Module:table

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--[[ ------------------------------------------------------------------------------------ -- table (formerly 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 export = {}  local collation_module = "Module:collation" local debug_track_module = "Module:debug/track" local function_module = "Module:fun" local math_module = "Module:math"  local table = table  local concat = table.concat local contains -- defined as export.contains local deep_copy -- defined as export.deepCopy local deep_equals -- defined as export.deepEquals local format = string.format local getmetatable = getmetatable local insert = table.insert local insert_if_not -- defined as export.insertIfNot local invert -- defined as export.invert local ipairs = ipairs local ipairs_default_iter = ipairs{export} local keys_to_list -- defined as export.keysToList local list_to_set -- defined as export.listToSet local next = next local num_keys -- defined as export.numKeys local pairs = pairs local pcall = pcall local raw_pairs -- defined as export.rawPairs local rawequal = rawequal local rawget = rawget local require = require local select = select local setmetatable = setmetatable local signed_index -- defined as export.signedIndex local sort = table.sort local sparse_ipairs -- defined as export.sparseIpairs local table_len -- defined as export.length local table_reverse -- defined as export.reverse local type = type  -- Plain equality function. local function plain_equals(a, b) return a == b end  --[==[ Loaders for functions in other modules, which overwrite themselves with the target function when called. This ensures modules are only loaded when needed, retains the speed/convenience of locally-declared pre-loaded functions, and has no overhead after the first call, since the target functions are called directly in any subsequent calls.]==] local function debug_track(...) debug_track = require(debug_track_module) return debug_track(...) end  local function is_callable(...) is_callable = require(function_module).is_callable return is_callable(...) end  local function is_integer(...) is_integer = require(math_module).is_integer return is_integer(...) end  local function is_positive_integer(...) is_positive_integer = require(math_module).is_positive_integer return is_positive_integer(...) end  local function string_sort(...) string_sort = require(collation_module).string_sort return string_sort(...) end  --[==[ Returns a clone of an object. If the object is a table, the value returned is a new table, but all subtables and functions are shared. Metamethods are respected unless the `raw` flag is set, but the returned table will have no metatable of its own.]==] function export.shallowCopy(orig, raw) if type(orig) ~= "table" then return orig end local copy, iter, state, init = {} if raw then iter, state = next, orig else iter, state, init = pairs(orig) -- Track instances of data loaded via `mw.loadData` being copied, which is very inefficient and usually unnecessary. -- `mw.loadData` sets the key "mw_loadData" to true in the metatable. local mt = getmetatable(orig) if mt and type(mt) == "table" and rawget(mt, "mw_loadData") == true then debug_track("table/shallowCopy/loaded data") end end for k, v in iter, state, init do copy[k] = v end return copy end  do local function make_copy(orig, seen, mt_flag, keep_loaded_data, tracked) if type(orig) ~= "table" then return orig end local memoized = seen[orig] if memoized ~= nil then return memoized end local mt, iter, state, init = getmetatable(orig) -- `mt` could be a non-table if `__metatable` has been used, but discard it in such cases. if not (mt and type(mt) == "table") then mt, iter, state, init = nil, next, orig, nil -- Data loaded via `mw.loadData`, which sets the key "mw_loadData" to true in the metatable. elseif rawget(mt, "mw_loadData") == true then if keep_loaded_data then seen[orig] = orig return orig -- Track instances of such data being copied, which is very inefficient and usually unnecessary. elseif not tracked then debug_track("table/deepCopy/loaded data") tracked = true end -- Discard the metatable, and use the `__pairs` metamethod. mt, iter, state, init = nil, pairs(orig) -- Otherwise, keep `mt`. else -- Track copied metatables to find any instances where it's really necessary, as it would be preferable for the default to be `pairs` instead of `next` (i.e. using __pairs if present, returning a table with no metatable). if not tracked then debug_track("table/deepCopy/copied metatable") tracked = true end iter, state, init = next, orig, nil end local copy = {} seen[orig] = copy for k, v in iter, state, init do copy[make_copy(k, seen, mt_flag, keep_loaded_data, tracked)] = make_copy(v, seen, mt_flag, keep_loaded_data, tracked) end if mt == nil or mt_flag == "none" then return copy elseif mt_flag ~= "keep" then mt = make_copy(mt, seen, mt_flag, keep_loaded_data, tracked) end return setmetatable(copy, mt) end  --[==[ Recursive deep copy function. Preserves copied identities of subtables. A more powerful version of {mw.clone}, with customizable options. * By default, metatables are copied, except for data loaded via {mw.loadData} (see below). If `metatableFlag` is set to "none", the copy will not have any metatables at all. Conversely, if `metatableFlag` is set to "keep", then the cloned table (and all its members) will have the exact same metatable as their original version. * If `keepLoadedData` is true, then any data