Difference between revisions of "Module:TableTools"

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--[[
+
-- This module includes a number of functions that can be useful when dealing with Lua tables.
−
------------------------------------------------------------------------------------
+
−
--                              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 = {}
 
local p = {}
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local floor = math.floor
 
local floor = math.floor
 
local infinity = math.huge
 
local infinity = math.huge
−
local checkType = libraryUtil.checkType
 
  
 
--[[
 
--[[
−
------------------------------------------------------------------------------------
+
-----------------------------------------------------------------------------------
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-- isPositiveInteger
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-- Helper functions
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--
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-----------------------------------------------------------------------------------
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-- 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
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-- 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
 
  
−
--[[
+
local function isPositiveInteger(num)
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------------------------------------------------------------------------------------
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-- Returns true if the given number is a positive integer, and false if not.
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-- isNan
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if type(num) == 'number' and num >= 1 and floor(num) == num and num < infinity then
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--
+
−
-- This function returns true if the given number is a NaN value, and false
+
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-- if not. Although it doesn't operate on tables, it is included here as it is
+
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-- 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.
+
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------------------------------------------------------------------------------------
+
−
--]]
+
−
function p.isNan(v)
+
−
if type(v) == 'number' and tostring(v) == '-nan' then
+
 
return true
 
return true
 
else
 
else
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--[[
 
--[[
−
------------------------------------------------------------------------------------
+
-----------------------------------------------------------------------------------
−
-- shallowClone
+
-- compressSparseArray
 
--
 
--
−
-- This returns a clone of a table. The value returned is a new table, but all
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-- This takes an array with one or more nil values, and removes the nil values
−
-- subtables and functions are shared. Metamethods are respected, but the returned
+
-- while preserving the order, so that the array can be safely traversed with
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-- table will have no metatable of its own.
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-- ipairs.
−
------------------------------------------------------------------------------------
+
-----------------------------------------------------------------------------------
 
--]]
 
--]]
−
function p.shallowClone(t)
+
function p.compressSparseArray(t)
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local ret = {}
+
local nums, ret = {}, {}
−
for k, v in pairs(t) do
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−
ret[k] = v
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−
end
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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)
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checkType('removeDuplicates', 1, t, 'table')
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local isNan = p.isNan
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local ret, exists = {}, {}
+
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for i, v in ipairs(t) do
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if isNan(v) then
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-- NaNs can't be table keys, and they are also unique, so we don't need to check existence.
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ret[#ret + 1] = v
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else
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if not exists[v] then
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ret[#ret + 1] = v
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exists[v] = true
+
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end
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end
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end
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return ret
+
−
end
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−
 
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--[[
+
−
------------------------------------------------------------------------------------
+
−
-- numKeys
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−
--
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-- This takes a table and returns an array containing the numbers of any numerical
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-- keys that have non-nil values, sorted in numerical order.
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------------------------------------------------------------------------------------
+
−
--]]
+
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function p.numKeys(t)
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checkType('numKeys', 1, t, 'table')
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−
local isPositiveInteger = p.isPositiveInteger
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local nums = {}
+
 
for k, v in pairs(t) do
 
for k, v in pairs(t) do
 
if isPositiveInteger(k) then
 
if isPositiveInteger(k) then
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end
 
end
 
table.sort(nums)
 
table.sort(nums)
−
return nums
 
−
end
 
−
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- affixNums
 
−
--
 
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-- This takes a table and returns an array containing the numbers of keys with the
 
−
-- specified prefix and suffix. For example, for the table
 
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-- {a1 = 'foo', a3 = 'bar', a6 = 'baz'} and the prefix "a", affixNums will
 
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-- return {1, 3, 6}.
 
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------------------------------------------------------------------------------------
 
−
--]]
 
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function p.affixNums(t, prefix, suffix)
 
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checkType('affixNums', 1, t, 'table')
 
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checkType('affixNums', 2, prefix, 'string', true)
 
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checkType('affixNums', 3, suffix, 'string', true)
 
−
 
−
local function cleanPattern(s)
 
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-- Cleans a pattern so that the magic characters ()%.[]*+-?^$ are interpreted literally.
 
