Module:array
Returns an array constructor that produces a table that has a number of functions available as methods: the table library functions, and various vanilla Lua functions and functions from Module:table and Module:fun that operate on arrays or on tables with integer keys.
local Array = require("Module:array")
local nums = Array() -- or Array:new()
nums:type() --> "array"
for i = 1, 5 do
nums:insert(i)
end
nums:concat(", ") --> "1, 2, 3, 4, 5"
local squares = nums:map(function (num) return num ^ 2 end) -- Returns new array.
squares:concat(', ') --> "1, 4, 9, 16, 25"
local even_squares = squares:filter(function (square) return square % 2 == 0 end)
even_squares:concat(", ") --> "4, 16"
The functions from Module:table and Module:fun are loaded as needed.
Functions from Module:table:
compressSparseArray(aliascompress),contains,invert,isArray,length,listToSet(aliastoSet),maxIndex,numKeys,removeDuplicates,reverse,reverseIpairs,serialCommaJoin,sparseIpairs
Functions from Module:fun. These have a function as the second argument (first argument of method):
all,filter,fold,map,some
These functions are included in a funcs subtable of an array (awkward):
affixNums,keysToList,numKeys
The following functions return an array (with the array metatable):
affixNums,compressSparseArray,keysToList,numKeys,removeDuplicates,reverse
The names with underscores instead of camel case can be used as aliases: for instance, arr:to_set() instead of arr:toSet().
The array constructor behaves differently depending on the arguments supplied to it. Without arguments, it creates an empty table. Given a single table, it adds the metatable to it. If the table has been loaded with mw.loadData, it duplicates the table, removing the metatable that is found in tables loaded with mw.loadData. Otherwise, it creates a new table (array) containing the arguments.
The array constructor does this by adding a metatable. This is similar to how all strings have a metatable that allows the string library functions to be used as methods: for instance, ("abc"):sub(1, 1) for string.sub("abc", 1, 1).
local Array = {}
local array_constructor
-- Copy table library so as not to unexpectedly change the behavior of code that
-- uses it.
local array_methods = mw.clone(table)
-- Create version of table.sort that returns the table.
array_methods.sort = function (t, comp)
table.sort(t, comp)
return t
end
-- ipairs and unpack operate on arrays.
array_methods.ipairs = ipairs
array_methods.unpack = unpack
function array_methods:type()
local mt = getmetatable(self)
return type(mt) == "table" and mt.__type or nil
end
function array_methods:adjustIndex(index)
index = math.floor(index)
if index < 0 then
index = #self + index + 1
end
return index
end
-- string.sub-style slicing.
function array_methods:slice(i, j)
if i == nil then
i = 1
elseif type(i) == "number" then
i = self:adjust_index(i)
else
error("Expected number, got " .. type(i))
end
if j == nil or type(j) == "number" then
j = self:adjust_index(j or -1)
else
error("Expected number, got " .. type(j))
end
local new_arr = array_constructor()
local k = 0
for index = i, j do
k = k + 1
new_arr[k] = self[index]
end
return new_arr
end
-- A function to convert string key-table modules such
-- as [[Module:languages/data/2]] into arrays.
-- "from" is a bad name.
-- field_for_key supplies the field name in which the
-- key will be stored.
local function to_array(map, field_for_key)
m_table = m_table or require "Module:table"
local arr = {}
local i = 0
for key, val in pairs(map) do
i = i + 1
local new_val = m_table.shallowcopy(val)
if field_for_key then
new_val[field_for_key] = key
end
arr[i] = new_val
end
return array_constructor(arr)
end
-- Functions from [[Module:table]] that operate on arrays or sparse arrays.
-- List copied from [[Module:table/documentation]].
local operate_on_array = {
-- non-sparse
"removeDuplicates", "length", "contains", "serialCommaJoin",
"reverseIpairs", "reverse", "invert", "listToSet", "isArray",
-- sparse
"numKeys", "maxIndex", "compressSparseArray", "sparseIpairs",
-- tables in general
"shallowcopy", "deepcopy",
}
-- Not all of these operate on arrays.
local create_new_array = {
-- Functions from [[Module:table]] that create an array.
