Module documentation
This documentation is transcluded from Module:Array/doc. [edit] [history] [purge]
Module:Array requires libraryUtil.
Module:Array is required by Module:DependencyList.

This module is a helper module to be used by other modules; it may not designed to be invoked directly. See Brighter Shores:Lua/Helper modules for a full list and more information. For a full list of modules using this helper click here

FunctionTypeUse
all( arr, [fn] )arr: any[]
fn?: any
-> boolean
Behaviour depends on the value of fn:
  • nil - Checks that the array doesn't contain any false elements.
  • fun(elem: any, i?: integer): boolean - Returns true if fn returns true for every element.
  • number | table | boolean - Checks that all elements in arr are equal to this value.
any( arr, [fn] )arr: any[]
fn?: any
-> boolean
Behaviour depends on the value of fn:
  • nil - Checks that the array contains at least one non false element.
  • fun(elem: any, i?: integer): boolean - Returns true if fn returns true for at least one element.
  • number | table | boolean - Checks that arr contains this value.
clean( arr )arr: any[]
-> any[]
Recursively removes all metatables.
clone( arr, [deep] )arr: any[]
deep?: boolean
-> any[]
Make a copy of the input table. Preserves metatables.
contains( arr, val )arr: any[]
val: any
-> boolean
Check if arr contains val.
containsAny( arr, t )arr: any[]
t: any[]
-> boolean
Check if arr contains any of the values in the table t.
containsAll( arr, t )arr: any[]
t: any[]
-> boolean
Check if arr contains all values in the table t.
convolve( x, y )x: number[]
y: number[]
-> number[]
Convolute two number arrays.
condenseSparse( arr )arr: any[]
-> any[]
Remove nil values from arr while preserving order.
count( arr, fn )arr: any[]
fn: any
-> integer
Behaviour depends on value of val:
  • nil - Counts the number of non false elements.
  • fun(elem: any): boolean - Count the number of times the function returned true.
  • boolean | number | table - Counts the number of times this value occurs in arr.
diff( arr, [order|1] )arr: number[]
order?: number
-> number[]
Differentiates arr. The length of the result is #arr - order long.
each( arr, fn )arr: any[]
fn: fun(elem: any, i?: integer)
Loops over the array part of arr and passes each element as the first argument to fn. This function returns nothing.
filter( arr, fn )arr: any[]
fn: fun(elem: any, i?: integer): boolean
-> any[]
Makes a copy of arr with only elements for which fn returned true.
find( arr, fn, [default] )arr: any[]
fn: any
default?: any
-> any?, integer?
Behaviour depends on the value of fn:
  • fun(elem: any, i?: integer): boolean - Find the first elements for which fn returns true.
  • boolean | number | table - Find the first occurance of this value.
Returns two values: the element itself and its index.
find_index( arr, fn, [default] )arr: any[]
fn: any
default?: any
-> integer?
Behaviour depends on the value of fn:
  • fun(elem: any, i?: integer): boolean - Find the index of the first elements for which fn returns true.
  • boolean | number | table - Find the index of the first occurance of this value.
get( arr, indexes )arr: any[]
indexes: integer|integer[]
-> any[]
Extracts a subset of arr.
int( arr, [start|1], [stop|#arr] )arr: number[]
start?: number
stop?: number
-> number[]
Integrates arr from index start to stop. Effectively does {startnarr[n]|n[start,stop]}.
intersect( arr1, arr2 )arr1: any[]
arr2: any[]
-> any[]
Returns an array with elements that are present in both tables.
intersects( arr1, arr2 )arr1: any[]
arr2: any[]
-> boolean
Checks if the two inputs have at least one element in common.
insert( arr, val, [index], [unpackVal] )
insert( arr, val, [unpackVal] )
arr: any[]
val: any
index?: integer
unpackVal?: boolean
-> any[]
Inserts values into arr. If val is an array and unpackVal is true then the individual elements of val are inserted. index is the location to start the insertion. Default is at the end of arr.
last( arr )arr: any[]
-> any
Returns the last element of arr.
len( arr )arr: any[]
-> integer
Returns the length of the array but it also works on proxy arrays like mw.loadData or mw.loadJsonData.
map( arr, fn )arr: any[]
fn: fun(elem: any, i?: integer): any
-> any[]
Returns a new table were each element of arr is modified by fn.
max_by( arr, fn )arr: any[]
fn: fun(elem: any): any
-> any, integer
Find the element for which fn returned the largest value. The returned value of fn needs to be comparable using the < operator. Returns three values: The element with the largest fn value, its fn result, and its index.
max( arr )arr: any[]
-> any, integer
Find the largest value in the array. The values need to be comparable using the < operator. Returns two values: the element and its index.
min( arr )arr: any[]
-> any, integer
Find the smallest value in the array. The values need to be comparable using the < operator. Returns two values: the element and its index.
new( [arr|{}] )arr?: any[]
-> any[]
Turn the input table into an Array. This makes it possible to use the colon : operator to access the Array methods. It also enables the use of math operators with the array.
local x = arr.new{ 1, 2, 3 }
local y = arr{ 4, 5, 6 } -- Alternative notation

mw.logObject( -x ) --> { -1, -2, -3 }
mw.logObject( x + 2 ) --> { 3, 4, 5 }
mw.logObject( x - 2 ) --> { -1, 0, 1 }
mw.logObject( x * 2 ) --> { 2, 4, 6 }
mw.logObject( x / 2 ) --> { 0.5, 1, 1.5 }
mw.logObject( x ^ 2 ) --> { 1, 4, 9 }

mw.logObject( x + y ) --> { 5, 7, 9 }
mw.logObject( x .. y ) --> { 1, 2, 3, 4, 5, 6 }
mw.logObject( (x .. y):reject{3, 4, 5} ) --> { 1, 2, 6 }
mw.logObject( x:sum() ) --> 6

