Module:TableTools

--[[

--                              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. Yes. --

--]]

local libraryUtil = require('libraryUtil')

local p = {}

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

--[[

-- 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) return type(v) == 'number' and v >= 1 and floor(v) == v and v < infinity 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) return type(v) == 'number' and tostring(v) == '-nan' 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)

local function cleanPattern(s) -- Cleans a pattern so that the magic characters %.[]*+-?^$ are interpreted literally. return s:gsub('([%(%)%%%.%[%]%*%+%-%?%^%$])', '%%%1') end

prefix = prefix or '' suffix = suffix or '' prefix = cleanPattern(prefix) suffix = cleanPattern(suffix) 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

--[[

-- numData -- -- Given a table with keys like ("foo1", "bar1", "foo2", "baz2"), returns a table -- of subtables in the format -- { [1] = {foo = 'text', bar = 'text'}, [2] = {foo = 'text', baz = 'text'} } -- Keys that don't end with an integer are stored in a subtable named "other". -- The compress option compresses the table so that it can be iterated over with -- ipairs.

--]] function p.numData(t, compress) checkType('numData', 1, t, 'table') checkType('numData', 2, compress, 'boolean', true) local ret = {} for k, v in pairs(t) do		local prefix, num = mw.ustring.match(tostring(k), '^([^0-9]*)([1-9][0-9]*)$') if num then num = tonumber(num) local subtable = ret[num] or {} if prefix == '' then -- Positional parameters match the blank string; put them at the start of the subtable instead. prefix = 1 end subtable[prefix] = v			ret[num] = subtable else local subtable = ret.other or {} subtable[k] = v			ret.other = subtable end end if compress then local other = ret.other ret = p.compressSparseArray(ret) 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') 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] 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) checkType('size', 1, t, 'table') local i = 0 for k in pairs(t) do		i = i + 1 end return i end

local function defaultKeySort(item1, item2) -- "number" < "string", so numbers will be sorted before strings. local type1, type2 = type(item1), type(item2) if type1 ~= type2 then return type1 < type2 else -- This will fail with table, boolean, function. return item1 < item2 end end

--	Returns a list of the keys in a table, sorted using either a default	comparison function or a custom keySort function. function p.keysToList(t, keySort, checked) if not checked then checkType('keysToList', 1, t, 'table') checkTypeMulti('keysToList', 2, keySort, { 'function', 'boolean', 'nil' }) end local list = {} local index = 1 for key, value in pairs(t) do		list[index] = key index = index + 1 end if keySort ~= false then keySort = type(keySort) == 'function' and keySort or defaultKeySort table.sort(list, keySort) end return list end

--	Iterates through a table, with the keys sorted using the keysToList function.	If there are only numerical keys, sparseIpairs is probably more efficient. function p.sortedPairs(t, keySort) checkType('sortedPairs', 1, t, 'table') checkType('sortedPairs', 2, keySort, 'function', true) local list = p.keysToList(t, keySort, true) local i = 0 return function i = i + 1 local key = list[i] if key ~= nil then return key, t[key] else return nil, nil end end end

--	Returns true if all keys in the table are consecutive integers starting at 1. -- function p.isArray(t) checkType("isArray", 1, t, "table") local i = 0 for k, v in pairs(t) do		i = i + 1 if t[i] == nil then return false end end return true end

-- { "a", "b", "c" } -> { a = 1, b = 2, c = 3 } function p.invert(array) checkType("invert", 1, array, "table") local map = {} for i, v in ipairs(array) do		map[v] = i	end return map end

--	{ "a", "b", "c" } -> { ["a"] = true, ["b"] = true, ["c"] = true } -- function p.listToSet(t) checkType("listToSet", 1, t, "table") local set = {} for _, item in ipairs(t) do		set[item] = true end return set end

--	Recursive deep copy function.	Preserves identities of subtables. local function _deepCopy(orig, includeMetatable, already_seen) -- Stores copies of tables indexed by the original table. already_seen = already_seen or {} local copy = already_seen[orig] if copy ~= nil then return copy end if type(orig) == 'table' then copy = {} for orig_key, orig_value in pairs(orig) do			copy[deepcopy(orig_key, includeMetatable, already_seen)] = deepcopy(orig_value, includeMetatable, already_seen) end already_seen[orig] = copy if includeMetatable then local mt = getmetatable(orig) if mt ~= nil then local mt_copy = deepcopy(mt, includeMetatable, already_seen) setmetatable(copy, mt_copy) already_seen[mt] = mt_copy end end else -- number, string, boolean, etc copy = orig end return copy end

function p.deepCopy(orig, noMetatable, already_seen) checkType("deepCopy", 3, already_seen, "table", true) return _deepCopy(orig, not noMetatable, already_seen) end

--	Concatenates all values in the table that are indexed by a number, in order.	sparseConcat{ a, nil, c, d } =>  "acd"	sparseConcat{ nil, b, c, d }  =>  "bcd" function p.sparseConcat(t, sep, i, j)	local list = {} local list_i = 0 for _, v in p.sparseIpairs(t) do		list_i = list_i + 1 list[list_i] = v	end return table.concat(list, sep, i, j) end

-- -- Finds the length of an array, or of a quasi-array with keys such -- as "data1", "data2", etc., using an exponential search algorithm. -- It is similar to the operator

function p.length(t, prefix) -- requiring module inline so that Module:Exponential search -- which is only needed by this one function -- doesn't get millions of transclusions local expSearch = require("Module:Exponential search") checkType('length', 1, t, 'table') checkType('length', 2, prefix, 'string', true) return expSearch(function(i)		local key		if prefix then			key = prefix .. tostring(i)		else			key = i		end		return t[key] ~= nil	end) or 0 end function p.inArray(arr, valueToFind) checkType("inArray", 1, arr, "table") -- if valueToFind is nil, error? for _, v in ipairs(arr) do		if v == valueToFind then return true end end return false end

return p