loaded via {mw.loadData} will not be copied, and the original will be used instead. This is useful in iterative contexts where it is necessary to copy data being destructively modified, because objects loaded via mw.loadData are immutable. * Notes: *# Protected metatables will not be copied (i.e. those hidden behind a __metatable metamethod), as they are not  accessible by Lua's design. Instead, the output of the __metatable method will be used instead. *# When iterating over the table, the __pairs metamethod is ignored, since this can prevent the table from being properly cloned. *# Data loaded via mw.loadData is a special case in two ways: the metatable is stripped, because otherwise the cloned table throws errors when accessed; in addition, the __pairs metamethod is used, since otherwise the cloned table would be empty.]==] function export.deepCopy(orig, metatableFlag, keepLoadedData) return make_copy(orig, {}, metatableFlag, keepLoadedData) end deep_copy = export.deepCopy end  --[==[ Given an array and a signed index, returns the true table index. If the signed index is negative, the array will be counted from the end, where {-1} is the highest index in the array; otherwise, the returned index will be the same. To aid optimization, the first argument may be a number representing the array length instead of the array itself; this is useful when the array length is already known, as it avoids recalculating it each time this function is called.]==] function export.signedIndex(t, k) if not is_integer(k) then error("index must be an integer") end return k < 0 and (type(t) == "table" and table_len(t) or t) + k + 1 or k end signed_index = export.signedIndex  --[==[ Returns the highest positive integer index of a table or array that possibly has holes in it, or otherwise 0 if no positive integer keys are found. Note that this differs from `table.maxn`, which returns the highest positive numerical index, even if it is not an integer.]==] function export.maxIndex(t) local max = 0 for k in pairs(t) do if is_positive_integer(k) and k > max then max = k end end return max end  --[==[ Append any number of lists together and returns the result. Compare the Lisp expression {(append list1 list2 ...)}.]==] function export.append(...) local args, list, n = {...}, {}, 0 for i = 1, select("#", ...) do local t, j = args[i], 0 while true do j = j + 1 local v = t[j] if v == nil then break end n = n + 1 list[n] = v end end return list end  --[==[ Extend an existing list by a new list, modifying the existing list in-place. Compare the Python expression {list.extend(new_items)}.  `options` is an optional table of additional options to control the behavior of the operation. The following options are recognized: * `insertIfNot`: Use {export.insertIfNot()} instead of {table.insert()}, which ensures that duplicate items do not get  inserted (at the cost of an O((M+N)*N) operation, where M = #list and N = #new_items). * `comparison`: As in {insertIfNot()}. Ignored otherwise. * `key`: As in {insertIfNot()}. Ignored otherwise. * `pos`: As in {insertIfNot()}. Ignored otherwise.]==] function export.extend(t, new_items, options) local i, insert_if_not_option = 0, options and options.insertIfNot while true do i = i + 1 local item = new_items[i] if item == nil then return elseif insert_if_not_option then insert_if_not(t, item, options) else insert(t, item) end end end export.extendList = export.extend  --[==[ Given a list, returns a new list consisting of the items between the start index `i` and end index `j` (inclusive). `i` defaults to `1`, and `j` defaults to the length of the input list.]==] function export.slice(t, i, j) local t_len = table_len(t) i = i and signed_index(t_len, i) or 1 local list, offset = {}, i - 1 for key = i, j and signed_index(t_len, j) or t_len do list[key - offset] = t[key] end return list end  do local pos_nan, neg_nan --[==[ Remove any duplicate values from a list, ignoring non-positive-integer keys. The earliest value is kept, and all subsequent duplicate values are removed, but otherwise the list order is unchanged.]==] function export.removeDuplicates(t) local list, seen, i, n = {}, {}, 0, 0 while true do i = i + 1 local v = t[i] if v == nil then return list end local memo_key if v == v then memo_key = v -- NaN elseif format("%f", v) == "nan" then if not pos_nan then pos_nan = {} end memo_key = pos_nan -- -NaN else if not neg_nan then neg_nan = {} end memo_key = neg_nan end if not seen[memo_key] then n = n + 1 list[n], seen[memo_key] = v, true end end end end  --[==[ Given a table, return an array containing all positive integer keys, sorted in numerical order.]==] function export.numKeys(t) local nums, i = {}, 0 for k in pairs(t) do if is_positive_integer(k) then i = i + 1 nums[i] = k end end sort(nums) return nums end num_keys = export.numKeys  --[==[ This takes a list with one or more nil values, and removes the nil values while preserving the order, so that the list can be safely traversed with ipairs.]==] function export.compressSparseArray(t) local list, keys, i = {}, num_keys(t), 0 while true do i = i + 1 local k = keys[i] if k == nil then return list end list[i] = t[k] end end  --[==[ An iterator which works like `pairs`, but ignores any `__pairs` metamethod.]==] function export.rawPairs(t) return next, t, nil end raw_pairs = export.rawPairs  --[==[ An iterator which works like `ipairs`, but ignores any `__ipairs` metamethod.]