mw.logObject( x:update( {1, 3}, y:get{2, 3} * 2 ) ) --> { 10, 2, 12 }
newIncrementor( [start|1], [step|1] )start?: number
step?: number
-> Incrementor
Returns a new incrementor function. Every time this incrementor function is called it returns a number step higher than the previous call. The current value can be obtained with inc.n or set inc.n = number where inc is an incrementor function. The step size can be changed with inc.step = number.
range( stop )
range( start, stop, [step|1] )
start: number
stop: number
step?: number
-> number[]
Returns a table containing a sequence of numbers from start to stop (both inclusive if ints, end-exclusive if floats) by step. range(4) produces {1, 2, 3, 4} (start defaults to 1). range(0, 4) produces {0, 1, 2, 3, 4}. When step is given, it specifies the increment (or decrement).
reduce( arr, fn, [accumulator|arr[1]] )arr: any[]
fn: fun(elem: any, acc: any, i?: integer): any
accumulator?: any
-> any
Condenses the array into a single value.

For each element fn is called with the current element, the current accumulator, and the current element index. The returned value of fn becomes the accumulator for the next element.

If no accumulator value is given at the start then the first element off arr becomes the accumulator and the iteration starts from the second element.

local t = { 1, 2, 3, 4 }
local sum = arr.reduce( t, function(elem, acc) return acc + elem end ) -- sum == 10
reject( arr, val )arr: any[]
val: any
-> any[]
Make a copy off arr with certain values removed.

Behaviour for different values of val:

  • boolean | number - Remove values equal to this.
  • table - Remove all values in this table.
  • fun(elem: any, i?: integer): boolean - Remove elements for which the functions returns true.
rep( val, n )val: any
n: number
-> any[]
Returns a table with n copies of val.
scan( arr, fn, [accumulator|arr[1]] )arr: any[]
fn: fun(elem: any, acc: any, i?: integer): any
accumulator?: any
-> any[]
Condenses the array into a single value while saving every accumulator value.

For each element fn is called with the current element, the current accumulator, and the current element index. The returned value of fn becomes the accumulator for the next element.

If no accumulator value is given at the start then the first element off arr becomes the accumulator and the iteration starts from the second element.

local t = { 1, 2, 3, 4 }
local x = arr.scan( t, function(elem, acc) return acc + elem end ) -- x = { 1, 3, 6, 10 }
set( arr, indexes, values )arr: any[]
indexes: integer|integer[]
values: any|any[]
-> any[]
Update a range of index with a range of values.

If if only one value is given but multiple indexes than that value is set for all those indexes.

If values is a table then it must of the same length as indexes.
slice( arr, [start|1], [stop|#arr] )
slice( arr, stop )
arr: any[]
start?: number
stop?: number
-> any[]
Returns a table containing all the elements of arr between the start and stop indices. The start and stop indices are inclusive. If start or stop are negative values then they are referenced to the end of the table.
split( arr, index )arr: any[]
index: number
-> any[], any[]
Split arr into two arrays. Retuns two tables. The first contains elements from [1, index], and the second from [index + 1, #arr].
sum( arr )arr: number[]
-> number
Returns the sum of all elements of arr.
take( arr, count, [start|1] )arr: any[]
count: number
start?: number
-> any[]
Extract a subtable from arr of count elements long starting from the start index.
take_every( arr, n, [start|1], [count|#arr] )arr: any[]
n: integer
start?: integer
count?: integer
-> any[]
Extract a subtable from arr.
local t = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }
local x = arr.take_every( t, 2 )       --> x = { 1, 3, 5, 7, 9 }
local x = arr.take_every( t, 2, 3 )    --> x = { 3, 5, 7, 9 }
local x = arr.take_every( t, 2, 3, 2 ) --> x = { 3, 5 }
unique( arr, [fn] )arr: any[]
fn?: fun(elem: any): any
-> any[]
Return a new table with all duplicates removed. fn is an optional function to generate an id for each element. The result will then contain elements that generated unique ids. The order of first occurance is preserved.
zip( ... )...any[]
-> any[][]
Combine elements with the same index from multiple arrays.
local x = {1, 2, 3}
local y = {4, 5, 6, 7}
local z = arr.zip( x, y ) --> z = { { 1, 4 }, { 2, 5 }, { 3, 6 }, { 7 } }
Example:
local arr = require( 'Module:Array' )

local x = arr{1, 2, 3, 4, 10}
local y = arr{'a', 'b', 'b', 1}

arr.any( x, function( item ) return item == 3 end ) --> true
arr.all( y, function( item ) return type( item ) == 'string' end ) --> false
arr.map( x, function( item ) return item * 2 end ) --> { 2, 4, 6, 8, 20 }
arr.filter( y, function( item ) return type( item ) == 'string' end ) --> { "a", "b", "b" }
arr.reject( y, function( item ) return type( item ) == 'string' end ) --> { 1 }
arr.find( x, function( item ) return item > 5 end ) --> 10,  5
arr.find_index( y, function( item ) return type( item ) ~= 'string' end ) --> 4
arr.max_by( x, function( item ) return item * 2 end ) --> 10, 20, 5
arr.reduce( x, function( item, acc ) return acc + item*item end, 5 ) --> 135
arr.range( 10, 1, -3 ) --> { 10, 7, 4, 1 }
arr.scan( x, function( item, acc ) return acc + item*item end, 5 ) --> { 6, 10, 19, 35, 135 }
arr.slice( x, 2, 4 ) --> { 2, 3, 4 }
arr.split( x, 2 ) --> { 1, 2 }, { 3, 4, 10 }
arr.sum( x ) --> 20
arr.take( x, 2 ) --> { 1, 2 }
arr.take_every( x, 2 ) --> { 1, 3, 10 }
arr.unique( y ) --> { "a", "b", 1 }
arr.zip( x, y, {20, 30} ) --> { { 1, "a", 20 }, { 2, "b", 30 }, { 3, "b" }, { 4, 1 }, { 10 } }
arr.intersect( x, y ) --> { 1 }
arr.intersects( x, y ) --> true
arr.contains({ 1, 2, 3}, 3) --> true
arr.diff( x ) --> { 1, 1, 1, 6 }
arr.int( x ) --> { 1, 3, 6, 10, 20 }
arr.insert( x, y, 3 ) --> { 1, 2, { "a", "b", "b", 1 }, 3, 4, 10 }

