--[[ ------------------------------------------------------------------------------------ -- 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.  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 #, 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 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