# Module:TableTools

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-- 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 v ~= v 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) checkType('shallowClone', 1, t, 'table') 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(arr) checkType('removeDuplicates', 1, arr, 'table') local isNan = p.isNan local ret, exists = {}, {} for _, v in ipairs(arr) 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 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 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 _ 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 elseif type1 == 'table' or type1 == 'boolean' or type1 == 'function' then return tostring(item1) < tostring(item2) else return item1 < item2 end end

-- keysToList -- -- Returns an array 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 arr = {} local index = 1 for k in pairs(t) do arr[index] = k index = index + 1 end

if keySort ~= false then keySort = type(keySort) == 'function' and keySort or defaultKeySort table.sort(arr, keySort) end

return arr end

-- sortedPairs -- -- 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 arr = p.keysToList(t, keySort, true)

local i = 0 return function () i = i + 1 local key = arr[i] if key ~= nil then return key, t[key] else return nil, nil end end end

-- isArray -- -- Returns true if the given value is a table and all keys are consecutive -- integers starting at 1.

function p.isArray(v) if type(v) ~= 'table' then return false end local i = 0 for _ in pairs(v) do i = i + 1 if v[i] == nil then return false end end return true end

-- isArrayLike -- -- Returns true if the given value is iterable and all keys are consecutive -- integers starting at 1.

function p.isArrayLike(v) if not pcall(pairs, v) then return false end local i = 0 for _ in pairs(v) do i = i + 1 if v[i] == nil then return false end end return true end

-- invert -- -- Transposes the keys and values in an array. For example, {"a", "b", "c"} -> -- {a = 1, b = 2, c = 3}. Duplicates are not supported (result values refer to -- the index of the last duplicate) and NaN values are ignored.

function p.invert(arr) checkType("invert", 1, arr, "table") local isNan = p.isNan local map = {} for i, v in ipairs(arr) do if not isNan(v) then map[v] = i end end

return map end

-- listToSet -- -- Creates a set from the array part of the table. Indexing the set by any of the -- values of the array returns true. For example, {"a", "b", "c"} -> -- {a = true, b = true, c = true}. NaN values are ignored as Lua considers them -- never equal to any value (including other NaNs or even themselves).

function p.listToSet(arr) checkType("listToSet", 1, arr, "table") local isNan = p.isNan local set = {} for _, v in ipairs(arr) do if not isNan(v) then set[v] = true end end

return set end

-- deepCopy -- -- 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

-- sparseConcat -- -- 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 arr = {}

local arr_i = 0 for _, v in p.sparseIpairs(t) do arr_i = arr_i + 1 arr[arr_i] = v end

return table.concat(arr, sep, i, j) end

-- length -- -- 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 #, 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: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

-- inArray -- -- Returns true if valueToFind is a member of the array, and false otherwise.

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

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