inc = arr.newIncrementor( 10, 5 )
print( inc() ) --> 10
print( inc() ) --> 15

local libraryUtil = require('libraryUtil')
local checkType = libraryUtil.checkType
local checkTypeMulti = libraryUtil.checkTypeMulti

---Returns the length of the array but it also works on proxy arrays
---@param arr any[]
---@return integer
local function len(arr)
	local l = #arr
	if l == 0 then
		if arr[1] ~= nil then
			-- Exponential search to find length of proxy table
			local low = 1
			local high = 1
			local ceil = math.ceil
			while arr[high] ~= nil do
				high = high * 2
			end
			while low ~= high do
				local m = ceil((low + high) / 2)
				if arr[m] == nil then
					high = m - 1
				else
					low = m
				end
			end
			return low
		else
			return 0
		end
	else
		return l
	end
end

---@class Array
---@operator call(any[]): Array
---@operator concat(any[]): Array
---@operator concat(number|string|function): string
---@operator unm: Array
---@operator add(number|number[]|Array): Array
---@operator sub(number|number[]|Array): Array
---@operator mul(number|number[]|Array): Array
---@operator div(number|number[]|Array): Array
---@operator pow(number|number[]|Array): Array
local Array = {
	pop = table.remove,
	len = len
}
Array.__index = Array

setmetatable(Array, {
	__index = table,
	__call = function (_, arr)
		return Array.new(arr)
	end
})

function Array.__concat(lhs, rhs)
	if type(lhs) == 'table' and type(rhs) == 'table' then
		local res = {}
		local l1 = len(lhs)
		for i = 1, l1 do
			res[i] = lhs[i]
		end
		for i = 1, len(rhs) do
			res[l1 + i] = rhs[i]
		end
		return setmetatable(res, getmetatable(lhs) or getmetatable(rhs))
	else
		return tostring(lhs) .. tostring(rhs)
	end
end

function Array.__unm(arr)
	return Array.map(arr, function(x) return -x end)
end

---@param lhs number|number[]|Array
---@param rhs number|number[]|Array
---@param funName string
---@param opName string
---@param fun fun(lhs: number, rhs: number): number
---@return Array
local function mathTemplate(lhs, rhs, funName, opName, fun)
	checkTypeMulti('Module:Array.' .. funName, 1, lhs, {'number', 'table'})
	checkTypeMulti('Module:Array.' .. funName, 2, rhs, {'number', 'table'})
	local res = {}

	if type(lhs) == 'number' then
		for i = 1, len(rhs) do
			res[i] = fun(lhs, rhs[i])
		end
	elseif type(rhs) == 'number' then
		for i = 1, len(lhs) do
			res[i] = fun(lhs[i], rhs)
		end
	else
		assert(len(lhs) == len(rhs), string.format('Elementwise %s failed because arrays have different sizes (left: %d, right: %d)', opName, len(lhs), len(rhs)))
		for i = 1, len(lhs) do
			res[i] = fun(lhs[i], rhs[i])
		end
	end

	return setmetatable(res, getmetatable(lhs) or getmetatable(rhs))
end

function Array.__add(lhs, rhs)
	return mathTemplate(lhs, rhs, '__add', 'addition', function(x, y) return x + y end)
end

function Array.__sub(lhs, rhs)
	return mathTemplate(lhs, rhs, '__sub', 'substraction', function(x, y) return x - y end)
end

function Array.__mul(lhs, rhs)
	return mathTemplate(lhs, rhs, '__mul', 'multiplication', function(x, y) return x * y end)
end

function Array.__div(lhs, rhs)
	return mathTemplate(lhs, rhs, '__div', 'division', function(x, y) return x / y end)
end

function Array.__pow(lhs, rhs)
	return mathTemplate(lhs, rhs, '__pow', 'exponentiation', function(x, y) return x ^ y end)
end

function Array.__eq(lhs, rhs)
	if len(lhs) ~= len(rhs) then
		return false
	end
	for i = 1, len(lhs) do
		if lhs[i] ~= rhs[i] then
			return false
		end
	end
	return true
end

---Behaviour depends on the value of `fn`:
---* `nil` - Checks that the array doesn't contain any **false** elements.
---* `fun(elem: any, i?: integer): boolean` - Returns **true** if `fn` returns **true** for every element.
---* `number` | `table` | `boolean` - Checks that all elements in `arr` are equal to this value.
---@param arr any[]
---@param fn? any
---@return boolean
function Array.all(arr, fn)
	checkType('Module:Array.all', 1, arr, 'table')
	if fn == nil then fn = function(item) return item end end
	if type(fn) ~= 'function' then
		local val = fn
		fn = function(item) return item == val end
	end
	for i = 1, len(arr) do
		---@diagnostic disable-next-line: redundant-parameter
		if not fn(arr[i], i) then
			return false
		end
	end
	return true
end