==] function export.rawIpairs(t) return ipairs_default_iter, t, 0 end  do local current --[==[ An iterator which works like `pairs`, except that it also respects the `__index` metamethod. This works by iterating over the input table with `pairs`, followed by the table at its `__index` metamethod (if any). This is then repeated for that table's `__index` table and so on, with any repeated keys being skipped over, until there are no more tables, or a table repeats (so as to prevent an infinite loop). If `__index` is a function, however, then it is ignored, since there is no way to iterate over its return values.  A `__pairs` metamethod will be respected for any given table instead of iterating over it directly, but these will be ignored if the `raw` flag is set.  Note: this function can be used as a `__pairs` metamethod. In such cases, it does not call itself, since this would cause an infinite loop, so it treats the relevant table as having no `__pairs` metamethod. Other `__pairs` metamethods on subsequent tables will still be respected.]==] function export.indexPairs(t, raw) -- If there's no metatable, result is identical to `pairs`. -- To prevent infinite loops, act like `pairs` if `current` is set with `t`, which means this function is being used as a __pairs metamethod. if current and current[t] or getmetatable(t) == nil then return next, t, nil end  -- `seen_k` memoizes keys, as they should never repeat; `seen_t` memoizes tables iterated over. local seen_k, seen_t, iter, state, k, v, success = {}, {[t] = true}  return function() while true do if iter == nil then -- If `raw` is set, use `next`. if raw then iter, state, k = next, t, nil -- Otherwise, call `pairs`, setting `current` with `t` so that export.indexPairs knows to return `next` if it's being used as a metamethod, as this prevents infinite loops. `t` is then unset, so that `current` doesn't get polluted if the loop breaks early. else if not current then current = {} end current[t] = true -- Use `pcall`, so that `t` can always be unset from `current`. success, iter, state, k = pcall(pairs, t) current[t] = nil -- If there was an error, raise it. if not success then error(iter) end end end while true do -- It's possible for a `__pairs` metamethod to return additional values, but assume there aren't any, since this iterator specifically relates to table indexes. k, v = iter(state, k) if k == nil then break -- If a repeated key is found, skip and iterate again. elseif not seen_k[k] then seen_k[k] = true return k, v end end -- If there's an __index metamethod, iterate over it iff it's a table not already seen before. local mt = getmetatable(t) -- `mt` might not be a table if __metatable is used. if not mt or type(mt) ~= "table" then return nil end seen_t[t] = true t = rawget(mt, "__index") if not t or type(t) ~= "table" then return nil -- Throw error if it's been seen before. elseif seen_t[t] then error("loop in gettable") end iter = nil -- New `iter` will be generated on the next iteration of the while loop. end end end end  do local function ipairs_func(t, i) i = i + 1 local v = t[i] if v ~= nil then return i, v end end  --[==[ An iterator which works like `ipairs`, except that it also respects the `__index` metamethod. This works by looking up values in the table, iterating integers from key `1` until no value is found.]==] function export.indexIpairs(t) -- If there's no metatable, just use the default ipairs iterator. return getmetatable(t) == nil and ipairs_default_iter or ipairs_func, t, 0 end end  --[==[ An iterator which works like `indexIpairs`, but which only returns the value.]==] function export.iterateList(t) local i = 0 return function() i = i + 1 return t[i] end end  --[==[ This is an iterator for sparse arrays. It can be used like ipairs, but can handle nil values.]==] function export.sparseIpairs(t) local keys, i = num_keys(t), 0 return function() i = i + 1 local k = keys[i] if k ~= nil then return k, t[k] end end end sparse_ipairs = export.sparseIpairs  --[==[ This returns the size of a key/value pair table. If `raw` is set, then metamethods will be ignored, giving the true table size.  For arrays, it is faster to use `export.length`.]==] function export.size(t, raw) local i, iter, state, init = 0 if raw then iter, state, init = next, t, nil else iter, state, init = pairs(t) end for _ in iter, state, init do i = i + 1 end return i end  --[==[ This returns the length of a table, or the first integer key n counting from 1 such that t[n + 1] is nil. It is a more reliable form of the operator `#`, which can become unpredictable under certain circumstances due to the implementation of tables under the hood in Lua, and therefore should not be used when dealing with arbitrary tables. `#` also does not use metamethods, so will return the wrong value in cases where it is desirable to take these into account (e.g. data loaded via `mw.loadData`). If `raw` is set, then metamethods will be ignored, giving the true table length.  For arrays, this function is faster than `export.size`.]