Difference between revisions of "TableTools"
From Unofficial Stationeers Wiki
(add getNumKeys function and improve the comments, add the beginnings of a sparseIpairs function) |
(finish sparseIpairs) |
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| Line 72: | Line 72: | ||
----------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------- | ||
--]] | --]] | ||
| − | + | function p.sparseIpairs(t) | |
| − | + | local nums = p.getNumKeys(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 | ||
return p | return p | ||
Revision as of 06:45, 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)
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
return p