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s = s:gsub('([%(%)%%%.%[%]%*%+%-%?%^%$])', '%%%1')
 
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return s
 
−
end
 
−
 
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prefix = prefix or ''
 
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suffix = suffix or ''
 
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prefix = cleanPattern(prefix)
 
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suffix = cleanPattern(suffix)
 
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local pattern = '^' .. prefix .. '([1-9]%d*)' .. suffix .. '$'
 
−
 
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local nums = {}
 
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for k, v in pairs(t) do
 
−
if type(k) == 'string' then
 
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local num = mw.ustring.match(k, pattern)
 
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if num then
 
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nums[#nums + 1] = tonumber(num)
 
−
end
 
−
end
 
−
end
 
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table.sort(nums)
 
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return nums
 
−
end
 
−
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- numData
 
−
--
 
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-- Given a table with keys like ("foo1", "bar1", "foo2", "baz2"), returns a table
 
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-- of subtables in the format
 
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-- { [1] = {foo = 'text', bar = 'text'}, [2] = {foo = 'text', baz = 'text'} }
 
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-- Keys that don't end with an integer are stored in a subtable named "other".
 
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-- The compress option compresses the table so that it can be iterated over with
 
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-- ipairs.
 
−
------------------------------------------------------------------------------------
 
−
--]]
 
−
function p.numData(t, compress)
 
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checkType('numData', 1, t, 'table')
 
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checkType('numData', 2, compress, 'boolean', true)
 
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local ret = {}
 
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for k, v in pairs(t) do
 
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local prefix, num = mw.ustring.match(tostring(k), '^([^0-9]*)([1-9][0-9]*)$')
 
−
if num then
 
−
num = tonumber(num)
 
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local subtable = ret[num] or {}
 
−
if prefix == '' then
 
−
-- Positional parameters match the blank string; put them at the start of the subtable instead.
 
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prefix = 1
 
−
end
 
−
subtable[prefix] = v
 
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ret[num] = subtable
 
−
else
 
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local subtable = ret.other or {}
 
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subtable[k] = v
 
−
ret.other = subtable
 
−
end
 
−
end
 
−
if compress then
 
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local other = ret.other
 
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ret = p.compressSparseArray(ret)
 
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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')
 
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local ret = {}
 
−
local nums = p.numKeys(t)
 
 
for _, num in ipairs(nums) do
 
for _, num in ipairs(nums) do
 
ret[#ret + 1] = t[num]
 
ret[#ret + 1] = t[num]
 
end
 
end
 
return ret
 
return ret
−
end
 
−
 
−
--[[
 
−
------------------------------------------------------------------------------------
 
−
-- sparseIpairs
 
−
--
 
−
-- This is an iterator for sparse arrays. It can be used like ipairs, but can
 
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-- handle nil values.
 
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------------------------------------------------------------------------------------
 
−
--]]
 
−
function p.sparseIpairs(t)
 
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checkType('sparseIpairs', 1, t, 'table')
 
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local nums = p.numKeys(t)
 
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local i = 0
 
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local lim = #nums
 
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return function ()
 
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i = i + 1
 
−
if i <= lim then
 
−
local key = nums[i]
 
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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)
 
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checkType('size', 1, t, 'table')
 
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local i = 0
 
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for k in pairs(t) do
 
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i = i + 1
 
−
end
 
−
return i
 
 
end
 
end
  
 
return p
 
return p

Revision as of 11:40, 15 December 2013

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

Script error: Lua error: Internal error: The interpreter exited with status 126. 

-- This module includes a number of functions that can be useful when dealing with Lua tables.

local p = {}

-- Define often-used variables and functions.
local floor = math.floor
local infinity = math.huge

--[[
-----------------------------------------------------------------------------------
-- Helper functions
-----------------------------------------------------------------------------------
--]]

local function isPositiveInteger(num)
	-- Returns true if the given number is a positive integer, and false if not.
	if type(num) == 'number' and num >= 1 and floor(num) == num and num < infinity then
		return true
	else
		return false
	end
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)
	local nums, ret = {}, {}
	for k, v in pairs(t) do
		if isPositiveInteger(k) then
			nums[#nums + 1] = k
		end
	end
	table.sort(nums)
	for _, num in ipairs(nums) do
		ret[#ret + 1] = t[num]
	end
	return ret
end

return p
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