==] function export.length(t, raw) local n = 0 if raw then for i in ipairs_default_iter, t, 0 do n = i end return n end repeat n = n + 1 until t[n] == nil return n - 1 end table_len = export.length  do local function is_equivalent(a, b, seen, include_mt, equal_func, pairs_func) -- Simple equality check. if equal_func(a, b) then return true -- If not equal, a and b can only be equivalent if they're both tables. elseif not (type(a) == "table" and type(b) == "table") then return false end -- If `a` and `b` have been compared before, return the memoized result. This will usually be true, since failures normally fail the whole check outright, but match failures can occur during the laborious check without this happening, so it could be false. local memo_a = seen[a] if memo_a then local result = memo_a[b] if result ~= nil then return result end -- To avoid recursive references causing infinite loops, assume the tables currently being compared are equivalent by memoizing them as true; this will be corrected to false if there's a match failure. memo_a[b] = true else memo_a = {[b] = true} seen[a] = memo_a end -- Don't bother checking `memo_b` for `a`, since if `a` and `b` had been compared before, then `b` would be in `memo_a`. local memo_b = seen[b] if memo_b then memo_b[a] = true else memo_b = {[a] = true} seen[b] = memo_b end -- If `include_mt` is set, check the metatables are equivalent. if include_mt and not is_equivalent(getmetatable(a), getmetatable(b), seen, true, equal_func, pairs_func) then memo_a[b], memo_b[a] = false, false return false end -- Copy all key/values pairs in `b` to `remaining_b`, and count the size: this uses `pairs_func`, which will also be used to iterate over `a`, ensuring that `a` and `b` are iterated over in the same way. This is necessary to ensure that `export.deepEquals(a, b)` and `export.deepEquals(b, a)` always give the same result. Simply iterating over `a` while accessing keys in `b` for comparison would ignore any `__pairs` metamethod that `b` has, which could cause non-symmetrical outputs if `__pairs` returns more or less than the complete set of key/value pairs accessible via `__index`, so using `pairs_func` for both `a` and `b` prevents this. -- TODO: handle exotic `__pairs` methods which return the same key multiple times with different values. local remaining_b, size_b = {}, 0 for k_b, v_b in pairs_func(b) do remaining_b[k_b], size_b = v_b, size_b + 1 end -- Fast check: iterate over the keys in `a`, checking if an equivalent value exists at the same key in `remaining_b`. As matches are found, key/value pairs are removed from `remaining_b`. If any keys in `a` or `remaining_b` are tables, the fast check will only work if the exact same object exists as a key in the other table. Any others from `a` that don't match anything in `remaining_b` are added to `remaining_a`, while those in `remaining_b` that weren't found will still remain once the loop ends. `remaining_a` and `remaining_b` are then compared at the end with the laborious check. local size_a, remaining_a = 0 for k, v_a in pairs_func(a) do local v_b = remaining_b[k] -- If `k` isn't in `remaining_b`, `a` and `b` can't be equivalent unless it's a table. if v_b == nil then if type(k) ~= "table" then memo_a[b], memo_b[a] = false, false return false -- Otherwise, add the `k`/`v_a` pair to `remaining_a` for the laborious check. elseif not remaining_a then remaining_a = {} end remaining_a[k], size_a = v_a, size_a + 1 -- Otherwise, if `k` exists in `a` and `remaining_b`, `v_a` and `v_b` must be equivalent for there to be a match. elseif is_equivalent(v_a, v_b, seen, include_mt, equal_func, pairs_func) then remaining_b[k], size_b = nil, size_b - 1 else memo_a[b], memo_b[a] = false, false return false end end -- Must be the same number of remaining keys in each table. if size_a ~= size_b then memo_a[b], memo_b[a] = false, false return false -- If the size is 0, there's nothing left to check. elseif size_a == 0 then return true end -- Laborious check: since it's not possible to use table lookups, check each key/value pair in `remaining_a` against every key/value pair in `remaining_b` until a match is found, removing the matching key/value pair from `remaining_b` each time, to ensure one-to-one correspondence. for k_a, v_a in next, remaining_a do local success for k_b, v_b in next, remaining_b do -- Keys/value pairs must be equivalent in order to match. if ( -- Check values first for speed, since they might not be tables. is_equivalent(v_a, v_b, seen, include_mt, equal_func, pairs_func) and is_equivalent(k_a, k_b, seen, include_mt, equal_func, pairs_func) ) then -- Remove matched key from `remaining_b`, and break the inner loop. success, remaining_b[k_b] = true, nil break end end -- Fail if `remaining_b` runs out of keys, as the `k_a`/`v_a` pair still hasn't matched. if not success then memo_a[b], memo_b[a] = false, false return false end end -- If every key/value pair in `remaining_a` matched with one in `remaining_b`, `a` and `b` must be equivalent. Note that `remaining_b` will now be empty, since the laborious check only starts if `remaining_a` and `remaining_b` are the same size. return true end  --[==[ Recursively compare two values that may be tables, and returns true if all key-value pairs are structurally equivalent. Note that this handles arbitrary nesting of subtables (including recursive nesting) to any depth, for keys as well as values.  If `include_mt` is true, then metatables are also compared. If `raw` is true, then metamethods are not used during the comparison.]==] function export.deepEquals(a, b, include_mt, raw) if raw then debug_track("table/deepEquals/raw") end return is_equivalent(a, b, {}, include_mt, raw and rawequal or plain_equals, raw and raw_pairs or pairs) end deep_equals = export.deepEquals end  do local function get_nested(t, k, ...) if t == nil then return nil elseif select("#", ...) ~= 0 then return get_nested(t[k], ...) end return t[k] end  --[==[ Given a table and an arbitrary number of keys, will successively access subtables using each key in turn, returning the value at the final key. For example, if {t} is { {[1] = {[2] = {[3] = "foo"}}}}, {export.getNested(t, 1, 2, 3)} will return {"foo"}.  