Extension:Scribunto/Справочник Lua

From MediaWiki.org
Jump to navigation Jump to search
This page is a translated version of the page Extension:Scribunto/Lua reference manual and the translation is 11% complete.

Outdated translations are marked like this.
Other languages:
Bahasa Indonesia • ‎Deutsch • ‎English • ‎Esperanto • ‎Tiếng Việt • ‎asturianu • ‎español • ‎français • ‎italiano • ‎magyar • ‎polski • ‎português do Brasil • ‎русский • ‎українська • ‎עברית • ‎မြန်မာဘာသာ • ‎中文 • ‎日本語 • ‎한국어
shortcuts:
Lua manual
LUAREF

Это руководство по Lua в том виде, в каком он используется в MediaWiki с расширением Scribunto . Некоторые части производны от Lua 5.1 reference manual, доступного под лицензией MIT.

Contents

Введение

Первые шаги

На википроекте с MediaWiki с подключенным Scribunto создайте страницу с заголовком, начинающимся[1] с Module:, например, Module:Bananas. На эту новую страницу скопируйте следующий текст:

local p = {} -- p означает package (пакет)

function p.hello( frame )
    return "Hello, world!"
end

return p

Сохраните это, а затем на другой странице (не в модуле) напишите:

{{#invoke:Bananas|hello}}

при этом имя «Bananas» следует заменить на имя модуля, который вы только что создали. Этот текст вызовет функцию «hello» из вашего модуля. После сохранения строки {{#invoke:Bananas|hello}} в коде другой страницы и вызове её на просмотр, текст вызова функции заменится на тот, который возвращает функция. В данном случае — «Hello, world!»

Лучшим вариантом использования кода на Lua следует признать шаблоны. С точки зрения вызывающей страницы нет разницы, написан ли шаблон с использованием Lua или на чистом викитексте. Но при использовании Lua только в шаблонах в основное пространство вики не вводится дополнительный усложнённый синтаксис.

Структура модуля

Сам по себе модуль должен возвращать Lua-таблицу, содержащую функции, которые можно вызвать через {{#invoke:}}. Обычно объявляют, как показано выше, локальную переменную, в которую помещается таблица, к этой таблице добавляют функции, и в конце кода модуля эту таблицу возвращают.

Все функции, не добавленные к этой таблице, глобальные они или локальные, через {{#invoke:}} доступны не будут; однако глобальные будут доступны из других модулей, загруженных с помощью require(). Обычно хорошим стилем для модуля будет объявить все функции и переменные локально.

Доступ к параметрам из викитекста

Функциям, вызываемым с помощью {{#invoke:}} передаётся единственный параметр, а именно объект frame. Для доступа к параметрам, переданным через {{#invoke:}}, в коде обычно используется таблица args объекта frame. Та же таблица может быть использована для доступа к параметрам, переданным в шаблон, содержащий {{#invoke:}}. Для этого необходимо предварительно вызвать метод frame:getParent() и получить доступ к args этого фрейма.

Также объект frame используется для доступа к специфичным для конкретного контекста возможностям парсера викитекста, например, к вызову функций парсера, вызову шаблонов или обработке произвольных строк викитекста.

Возвращаемый текст

Обычно функция модуля возвращает одну символьную строку (строковый литерал); все возвращаемые значения пропускаются через tostring(), а затем конкатенируются (сшиваются) без разделителей. Именно эта строка и встраивается в викитекст в качестве результата вызова {{#invoke:}}.

В этот момент разбора страницы шаблоны уже развёрнуты, функции парсера и теги расширений уже выполнены, а предварительные преобразования (например, подстановка подписи вместо тильд или конвейерный приём [pipe trick]) уже совершены. Поэтому модуль не может использовать эти возможности в выходном тексте. Например, если модуль возвращает "Hello, [[world]]! {{welcome}}", то на странице это будет выглядеть как "Hello, world! {{welcome}}".

Также следует помнить, что подстановки вида subst выполняются на ранней стадии обработки, поэтому код {{subst:#invoke:имяМодуля}} выполнится не при первом сохранении. Другие подстановки сработают, а эта останется «висеть» в викитексте и выполнится только при следующем редактировании. Следует избегать таких приёмов.

Документирование модуля

Scribunto позволяет документировать модули, автоматически связывая модуль с викитекстовой страницей документации; по умолчанию для этого используется подстраница модуля с именем «/doc», содержимое которой внедряется над исходным кодом страницы модуля. Например, документация для модуля «Module:Bananas» будет размещена в «Module:Bananas/doc».

Документирование модуля может быть настроено с помощью следующих сообщений пространства имён MediaWiki (MediaWiki-namespace messages):

  • scribunto-doc-page-name: устанавливает имя страницы, используемой для документирования. Значение по умолчанию «Module:$1/doc», т. е. подстраница /doc модуля. Здесь $1 — код, который возвращает название модуля (без префикса Module:). Если это сообщение указывает на страницу пространства имён модулей, то такая страница будет интерпретироваться как викитекст, а не как код на Lua, и её нельзя будет вызывать с помощью {{#invoke:}}. Также следует помнить, что в этом сообщении нельзя использовать функции парсера и другие расширения, доступные через фигурные скобки.
  • scribunto-doc-page-does-not-exist: устанавливает текст, который будет выведен, если страница документации не существует. Имя страницы модуля находится в переменной $1. Значение по умолчанию — пустая строка.
  • scribunto-doc-page-show: устанавливает текст, который будет возвращён, если страница документации существует. По умолчанию содержит скомпилированный текст страницы документации (для последующего внедрения). Переменная $1 содержит имя модуля.
  • scribunto-doc-page-header: устанавливает заголовок, который будет показан при просмотре самой страницы документации. Переменная $1 содержит имя модуля (вместе с префиксом Module:). По умолчанию выводит короткий текст курсивом.

Обратите внимание на то, что на страницы модулей нельзя напрямую добавить ссылки на категории или интервики-ссылки. Они могут быть добавлены на страницу документации между тегами <includeonly>...</includeonly>. Тогда они будут применены к модулю, когда страница документации будет внедрена в страницу модуля.

Язык Lua

Токены

Имена в Lua (также называемые идентификаторами) могут быть любыми текстовыми строками, состоящими из букв, цифр и знаков подчёркивания, но не начинающимися с числа. Имена регистрозависимы, т. е. «foo», «Foo», и «FOO», это разные имена.

Нижеследующие ключевые слова зарезервированы и не могут быть использованы в качестве имён:

  • and
  • break
  • do
  • else
  • elseif
  • end
  • false
  • for
  • function
  • if
  • in
  • local
  • nil
  • not
  • or
  • repeat
  • return
  • then
  • true
  • until
  • while

Имена, начинающиеся с символа подчеркивания, за которым следуют заглавные буквы, зарезервированы для внутренних глобальных переменных Lua.

Другие токены:

  • #
  • %
  • (
  • )
  • *
  • +
  • ,
  • -
  • .
  • ..
  • ...
  • /
  • :
  • ;
  • <
  • <=
  • =
  • ==
  • >
  • >=
  • [
  • ]
  • ^
  • {
  • }
  • ~=

Комментарии

Комментарий начинается с символов -- в любом месте кода, кроме символьных строк. Если после -- сразу же идёт открывающая широкая скобка, то комментарий будет продолжаться до соответствующей закрывающей широкой скобки; в противном случае комментарий продолжается до конца строки.

-- Комментарий в Lua начинается с двойного дефиса и продолжается до конца строки.
--[[ Многострочные символьные строки (строковые литералы) и комментарии
     оформляются двойными квадратными скобками. ]]
--[=[ Комментарии, оформленные так, могут иметь другие вложенные --[[комментарии]]. ]=]
--[==[ Комментарии, похожие на этот, могут иметь другие
      --[===[ пространные --[=[комментарии,]=] --вложенные
        ]===] многократно, даже если все они
      --[[ неправильно оформлены широкими скобками! ]===]
  ]==]

Типы данных

Lua — динамически типизированный язык, что означает, что переменные и аргументы функции не имеют типа, а только назначенные им значения. Но все значения имеют тип.

Lua имеет восемь базовых типов данных, однако только шесть из них задействованы в расширении Scribunto. Узнать тип значения можно с помощью функции type().

Функция tostring() конвертирует значение в символьную строку. Функция tonumber() может сконвертировать значение в число, если это возможно. Если нет — вернёт nil. Других функций, существующих только для преобразования типа данных, в Lua нет.

Числа автоматически преобразуются в символьные строки, когда используются в ситуации, в которой ожидается вывод именно строкового литерала. Например, при использовании с оператором конкатенации. Соответственно строковый литерал, если он в принципе распознаётся функцией tonumber(), автоматически конвертируется в число при использовании арифметических операторов. Если же ожидается вывод логического значения, то получение любого другого , кроме nil или false, интерпретируется как true.

nil

Значение «nil» имеет тип данных nil и существует для представления ситуации отсутствующего значения.

Nil не может использоваться в качестве ключа в таблице, и нет никакой разницы между неназначенным ключом таблицы и ключом, назначенным значением nil.

При преобразовании nil в строковый литерал получим строку из трёх символов: "nil". При преобразовании nil в логическое значение получим false.

boolean

Логических (булевых) значений два: true и false.

Если преобразовать их в символьные строки, получим слова "true" и "false".

В отличие от многих других языков, логические значения не могут быть напрямую преобразованы в числа. Также в Lua только false и nil в логических операциях считаются значением false; число 0 или пустая символьная строка считаются значением true.

string

Строки Lua считаются серией 8-битных байтов; в зависимости от применения их можно интерпретировать в любой конкретной кодировке.