---Behaviour depends on the value of `fn`:
---* `nil` - Checks that the array contains at least one non **false** element.
---* `fun(elem: any, i?: integer): boolean` - Returns **true** if `fn` returns **true** for at least one element.
---* `number` | `table` | `boolean` - Checks that `arr` contains this value.
---@param arr any[]
---@param fn? any
---@return boolean
function Array.any(arr, fn)
	checkType('Module:Array.any', 1, arr, 'table')
	if fn == nil then fn = function(item) return item end end
	if type(fn) ~= 'function' then
		local val = fn
		fn = function(item) return item == val end
	end
	for i = 1, len(arr) do
		---@diagnostic disable-next-line: redundant-parameter
		if fn(arr[i], i) then
			return true
		end
	end
	return false
end

---Recursively removes all metatables.
---@param arr any[]
---@return any[]
function Array.clean(arr)
	checkType('Module:Array.clean', 1, arr, 'table')
	for i = 1, len(arr) do
		if type(arr[i]) == 'table' then
			Array.clean(arr[i])
		end
	end
	setmetatable(arr, nil)
	return arr
end

---Make a copy of the input table. Preserves metatables.
---@generic T: any[]
---@param arr T
---@param deep? boolean # Recursively clone subtables if **true**.
---@return T
function Array.clone(arr, deep)
	checkType('Module:Array.clone', 1, arr, 'table')
	checkType('Module:Array.clone', 2, deep, 'boolean', true)
	local res = {}
	for i = 1, len(arr) do
		if deep == true and type(arr[i]) == 'table' then
			res[i] = Array.clone(arr[i], true)
		else
			res[i] = arr[i]
		end
	end
	return setmetatable(res, getmetatable(arr))
end

---Check if `arr` contains `val`.
---@param arr any[]
---@param val any
---@return boolean
function Array.contains(arr, val)
	checkType('Module:Array.contains', 1, arr, 'table')
	for i = 1, len(arr) do
		if arr[i] == val then
			return true
		end
	end
	return false
end

---Check if `arr` contains any of the values in the table `t`.
---@param arr any[]
---@param t any[]
---@return boolean
function Array.containsAny(arr, t)
	checkType('Module:Array.containsAny', 1, arr, 'table')
	checkType('Module:Array.containsAny', 2, t, 'table')
	local lookupTbl = {}
	for i = 1, len(t) do
		lookupTbl[t[i]] = true
	end
	for i = 1, len(arr) do
		if lookupTbl[arr[i]] then
			return true
		end
	end
	return false
end

---Check if `arr` contains all values in the table `t`.
---@param arr any[]
---@param t any[]
---@return boolean
function Array.containsAll(arr, t)
	checkType('Module:Array.containsAll', 1, arr, 'table')
	checkType('Module:Array.containsAll', 2, t, 'table')
	local lookupTbl = {}
	local trueCount = 0
	local l = len(t)
	for i = 1, l do
		lookupTbl[t[i]] = false
	end
	for i = 1, len(arr) do
		if lookupTbl[arr[i]] == false then
			lookupTbl[arr[i]] = true
			trueCount = trueCount + 1
		end
		if trueCount == l then
			return true
		end
	end
	return false
end

---Convolute two number arrays.
---@generic T: number[]
---@param x T
---@param y T
---@return T
function Array.convolve(x, y)
	checkType('Module:Array.convolve', 1, x, 'table')
	checkType('Module:Array.convolve', 2, y, 'table')
	local z = {}
    local xLen, yLen = len(x), len(y)
    for j = 1, (xLen + yLen - 1) do
        local sum = 0
        for k = math.max(1, j - yLen + 1), math.min(xLen, j) do
            sum = sum + x[k] * y[j-k+1]
        end
        z[j] = sum
    end
    return setmetatable(z, getmetatable(x) or getmetatable(y))
end

---Remove **nil** values from `arr` while preserving order.
---@generic T: any[]
---@param arr T
---@return T
function Array.condenseSparse(arr)
	checkType('Module:Array.condenseSparse', 1, arr, 'table')
	local keys = {}
	local res = {}
	local l = 0
	for k in pairs(arr) do
		l = l + 1
		keys[l] = k
	end
	table.sort(keys)
	for i =  1, l do
		res[i] = arr[keys[i]]
	end
	return setmetatable(res, getmetatable(arr))
end

---Behaviour depends on value of `val`:
---* `nil` - Counts the number of non **false** elements.
---* `fun(elem: any): boolean` - Count the number of times the function returned **true**.
---* `boolean` | `number` | `table` - Counts the number of times this value occurs in `arr`.
---@param arr any[]
---@param val? any
---@return integer
function Array.count(arr, val)
	checkType('Module:Array.count', 1, arr, 'table')
	if val == nil then val = function(item) return item end end
	if type(val) ~= 'function' then
		local _val = val
		val = function(item) return item == _val end
	end
	local count = 0
	for i = 1, len(arr) do
		if val(arr[i]) then
			count = count + 1
		end
	end
	return count
end

---Differentiate the array
---@generic T: number[]
---@param arr T
---@param order number? # Oder of the differentiation. Default is 1.
---@return T # Length is `#arr - order`
function Array.diff(arr, order)
	checkType('Module:Array.diff', 1, arr, 'table')
	checkType('Module:Array.diff', 2, order, 'number', true)
	local res = {}
	for i = 1, len(arr) - 1 do
		res[i] = arr[i+1] - arr[i]
	end
	if order and order > 1 then
		return Array.diff(res, order - 1)
	end
	return setmetatable(res, getmetatable(arr))
end

---Loops over `arr` and passes each element as the first argument to `fn`. This function returns nothing.
---@param arr any[]
---@param fn fun(elem: any, i?: integer)
function Array.each(arr, fn)
	checkType('Module:Array.each', 1, arr, 'table')
	checkType('Module:Array.each', 2, fn, 'function')
	for i = 1, len(arr) do
		fn(arr[i], i)
	end
end