If no subtable exists for a given key value, returns nil, but will throw an error if a non-table is found at an intermediary key.]==] function export.getNested(t, ...) if t == nil or select("#", ...) == 0 then error("Must provide a table and at least one key.") end return get_nested(t, ...) end end  do local function set_nested(t, v, k, ...) if select("#", ...) == 0 then t[k] = v return end local next_t = t[k] if next_t == nil then -- If there's no next table while setting nil, there's nothing more to do. if v == nil then return end next_t = {} t[k] = next_t end return set_nested(next_t, v, ...) end  --[==[ Given a table, value and an arbitrary number of keys, will successively access subtables using each key in turn, and sets the value at the final key. For example, if {t} is { {} }, {export.setNested(t, "foo", 1, 2, 3)} will modify {t} to { {[1] = {[2] = {[3] = "foo"} } } }.  If no subtable exists for a given key value, one will be created, but the function will throw an error if a non-table value is found at an intermediary key.  Note: the parameter order (table, value, keys) differs from functions like rawset, because the number of keys can be arbitrary. This is to avoid situations where an additional argument must be appended to arbitrary lists of variables, which can be awkward and error-prone: for example, when handling variable arguments ({{lua|...}}) or function return values.]==] function export.setNested(t, ...) if t == nil or select("#", ...) < 2 then error("Must provide a table and at least one key.") end return set_nested(t, ...) end end  do local function get_options(options) if options == nil then return deep_equals end local comp_func, key_func = options.comparison, options.key if comp_func == nil then comp_func = deep_equals elseif comp_func == "==" then comp_func = plain_equals end return comp_func, key_func end  --[==[ Given a list and a value to be found, returns the value's index if the value is in the array portion of the list, or false if not found.  `options` is an optional table of additional options to control the behavior of the operation. The following options are recognized: * `comparison`: Function of two arguments to compare whether `item` is equal to an existing item in `list`. If unspecified, items are considered equal if either the standard equality operator {==} or {deepEquals} return {true}. As a special case, if the string value {"=="} is specified, then the standard equality operator alone will be used. * `key`: Function of one argument to return a comparison key, which will be used with the comparison function. The key function is applied to both `item` and the existing item in `list` to compare against, and the comparison is done against the results.]==] function export.contains(list, x, options) local comp_func, key_func = get_options(options) if key_func ~= nil then x = key_func(x) end local i = 0 while true do i = i + 1 local v = list[i] if v == nil then return false elseif key_func ~= nil then v = key_func(v) end if comp_func(v, x) then return i end end end contains = export.contains  --[==[ Given a table and a value to be found, returns the value's key if the value is in the table. Comparison is by value, using `deepEquals`.  `options` is an optional table of additional options to control the behavior of the operation. The available options are the same as those for {contains}.  Note: if multiple keys have the specified value, this function returns the first key found; it is not possible to reliably predict which key this will be.]==] function export.keyFor(t, x, options) local comp_func, key_func = get_options(options) if key_func ~= nil then x = key_func(x) end for k, v in pairs(t) do if key_func ~= nil then v = key_func(v) end if comp_func(v, x) then return k end end end end  --[==[ Given a `list` and a `new_item` to be inserted, append the value to the end of the list if not already present (or insert at an arbitrary position, if `options.pos` is given; see below). Comparison is by value, using {deepEquals}.  `options` is an optional table of additional options to control the behavior of the operation. The following options are recognized: * `pos`: Position at which insertion happens (i.e. before the existing item at position `pos`). * `comparison`: Function of two arguments to compare whether `item` is equal to an existing item in `list`. If unspecified, items are considered equal if either the standard equality operator {==} or {deepEquals} return {true}. As a special case, if the string value {"=="} is specified, then the standard equality operator alone will be used. * `key`: Function of one argument to return a comparison key, which will be used with the comparison function. The key function is applied to both `item` and the existing item in `list` to compare against, and the comparison is done against the results. This is useful when inserting a complex structure into an existing list while avoiding duplicates. * `combine`: Function of three arguments (the existing item, the new item and the position, respectively) to combine an existing item with `new_item`, when `new_item` is found in `list`. If unspecified, the existing item is left alone.  Returns {false} if an entry is already found, or {true} if inserted.  