Строковые литералы ограничиваются одинарными или двойными кавычками (' или "). Так же, как в JavaScript, но не так, как в PHP, между одинарными и двойными кавычками нет разницы. Определены следующие управляющие последовательности (escape-последовательности):

  • \a (bell, звуковой сигнал, байт 7)
  • \b (backspace, возврат на 1 позицию, байт 8)
  • \t (horizontal tab, горизонтальная табуляция, байт 9)
  • \n (newline, перевод строки, байт 10)
  • \v (vertical tab, вертикальная табуляция, байт 11)
  • \f (form feed, прогон страницы (FF), байт 12)
  • \r (carriage return, возврат каретки, байт 13)
  • \" (double quote, двойные кавычки, байт 34)
  • \' (single quote, одинарные кавычки, байт 39)
  • \\ (backslash, обратный слеш, байт 92)

Литерал новой строки также может быть включен в символьную строку с экранированием обратным слешем. Байты тоже можно использовать в escape-последовательности вида '\ddd', где ddd — это десятичное значение байта в диапазоне 0—255. Чтобы включить символы Unicode с использованием управляющих последовательностей, необходимо указать отдельные байты кодировки UTF-8 (от одного до четырёх); в общем, будет проще вводить символы Unicode напрямую.

Строковые литералы могут быть обозначены с использованием широких скобок. Открывающая широкая скобка состоит из двух подряд открывающих квадратных скобок между которыми может располагаться произвольное количество знаков равенства, например, [[, [=[ или [=====[. Открывающей широкой скобке должна соответствовать закрывающая широкая скобка, например, ]], ]=] или ]=====]. В качестве особого случая: если литерал newline следует сразу же после открывающей широкой скобки, он не включается в символьную строку, но если литерал newline стоит непосредственно перед закрывающей широкой скобкой, то он в символьную строку входит. В символьных строках, ограниченных широкими скобками, управляющие последовательности не используются.

-- Эта символьная строка, ограниченная широкими скобками
foo = [[
bar\tbaz
]]

-- эквивалентна этой, ограниченной кавычками
bar = 'bar\\tbaz\n'

Следует помнить, что все строки считаются истинными (true) при преобразовании к логическому типу данных (boolean). Это не похоже на большинство других языков программирования, где пустая строка обычно считается ложной (false).

number

Lua имеет только один числовой тип, который обычно представляется как значение двойной точности с плавающей запятой. В этом формате целые числа между -9007199254740992 и 9007199254740992 могут быть представлены точно, в то время как большие числа и числа с дробной частью могут пострадать от ошибки округления.

В числовых константах используется точка (.) в качестве десятичного разделителя и не используются разделители групп разрядов, например, 123456.78. Также числа могут быть представлены с использованием экспоненциальной записи без пробелов, например, 1.23e-10, 123.45e20, или 1.23E5. Целые числа могут быть представлены в шестнадцатиричном виде с использованием префикса 0x, например, 0x3A.

Хотя и NaN, и бесконечности обоих знаков правильно хранятся и обрабатываются в Lua, под них не предоставлено соответствующих литералов. Константа math.huge хранит положительную бесконечность, а с помощью делений 1/0 или 0/0 можно быстро сгенерировать NaN.

Следует помнить, что при преобразовании к логическому типу данных все числа дают true. Это не похоже на большинство других языков программирования, где число 0 обычно даёт false. При конвертации в символьную строку все конечные числа переводятся в десятичную форму, если необходимо — в экспоненциальной форме; NaN даёт "nan" или "-nan"; бесконечности — "inf" или "-inf".

table

Таблицы Lua — это ассоциативные массивы, похожие на массивы PHP или объекты JavaScript.

Таблицы создаются с использованием фигурных скобок. Пустая таблица: {}. Чтобы заполнить поля таблицы при создании, в фигурные скобки можно включить список спецификаторов полей, разделенных запятыми и/или точками с запятой. Они принимают любую из нескольких форм:

  • [выражение1] = выражение2 здесь (первое) значение выражения1 используется как ключ, а (первое) значение выражения2 является значением.
  • имя = выражение, что эквивалентно ["имя"] = выражение
  • выражение, что примерно эквивалентно [i] = выражение, где i является целым числом, а счёт начинается с 1 и увеличивается на 1 для каждого следующего спецификатора поля. Если последнему спецификатору будет соответствовать выражение, имеющее несколько значений, то будут использованы все они; в противном случае сохраняется только первое значение выражения.

Обращаться к полям таблицы можно с использованием формы записи с квадратными скобками, например, таблица[ключ]. Символьные ключи, если они соответствуют требованиям к именам, позволяют использовать запись с точкой, например, таблица.ключ, что эквивалентно записи таблица['ключ']. Если значением поля таблицы является функция, её вызов может быть осуществлён в форме записи с двоеточием; например, таблица:функ( … ), что соответствует таблица['функ']( таблица, … ) или таблица.функ( таблица, … ).

Последовательностью называют таблицу с не-nil значениями, ключами для которых служат целые положительные числа от 1 до N (т. е. натуральные числа — прим. пер.), а для ключей, бо́льших N, значения не определены (nil). Множество функций Lua работают только с последовательностями и игнорируют ключи не натурального ряда.

В отличие от многих других языков, таких как PHP или JavaScript, любое значение, кроме nil и NaN, может использоваться как ключ, и преобразование типов при этом не выполняется. Всё, представленное ниже, валидно и различается между собой:

-- Создание таблицы
t = {}
t["foo"] = "foo"
t.bar = "bar"
t[1] = "один"
t[2] = "два"
t[3] = "три"
t[12] = "число двенадцать"
t["12"] = "строка двенадцать"
t[true] = "истина"
t[tonumber] = "да, функции тоже могут быть ключами таблицы"
t[t] = "да, таблица также может быть ключом для таблицы. Даже для себя самой."

-- Теперь создаём таблицу, в целом эквивалентную верхней
t2 = {
    foo = "foo",
    bar = "bar",
    "один",
    "два",
    [12] = "число двенадцать",
    ["12"] = "строка двенадцать",
    "три",
    [true] = "истина",
    [tonumber] = "да, функции тоже могут быть ключами таблицы",
}
t2[t2] = "да, таблица также может быть ключом для таблицы. Даже для себя самой."

Аналогично, любое значение, кроме nil, может быть сохранено как значение таблицы. Хранение nil эквивалентно удалению ключа из таблицы, и обращение к несуществующему ключу даст значение nil.

Следует помнить, что в Lua неявного копирования таблиц не происходит; если таблица передаётся в качестве аргумента функции, которая затем изменяет ключи или значения таблицы, то эти изменения будут видны в вызывающем коде.

При преобразовании таблицы к символьной строке получим результат "table", но это может быть переопределено с помощью метаметода __tostring . При логическом преобразовании даже пустая таблица даёт true.

function

Функции в Lua являются значениями первого класса: они могут создаваться анонимно, передаваться как аргументы, назначаться переменным и т. д.

Функции создаются с помощью ключевого слова function и вызывается с помощью круглых скобок. Синтаксический сахар доступен для именованных функций, локальных функций и функций, которые являются значениями в таблице. Подробнее это изложено ниже в разделах Объявление функций и Вызов функций.

Функции в Lua являются замыканием, что означает, что они поддерживают ссылку на область, в которой они объявлены, и могут обращаться к переменным в этой области и управлять ими.

Like tables, if a function is assigned to a different variable or passed as an argument to another function, it is still the same underlying "function object" that will be called.

При преобразовании в строку результатом является "функция".

Неподдерживаемые типы

The userdata type is used to hold opaque values for extensions to Lua written in other languages; for example, a userdata might be used to hold a C pointer or struct. To allow for use of Scribunto in hosting environments where custom-compiled code is not allowed, no such extensions are used.

The thread type represents the handles for coroutines, which are not available in Scribunto's sandbox.

Metatables

Every table may have an associated table known as a metatable. The fields in the metatable are used by some operators and functions to specify different or fallback behavior for the table. The metatable for a table may be accessed using the getmetatable() function, and set with the setmetatable() function.

When being accessed for their meta functions, metatable fields are accessed as if with rawget().

Metatable fields that affect the table itself are:

__index
This is used when a table access t[key] would return nil. If the value of this field is a table, the access will be repeated in that table, i.e. __index[key] (which may invoke that table's metatable's __index). If the value of this field is a function, the function will be called as __index( t, key ). The rawget() function bypasses this metamethod.
__newindex
This is used when assigning a key to a table t[key] = value where rawget( t, key ) would return nil. If the value of this field is a table, the assignment will be repeated in that table, i.e. __newindex[key] = value (which may invoke that table's metatable's __newindex). If the value of this field is a function, the function will be called as __newindex( t, key, value ). The rawset() function bypasses this metamethod.
__call
This is used when function call syntax is used on a table, t( ··· ). The value must be a function, which is called as something like __call( t, ··· ).
__mode
This is used to make tables holding weak references. The value must be a string. By default, any value that is used as a key or as a value in a table will not be garbage collected. But if this metafield contains the letter 'k', keys may be garbage collected if there are no non-weak references, and if it contains 'v' values may be; in either case, both the corresponding key and value are removed from the table. Note that behavior is undefined if this field is altered after the table is used as a metatable.

Other metatable fields include:

For binary operators, Lua looks first at the left argument's metatable (if any) then the right's when looking for a metamethod to use.
For relational operators, the metamethod is only used if the same function is specified in both arguments' metatables. Different anonymous functions, even with identical body and closure, may not be considered the same.
* __metatable affects both getmetatable() and setmetatable()

Note: In Lua, all strings also share a single metatable, in which __index refers to the string table. This metatable is not accessible in Scribunto, nor is the referenced string table; the string table available to modules is a copy.

Variables

Variables are places that store values. There are three kinds of variables in Lua: global variables, local variables, and table fields.

A name represents a global or local variable (or a function argument, which is just a kind of local variable). Variables are assumed to be global unless explicitly declared as local using the local keyword. Any variable that has not been assigned a value is considered to have a nil value.

Global variables are stored in a standard Lua table called an environment; this table is often available as the global variable _G. It is possible to set a metatable for this global variable table; the __index and __newindex metamethods will be called for accesses of and assignments to global variables just as they would for accesses of and assignments to fields in any other table.

The environment for a function may be accessed using the getfenv() function and changed using the setfenv() function; in Scribunto, these functions are severely restricted if they are available at all.

Local variables are lexically scoped; see Local variable declarations for details.