---Makes a copy of `arr` with only elements for which `fn` returned **true**.
---@generic T: any[]
---@param arr T
---@param fn fun(elem: any, i?: integer): boolean
---@return T
function Array.filter(arr, fn)
	checkType('Module:Array.filter', 1, arr, 'table')
	checkType('Module:Array.filter', 2, fn, 'function')
	local r = {}
	local l = 0
	for i = 1, len(arr) do
		if fn(arr[i], i) then
			l = l + 1
			r[l] = arr[i]
		end
	end
	return setmetatable(r, getmetatable(arr))
end

---Find the first elements for which `fn` returns **true**.
---@param arr any[]
---@param fn any # A value to look for or a function of the form `fun(elem: any, i?: integer): boolean`.
---@param default? any # Value to return if no element passes the test.
---@return any? elem # The first element that passed the test.
---@return integer? i # The index of the item that passed the test.
function Array.find(arr, fn, default)
	checkType('Module:Array.find', 1, arr, 'table')
	checkTypeMulti('Module:Array.find_index', 2, fn, {'function', 'table', 'number', 'boolean'})
	if type(fn) ~= 'function' then
		local _val = fn
		fn = function(item) return item == _val end
	end
	for i = 1, len(arr) do
		---@diagnostic disable-next-line: redundant-parameter
		if fn(arr[i], i) then
			return arr[i], i
		end
	end
	return default, nil
end

---Find the index of `val`.
---@param arr any[]
---@param val any # A value to look for or a function of the form `fun(elem: any, i?: integer): boolean`.
---@param default? any # Value to return if no element passes the test.
---@return integer?
function Array.find_index(arr, val, default)
	checkType('Module:Array.find_index', 1, arr, 'table')
	checkTypeMulti('Module:Array.find_index', 2, val, {'function', 'table', 'number', 'boolean'})
	if type(val) ~= 'function' then
		local _val = val
		val = function(item) return item == _val end
	end
	for i = 1, len(arr) do
		---@diagnostic disable-next-line: redundant-parameter
		if val(arr[i], i) then
			return i
		end
	end
	return default
end

---Extracts a subset of `arr`.
---@generic T: any[]
---@param arr T
---@param indexes integer|integer[] # Indexes of the elements.
---@return T
function Array.get(arr, indexes)
	checkType('Module:Array.set', 1, arr, 'table')
	checkTypeMulti('Module:Array.set', 2, indexes, {'table', 'number'})
	if type(indexes) == 'number' then
		indexes = {indexes}
	end
	local res = {}
	for i = 1, len(indexes) do
		 res[i] = arr[indexes[i]]
	end
	return setmetatable(res, getmetatable(arr))
end

---Integrates the array. Effectively does $\left\{\sum^{n}_{start}{arr[n]} \,\Bigg|\, n \in [start, stop]\right\}$.
---@generic T: number[]
---@param arr T # number[]
---@param start? integer # Index where to start the summation. Defaults to 1.
---@param stop? integer # Index where to stop the summation. Defaults to #arr.
---@return T
function Array.int(arr, start, stop)
	checkType('Module:Array.int', 1, arr, 'table')
	checkType('Module:Array.int', 2, start, 'number', true)
	checkType('Module:Array.int', 3, stop, 'number', true)
	local res = {}
	start = start or 1
	stop = stop or len(arr)
	res[1] = arr[start]
	for i = 1, stop - start do
		res[i+1] = res[i] + arr[start + i]
	end
	return setmetatable(res, getmetatable(arr))
end

---Returns an array with elements that are present in both tables.
---@generic T: any[]
---@param arr1 T
---@param arr2 T
---@return T
function Array.intersect(arr1, arr2)
	checkType('Module:Array.intersect', 1, arr1, 'table')
	checkType('Module:Array.intersect', 2, arr2, 'table')
	local arr2Elements = {}
	local res = {}
	local l = 0
	Array.each(arr2, function(item) arr2Elements[item] = true end)
	Array.each(arr1, function(item)
		if arr2Elements[item] then
			l = l + 1
			res[l] = item
		end
	end)
	return setmetatable(res, getmetatable(arr1) or getmetatable(arr2))
end

---Checks if the two inputs have at least one element in common.
---@param arr1 any[]
---@param arr2 any[]
---@return boolean
function Array.intersects(arr1, arr2)
	checkType('Module:Array.intersects', 1, arr1, 'table')
	checkType('Module:Array.intersects', 2, arr2, 'table')
	local small = {}
	local large
	if len(arr1) <= len(arr2) then
		Array.each(arr1, function(item) small[item] = true end)
		large = arr2
	else
		Array.each(arr2, function(item) small[item] = true end)
		large = arr1
	end
	return Array.any(large, function(item) return small[item] end)
end

---Inserts values into `arr`.
---@generic T: any[]
---@param arr T
---@param val any # If `val` is an array and `unpackVal` is **true** then the individual elements of `val` are inserted.
---@param index? integer # Location to start the insertion. Default is at the end of `arr`.
---@param unpackVal? boolean # Default is **false**.
---@return T
---@overload fun(arr: T, val: any, unpackVal: boolean): T
function Array.insert(arr, val, index, unpackVal)
	checkType('Module:Array.insert', 1, arr, 'table')
	checkTypeMulti('Module:Array.insert', 3, index, {'number', 'boolean', 'nil'})
	checkType('Module:Array.insert', 4, unpackVal, 'boolean', true)
	if type(index) == 'boolean'  then
		unpackVal, index = index, nil
	end
	local l = len(arr)
	index = index or (l + 1)
	local mt = getmetatable(arr)
	setmetatable(arr, nil)

	if unpackVal and type(val) == 'table' then
		local l2 = len(val)
		for i = 0, l - index do
			arr[l + l2 - i] = arr[l - i]
		end
		for i = 0, l2 - 1 do
			arr[index + i] = val[i + 1]
		end
	else
		table.insert(arr, index, val)
	end

	return setmetatable(arr, mt)
end

---Returns the last element of `arr`.
---@param arr any[]
---@param offset? integer
---@return any
function Array.last(arr, offset)
	checkType('Module:Array.last', 1, arr, 'table')
	checkType('Module:Array.last', 2, offset, 'number', true)
	return arr[len(arr) + offset]
end