-- List copied from [[Module:table/documentation]].
"removeDuplicates", "numKeys", "affixNums", "compressSparseArray",
"keysToList", "reverse",
-- Functions from [[Module:table]] that create an table.
"shallowcopy", "deepcopy",
-- Functions from [[Module:fun]] that create an array.
"map", "filter",
}
-- Functions from [[Module:fun]] that take an array in the second argument.
-- They just have to have the argument order reversed to work as methods of the
-- array object.
local second_argument_is_array = { "map", "some", "all", "filter" }
-- Add aliases for the functions from [[Module:table]] whose names
-- contain "array" or "list", which is redundant, and whose names don't conform
-- to the usual camel case.
-- The key redirects to the value.
local alias_of = {
compress = "compressSparseArray", keys = "keysToList", toSet = "listToSet",
deepCopy = "deepcopy", shallowCopy = "shallowcopy",
}
local function get_module_function(key, module, module_name)
return module[key]
or error("No function named " .. tostring(key) .. " in Module:" .. module_name)
end
local function wrap_in_array_constructor(func)
return function (...)
return array_constructor(func(...))
end
end
local function create_array_generating_func(key, module, module_name)
return wrap_in_array_constructor(get_module_function(key, module, module_name))
end
local function reverse_arguments(func)
return function (a, b)
return func(b, a, true)
end
end
local function underscore_to_camel_case(str)
if type(str) ~= "string" then return str end
str = str:gsub("_(.)", string.upper)
return str
end
local m_table, m_fun
local Array = {}
Array.__type = "array"
function Array:__index(key)
if type(key) ~= "string" then
return nil
end
-- Convert underscores to camel case: num_keys -> numKeys.
key = underscore_to_camel_case(key)
local val = array_methods[key]
if val then
return val
end
key = alias_of[key] or key
local func
m_table = m_table or require "Module:table"
if m_table.contains(operate_on_array, key) then
if m_table.contains(create_new_array, key) then
func = create_array_generating_func(key, m_table, "table")
else
func = m_table[key]
end
elseif m_table.contains(second_argument_is_array, key) then
m_fun = m_fun or require "Module:fun"
local raw_func = reverse_arguments(get_module_function(key, m_fun, "fun"))
if m_table.contains(create_new_array, key) then
func = wrap_in_array_constructor(raw_func)
else
func = raw_func
end
elseif key == "fold" then
m_fun = m_fun or require "Module:fun"
local raw_func = get_module_function(key, m_fun, "fun")
func = function(t, func, accum)
return raw_func(func, t, accum)
end
end
if func then
array_methods[key] = func
return func
end
end
function Array.__add(a, b)
if type(a) == 'table' and type(b) == 'table' then
m_table = m_table or require "Module:table"
local new_arr = array_constructor(m_table.shallowcopy(a))
for _, val in ipairs(b) do
new_arr:insert(val)
end
return new_arr
end
end
function Array:new(...)
local arr
if select("#", ...) == 1 and type((...)) == "table" then
arr = ...
local mt = getmetatable(arr)
-- If table has been loaded with mw.loadData, copy it to avoid the
-- limitations of it being a virtual table.
if mt and mt.mw_loadData then
m_table = m_table or require "Module:table"
arr = m_table.shallowcopy(arr)
end
else
arr = { ... }
end
return setmetatable(arr, self)
end
-- Declared as local above.
function array_constructor(...)
return Array:new(...)
end
local array_generating_funcs = { from = to_array }
local Array_library_mt = {
__call = Array.new, __index = array_generating_funcs
}
setmetatable(Array, Array_library_mt)
function Array_library_mt:__index(key)
key = underscore_to_camel_case(key)
key = alias_of[key] or key
if array_generating_funcs[key] then
return array_generating_funcs[key]
end
m_table = m_table or require "Module:table"
if m_table.contains(create_new_array, key) then
local func = create_array_generating_func(key, m_table, "table")
array_generating_funcs[key] = func
return func
end
end
return Array