Expressions

An expression is something that has values: literals (numbers, strings, true, false, nil), anonymous function declarations, table constructors, variable references, function calls, the vararg expression, expressions wrapped in parentheses, unary operators applied to expressions, and expressions combined with binary operators.

Most expressions have one value; function calls and the vararg expression can have any number. Note that wrapping a function call or vararg expression in parentheses will lose all except the first value.

Expression lists are comma-separated lists of expressions. All except the last expression are forced to one value (dropping additional values, or using nil if the expression has no values); all values from the last expression are included in the values of the expression list.

Arithmetic operators

Lua supports the usual arithmetic operators: addition, subtraction, multiplication, division, modulo, exponentiation, and negation.

When all operands are numbers or strings for which tonumber() returns non-nil, the operations have their usual meaning.

If either operand is a table with an appropriate metamethod, the metamethod will be called.

Operator Function Example Metamethod Notes
+ Addition a + b __add
- Subtraction a - b __sub
* Multiplication a * b __mul
/ Division a / b __div division by zero is not an error; NaN or infinity will be returned
% Modulo a % b __mod defined as a % b == a - math.floor( a / b ) * b
^ Exponentiation a ^ b __pow non-integer exponents are allowed
- Negation -a __unm

Relational operators

The relational operators in Lua are ==, ~=, <, >, <=, and >=. The result of a relational operator is always a boolean.

Equality (==) first compares the types of its operands; if they are different, the result is false. Then it compares the values: nil, boolean, number, and string are compared in the expected manner. Functions are equal if they refer to the exact same function object; function() end == function() end will return false, as it is comparing two different anonymous functions. Tables are by default compared in the same manner, but this may be changed using the __eq metamethod.

Inequality (~=) is the exact negation of equality.

For the ordering operators, if both are numbers or both are strings, they are compared directly. Next, metamethods are checked:

  • a < b uses __lt
  • a <= b uses __le if available, or if __lt is available then it is considered equivalent to not ( b < a )
  • a > b is considered equivalent to b < a
  • a >= b is considered equivalent to b <= a

If the necessary metamethods are not available, an error is raised.

Logical operators

The logical operators are and, or, and not. All use the standard interpretation where nil and false are considered false and anything else is considered true.

For and, if the left operand is considered false then it is returned and the second operand is not evaluated; otherwise the second operand is returned.

For or, if the left operand is considered true then it is returned and the second operand is not evaluated; otherwise the second operand is returned.

For not, the result is always true or false.

Note that and and or short circuit. For example, foo() or bar() will only call bar() if foo() returns false or nil as its first value.

Concatenation operator

The concatenation operator is two dots, used as a .. b. If both operands are numbers or strings, they are converted to strings and concatenated. Otherwise if a __concat metamethod is available, it is used. Otherwise, an error is raised.

Note that Lua strings are immutable and Lua does not provide any sort of "string builder", so a loop that repeatedly does a = a .. b will have to create a new string for each iteration and eventually garbage-collect the old strings. If many strings need concatenating, it may be faster to use string.format() or to insert all the strings into a sequence and use table.concat() at the end.

Length operator

The length operator is #, used as #a. If a is a string, it returns the length in bytes. If a is a sequence table, it returns the length of the sequence.

If a is a table that is not a sequence, the #a may return any value N such that a[N] is not nil and a[N+1] is nil, even if there are non-nil values at higher indexes. For example,

-- This is not a sequence, because a[3] is nil and a[4] is not
a = { 1, 2, nil, 4 }

-- This may output either 2 or 4.
-- And this may change even if the table is not modified.
mw.log( #a )

Operator precedence

Lua's operator precedence or order of operations, from highest to lowest:

  1. ^
  2. not # - (negation)
  3. * / %
  4. + - (subtraction)
  5. ..
  6. < > <= >= ~= ==
  7. and
  8. or

Within a precedence level, most binary operators are left-associative, i.e. a / b / c is interpreted as (a / b) / c. Exponentiation and concatenation are right-associative, i.e. a ^ b ^ c is interpreted as a ^ (b ^ c).

Function calls

Lua function calls look like those in most other languages: a name followed by a list of arguments in parentheses:

func( expression-list )

As is usual with expression lists in Lua, the last expression in the list may supply multiple argument values.

If the function is called with fewer values in the expression list than there are arguments in the function definition, the extra arguments will have a nil value. If the expression list contains more values than there are arguments, the excess values are discarded. It is also possible for a function to take a variable number of arguments; see Function declarations for details.

Lua also allows direct calling of a function return value, i.e. func()(). If an expression more complex than a variable access is needed to determine the function to be called, a parenthesized expression may be used in place of the variable access.

Lua has syntactic sugar for two common cases. The first is when a table is being used as an object, and the function is to be called as a method on the object. The syntax

table:name( expression-list )

is exactly equivalent to

table.name( table, expression-list )

The second common case is Lua's method of implementing named arguments by passing a table containing the name-to-value mappings as the only positional argument to the function. In this case, the parentheses around the argument list may be omitted. This also works if the function is to be passed a single literal string. For example, the calls

func{ arg1 = exp, arg2 = exp }
func"string"

are equivalent to

func( { arg1 = exp, arg2 = exp } )
func( "string" )

These may be combined; the following calls are equivalent:

table:name{ arg1 = exp, arg2 = exp }
table.name( table, { arg1 = exp, arg2 = exp } )

Function declarations

The syntax for function declaration looks like this:

function ( var-list )
    block
end

All variables in var-list are local to the function, with values assigned from the expression list in the function call. Additional local variables may be declared inside the block.

When the function is called, the statements in block are executed after local variables corresponding to var-list are created and assigned values. If a return statement is reached, the block is exited and the values of the function call expression are those given by the return statement. If execution reaches the end of the function's block without encountering a return statement, the result of the function call expression has zero values.

Lua functions are lexical closures. A common idiom is to declare "private static" variables as locals in the scope where the function is declared. For example,

-- This returns a function that adds a number to its argument
function makeAdder( n )
    return function( x )
        -- The variable n from the outer scope is available here to be added to x
        return x + n
    end
end

local add5 = makeAdder( 5 )
mw.log( add5( 6 ) )
-- prints 11

A function may be declared to accept a variable number of arguments, by specifying ... as the final item in the var-list:

function ( var-list, ... )
    block
end

Within the block, the varargs expression ... may be used, with the result being all the extra values in the function call. For example,

local join = function ( separator, ... )
    -- get the extra arguments as a table
    local args = { ... }
    -- get the count of extra arguments, correctly
    local n = select( '#', ... )
    return table.concat( args, separator, 1, n )
end

join( ', ', 'foo', 'bar', 'baz' )
-- returns the string "foo, bar, baz"

The select() function is designed to work with the varargs expression; in particular, select( '#', ... ) should be used instead of #{ ... } to count the number of values in the varargs expression, because { ... } may not be a sequence.

Lua provides syntactic sugar to combine function declaration and assignment to a variable; see Function declaration statements for details.

Note that this will not work:

local factorial = function ( n )
    if n <= 2 then
        return n
    else
        return n * factorial( n - 1 )
    end
end

Since the function declaration is processed before the local variable assignment statement is complete, "factorial" inside the function body refers to the (probably undefined) variable of that name in an outer scope. This problem may be avoided by declaring the local variable first and then assigning it in a subsequent statement, or by using the function declaration statement syntax.

Statements

A statement is the basic unit of execution: one assignment, control structure, function call, variable declaration, etc.

A chunk is a sequence of statements, optionally separated by semicolons. A chunk is basically considered the body of an anonymous function, so it can declare local variables, receive arguments, and return values.

A block is also a sequence of statements, just like a chunk. A block can be delimited to create a single statement: do block end. These may be used to limit the scope of local variables, or to add a return or break in the middle of another block.

Assignments

variable-list = expression-list

The variable-list is a comma-separated list of variables; the expression-list is a comma-separated list of one or more expressions. All expressions are evaluated before any assignments are performed, so a, b = b, a will swap the values of a and b.

Local variable declarations

local variable-list

local variable-list = expression-list

Local variables may be declared anywhere within a block or chunk. The first form, without an expression list, declares the variables but does not assign a value so all variables have nil as a value. The second form assigns values to the local variables, as described in Assignments above.

Note that visibility of the local variable begins with the statement after the local variable declaration. So a declaration like local x = x declares a local variable x and assigns it the value of x from the outer scope. The local variable remains in scope until the end of the innermost block containing the local variable declaration.

Control structures

while exp do block end

The while statement repeats a block as long as an expression evaluates to a true value.

repeat block until exp

The repeat statement repeats a block until an expression evaluates to a true value. Local variables declared inside the block may be accessed in the expression.

for name = exp1, exp2, exp3 do block end
for name = exp1, exp2 do block end

This first form of the for loop will declare a local variable, and repeat the block for values from exp1 to exp2 adding exp3 on each iteration. Note that exp3 may be omitted entirely, in which case 1 is used, but non-numeric values such as nil and false are an error. All expressions are evaluated once before the loop is started.

This form of the for loop is roughly equivalent to

 do
     local var, limit, step = tonumber( exp1 ), tonumber( exp2 ), tonumber( exp3 )
     if not ( var and limit and step ) then
         error()
     end
     while ( step > 0 and var <= limit ) or ( step <= 0 and var >= limit ) do
         local name = var
         block
         var = var + step
     end
 end

except that the variables var, limit, and step are not accessible anywhere else. Note that the variable name is local to the block; to use the value after the loop, it must be copied to a variable declared outside the loop.

for var-list in expression-list do block end

The second form of the for loop works with iterator functions. As in the first form, the expression-list is evaluated only once before beginning the loop.

This form of the for loop is roughly equivalent to

 do
     local func, static, var = expression-list
     while true do
         local var-list = func( static, var )
         var = var1  -- ''var1'' is the first variable in ''var-list''
         if var == nil then
             break
         end
         block
     end
 end

except that again the variables func, static, and var are not accessible anywhere else. Note that the variables in var-list are local to the block; to use them after the loop, they must be copied to variables declared outside the loop.