---Returns a new table were each element of `arr` is modified by `fn`.
---@generic T: any[]
---@param arr T
---@param fn fun(elem: any, i?: integer): any # First argument is the current element, the second argument is the index of the current element.
---@return T
function Array.map(arr, fn)
	checkType('Module:Array.map', 1, arr, 'table')
	checkType('Module:Array.map', 2, fn, 'function')
	local l = 0
	local r = {}
	for i = 1, len(arr) do
		local tmp = fn(arr[i], i)
		if tmp ~= nil then
			l = l + 1
			r[l] = tmp
		end
	end
	return setmetatable(r, getmetatable(arr))
end

---Find the element for which `fn` returned the largest value.
---@param arr any[]
---@param fn fun(elem: any): any # The returned value needs to be comparable using the `<` operator.
---@return any elem # The element with the largest `fn` value.
---@return integer i # The index of this element.
function Array.max_by(arr, fn)
	checkType('Module:Array.max_by', 1, arr, 'table')
	checkType('Module:Array.max_by', 2, fn, 'function')
	return unpack(Array.reduce(arr, function(new, old, i)
		local y = fn(new)
		return y > old[2] and {new, y, i} or old
	end, {nil, -math.huge}))
end

---Find the largest value in the array.
---@param arr any[] # The values need to be comparable using the `<` operator.
---@return any elem
---@return integer i # The index of the largest value.
function Array.max(arr)
	checkType('Module:Array.max', 1, arr, 'table')
	local val, _, i = Array.max_by(arr, function(x) return x end)
	return val, i
end

---Find the smallest value in the array.
---@param arr any[] # The values need to be comparable using the `<` operator.
---@return any elem
---@return integer i # The index of the smallest value.
function Array.min(arr)
	checkType('Module:Array.min', 1, arr, 'table')
	local val, _, i = Array.max_by(arr, function(x) return -x end)
	return val, i
end

---Turn the input table into an Array. This makes it possible to use the colon `:` operator to access the Array methods.
---
---It also enables the use of math operators with the array.
---```
---local x = arr.new{ 1, 2, 3 }
---local y = arr{ 4, 5, 6 } -- Alternative notation
---
---print( -x ) --> { -1, -2, -3 }
---print( x + 2 ) --> { 3, 4, 5 }
---print( x - 2 ) --> { -1, 0, 1 }
---print( x * 2 ) --> { 2, 4, 6 }
---print( x / 2 ) --> { 0.5, 1, 1.5 }
---print( x ^ 2 ) --> { 1, 4, 9 }
---
---print( x + y ) --> { 5, 7, 9 }
---print( x .. y ) --> { 1, 2, 3, 4, 5, 6 }
---print( (x .. y):reject{3, 4, 5} ) --> { 1, 2, 6 }
---print( x:sum() ) --> 6
---
---print( x:update( {1, 3}, y:get{2, 3} * 2 ) ) --> { 10, 2, 12 }
---```
---@param arr? any[]
---@return Array
function Array.new(arr)
	local obj = arr or {}
	for _, v in pairs(obj) do
		if type(v) == 'table' then
			Array.new(v)
		end
	end

	if getmetatable(obj) == nil then
		setmetatable(obj, Array)
	end

	return obj
end

---Creates an object that returns a value that is `step` higher than the previous value each time it gets called.
---
---The stored value can be read without incrementing by reading the `val` field.
---
---A new stored value can be set through the `val` field.
---
---A new step size can be set through the `step` field.
---```
---local inc = arr.newIncrementor(10, 5)
---print( inc() ) --> 10
---print( inc() ) --> 15
---print( inc.val ) --> 15
---inc.val = 100
---inc.step = 20
---print( inc.val ) --> 100
---print( inc() ) --> 120
---```
---@param start? number # Default is 1.
---@param step? number # Default is 1.
---@return Incrementor
function Array.newIncrementor(start, step)
	checkType('Module:Array.newIncrementor', 1, start, 'number', true)
	checkType('Module:Array.newIncrementor', 2, step, 'number', true)
	step = step or 1
	local n = (start or 1) - step
	---@class Incrementor
	local obj = {}
	return setmetatable(obj, {
		__call = function() n = n + step return n end,
		__tostring = function() return tostring(n) end,
		__index = function() return n end,
		__newindex = function(self, k, v)
			if k == 'step' and type(v) == 'number' then
				step = v
			elseif type(v) == 'number' then
				n = v
			end
		end,
		__concat = function(x, y) return tostring(x) .. tostring(y) end
	})
end

---Returns a range of numbers.
---@param start number # Start value inclusive.
---@param stop number # Stop value inclusive for integers, exclusive for floats.
---@param step? number # Default is 1.
---@return Array
---@overload fun(stop: number): Array
function Array.range(start, stop, step)
	checkType('Module:Array.range', 1, start, 'number')
	checkType('Module:Array.range', 2, stop, 'number', true)
	checkType('Module:Array.range', 3, step, 'number', true)
	local arr = {}
	local len = 0
	if not stop then
		stop = start
		start = 1
	end
	for i = start, stop, step or 1 do
		len = len + 1
		arr[len] = i
	end
	return setmetatable(arr, Array)
end

