Module:TableTools
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 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 a 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 --[[ ------------------------------------------------------------------------------------ -- getUnion -- -- 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, 3, 5, bar = 6}, getUnion will return -- {1, 2, 3, 4, 5, 6, 7}. ------------------------------------------------------------------------------------ --]] function p.getUnion(...) local arrays = {...} local vals, ret = {}, {} for _, t in ipairs(arrays) do for k, v in pairs(t) do vals[v] = true end end for val in pairs(vals) do ret[#ret + 1] = val end table.sort(ret) 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 --[[ ------------------------------------------------------------------------------------ -- getAffixNums -- -- 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", getAffixNums will -- return {1, 3, 6}. ------------------------------------------------------------------------------------ --]] function p.getAffixNums(t, prefix, suffix) prefix = prefix or '' suffix = suffix or '' local nums = {} for k, v in pairs(t) do if type(k) == 'string' then local num = mw.ustring.match(k, '^' .. prefix .. '([1-9]%d*)' .. suffix .. '$') 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) 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