Often the expression-list is a single function call that returns the three values. If the iterator function can be written so it only depends on the parameters passed into it, that would be the most efficient. If not, Programming in Lua suggests that a closure be preferred to returning a table as the static variable and updating its members on each iteration.

if exp1 then block1 elseif exp2 then block2 else block3 end

Executes block1 if exp1 returns true, otherwise executes block2 if exp2 returns true, and block3 otherwise. The else block3 portion may be omitted, and the elseif exp2 then block2 portion may be repeated or omitted as necessary.

return expression-list

The return statement is used to return values from a function or a chunk (which is just a function). The expression-list is a comma-separated list of zero or more expressions.

Lua implements tail calls: if expression-list consists of exactly one expression which is a function call, the current stack frame will be reused for the call to that function. This has implication for functions that deal with the call stack, such as getfenv() and debug.traceback().

The return statement must be the last statement in its block. If for some reason a return is needed in the middle of a block, an explicit block do return end may be used.

break

The break statement is used to terminate the execution of a while, repeat, or for loop, skipping to the next statement after the loop.

The break statement must be the last statement in its block. If for some reason a break is needed in the middle of a block, an explicit block do break end may be used.

Function calls as statements

A function call may be used as a statement; in this case, the function is being called only for any side effects it may have (e.g. mw.log() logs values) and any return values are discarded.

Function declaration statements

Lua provides syntactic sugar to make declaring a function and assigning it to a variable more natural. The following pairs of declarations are equivalent

-- Basic declaration
function func( var-list ) block end
func = function ( var-list ) block end
-- Local function
local function func( var-list ) block end
local func; func = function ( var-list ) block end
-- Function as a field in a table
function table.func( var-list ) block end
table.func = function ( var-list ) block end
-- Function as a method in a table
function table:func( var-list ) block end
table.func = function ( self, var-list ) block end

Note the colon notation here parallels the colon notation for function calls, adding an implicit argument named "self" at the beginning of the arguments list.

Error handling

Errors may be "thrown" using the error() and assert() functions. To "catch" errors, use pcall() or xpcall(). Note that certain internal Scribunto errors cannot be caught in Lua code.

Garbage collection

Lua performs automatic memory management. This means that you have to worry neither about allocating memory for new objects nor about freeing it when the objects are no longer needed. Lua manages memory automatically by running a garbage collector from time to time to collect all dead objects (that is, objects that are no longer accessible from Lua) and objects that are only reachable via weak references. All memory used by Lua is subject to automatic management: tables, functions, strings, etc.

Garbage collection happens automatically, and cannot be configured from within Scribunto.

Standard libraries

The standard Lua libraries provide essential services and performance-critical functions to Lua. Only those portions of the standard libraries that are available in Scribunto are documented here.

Basic functions

_G

This variable holds a reference to the current global variable table; the global variable foo may also be accessed as _G.foo. Note, however, that there is nothing special about _G itself; it may be reassigned in the same manner as any other variable:

foo = 1
mw.log( foo ) -- logs "1"
_G.foo = 2
mw.log( foo ) -- logs "2"
_G = {}       -- _G no longer points to the global variable table
_G.foo = 3
mw.log( foo ) -- still logs "2"

The global variable table may be used just like any other table. For example,

-- Call a function whose name is stored in a variable
_G[var]()

-- Log the names and stringified values of all global variables
for k, v in pairs( _G ) do
   mw.log( k, v )
end

-- Log the creation of new global variables
setmetatable( _G, {
    __newindex = function ( t, k, v )
         mw.log( "Creation of new global variable '" .. k .. "'" )
         rawset( t, k, v )
    end
} )

_VERSION

A string containing the running version of Lua, e.g. "Lua 5.1".

assert

assert( v, message, ... )

If v is nil or false, issues an error. In this case, message is used as the text of the error: if nil (or unspecified), the text is "assertion failed!"; if a string or number, the text is that value; otherwise assert itself will raise an error.

If v is any other value, assert returns all arguments including v and message.

A somewhat common idiom in Lua is for a function to return a "true" value in normal operation, and on failure return nil or false as the first value and an error message as the second value. Easy error checking can then be implemented by wrapping the call in a call to assert:

-- This doesn't check for errors
local result1, result2, etc = func( ... )

-- This works the same, but does check for errors
local result1, result2, etc = assert( func( ... ) )

error

error( message, level )

Issues an error, with text message.

error normally adds some information about the location of the error. If level is 1 or omitted, that information is the location of the call to error itself; 2 uses the location of the call of the function that called error; and so on. Passing 0 omits inclusion of the location information.

getfenv

getfenv( f )

Note this function may not be available, depending on allowEnvFuncs in the engine configuration.

Returns an environment (global variable table), as specified by f:

  • If 1, nil, or omitted, returns the environment of the function calling getfenv. Often this will be the same as _G.
  • Integers 2–10 return the environment of functions higher in the call stack. For example, 2 returns the environment for the function that called the current function, 3 returns the environment for the function calling that function, and so on. An error will be raised if the value is higher than the number of function calls in the stack, or if the targeted stack level returned with a tail call.
  • Passing a function returns the environment that will be used when that function is called.

The environments used by all standard library functions and Scribunto library functions are protected. Attempting to access these environments using getfenv will return nil instead.

getmetatable

getmetatable( table )

Returns the metatable of a table. Any other type will return nil.

If the metatable has a __metatable field, that value will be returned instead of the actual metatable.

ipairs

ipairs( t )

Returns three values: an iterator function, the table t, and 0. This is intended for use in the iterator form of for:

for i, v in ipairs( t ) do
    block
end

This will iterate over the pairs ( 1, t[1] ), ( 2, t[2] ), and so on, stopping when t[i] would be nil.

The standard behavior may be overridden by providing an __ipairs metamethod. If that metamethod exists, the call to ipairs will return the three values returned by __ipairs( t ) instead.

next

next( table, key )

This allows for iterating over the keys in a table. If key is nil or unspecified, returns the "first" key in the table and its value; otherwise, it returns the "next" key and its value. When no more keys are available, returns nil. It is possible to check whether a table is empty using the expression next( t ) == nil.

Note that the order in which the keys are returned is not specified, even for tables with numeric indexes. To traverse a table in numerical order, use a numerical for or ipairs.

Behavior is undefined if, when using next for traversal, any non-existing key is assigned a value. Assigning a new value (including nil) to an existing field is allowed.

pairs

pairs( t )

Returns three values: an iterator function (next or a work-alike), the table t, and nil. This is intended for use in the iterator form of for:

for k, v in pairs( t ) do
    -- process each key-value pair
end

This will iterate over the key-value pairs in t just as next would; see the documentation for next for restrictions on modifying the table during traversal.

The standard behavior may be overridden by providing a __pairs metamethod. If that metamethod exists, the call to pairs will return the three values returned by __pairs( t ) instead.

pcall

pcall( f, ... )

Calls the function f with the given arguments in protected mode. This means that if an error is raised during the call to f, pcall will return false and the error message raised. If no error occurs, pcall will return true and all values returned by the call.

In pseudocode, pcall might be defined something like this:

function pcall( f, ... )
    try
        return true, f( ... )
    catch ( message )
        return false, message
    end
end

rawequal

rawequal( a, b )

This is equivalent to a == b except that it ignores any __eq metamethod.

rawget

rawget( table, k )

This is equivalent to table[k] except that it ignores any __index metamethod.

rawset

rawset( table, k, v )

This is equivalent to table[k] = v except that it ignores any __newindex metamethod.

select

select( index, ... )

If index is a number, returns all arguments in ... after that index. If index is the string '#', returns the count of arguments in ....

In other words, select is something roughly like the following except that it will work correctly even when ... contains nil values (see documentation for # and unpack for the problem with nils).

function select( index, ... )
    local t = { ... }
    if index == '#' then
        return #t
    else
        return unpack( t, index )
    end
end

setmetatable

setmetatable( table, metatable )

Sets the metatable of a table. metatable may be nil, but must be explicitly provided.

If the current metatable has a __metatable field, setmetatable will throw an error.

tonumber

tonumber( value, base )

Tries to convert value to a number. If it is already a number or a string convertible to a number, then tonumber returns this number; otherwise, it returns nil.

The optional base (default 10) specifies the base to interpret the numeral. The base may be any integer between 2 and 36, inclusive. In bases above 10, the letter 'A' (in either upper or lower case) represents 10, 'B' represents 11, and so forth, with 'Z' representing 35.

In base 10, the value may have a decimal part, be expressed in E notation, and may have a leading "0x" to indicate base 16. In other bases, only unsigned integers are accepted.

tostring

tostring( value )

Converts value to a string. See Data types above for details on how each type is converted.

The standard behavior for tables may be overridden by providing a __tostring metamethod. If that metamethod exists, the call to tostring will return the single value returned by __tostring( value ) instead.

type

type( value )

Returns the type of value as a string: "nil", "number", "string", "boolean", "table", or "function".

unpack

unpack( table, i, j )

Returns values from the given table, something like table[i], table[i+1], ···, table[j] would do if written out manually. If nil or not given, i defaults to 1 and j defaults to #table.

Note that results are not deterministic if table is not a sequence and j is nil or unspecified; see Length operator for details.

xpcall

xpcall( f, errhandler )

This is much like pcall, except that the error message is passed to the function errhandler before being returned.

In pseudocode, xpcall might be defined something like this:

function xpcall( f, errhandler )
    try
        return true, f()
    catch ( message )
        message = errhandler( message )
        return false, message
    end
end

Debug library

debug.traceback

debug.traceback( message, level )

Returns a string with a traceback of the call stack. An optional message string is appended at the beginning of the traceback. An optional level number tells at which stack level to start the traceback.