---Condenses the array into a single value.
---
---For each element `fn` is called with the current element, the current accumulator, and the current element index. The returned value of `fn` becomes the accumulator for the next element.
---
---If no `accumulator` value is given at the start then the first element off `arr` becomes the accumulator and the iteration starts from the second element.
---```
---local t = { 1, 2, 3, 4 }
---local sum = arr.reduce( t, function(elem, acc) return acc + elem end ) -- sum == 10
---```
---@param arr any[]
---@param fn fun(elem: any, acc: any, i?: integer): any # The result of this function becomes the `acc` for the next element.
---@param accumulator? any
---@return any # This is the last accumulator value.
function Array.reduce(arr, fn, accumulator)
	checkType('Module:Array.reduce', 1, arr, 'table')
	checkType('Module:Array.reduce', 2, fn, 'function')
	local acc = accumulator
	local start = 1
	if acc == nil then
		acc = arr[1]
		start = 2
	end
	for i = start, len(arr) do
		acc = fn(arr[i], acc, i)
	end
	return acc
end

---Make a copy off `arr` with certain values removed.
---
---Behaviour for different values of `val`:
---* `boolean` | `number` - Remove values equal to this.
---* `table` - Remove all values in this table.
---* `fun(elem: any, i?: integer): boolean` - Remove elements for which the functions returns **true**.
---@generic T: any[]
---@param arr T
---@param val table|function|number|boolean
---@return T
function Array.reject(arr, val)
	checkType('Module:Array.reject', 1, arr, 'table')
	checkTypeMulti('Module:Array.reject', 2, val, {'function', 'table', 'number', 'boolean'})
	if type(val) ~= 'function' and type(val) ~= 'table' then
		val = {val}
	end
	local r = {}
	local l = 0
	if type(val) == 'function' then
		for i = 1, len(arr) do
			if not val(arr[i], i) then
				l = l + 1
				r[l] = arr[i]
			end
		end
	else
		local rejectMap = {}
		Array.each(val --[[@as any[] ]], function(item) rejectMap[item] = true end)
		for i = 1, len(arr) do
			if not rejectMap[arr[i]] then
				l = l + 1
				r[l] = arr[i]
			end
		end
	end
	return setmetatable(r, getmetatable(arr))
end

---Returns an Array with `val` repeated `n` times.
---@param val any
---@param n integer
---@return Array
function Array.rep(val, n)
	checkType('Module:Array.rep', 2, n, 'number')
	local r = {}
	for i = 1, n do
		r[i] = val
	end
	return setmetatable(r, Array)
end

---Condenses the array into a single value while saving every accumulator value.
---
---For each element `fn` is called with the current element, the current accumulator, and the current element index. The returned value of `fn` becomes the accumulator for the next element.
---
---If no `accumulator` value is given at the start then the first element off `arr` becomes the accumulator and the iteration starts from the second element.
---```
---local t = { 1, 2, 3, 4 }
---local x = arr.scan( t, function(elem, acc) return acc + elem end ) -- x = { 1, 3, 6, 10 }
---```
---@generic T: any[]
---@param arr T
---@param fn fun(elem: any, acc: any, i?: integer): any # Returned value becomes the accumulator for the next element.
---@param accumulator? any
---@return T
function Array.scan(arr, fn, accumulator)
	checkType('Module:Array.scan', 1, arr, 'table')
	checkType('Module:Array.scan', 2, fn, 'function')
	local acc = accumulator
	local r = {}
	for i = 1, len(arr) do
		if i == 1 and not accumulator then
			acc = arr[i]
		else
			acc = fn(arr[i], acc, i)
		end
		r[i] = acc
	end
	return setmetatable(r, getmetatable(arr))
end

---Update a range of index with a range of values.
---
---If if only one value is given but multiple indexes than that value is set for all those indexes.
---
---If `values` is a table then it must of the same length as `indexes`.
---@generic T: any[]
---@param arr T
---@param indexes integer|integer[]
---@param values any|any[]
---@return T
function Array.set(arr, indexes, values)
	checkType('Module:Array.set', 1, arr, 'table')
	checkTypeMulti('Module:Array.set', 2, indexes, {'table', 'number'})
	local mt = getmetatable(arr)
	setmetatable(arr, nil)
	if type(indexes) == 'number' then
		indexes = {indexes}
	end
	if type(values) == 'table' then
		assert(len(indexes) == len(values), string.format("Module:Array.set: 'indexes' and 'values' arrays are not equal length (#indexes = %d, #values = %d)", len(indexes), len(values)))
		for i = 1, len(indexes) do
			arr[indexes[i]] = values[i]
		end
	else
		for i = 1, len(indexes) do
			arr[indexes[i]] = values
		end
	end
	return setmetatable(arr, mt)
end

---Extract a subtable from `arr`.
---@generic T: any[]
---@param arr T
---@param start integer # Start index. Use negative values to count form the end of the array.
---@param stop integer # Stop index. Use negative values to count form the end of the array.
---@return T
---@overload fun(arr: T, stop: integer): T
function Array.slice(arr, start, stop)
	checkType('Module:Array.slice', 1, arr, 'table')
	checkType('Module:Array.slice', 2, start, 'number', true)
	checkType('Module:Array.slice', 3, stop, 'number', true)
	start = start or len(arr)
	if start < 0 then
		start = len(arr) + start
	end
	if stop == nil then
		stop = start
		start = 1
	end
	if stop < 0 then
		stop = len(arr) + stop
	end
	local r = {}
	local len = 0
	for i = start, stop do
		len = len + 1
		r[len] = arr[i]
	end
	return setmetatable(r, getmetatable(arr))
end