For compatibility, `pos` can be specified directly as the third argument in place of `options`, but this is not recommended for new code.  NOTE: This function is O(N) in the size of the existing list. If you use this function in a loop to insert several items, you will get O(M*(M+N)) behavior, effectively O((M+N)^2). Thus it is not recommended to use this unless you are sure the total number of items will be small. (An alternative for large lists is to insert all the items without checking for duplicates, and use {removeDuplicates()} at the end.)]==] function export.insertIfNot(list, new_item, options) local pos if type(options) == "number" then pos, options = options, nil end local i = contains(list, new_item, options) if i then local combine_func = options and options.combine if combine_func ~= nil then local newval = combine_func(list[i], new_item, i) if newval ~= nil then list[i] = newval end end return false elseif pos == nil then pos = options and options.pos if pos == nil then return insert(list, new_item) end end insert(list, pos, new_item) end insert_if_not = export.insertIfNot  do local types local function get_types() types, get_types = invert{ "number", "boolean", "string", "table", "function", "thread", "userdata" }, nil return types end  local function less_than(key1, key2) return key1 < key2 end  -- The default sorting function used in export.keysToList if `keySort` is not given. local function default_compare(key1, key2) local type1, type2 = type(key1), type(key2) if type1 ~= type2 then -- If the types are different, sort numbers first, functions last, and all other types alphabetically. return (types or get_types())[type1] < types[type2] -- `string_sort` fixes a bug in < which causes all codepoints above U+FFFF to be treated as equal. elseif type1 == "string" then return string_sort(key1, key2) elseif type1 == "number" then return key1 < key2 -- Attempt to compare tables, in case there's a metamethod. elseif type1 == "table" then local success, result = pcall(less_than, key1, key2) if success then return result end -- Sort true before false. elseif type1 == "boolean" then return key1 end return false end  --[==[ Returns a list of the keys in a table, sorted using either the default `table.sort` function or a custom `keySort` function.  If there are only numerical keys, `export.numKeys` is probably faster.]==] function export.keysToList(t, keySort) local list, i = {}, 0 for key in pairs(t) do i = i + 1 list[i] = key end -- Use specified sort function, or otherwise `default_compare`. sort(list, keySort or default_compare) return list end keys_to_list = export.keysToList end  --[==[ Iterates through a table, with the keys sorted using the keysToList function.  If there are only numerical keys, `export.sparseIpairs` is probably faster.]==] function export.sortedPairs(t, keySort) local list, i = keys_to_list(t, keySort), 0 return function() i = i + 1 local k = list[i] if k ~= nil then return k, t[k] end end end  --[==[ Iterates through a table using `ipairs` in reverse.  `__ipairs` metamethods will be used, including those which return arbitrary (i.e. non-array) keys, but note that this function assumes that the first return value is a key which can be used to retrieve a value from the input table via a table lookup. As such, `__ipairs` metamethods for which this assumption is not true will not work correctly.  If the value `nil` is encountered early (e.g. because the table has been modified), the loop will terminate early.]==] function export.reverseIpairs(t) -- `__ipairs` metamethods can return arbitrary keys, so compile a list. local keys, i = {}, 0 for k in ipairs(t) do i = i + 1 keys[i] = k end return function() if i == 0 then return nil end local k = keys[i] -- Retrieve `v` from the table. These aren't stored during the initial ipairs loop, so that they can be modified during the loop. local v = t[k] -- Return if not an early nil. if v ~= nil then i = i - 1 return k, v end end end  local function getIteratorValues(i, j , step, t_len) i, j = i and signed_index(t_len, i), j and signed_index(t_len, j) if step == nil then i, j = i or 1, j or t_len return i, j, j < i and -1 or 1 elseif step == 0 or not is_integer(step) then error("step must be a non-zero integer") elseif step < 0 then return i or t_len, j or 1, step end return i or 1, j or t_len, step end  --[==[ Given an array `list` and function `func`, iterate through the array applying {func(r, k, v)}, and returning the result, where `r` is the value calculated so far, `k` is an index, and `v` is the value at index `k`. For example, {reduce(array, function(a, _, v) return a + v end)} will return the sum of `array`.  Optional arguments: * `i`: start index; negative values count from the end of the array * `j`: end index; negative values count from the end of the array * `step`: step increment These must be non-zero integers. The function will determine where to iterate from, whether to iterate forwards or backwards and by how much, based on these inputs (see examples below for default behaviours).  Examples: # No values for i, j or step results in forward iteration from the start to the end in steps of 1 (the default). # step=-1 results in backward iteration from the end to the start in steps of 1. # i=7, j=3 results in backward iteration from indices 7 to 3 in steps of 1 (i.e. step=-1). # j=-3 results in forward iteration from the start to the 3rd last index. # j=-3, step=-1 results in backward iteration from the end to the 3rd last index.]