copy=_deepCopy(mt,includeMetatable,already_seen)setmetatable(copy,mt_copy)already_seen[mt]=mt_copyendendelse-- number, string, boolean, etccopy=origendreturncopyendfunctionp.deepCopy(orig,noMetatable,already_seen)checkType("deepCopy",3,already_seen,"table",true)return_deepCopy(orig,notnoMetatable,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"------------------------------------------------------------------------------------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 valueToFind is a member of the array, and false otherwise.------------------------------------------------------------------------------------functionp.inArray(arr,valueToFind)checkType("inArray",1,arr,"table")-- if valueToFind is nil, error?for_,vinipairs(arr)doifv==valueToFindthenreturntrueendendreturnfalseendreturnp