---Split `arr` into two arrays.
---@generic T: any[]
---@param arr T
---@param index integer # Index to split on.
---@return T x # [1, index]
---@return T y # [index + 1, #arr]
function Array.split(arr, index)
	checkType('Module:Array.split', 1, arr, 'table')
	checkType('Module:Array.split', 2, index, 'number')
	local x = {}
	local y = {}
	for i = 1, len(arr) do
		table.insert(i <= index and x or y, arr[i])
	end
	return setmetatable(x, getmetatable(arr)), setmetatable(y, getmetatable(arr))
end

---Returns the sum of all elements of `arr`.
---@param arr number[]
---@return number
function Array.sum(arr)
	checkType('Module:Array.sum', 1, arr, 'table')
	local res = 0
	for i = 1, len(arr) do
		res = res + arr[i]
	end
	return res
end

---Extract a subtable from `arr`.
---@generic T: any[]
---@param arr T
---@param count integer # Length of the subtable.
---@param start? integer # Start index. Default is 1.
---@return T
function Array.take(arr, count, start)
	checkType('Module:Array.take', 1, arr, 'table')
	checkType('Module:Array.take', 2, count, 'number')
	checkType('Module:Array.take', 3, start, 'number', true)
	local x = {}
	start = start or 1
	for i = start, math.min(len(arr), count + start - 1) do
		table.insert(x, arr[i])
	end
	return setmetatable(x, getmetatable(arr))
end

---Extract a subtable from `arr`.
---```
---local t = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }
---local x = arr.take_every( t, 2 )       --> x = { 1, 3, 5, 7, 9 }
---local x = arr.take_every( t, 2, 3 )    --> x = { 3, 5, 7, 9 }
---local x = arr.take_every( t, 2, 3, 2 ) --> x = { 3, 5 }
--- ```
---@generic T: any[]
---@param arr T
---@param n integer # Step size.
---@param start? integer # Start index.
---@param count? integer # Max amount of elements to get.
---@return T
function Array.take_every(arr, n, start, count)
	checkType('Module:Array.take_every', 1, arr, 'table')
	checkType('Module:Array.take_every', 2, n, 'number')
	checkType('Module:Array.take_every', 3, start, 'number', true)
	checkType('Module:Array.take_every', 4, count, 'number', true)
	count = count or len(arr)
	start = start or 1
	local stop = math.min(len(arr), start + n * (count - 1))
	local r = {}
	local l = 0
	for i = start, stop, n do
		l = l + 1
		r[l] = arr[i]
	end
	return setmetatable(r, getmetatable(arr))
end

---Return a new table with all duplicates removed.
---@generic T: any[]
---@param arr T
---@param fn? fun(elem: any): any # Function to generate an id for each element. The result will then contain elements that generated unique ids.
---@return T
function Array.unique(arr, fn)
	checkType('Module:Array.unique', 1, arr, 'table')
	checkType('Module:Array.unique', 2, fn, 'function', true)
	fn = fn or function(item) return item end
	local r = {}
	local l = 0
	local hash = {}
	for i = 1, len(arr) do
		local id = fn(arr[i])
		if not hash[id] then
			l = l + 1
			r[l] = arr[i]
			hash[id] = true
		end
	end
	return setmetatable(r, getmetatable(arr))
end

---Combine elements with the same index from multiple arrays.
---```
---local x = {1, 2, 3}
---local y = {4, 5, 6, 7}
---local z = arr.zip( x, y ) --> z = { { 1, 4 }, { 2, 5 }, { 3, 6 }, { 7 } }
---```
---@param ... any[]
---@return Array
function Array.zip(...)
	local arrs = { ... }
	checkType('Module:Array.zip', 1, arrs[1], 'table')
	local r = {}
	local _, longest = Array.max_by(arrs, function(arr) return len(arr) end)
	for i = 1, longest do
		local q = {}
		for j = 1, len(arrs) do
			table.insert(q, arrs[j][i])
		end
		table.insert(r, setmetatable(q, Array))
	end
	return setmetatable(r, Array)
end

-- Range indexing has a performance impact so this is placed in a separate subclass
Array.RI_mt = {}
for k, v in pairs(Array) do
	Array.RI_mt[k] = v
end

function Array.RI_mt.__index(t, k)
	if type(k) == 'table' then
		local res = {}
		for i = 1, len(k) do
			res[i] = t[k[i]]
		end
		return setmetatable(res, Array)
	else
		return Array[k]
	end
end

function Array.RI_mt.__newindex(t, k, v)
	if type(k) == 'table' then
		if type(v) == 'table' then
			for i = 1, len(k) do
				t[k[i]] = v[i]
			end
		else
			for i = 1, len(k) do
				t[k[i]] = v
			end
		end
	else
		rawset(t, k, v)
	end
end

---Enable range indexing on the input array.
---
---This has a performance impact on reads and writes to the table.
---```
---local t = arr{10, 11, 12, 13, 14, 15}:ri()
---print( t[{2, 3}] ) --> { 11, 12 }
---```
---@param arr any[]
---@param recursive? boolean # Default is false.
---@return Array
function Array.ri(arr, recursive)
	checkType('Module:Array.ri', 1, arr, 'table')
	checkType('Module:Array.ri', 2, recursive, 'boolean', true)
	arr = arr or {}
	if recursive then
		for _, v in pairs(arr) do
			if type(v) == 'table' then
				Array.ri(v, true)
			end
		end
	end

	if getmetatable(arr) == nil or getmetatable(arr) == Array then
		setmetatable(arr, Array.RI_mt)
	end

	return arr
end

---Globally enable range indexing on all Array objects by default.
---@param set boolean
function Array.allwaysAllowRangeIndexing(set)
	checkType('Module:Array.allwaysAllowRangeIndexing', 1, set, 'boolean')
	if set then
		Array.__index = Array.RI_mt.__index
		Array.__newindex = Array.RI_mt.__newindex
	else
		Array.__index = Array
		Array.__newindex = nil
	end
end

return Array