Math library

math.abs

math.abs( x )

Returns the absolute value of x.

math.acos

math.acos( x )

Returns the arc cosine of x (given in radians).

math.asin

math.asin( x )

Returns the arc sine of x (given in radians).

math.atan

math.atan( x )

Returns the arc tangent of x (given in radians).

math.atan2

math.atan2( y, x )

Returns the arc tangent of y/x (given in radians), using the signs of both parameters to find the quadrant of the result.

math.ceil

math.ceil( x )

Returns the smallest integer larger than or equal to x.

math.cos

math.cos( x )

Returns the cosine of x (given in radians).

math.cosh

math.cosh( x )

Returns the hyperbolic cosine of x.

math.deg

math.deg( x )

Returns the angle x (given in radians) in degrees.

math.exp

math.exp( x )

Returns the value .

math.floor

math.floor( x )

Returns the largest integer smaller than or equal to x.

math.fmod

math.fmod( x, y )

Returns the remainder of the division of x by y that rounds the quotient towards zero. For example, math.fmod( 10, 3 ) yields 1.

math.frexp

math.frexp( x )

Returns two values m and e such that:

  • If x is finite and non-zero: , e is an integer, and the absolute value of m is in the range
  • If x is zero: m and e are 0
  • If x is NaN or infinite: m is x and e is not specified

math.huge

The value representing positive infinity; larger than or equal to any other numerical value.

math.ldexp

math.ldexp( m, e )

Returns (e should be an integer).

math.log

math.log( x )

Returns the natural logarithm of x.

math.log10

math.log10( x )

Returns the base-10 logarithm of x.

math.max

math.max( x, ... )

Returns the maximum value among its arguments.

Behavior with NaNs is not specified. With the current implementation, NaN will be returned if x is NaN, but any other NaNs will be ignored.

math.min

math.min( x, ... )

Returns the minimum value among its arguments.

Behavior with NaNs is not specified. With the current implementation, NaN will be returned if x is NaN, but any other NaNs will be ignored.

math.modf

math.modf( x )

Returns two numbers, the integral part of x and the fractional part of x. For example, math.modf( 1.25 ) yields 1, 0.25.

math.pi

The value of .

math.pow

math.pow( x, y )

Equivalent to x^y.

math.rad

math.rad( x )

Returns the angle x (given in degrees) in radians.

math.random

math.random( m, n )

Returns a pseudo-random number.

The arguments m and n may be omitted, but if specified must be convertible to integers.

  • With no arguments, returns a real number in the range
  • With one argument, returns an integer in the range
  • With two arguments, returns an integer in the range

math.randomseed

math.randomseed( x )

Sets x as the seed for the pseudo-random generator.

Note that using the same seed will cause math.random to output the same sequence of numbers.

math.sin

math.sin( x )

Returns the sine of x (given in radians).

math.sinh

math.sinh( x )

Returns the hyperbolic sine of x.

math.sqrt

math.sqrt( x )

Returns the square root of x. Equivalent to x^0.5.

math.tan

math.tan( x )

Returns the tangent of x (given in radians).

math.tanh

math.tanh( x )

Returns the hyperbolic tangent of x.

Operating system library

os.clock

os.clock()

Returns an approximation of the amount in seconds of CPU time used by the program.

os.date

os.date( format, time )

Language library's formatDate may be used for more comprehensive date formatting

Returns a string or a table containing date and time, formatted according to format. If the format is omitted or nil, "%c" is used.

If time is given, it is the time to be formatted (see os.time()). Otherwise the current time is used.

If format starts with '!', then the date is formatted in UTC rather than the server's local time. After this optional character, if format is the string "*t", then date returns a table with the following fields:

  • year (full)
  • month (1–12)
  • day (1–31)
  • hour (0–23)
  • min (0–59)
  • sec (0–60)
  • wday (weekday, Sunday is 1)
  • yday (day of the year)
  • isdst (daylight saving flag, a boolean; may be absent if the information is not available)

If format is not "*t", then date returns the date as a string, formatted according to the same rules as the C function strftime.

os.difftime

os.difftime( t2, t1 )

Returns the number of seconds from t1 to t2.

os.time

os.time( table )

Returns a number representing the current time.

When called without arguments, returns the current time. If passed a table, the time encoded in the table will be parsed. The table must have the fields "year", "month", and "day", and may also include "hour" (default 12), "min" (default 0), "sec" (default 0), and "isdst".

Package library

require

require( modulename )

Loads the specified module.

First, it looks in package.loaded[modulename] to see if the module is already loaded. If so, returns package.loaded[modulename].

Otherwise, it calls each loader in the package.loaders sequence to attempt to find a loader for the module. If a loader is found, that loader is called. The value returned by the loader is stored into package.loaded[modulename] and is returned.

See the documentation for package.loaders for information on the loaders available.

For example, if you have a module "Module:Giving" containing the following:

local p = {}

p.someDataValue = 'Hello!'

return p

You can load this in another module with code such as this:

local giving = require( "Module:Giving" )

local value = giving.someDataValue -- value is now 'Hello!'

package.loaded

This table holds the loaded modules. The keys are the module names, and the values are the values returned when the module was loaded.

package.loaders

This table holds the sequence of searcher functions to use when loading modules. Each searcher function is called with a single argument, the name of the module to load. If the module is found, the searcher must return a function that will actually load the module and return the value to be returned by require. Otherwise, it must return nil.

Scribunto provides two searchers:

  1. Look in package.preload[modulename] for the loader function
  2. Look in the modules provided with Scribunto for the module name, and if that fails look in the Module: namespace. The "Module:" prefix must be provided.

Note that the standard Lua loaders are not included.

package.preload

This table holds loader functions, used by the first searcher Scribunto includes in package.loaders.

package.seeall

package.seeall( table )

Sets the __index metamethod for table to _G.

String library

In all string functions, the first character is at position 1, not position 0 as in C, PHP, and JavaScript. Indexes may be negative, in which case they count from the end of the string: position -1 is the last character in the string, -2 is the second-last, and so on.

Warning: The string library assumes one-byte character encodings. It cannot handle Unicode characters. To operate on Unicode strings, use the corresponding methods in the Scribunto Ustring library.

string.byte

string.byte( s, i, j )

If the string is considered as an array of bytes, returns the byte values for s[i], s[i+1], ···, s[j]. The default value for i is 1; the default value for j is i. Identical to mw.ustring.byte().

string.char

string.char( ... )

Receives zero or more integers. Returns a string with length equal to the number of arguments, in which each character has the byte value equal to its corresponding argument.

local value = string.char( 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x21 ) -- value is now 'Hello!'

See mw.ustring.char() for a similar function that uses Unicode codepoints rather than byte values.

string.find

string.find( s, pattern, init, plain )

Looks for the first match of pattern in the string s. If it finds a match, then find returns the offsets in s where this occurrence starts and ends; otherwise, it returns nil. If the pattern has captures, then in a successful match the captured values are also returned after the two indices.

A third, optional numerical argument init specifies where to start the search; its default value is 1 and can be negative. A value of true as a fourth, optional argument plain turns off the pattern matching facilities, so the function does a plain "find substring" operation, with no characters in pattern being considered "magic".

Note that if plain is given, then init must be given as well.

See mw.ustring.find() for a similar function extended as described in Ustring patterns and where the init offset is in characters rather than bytes.

string.format

string.format( formatstring, ... )

Returns a formatted version of its variable number of arguments following the description given in its first argument (which must be a string).

The format string uses a limited subset of the printf format specifiers:

  • Recognized flags are '-', '+', ' ', '#', and '0'.
  • Integer field widths up to 99 are supported. '*' is not supported.
  • Integer precisions up to 99 are supported. '*' is not supported.
  • Length modifiers are not supported.
  • Recognized conversion specifiers are 'c', 'd', 'i', 'o', 'u', 'x', 'X', 'e', 'E', 'f', 'g', 'G', 's', '%', and the non-standard 'q'.
  • Positional specifiers (e.g. "%2$s") are not supported.

The conversion specifier 'q' is like 's', but formats the string in a form suitable to be safely read back by the Lua interpreter: the string is written between double quotes, and all double quotes, newlines, embedded zeros, and backslashes in the string are correctly escaped when written.

Conversion between strings and numbers is performed as specified in Data types; other types are not automatically converted to strings. Strings containing NUL characters (byte value 0) are not properly handled.

Identical to mw.ustring.format().

string.gmatch

string.gmatch( s, pattern )

Returns an iterator function that, each time it is called, returns the next captures from pattern over string s. If pattern specifies no captures, then the whole match is produced in each call.

For this function, a '^' at the start of a pattern is not magic, as this would prevent the iteration. It is treated as a literal character.

See mw.ustring.gmatch() for a similar function for which the pattern is extended as described in Ustring patterns.

string.gsub

string.gsub( s, pattern, repl, n )

Returns a copy of s in which all (or the first n, if given) occurrences of the pattern have been replaced by a replacement string specified by repl, which can be a string, a table, or a function. gsub also returns, as its second value, the total number of matches that occurred.

If repl is a string, then its value is used for replacement. The character % works as an escape character: any sequence in repl of the form %n, with n between 1 and 9, stands for the value of the n-th captured substring. The sequence %0 stands for the whole match, and the sequence %% stands for a single %.

If repl is a table, then the table is queried for every match, using the first capture as the key; if the pattern specifies no captures, then the whole match is used as the key.

If repl is a function, then this function is called every time a match occurs, with all captured substrings passed as arguments, in order; if the pattern specifies no captures, then the whole match is passed as a sole argument.

If the value returned by the table query or by the function call is a string or a number, then it is used as the replacement string; otherwise, if it is false or nil, then there is no replacement (that is, the original match is kept in the string).

See mw.ustring.gsub() for a similar function in which the pattern is extended as described in Ustring patterns.

string.len

string.len( s )

Returns the length of the string, in bytes. Is not confused by ASCII NUL characters. Equivalent to #s.

See mw.ustring.len() for a similar function using Unicode codepoints rather than bytes.

string.lower

string.lower( s )

Returns a copy of this string with all ASCII uppercase letters changed to lowercase. All other characters are left unchanged.

See mw.ustring.lower() for a similar function in which all characters with uppercase to lowercase definitions in Unicode are converted.

string.match

string.match( s, pattern, init )

Looks for the first match of pattern in the string. If it finds one, then match returns the captures from the pattern; otherwise it returns nil. If pattern specifies no captures, then the whole match is returned.

