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)

Returnstrueifvalueis a positive integer, andfalseif 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)

Returnstrueifvalueis a NaN value, andfalseif 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.cloneinstead.

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 firstnilvalue. (For arrays containingnilvalues, you can usecompressSparseArrayfirst.) 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{{{2}}}removeDuplicates will return{{{2}}}

numKeys

TableTools.numKeys(t)

Takes a tabletand 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{{{2}}},numKeys will return{{{2}}}.

affixNums

TableTools.affixNums(t,prefix,suffix)

Takes a tabletand returns an array containing the numbers of keys with the optional prefixprefixand the optional suffixsuffix.For example, for the table{{{2}}}and the prefix'a',affixNums will return{{{2}}}.All characters inprefixandsuffixare 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{{{2}}}.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 arraytwith 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{{{2}}},compressSparseArray will return{{{2}}}.

sparseIpairs

TableTools.sparseIpairs(t)

This is an iterator function for traversing a sparse arrayt.It is similar toipairs,but will continue to iterate until the highest numerical key, whereas ipairs may stop after the firstnilvalue. Any keys that are not positive integers are ignored.

Usually sparseIpairs is used in a genericforloop.

fori,vinTableTools.sparseIpairs(t)do
-- code block
end

Note that sparseIpairs uses thepairsfunction 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{{{2}}},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 table size, this function uses thepairsfunction 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.floor
localinfinity=math.huge
localcheckType=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.
------------------------------------------------------------------------------------
--]]
functionp.isPositiveInteger(v)
iftype(v)=='number'andv>=1andfloor(v)==vandv<infinitythen
returntrue
else
returnfalse
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.
------------------------------------------------------------------------------------
--]]
functionp.isNan(v)
iftype(v)=='number'andtostring(v)=='-nan'then
returntrue
else
returnfalse
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.
------------------------------------------------------------------------------------
--]]
functionp.shallowClone(t)
localret={}
fork,vinpairs(t)do
ret[k]=v
end
returnret
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.
------------------------------------------------------------------------------------
--]]
functionp.removeDuplicates(t)
checkType('removeDuplicates',1,t,'table')
localisNan=p.isNan
localret,exists={},{}
fori,vinipairs(t)do
ifisNan(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
ifnotexists[v]then
ret[#ret+1]=v
exists[v]=true
end
end
end
returnret
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.
------------------------------------------------------------------------------------
--]]
functionp.numKeys(t)
checkType('numKeys',1,t,'table')
localisPositiveInteger=p.isPositiveInteger
localnums={}
fork,vinpairs(t)do
ifisPositiveInteger(k)then
nums[#nums+1]=k
end
end
table.sort(nums)
returnnums
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}.
------------------------------------------------------------------------------------
--]]
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.
s=s:gsub('([%(%)%%%.%[%]%*%+%-%?%^%$])','%%%1')
returns
end

prefix=prefixor''
suffix=suffixor''
prefix=cleanPattern(prefix)
suffix=cleanPattern(suffix)
localpattern='^'..prefix..'([1-9]%d*)'..suffix..'$'

localnums={}
fork,vinpairs(t)do
iftype(k)=='string'then
localnum=mw.ustring.match(k,pattern)
ifnumthen
nums[#nums+1]=tonumber(num)
end
end
end
table.sort(nums)
returnnums
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.
------------------------------------------------------------------------------------
--]]
functionp.numData(t,compress)
checkType('numData',1,t,'table')
checkType('numData',2,compress,'boolean',true)
localret={}
fork,vinpairs(t)do
localprefix,num=mw.ustring.match(tostring(k),'^([^0-9]*)([1-9][0-9]*)$')
ifnumthen
num=tonumber(num)
localsubtable=ret[num]or{}
ifprefix==''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
localsubtable=ret.otheror{}
subtable[k]=v
ret.other=subtable
end
end
ifcompressthen
localother=ret.other
ret=p.compressSparseArray(ret)
ret.other=other
end
returnret
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.
------------------------------------------------------------------------------------
--]]
functionp.compressSparseArray(t)
checkType('compressSparseArray',1,t,'table')
localret={}
localnums=p.numKeys(t)
for_,numinipairs(nums)do
ret[#ret+1]=t[num]
end
returnret
end

--[[
------------------------------------------------------------------------------------
-- 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=0
locallim=#nums
returnfunction()
i=i+1
ifi<=limthen
localkey=nums[i]
returnkey,t[key]
else
returnnil,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.
------------------------------------------------------------------------------------
--]]
functionp.size(t)
checkType('size',1,t,'table')
locali=0
forkinpairs(t)do
i=i+1
end
returni
end

returnp