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. --

--]]

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. s = s:gsub('([%(%)%%%.%[%]%*%+%-%?%^%\$])', '%%%1') return s 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

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 exponental search algorithm. -- It is similar to the operator #, but may return -- a different value when there are gaps in the array portion of the table. -- Intended to be used on data loaded with mw.loadData. For other tables, use #. -- Note: #frame.args in frame object always be set to 0, regardless of -- the number of unnamed template parameters, so use this function for -- frame.args. --]]

function p.length(t, prefix) -- requiring module inline so that Module:Exponental 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