A third, optional numerical argument init specifies where to start the search; its default value is 1 and can be negative.

See mw.ustring.match() for a similar function in which the pattern is extended as described in Ustring patterns and the init offset is in characters rather than bytes.

string.rep

string.rep( s, n )

Returns a string that is the concatenation of n copies of the string s. Identical to mw.ustring.rep().

string.reverse

string.reverse( s )

Returns a string that is the string s reversed (bytewise).

string.sub

string.sub( s, i, j )

Returns the substring of s that starts at i and continues until j; i and j can be negative. If j is nil or omitted, -1 is used.

In particular, the call string.sub(s,1,j) returns a prefix of s with length j, and string.sub(s, -i) returns a suffix of s with length i.

See mw.ustring.sub() for a similar function in which the offsets are characters rather than bytes.

string.upper

string.upper( s )

Returns a copy of this string with all ASCII lowercase letters changed to uppercase. All other characters are left unchanged.

See mw.ustring.upper() for a similar function in which all characters with lowercase to uppercase definitions in Unicode are converted.

Patterns

Note that Lua's patterns are similar to regular expressions, but are not identical. In particular, note the following differences from regular expressions and PCRE:

  • The quoting character is percent (%), not backslash (\).
  • Dot (.) always matches all characters, including newlines.
  • No case-insensitive mode.
  • No alternation (the | operator).
  • Quantifiers (*, +, ?, and -) may only be applied to individual characters or character classes, not to capture groups.
  • The only non-greedy quantifier is -, which is equivalent to PCRE's *? quantifier.
  • No generalized finite quantifier (e.g. the {n,m} quantifier in PCRE).
  • The only zero-width assertions are ^, $, and the %f[set] "frontier" pattern; assertions such as PCRE's \b or (?=···) are not present.
  • Patterns themselves do not recognize character escapes such as '\ddd'. However, since patterns are strings these sort of escapes may be used in the string literals used to create the pattern-string.

Also note that a pattern cannot contain embedded zero bytes (ASCII NUL, "\0"). Use %z instead.

Also see Ustring patterns for a similar pattern-matching scheme using Unicode characters.

Character class

A character class is used to represent a set of characters. The following combinations are allowed in describing a character class:

  • x: (where x is not one of the magic characters ^$()%.[]*+-?) represents the character x itself.
  • .: (a dot) represents all characters.
  • %a: represents all ASCII letters.
  • %c: represents all ASCII control characters.
  • %d: represents all digits.
  • %l: represents all ASCII lowercase letters.
  • %p: represents all punctuation characters.
  • %s: represents all ASCII space characters.
  • %u: represents all ASCII uppercase letters.
  • %w: represents all ASCII alphanumeric characters.
  • %x: represents all hexadecimal digits.
  • %z: represents ASCII NUL, the zero byte.
  • %A: All characters not in %a.
  • %C: All characters not in %c.
  • %D: All characters not in %d.
  • %L: All characters not in %l.
  • %P: All characters not in %p.
  • %S: All characters not in %s.
  • %U: All characters not in %u.
  • %W: All characters not in %w.
  • %X: All characters not in %x.
  • %Z: All characters not in %z.
  • %x: (where x is any non-alphanumeric character) represents the character x. This is the standard way to escape the magic characters. Any punctuation character (even the non magic) can be preceded by a '%' when used to represent itself in a pattern.
  • [set]: represents the class which is the union of all characters in set. A range of characters can be specified by separating the end characters of the range with a '-'. All classes %x described above can also be used as components in set. All other characters in set represent themselves. For example, [%w_] (or [_%w]) represents all alphanumeric characters plus the underscore, [0-7] represents the octal digits, and [0-7%l%-] represents the octal digits plus the lowercase letters plus the '-' character.

    The interaction between ranges and classes is not defined. Therefore, patterns like [%a-z] or [a-%%] have no meaning.

  • [^set]: represents the complement of set, where set is interpreted as above.
Pattern items

A pattern item can be

  • a single character class, which matches any single character in the class;
  • a single character class followed by '*', which matches 0 or more repetitions of characters in the class. These repetition items will always match the longest possible sequence;
  • a single character class followed by '+', which matches 1 or more repetitions of characters in the class. These repetition items will always match the longest possible sequence;
  • a single character class followed by '-', which also matches 0 or more repetitions of characters in the class. Unlike '*', these repetition items will always match the shortest possible sequence;
  • a single character class followed by '?', which matches 0 or 1 occurrence of a character in the class;
  • %n, for n between 1 and 9; such item matches a substring equal to the n-th captured string (see below);
  • %bxy, where x and y are two distinct characters; such item matches strings that start with x, end with y, and where the x and y are balanced. This means that, if one reads the string from left to right, counting +1 for an x and -1 for a y, the ending y is the first y where the count reaches 0. For instance, the item %b() matches expressions with balanced parentheses.
  • %f[set], a frontier pattern; such item matches an empty string at any position such that the next character belongs to set and the previous character does not belong to set. The set set is interpreted as previously described. The beginning and the end of the subject are handled as if they were the character '\0'.
    Note that frontier patterns were present but undocumented in Lua 5.1, and officially added to Lua in 5.2. The implementation in Lua 5.2.1 is unchanged from that in 5.1.0.
Pattern

A pattern is a sequence of pattern items.

A '^' at the beginning of a pattern anchors the match at the beginning of the subject string. A '$' at the end of a pattern anchors the match at the end of the subject string. At other positions, '^' and '$' have no special meaning and represent themselves.

Captures

A pattern can contain sub-patterns enclosed in parentheses; they describe captures. When a match succeeds, the substrings of the subject string that match captures are stored ("captured") for future use. Captures are numbered according to their left parentheses. For instance, in the pattern (a*(.)%w(%s*)), the part of the string matching a*(.)%w(%s*) is stored as the first capture (and therefore has number 1); the character matching . is captured with number 2, and the part matching %s* has number 3.

Capture references can appear in the pattern string itself, and refer back to text that was captured earlier in the match. For example, ([a-z])%1 will match any pair of identical lowercase letters, while ([a-z])([a-z])([a-z])[a-z]%3%2%1 will match any 7-letter palindrome.

As a special case, the empty capture () captures the current string position (a number). For instance, if we apply the pattern "()aa()" on the string "flaaap", there will be two captures: 3 and 5.

Table library

Most functions in the table library assume that the table represents a sequence.

The functions table.foreach(), table.foreachi(), and table.getn() may be available but are deprecated. Use a for loop with pairs(), a for loop with ipairs(), and the length operator instead.

table.concat

table.concat( table, sep, i, j )

Given an array where all elements are strings or numbers, returns table[i] .. sep .. table[i+1] ··· sep .. table[j].

The default value for sep is the empty string, the default for i is 1, and the default for j is the length of the table. If i is greater than j, returns the empty string.

table.insert

table.insert( table, value )
table.insert( table, pos, value )

Inserts element value at position pos in table, shifting up other elements to open space, if necessary. The default value for pos is the length of the table plus 1, so that a call table.insert(t, x) inserts x at the end of table t.

Elements up to #table are shifted; see Length operator for caveats if the table is not a sequence.

table.maxn

table.maxn( table )

Returns the largest positive numerical index of the given table, or zero if the table has no positive numerical indices.

To do this, it iterates over the whole table. This is roughly equivalent to

function table.maxn( table )
    local maxn, k = 0, nil
    repeat
        k = next( table, k )
        if type( k ) == 'number' and k > maxn then
            maxn = k
        end
    until not k
    return maxn
end

table.remove

table.remove( table, pos )

Removes from table the element at position pos, shifting down other elements to close the space, if necessary. Returns the value of the removed element. The default value for pos is the length of the table, so that a call table.remove( t ) removes the last element of table t.

Elements up to #table are shifted; see Length operator for caveats if the table is not a sequence.

table.sort

table.sort( table, comp )

Sorts table elements in a given order, in-place, from table[1] to table[#table]. If comp is given, then it must be a function that receives two table elements, and returns true when the first is less than the second (so that not comp(a[i+1],a[i]) will be true after the sort). If comp is not given, then the standard Lua operator < is used instead.

The sort algorithm is not stable; that is, elements considered equal by the given order may have their relative positions changed by the sort.

Библиотеки Scribunto

Все библиотеки Scribunto находятся в таблице mw.

Основные функции

mw.addWarning

mw.addWarning( text )

Добавляет предупреждение, которое отображается над окном предварительного просмотра редактирования. text анализируется как викитекст.

mw.allToString

mw.allToString( ... )

Вызывает tostring() для всех аргументов, а затем объединяет их с символами табуляции в качестве разделителей.

mw.clone

mw.clone( value )

Создает глубокую копию значения. Все таблицы (и их метатаблицы) востановленны с нуля. Однако функции по-прежнему являются общими.

mw.getCurrentFrame

mw.getCurrentFrame()

Возвращает текущий объект frame, обычно объект frame из самого последнего #invoke.

mw.incrementExpensiveFunctionCount

mw.incrementExpensiveFunctionCount()

Добавляет к "expensive parser function" количество вызовов, и выдает исключение если оно превышает лимит (см. $wgExpensiveParserFunctionLimit).

mw.isSubsting

mw.isSubsting()

Возвращает true, если текущий #invoke является подстрокой, в противном случае false. См. раздел Возвращаемый текст выше, для рассмотрения различий между подстрокой и не подстрокой.

mw.loadData

mw.loadData( module )

Иногда модулю требуются большие таблицы данных; например, модулю общего назначения для преобразования единиц измерения может потребоваться большая таблица распознанных единиц измерения и их коэффициентов пересчета. И иногда эти модули будут использоваться много раз на одной странице. Разбор большой таблицы данных для каждого {{#invoke:}} может занять значительное количество времени. Чтобы избежать этой проблемы, предоставляется mw.loadData().

mw.loadData работает также как require(), со следующими отличиями:

  • Загруженный модуль вычисляется только один раз на странице, а не каждый раз при вызове {{#invoke:}}.
  • Загруженный модуль не записывается в package.loaded.
  • Значение, возвращаемое загруженным модулем, должно быть таблицей. Другие типы данных не поддерживаются.
  • Возвращаемая таблица (и все подтаблицы) могут содержать только логические значения, числа, строки и другие таблицы. Другие типы данных, в частности функции, не допускается.
  • Возвращаемая таблица (и все подтаблицы) могут не иметь метатаблиц.
  • Все ключи таблицы должны быть логическими, числовыми или строковыми.
  • Таблица фактически возвращеная mw.loadData() имеет метаметоды, предоставляющие доступ только для чтения к таблице, возвращаемой модулем.