==] function export.reduce(t, func, i, j, step) i, j, step = getIteratorValues(i, j, step, table_len(t)) local ret = t[i] for k = i + step, j, step do ret = func(ret, k, t[k]) end return ret end  do local function replace(t, func, i, j, step, generate) local t_len = table_len(t) -- Normalized i, j and step, based on the inputs. local norm_i, norm_j, norm_step = getIteratorValues(i, j, step, t_len) if norm_step > 0 then i, j, step = 1, t_len, 1 else i, j, step = t_len, 1, -1 end -- "Signed" variables are multiplied by -1 if `step` is negative. local t_new, signed_i, signed_j = generate and {} or t, norm_i * step, norm_j * step for k = i, j, step do -- Replace the values iff they're within the i to j range and `step` wouldn't skip the key. -- Note: i > j if `step` is positive; i < j if `step` is negative. Otherwise, the range is empty. local signed_k = k * step if signed_k >= signed_i and signed_k <= signed_j and (k - norm_i) % norm_step == 0 then t_new[k] = func(k, t[k]) -- Otherwise, add the existing value if `generate` is set. elseif generate then t_new[k] = t[k] end end return t_new end  --[==[ Given an array `list` and function `func`, iterate through the array applying {func(k, v)} (where `k` is an index, and `v` is the value at index `k`), replacing the relevant values with the result. For example, {apply(array, function(_, v) return 2 * v end)} will double each member of the array.  Optional arguments: * `i`: start index; negative values count from the end of the array * `j`: end index; negative values count from the end of the array * `step`: step increment These must be non-zero integers. The function will determine where to iterate from, whether to iterate forwards or backwards and by how much, based on these inputs (see examples below for default behaviours).  Examples: # No values for i, j or step results in forward iteration from the start to the end in steps of 1 (the default). # step=-1 results in backward iteration from the end to the start in steps of 1. # i=7, j=3 results in backward iteration from indices 7 to 3 in steps of 1 (i.e. step=-1). # j=-3 results in forward iteration from the start to the 3rd last index. # j=-3, step=-1 results in backward iteration from the end to the 3rd last index.]==] function export.apply(t, func, i, j, step) return replace(t, func, i, j, step, false) end  --[==[ Given an array `list` and function `func`, iterate through the array applying {func(k, v)} (where `k` is an index, and `v` is the value at index `k`), and return a shallow copy of the original array with the relevant values replaced. For example, {generate(array, function(_, v) return 2 * v end)} will return a new array in which each value has been doubled.  Optional arguments: * `i`: start index; negative values count from the end of the array * `j`: end index; negative values count from the end of the array * `step`: step increment These must be non-zero integers. The function will determine where to iterate from, whether to iterate forwards or backwards and by how much, based on these inputs (see examples below for default behaviours).  Examples: # No values for i, j or step results in forward iteration from the start to the end in steps of 1 (the default). # step=-1 results in backward iteration from the end to the start in steps of 1. # i=7, j=3 results in backward iteration from indices 7 to 3 in steps of 1 (i.e. step=-1). # j=-3 results in forward iteration from the start to the 3rd last index. # j=-3, step=-1 results in backward iteration from the end to the 3rd last index.]==] function export.generate(t, func, i, j, step) return replace(t, func, i, j, step, true) end end  --[==[ Given an array `list` and function `func`, iterate through the array applying {func(k, v)} (where `k` is an index, and `v` is the value at index `k`), and returning whether the function is true for all iterations.  Optional arguments: * `i`: start index; negative values count from the end of the array * `j`: end index; negative values count from the end of the array * `step`: step increment These must be non-zero integers. The function will determine where to iterate from, whether to iterate forwards or backwards and by how much, based on these inputs (see examples below for default behaviours).  Examples: # No values for i, j or step results in forward iteration from the start to the end in steps of 1 (the default). # step=-1 results in backward iteration from the end to the start in steps of 1. # i=7, j=3 results in backward iteration from indices 7 to 3 in steps of 1 (i.e. step=-1). # j=-3 results in forward iteration from the start to the 3rd last index. # j=-3, step=-1 results in backward iteration from the end to the 3rd last index.]==] function export.all(t, func, i, j, step) i, j, step = getIteratorValues(i, j, step, table_len(t)) for k = i, j, step do if not func(k, t[k]) then return false end end return true end  --[==[ Given an array `list` and function `func`, iterate through the array applying {func(k, v)} (where `k` is an index, and `v` is the value at index `k`), and returning whether the function is true for at least one iteration.  Optional arguments: * `i`: start index; negative values count from the end of the array * `j`: end index; negative values count from the end of the array * `step`: step increment These must be non-zero integers. The function will determine where to iterate from, whether to iterate forwards or backwards and by how much, based on these inputs (see examples below for default behaviours).  