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Difference between revisions of "TableTools"

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(reinstate shallowClone - saw a use for it in p.complement - and write p.valueComplement)
(split set functions out to Module:Set)
Line 96: Line 96:
 
end
 
end
 
return ret
 
return ret
−
end
+
end
−
 
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- union
 
−
--
 
−
-- This returns the union of the key/value pairs of n tables. If any of the tables
 
−
-- contain different values for the same table key, the table value is converted
 
−
-- to an array holding all of the different values.
 
−
------------------------------------------------------------------------------------
 
−
--]]
 
−
function p.union(...)
 
−
local lim = select('#', ...)
 
−
if lim < 2 then
 
−
error("too few arguments to 'union' (minimum is 2, received " .. lim .. ')', 2)
 
−
end
 
−
local ret, trackArrays = {}, {}
 
−
for i = 1, lim do
 
−
local t = select(i, ...)
 
−
checkType('union', i, t, 'table')
 
−
for k, v in pairs(t) do
 
−
local retKey = ret[k]
 
−
if retKey == nil then
 
−
ret[k] = v
 
−
elseif retKey ~= v then
 
−
if trackArrays[k] then
 
−
local array = ret[k]
 
−
local valExists
 
−
for _, arrayVal in ipairs(array) do
 
−
if arrayVal == v then
 
−
valExists = true
 
−
break
 
−
end
 
−
end
 
−
if not valExists then
 
−
array[#array + 1] = v
 
−
ret[k] = array
 
−
end
 
−
else
 
−
ret[k] = {ret[k], v}
 
−
trackArrays[k] = true
 
−
end
 
−
end
 
−
end
 
−
end
 
−
return ret
 
−
end
 
−
 
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- valueUnion
 
−
--
 
−
-- This returns the union of the values of n tables, as an array. For example, for
 
−
-- the tables {1, 3, 4, 5, foo = 7} and {2, bar = 3, 5, 6}, union will return
 
−
-- {1, 2, 3, 4, 5, 6, 7}.
 
−
------------------------------------------------------------------------------------
 
−
--]]
 
−
function p.valueUnion(...)
 
−
local lim = select('#', ...)
 
−
if lim < 2 then
 
−
error("too few arguments to 'valueUnion' (minimum is 2, received " .. lim .. ')', 2)
 
−
end
 
−
local isNan = p.isNan
 
−
local ret, exists = {}, {}
 
−
for i = 1, lim do
 
−
local t = select(i, ...)
 
−
checkType('valueUnion', i, t, 'table')
 
−
for k, v in pairs(t) do
 
−
if isNan(v) then
 
−
ret[#ret + 1] = v
 
−
elseif not exists[v] then
 
−
ret[#ret + 1] = v
 
−
exists[v] = true
 
−
end
 
−
end
 
−
end
 
−
return ret
 
−
end
 
−
 
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- intersection
 
−
--
 
−
-- This returns the intersection of the key/value pairs of n tables. Both the key
 
−
-- and the value must match to be included in the resulting table.
 
−
------------------------------------------------------------------------------------
 
−
--]]
 
−
function p.intersection(...)
 
−
local lim = select('#', ...)
 
−
if lim < 2 then
 
−
error("too few arguments to 'intersection' (minimum is 2, received " .. lim .. ')', 2)
 
−
end
 
−
local ret, track, pairCounts = {}, {}, {}
 
−
for i = 1, lim do
 
−
local t = select(i, ...)
 
−
checkType('intersection', i, t, 'table')
 
−
for k, v in pairs(t) do
 
−
local trackVal = track[k]
 
−
if trackVal == nil then
 
−
track[k] = v
 
−
pairCounts[k] = 1
 
−
elseif trackVal == v then
 
−
pairCounts[k] = pairCounts[k] + 1
 
−
end
 
−
end
 
−
end
 
−
for k, v in pairs(track) do
 
−
if pairCounts[k] == lim then
 
−
ret[k] = v
 
−
end
 
−
end
 
−
return ret
 
−
end
 
−
 
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- valueIntersection
 
−
--
 
−
-- This returns the intersection of the values of n tables, as an array. For
 
−
-- example, for the tables {1, 3, 4, 5, foo = 7} and {2, bar = 3, 5, 6},
 
−
-- intersection will return {3, 5}.
 
−
------------------------------------------------------------------------------------
 
−
--]]
 
−
function p.valueIntersection(...)
 
−
local lim = select('#', ...)
 