Упомянутый выше гипотетический модуль преобразования единиц измерения, может хранить код в "Module:Convert", а данные в "Module:Convert/data" и "Module:Convert" будет использовать local data = mw.loadData( 'Module:Convert/data' ) для эффективной загрузки данных.

mw.dumpObject

mw.dumpObject( object )

Сериализует object в удобочитаемое представление, а затем возвращает полученную строку.

mw.log

mw.log( ... )

Передает аргументы в mw.allToString(), затем добавляет полученную строку в буфер лога.

В консоли отладки функция print() является псевдонимом для этой функции.

mw.logObject

mw.logObject( object )
mw.logObject( object, prefix )

Вызывает mw.dumpObject() и добавляет полученную строку в буфер лога. Если указан префикс prefix, то он будет добавлен в буфер лога со знаком равенства перед добавлением сериализованной строки (т.е. записываемый текст будет "prefix = object-string").

Объект Frame

Объект frame - это интерфейс для параметров, переданных в {{#invoke:}}.

frame.args

Таблица для доступных аргументов переданных во frame. Например, если модуль вызывается из викитекста с

{{#invoke:module|function|arg1|arg2|name=arg3}}

То frame.args[1] будет возвращать "arg1", frame.args[2] будет возвращать "arg2", и frame.args['name'] (или frame.args.name) будет возвращать "arg3". Также можно перебирать аргументы с помощью pairs( frame.args ) или ipairs( frame.args ). However, due to how Lua implements table iterators, iterating over arguments will return them in an unspecified order, and there's no way to know the original order as they appear in wikitext.

Обратите внимание, что значения в этой таблице всегда строки; tonumber() может использоваться для преобразования их в числа, если это необходимо. Однако ключи являются числами, даже если явно предоставлено в вызове: {{#invoke:module|function|1|2=2}} дает строковые значения "1" и "2" индексируется цифровыми ключами 1 и 2.

Как и в вызовах шаблонов MediaWiki, у именованных аргументов будут удаленны начальные и конечные пробелы, как из имени, так и из значения, прежде чем они будут переданы Lua. В то время как у безымянных аргументов пробелы не будут удалены.

Для большей производительности, frame.args использует метатаблицу, а не непосредственно содержащую аргументы. Значения аргументов запрашиваются у MediaWiki по требованию. Это означает, что большинство других методов таблицы будут работать неправильно, включая #frame.args, next( frame.args ), и функции в Table library.

Если синтаксис препроцессора, такие как вызовы шаблона и аргументы в тройных скобках, включены в аргумент для #invoke, они будут расширены перед передачей в Lua. Если определенные теги записанные в XML нотации, такие как <pre>, <nowiki>, <gallery> и <ref>, включены в качестве аргументов для #invoke, то эти теги будут преобразованы в "strip markers" - специальные строки, начинающиеся с символа delete (ASCII 127), которые после возврата из #invoke заменяются на HTML.

frame:callParserFunction

frame:callParserFunction( name, args )
frame:callParserFunction( name, ... )
frame:callParserFunction{ name = string, args = table }

Note the use of named arguments.

Call a parser function, returning an appropriate string. Whenever possible, native Lua functions or Scribunto library functions should be preferred to this interface.

The following calls are approximately equivalent to the indicated wikitext:

-- {{ns:0}}
frame:callParserFunction{ name = 'ns', args = 0 }

-- {{#tag:nowiki|some text}}
frame:callParserFunction{ name = '#tag', args = { 'nowiki', 'some text' } }
frame:callParserFunction( '#tag', { 'nowiki', 'some text' } )
frame:callParserFunction( '#tag', 'nowiki', 'some text' )
frame:callParserFunction( '#tag:nowiki', 'some text' )

-- {{#tag:ref|some text|name=foo|group=bar}}
frame:callParserFunction{ name = '#tag:ref', args = {
    'some text', name = 'foo', group = 'bar'
} }

Note that, as with frame:expandTemplate(), the function name and arguments are not preprocessed before being passed to the parser function.

frame:expandTemplate

frame:expandTemplate{ title = title, args = table }

Note the use of named arguments.

This is transclusion. The call

frame:expandTemplate{ title = 'template', args = { 'arg1', 'arg2', name = 'arg3' } }

does roughly the same thing from Lua that {{template|arg1|arg2|name=arg3}} does in wikitext. As in transclusion, if the passed title does not contain a namespace prefix it will be assumed to be in the Template: namespace.

Note that the title and arguments are not preprocessed before being passed into the template:

-- This is roughly equivalent to wikitext like {{template|{{!}}}}
frame:expandTemplate{ title = 'template', args = { '|' } }

-- This is roughly equivalent to wikitext like {{template|{{((}}!{{))}}}}
frame:expandTemplate{ title = 'template', args = { '{{!}}' } }

frame:extensionTag

frame:extensionTag( name, content, args )
frame:extensionTag{ name = string, content = string, args = table_or_string }

This is equivalent to a call to frame:callParserFunction() with function name '#tag:' .. name and with content prepended to args.

-- These are equivalent
frame:extensionTag{ name = 'ref', content = 'some text', args = { name = 'foo', group = 'bar' } }
frame:extensionTag( 'ref', 'some text', { name = 'foo', group = 'bar' } )

frame:callParserFunction{ name = '#tag:ref', args = {
    'some text', name = 'foo', group = 'bar'
} }

-- These are equivalent
frame:extensionTag{ name = 'ref', content = 'some text', args = 'some other text' }
frame:callParserFunction{ name = '#tag:ref', args = {
    'some text', 'some other text'
} }

frame:getParent

frame:getParent()

Вызывается на объекте frame, созданным {{#invoke:}}, возвращает frame для страницы, которая вызвала {{#invoke:}}. Будучи вызвана на этом фрейме, вернет nil.

Например, если шаблон {{Example}} содержит код {{#invoke:ModuleName}}, а при вызове этого шаблона в него передаются аргументы ({{Example|arg1|arg2}}),то код mw.getCurrentFrame():getParent().args[1], mw.getCurrentFrame():getParent().args[2] записанный в Модуле:ModuleName вернет "arg1", "arg2".

frame:getTitle

frame:getTitle()

Возвращает заголовок в виде строки связанный с фреймом. Для фрейма созданного {{#invoke:}}, это название вызванного модуля.

frame:newChild

frame:newChild{ title = title, args = table }

Note the use of named arguments.

Create a new Frame object that is a child of the current frame, with optional arguments and title.

This is mainly intended for use in the debug console for testing functions that would normally be called by {{#invoke:}}. The number of frames that may be created at any one time is limited.

frame:preprocess

frame:preprocess( string )
frame:preprocess{ text = string }

This expands wikitext in the context of the frame, i.e. templates, parser functions, and parameters such as {{{1}}} are expanded. Certain special tags written in XML-style notation, such as <pre>, <nowiki>, <gallery> and <ref>, will be replaced with "strip markers" — special strings which begin with a delete character (ASCII 127), to be replaced with HTML after they are returned from #invoke.

If you are expanding a single template, use frame:expandTemplate instead of trying to construct a wikitext string to pass to this method. It's faster and less prone to error if the arguments contain pipe characters or other wikimarkup.

If you are expanding a single parser function, use frame:callParserFunction for the same reasons.

frame:getArgument

frame:getArgument( arg )
frame:getArgument{ name = arg }

Gets an object for the specified argument, or nil if the argument is not provided.

The returned object has one method, object:expand(), that returns the expanded wikitext for the argument.

frame:newParserValue

frame:newParserValue( text )
frame:newParserValue{ text = text }

Returns an object with one method, object:expand(), that returns the result of frame:preprocess( text ).

frame:newTemplateParserValue

frame:newTemplateParserValue{ title = title, args = table }

Note the use of named arguments.

Returns an object with one method, object:expand(), that returns the result of frame:expandTemplate called with the given arguments.

frame:argumentPairs

frame:argumentPairs()

Same as pairs( frame.args ). Included for backwards compatibility.

Hash library

mw.hash.hashValue

mw.hash.hashValue( algo, value )

Hashes a string value with the specified algorithm. Valid algorithms may be fetched using mw.hash.listAlgorithms().

mw.hash.listAlgorithms

mw.hash.listAlgorithms()

Returns a list of supported hashing algorithms, for use in mw.hash.hashValue().

HTML library

mw.html is a fluent interface for building complex HTML from Lua. A mw.html object can be created using mw.html.create.

Functions documented as mw.html.name are available on the global mw.html table; functions documented as mw.html:name and html:name are methods of an mw.html object (see mw.html.create).

A basic example could look like this:

local div = mw.html.create( 'div' )
div
     :attr( 'id', 'testdiv' )
     :css( 'width', '100%' )
     :wikitext( 'Some text' )
     :tag( 'hr' )
return tostring( div )
-- Output: <div id="testdiv" style="width:100%;">Some text<hr /></div>

mw.html.create

mw.html.create( tagName, args )

Creates a new mw.html object containing a tagName html element. You can also pass an empty string or nil as tagName in order to create an empty mw.html object.

args can be a table with the following keys:

  • args.selfClosing: Force the current tag to be self-closing, even if mw.html doesn't recognize it as self-closing
  • args.parent: Parent of the current mw.html instance (intended for internal usage)

mw.html:node

html:node( builder )

Appends a child mw.html (builder) node to the current mw.html instance. If a nil parameter is passed, this is a no-op. A (builder) node is a string representation of an html element.

mw.html:wikitext

html:wikitext( ... )

Appends an undetermined number of wikitext strings to the mw.html object.

