Module:TableTools: Difference between revisions
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>Mr. Stradivarius (start module with useful tools for dealing with Lua tables) |
>Mr. Stradivarius (add getNumKeys function and improve the comments, add the beginnings of a sparseIpairs function) |
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--[[ | --[[ | ||
----------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- | ||
-- | -- isPositiveInteger | ||
-- | |||
-- This function returns true if the given number 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 the table. | |||
----------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- | ||
--]] | --]] | ||
function p.isPositiveInteger(num) | |||
if type(num) == 'number' and num >= 1 and floor(num) == num and num < infinity then | if type(num) == 'number' and num >= 1 and floor(num) == num and num < infinity then | ||
return true | return true | ||
Line 20: | Line 23: | ||
return false | return false | ||
end | end | ||
end | |||
--[[ | |||
----------------------------------------------------------------------------------- | |||
-- getNumKeys | |||
-- | |||
-- 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.getNumKeys(t) | |||
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 | end | ||
Line 32: | Line 55: | ||
--]] | --]] | ||
function p.compressSparseArray(t) | function p.compressSparseArray(t) | ||
local | local ret = {} | ||
local nums = p.getNumKeys(t) | |||
table.sort(nums) | table.sort(nums) | ||
for _, num in ipairs(nums) do | for _, num in ipairs(nums) do | ||
Line 44: | Line 63: | ||
return ret | return ret | ||
end | end | ||
--[[ | |||
----------------------------------------------------------------------------------- | |||
-- sparseIpairs | |||
-- | |||
-- This is an iterator for sparse arrays. It can be used like ipairs, but can | |||
-- handle nil values. | |||
----------------------------------------------------------------------------------- | |||
--]] | |||
-- function p.sparseIpairs(t) | |||
-- local nums = p.getNumKeys(t) | |||
return p | return p |
Revision as of 06:33, 15 December 2013
Documentation for this module may be created at Module:TableTools/doc
-- 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 --[[ ----------------------------------------------------------------------------------- -- isPositiveInteger -- -- This function returns true if the given number 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 the table. ----------------------------------------------------------------------------------- --]] function p.isPositiveInteger(num) if type(num) == 'number' and num >= 1 and floor(num) == num and num < infinity then return true else return false end end --[[ ----------------------------------------------------------------------------------- -- getNumKeys -- -- 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.getNumKeys(t) 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 --[[ ----------------------------------------------------------------------------------- -- 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 ret = {} local nums = p.getNumKeys(t) table.sort(nums) 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) -- local nums = p.getNumKeys(t) return p