Examples: # No values for i, j or step results in forward iteration from the start to the end in steps of 1 (the default). # step=-1 results in backward iteration from the end to the start in steps of 1. # i=7, j=3 results in backward iteration from indices 7 to 3 in steps of 1 (i.e. step=-1). # j=-3 results in forward iteration from the start to the 3rd last index. # j=-3, step=-1 results in backward iteration from the end to the 3rd last index.]==] function export.any(t, func, i, j, step) i, j, step = getIteratorValues(i, j, step, table_len(t)) for k = i, j, step do if not not (func(k, t[k])) then return true end end return false end  --[==[ Joins an array with serial comma and serial conjunction, normally {"and"}. An improvement on {mw.text.listToText}, which doesn't properly handle serial commas.  Options: * `conj`: Conjunction to use; defaults to {"and"}. * `punc`: Punctuation to use; default to {","}. * `dontTag`: Don't tag the serial comma and serial {"and"}. For error messages, in which HTML cannot be used.]==] function export.serialCommaJoin(seq, options) local length = table_len(seq) if length == 0 then return "" elseif length == 1 then return seq[1] end  local conj = options and options.conj if conj == nil then conj = "and" end  if length == 2 then return seq[1] .. " " .. conj .. " " .. seq[2] end  local punc, dont_tag if options then punc = options.punc if punc == nil then punc = "," end dont_tag = options.dontTag else punc = "," end  local comma if dont_tag then comma = punc conj = " " .. conj .. " " else comma = "<span class=\"serial-comma\">" .. punc .. "</span>" conj = "<span class=\"serial-and\"> " .. conj .. "</span> " end  return concat(seq, punc .. " ", 1, length - 1) .. comma .. conj .. seq[length] end  --[==[ A function which works like `table.concat`, but respects any `__index` metamethod. This is useful for data loaded via `mw.loadData`.]==] function export.concat(t, sep, i, j) local list, k = {}, 0 while true do k = k + 1 local v = t[k] if v == nil then return concat(list, sep, i, j) end list[k] = v end end  --[==[ Concatenate 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 export.sparseConcat(t, sep, i, j) local list, k = {}, 0 for _, v in sparse_ipairs(t) do k = k + 1 list[k] = v end return concat(list, sep, i, j) end  --[==[ Values of numeric keys in array portion of table are reversed: { { "a", "b", "c" }} -> { { "c", "b", "a" }}]==] function export.reverse(t) local list, t_len = {}, table_len(t) for i = t_len, 1, -1 do list[t_len - i + 1] = t[i] end return list end table_reverse = export.reverse  function export.reverseConcat(t, sep, i, j) return concat(table_reverse(t), sep, i, j) end  --[==[ Invert a list. For example, {invert({ "a", "b", "c" })} -> { { a = 1, b = 2, c = 3 }}]==] function export.invert(list) local map, i = {}, 0 while true do i = i + 1 local v = list[i] if v == nil then return map end map[v] = i end end invert = export.invert  do local function flatten(t, list, seen, n) seen[t] = true local i = 0 while true do i = i + 1 local v = t[i] if v == nil then return n elseif type(v) == "table" then if seen[v] then error("loop in input list") end n = flatten(v, list, seen, n) else n = n + 1 list[n] = v end end end  --[==[ Given a list, which may contain sublists, flatten it into a single list. For example, {flatten({ "a", { "b", "c" }, "d" })} -> { { "a", "b", "c", "d" }}]==] function export.flatten(t) local list = {} flatten(t, list, {}, 0) return list end end  --[==[ Convert `list` (a table with a list of values) into a set (a table where those values are keys instead). This is a useful way to create a fast lookup table, since looking up a table key is much, much faster than iterating over the whole list to see if it contains a given value.  By default, each item is given the value true. If the optional parameter `value` is a function or functor, then it is called as an iterator, with the list index as the first argument, the item as the second (which will be used as the key), plus any additional arguments passed to {listToSet}; the returned value is used as the value for that list item. If `value` is anything else, then it is used as the fixed value for every item.]==] function export.listToSet(list, value, ...) local set, i, callable = {}, 0 if value == nil then value = true else callable = is_callable(value) end while true do i = i + 1 local item = list[i] if item == nil then return set end if callable then set[item] = value(i, item, ...) else set[item] = value end end end list_to_set = export.listToSet  --[==[ Returns true if all keys in the table are consecutive integers starting at 1.]==] function export.isArray(t) local i = 0 for _ in pairs(t) do i = i + 1 if t[i] == nil then return false end end return true end  --[==[ Returns true if the first list, taken as a set, is a subset of the second list, taken as set.]==] function export.isSubsetList(t1, t2) t2 = list_to_set(t2) local i = 0 while true do i = i + 1 local v = t1[i] if v == nil then return true elseif t2[v] == nil then return false end end end  --[==[ Returns true if the first map, taken as a set, is a subset of the second map, taken as set.]==] function export.isSubsetMap(t1, t2) for k in pairs(t1) do if t2[k] == nil then return false end end return true end  --[==[ Add a list of aliases for a given key to a table. The aliases must be given as a table.]==] function export.alias(t, k, aliases) for _, alias in pairs(aliases) do t[alias] = t[k] end end  return export