−
if lim < 2 then
 
−
error("too few arguments to 'valueIntersection' (minimum is 2, received " .. lim .. ')', 2)
 
−
end
 
−
local isNan = p.isNan
 
−
local vals, ret = {}, {}
 
−
local isSameTable = true -- Tracks table equality.
 
−
local tableTemp -- Used to store the table from the previous loop so that we can check table equality.
 
−
for i = 1, lim do
 
−
local t = select(i, ...)
 
−
checkType('valueIntersection', i, t, 'table')
 
−
if tableTemp and t ~= tableTemp then
 
−
isSameTable = false
 
−
end
 
−
tableTemp = t
 
−
for k, v in pairs(t) do
 
−
-- NaNs are never equal to any other value, so they can't be in the intersection.
 
−
-- Which is lucky, as they also can't be table keys.
 
−
if not isNan(v) then
 
−
local valCount = vals[v] or 0
 
−
vals[v] = valCount + 1
 
−
end
 
−
end
 
−
end
 
−
if isSameTable then
 
−
-- If all the tables are equal, then the intersection is that table (including NaNs).
 
−
-- All we need to do is convert it to an array and remove duplicate values.
 
−
for k, v in pairs(tableTemp) do
 
−
ret[#ret + 1] = v
 
−
end
 
−
return p.removeDuplicates(ret)
 
−
end
 
−
for val, count in pairs(vals) do
 
−
if count == lim then
 
−
ret[#ret + 1] = val
 
−
end
 
−
end
 
−
return ret
 
−
end
 
−
 
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- complement
 
−
--
 
−
-- This returns the relative complement of t1, t2, ..., in tn. The complement
 
−
-- is of key/value pairs. This is equivalent to all the key/value pairs that are in
 
−
-- tn but are not in t1, t2, ... tn-1.
 
−
------------------------------------------------------------------------------------
 
−
--]]
 
−
function p.complement(...)
 
−
local lim = select('#', ...)
 
−
if lim < 2 then
 
−
error("too few arguments to 'complement' (minimum is 2, received " .. lim .. ')', 2)
 
−
end
 
−
--[[
 
−
-- Now we know that we have at least two sets.
 
−
-- First, get all the key/value pairs in tn. We can't simply make ret equal to tn,
 
−
-- as that will affect the value of tn for the whole module.
 
−
--]]
 
−
local tn = select(lim, ...)
 
−
checkType('complement', lim, tn, 'table')
 
−
local ret = p.shallowClone(tn)
 
−
-- Remove all the key/value pairs in t1, t2, ..., tn-1.
 
−
for i = 1, lim - 1 do
 
−
local t = select(i, ...)
 
−
checkType('complement', i, t, 'table')
 
−
for k, v in pairs(t) do
 
−
if ret[k] == v then
 
−
ret[k] = nil
 
−
end
 
−
end
 
−
end
 
−
return ret
 
−
end
 
−
 
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- valueComplement
 
−
--
 
−
-- This returns an array containing the relative complement of t1, t2, ..., in tn.
 
−
-- The complement is of values only. This is equivalent to all the values that are
 
−
-- in tn but are not in t1, t2, ... tn-1.
 
−
------------------------------------------------------------------------------------
 
−
--]]
 
−
function p.valueComplement(...)
 
−
local lim = select('#', ...)
 
−
if lim < 2 then
 
−
error("too few arguments to 'valueComplement' (minimum is 2, received " .. lim .. ')', 2)
 
−
end
 
−
local isNan = p.isNan
 
−
local ret, exists = {}, {}
 
−
for i = 1, lim - 1 do
 
−
local t = select(i, ...)
 
−
checkType('valueComplement', i, t, 'table')
 
−
for k, v in pairs(t) do
 
−
if not isNan(v) then
 
−
-- NaNs cannot be table keys, and they are also unique so cannot be equal to anything in tn.
 
−
exists[v] = true
 
−
end
 
−
end
 
−
end
 
−
local tn = select(lim, ...)
 
−
checkType('valueComplement', lim, tn, 'table')
 
−
for k, v in pairs(tn) do
 
−
if isNan(v) or exists[v] == nil then
 
−
ret[#ret + 1] = v
 
−
end
 
−
end
 
−
return ret
 
−
end
 
  
 
--[[
 
--[[

Revision as of 23:46, 19 December 2013

Documentation for this module may be created at Module:TableTools/doc 

--[[
------------------------------------------------------------------------------------
--                               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)
	prefix = prefix or ''
	suffix = suffix or ''
	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

--[[
------------------------------------------------------------------------------------
-- 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]
		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
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