Note that this stops at the first nil item.

mw.html:newline

html:newline()

Appends a newline to the mw.html object.

mw.html:tag

html:tag( tagName, args )

Appends a new child node with the given tagName to the builder, and returns a mw.html instance representing that new node. The args parameter is identical to that of mw.html.create

mw.html:attr

html:attr( name, value )
html:attr( table )

Set an HTML attribute with the given name and value on the node. Alternatively a table holding name->value pairs of attributes to set can be passed. In the first form, a value of nil causes any attribute with the given name to be unset if it was previously set.

mw.html:getAttr

html:getAttr( name )

Get the value of a html attribute previously set using html:attr() with the given name.

mw.html:addClass

html:addClass( class )

Adds a class name to the node's class attribute. If a nil parameter is passed, this is a no-op.

mw.html:css

html:css( name, value )
html:css( table )

Set a CSS property with the given name and value on the node. Alternatively a table holding name->value pairs of properties to set can be passed. In the first form, a value of nil causes any property with the given name to be unset if it was previously set.

mw.html:cssText

html:cssText( css )

Add some raw css to the node's style attribute. If a nil parameter is passed, this is a no-op.

mw.html:done

html:done()

Returns the parent node under which the current node was created. Like jQuery.end, this is a convenience function to allow the construction of several child nodes to be chained together into a single statement.

mw.html:allDone

html:allDone()

Like html:done(), but traverses all the way to the root node of the tree and returns it.

Language library

Language codes are described at language code. Many of MediaWiki's language codes are similar to IETF language tags, but not all MediaWiki language codes are valid IETF tags or vice versa.

Functions documented as mw.language.name are available on the global mw.language table; functions documented as mw.language:name and lang:name are methods of a language object (see mw.language.new or mw.language.getContentLanguage).

mw.language.fetchLanguageName

mw.language.fetchLanguageName( code, inLanguage )

The full name of the language for the given language code: native name (language autonym) by default, name translated in target language if a value is given for inLanguage.

mw.language.fetchLanguageNames

mw.language.fetchLanguageNames()
mw.language.fetchLanguageNames( inLanguage )
mw.language.fetchLanguageNames( inLanguage, include )

Fetch the list of languages known to MediaWiki, returning a table mapping language code to language name.

By default the name returned is the language autonym; passing a language code for inLanguage returns all names in that language.

By default, only language names known to MediaWiki are returned; passing 'all' for include will return all available languages (e.g. from Extension:CLDR), while passing 'mwfile' will include only languages having customized messages included with MediaWiki core or enabled extensions. To explicitly select the default, 'mw' may be passed.

mw.language.getContentLanguage

mw.language.getContentLanguage()
mw.getContentLanguage()

Returns a new language object for the wiki's default content language.

mw.language.getFallbacksFor

mw.language.getFallbacksFor( code )

Returns a list of MediaWiki's fallback language codes for the specified code.

mw.language.isKnownLanguageTag

mw.language.isKnownLanguageTag( code )

Returns true if a language code is known to MediaWiki.

A language code is "known" if it is a "valid built-in code" (i.e. it returns true for mw.language.isValidBuiltInCode) and returns a non-empty string for mw.language.fetchLanguageName.

mw.language.isSupportedLanguage

mw.language.isSupportedLanguage( code )

Checks whether any localisation is available for that language code in MediaWiki.

A language code is "supported" if it is a "valid" code (returns true for mw.language.isValidCode), contains no uppercase letters, and has a message file in the currently-running version of MediaWiki.

It is possible for a language code to be "supported" but not "known" (i.e. returning true for mw.language.isKnownLanguageTag). Also note that certain codes are "supported" despite mw.language.isValidBuiltInCode returning false.

mw.language.isValidBuiltInCode

mw.language.isValidBuiltInCode( code )

Returns true if a language code is of a valid form for the purposes of internal customisation of MediaWiki.

The code may not actually correspond to any known language.

A language code is a "valid built-in code" if it is a "valid" code (i.e. it returns true for mw.language.isValidCode); consists of only ASCII letters, numbers, and hyphens; and is at least two characters long.

Note that some codes are "supported" (i.e. returning true from mw.language.isSupportedLanguage) even though this function returns false.

mw.language.isValidCode

mw.language.isValidCode( code )

Returns true if a language code string is of a valid form, whether or not it exists. This includes codes which are used solely for customisation via the MediaWiki namespace.

The code may not actually correspond to any known language.

A language code is valid if it does not contain certain unsafe characters (colons, single- or double-quotes, slashs, backslashs, angle brackets, ampersands, or ASCII NULs) and is otherwise allowed in a page title.

mw.language.new

mw.language.new( code )
mw.getLanguage( code )

Creates a new language object. Language objects do not have any publicly accessible properties, but they do have several methods, which are documented below.

There is a limit on the number of distinct language codes that may be used on a page. Exceeding this limit will result in errors.

mw.language:getCode

lang:getCode()

Returns the language code for this language object.

mw.language:getFallbackLanguages

lang:getFallbackLanguages()

Returns a list of MediaWiki's fallback language codes for this language object. Equivalent to mw.language.getFallbacksFor( lang:getCode() ).

mw.language:isRTL

lang:isRTL()

Returns true if the language is written right-to-left, false if it is written left-to-right.

mw.language:lc

lang:lc( s )

Converts the string to lowercase, honoring any special rules for the given language.

When the Ustring library is loaded, the mw.ustring.lower() function is implemented as a call to mw.language.getContentLanguage():lc( s ).

mw.language:lcfirst

lang:lcfirst( s )

Converts the first character of the string to lowercase, as with lang:lc().

mw.language:uc

lang:uc( s )

Converts the string to uppercase, honoring any special rules for the given language.

When the Ustring library is loaded, the mw.ustring.upper() function is implemented as a call to mw.language.getContentLanguage():uc( s ).

mw.language:ucfirst

lang:ucfirst( s )

Converts the first character of the string to uppercase, as with lang:uc().

mw.language:caseFold

lang:caseFold( s )

Converts the string to a representation appropriate for case-insensitive comparison. Note that the result may not make any sense when displayed.

mw.language:formatNum

lang:formatNum( n )
lang:formatNum( n, options )

Formats a number with grouping and decimal separators appropriate for the given language. Given 123456.78, this may produce "123,456.78", "123.456,78", or even something like "١٢٣٬٤٥٦٫٧٨" depending on the language and wiki configuration.

The options is a table of options, which can be:

  • noCommafy: Set true to omit grouping separators and use a dot (.) as the decimal separator. Digit transformation may still occur, which may include transforming the decimal separator.

mw.language:formatDate

lang:formatDate( format, timestamp, local )

Formats a date according to the given format string. If timestamp is omitted, the default is the current time. The value for local must be a boolean or nil; if true, the time is formatted in the wiki's local time rather than in UTC.

The format string and supported values for timestamp are identical to those for the #time parser function from Extension:ParserFunctions. Note however that backslashes may need to be doubled in a Lua string literal, since Lua also uses backslash as an escape character while wikitext does not:

-- This string literal contains a newline, not the two characters "\n", so it is not equivalent to {{#time:\n}}.
lang:formatDate( '\n' )

-- This is equivalent to {{#time:\n}}, not {{#time:\\n}}.
lang:formatDate( '\\n' )

-- This is equivalent to {{#time:\\n}}, not {{#time:\\\\n}}.
lang:formatDate( '\\\\n' )

mw.language:formatDuration

lang:formatDuration( seconds )
lang:formatDuration( seconds, allowedIntervals )

Breaks a duration in seconds into more human-readable units, e.g. 12345 to 3 hours, 25 minutes and 45 seconds, returning the result as a string.

allowedIntervals, if given, is a table with values naming the interval units to use in the response. These include 'millennia', 'centuries', 'decades', 'years', 'weeks', 'days', 'hours', 'minutes', and 'seconds'.

mw.language:parseFormattedNumber

lang:parseFormattedNumber( s )

This takes a number as formatted by lang:formatNum() and returns the actual number. In other words, this is basically a language-aware version of tonumber().

mw.language:convertPlural

lang:convertPlural( n, ... )
lang:convertPlural( n, forms )
lang:plural( n, ... )
lang:plural( n, forms )

This chooses the appropriate grammatical form from forms (which must be a sequence table) or ... based on the number n. For example, in English you might use n .. ' ' .. lang:plural( n, 'sock', 'socks' ) or n .. ' ' .. lang:plural( n, { 'sock', 'socks' } ) to generate grammatically-correct text whether there is only 1 sock or 200 socks.

The necessary values for the sequence are language-dependent, see localization of magic words and translatewiki's FAQ on PLURAL for some details.

mw.language:convertGrammar

lang:convertGrammar( word, case )
lang:grammar( case, word )

Note the different parameter order between the two aliases. convertGrammar matches the order of the method of the same name on MediaWiki's Language object, while grammar matches the order of the parser function of the same name, documented at Special:MyLanguage/Help:Magic words#Localisation.

This chooses the appropriate inflected form of word for the given inflection code case.

The possible values for word and case are language-dependent, see Special:MyLanguage/Help:Magic words#Localisation and translatewiki:Grammar for some details.

mw.language:gender

lang:gender( what, masculine, feminine, neutral )
lang:gender( what, { masculine, feminine, neutral } )

Chooses the string corresponding to the gender of what, which may be "male", "female", or a registered user name.

mw.language:getArrow

lang:getArrow( direction )

Returns a Unicode arrow character corresponding to direction:

  • forwards: Either "→" or "←" depending on the directionality of the language.
  • backwards: Either "←" or "→" depending on the directionality of the language.
  • left: "←"
  • right: "→"
  • up: "↑"
  • down: "↓"

mw.language:getDir

lang:getDir()

Returns "ltr" or "rtl", depending on the directionality of the language.

mw.language:getDirMark

lang:getDirMark( opposite )

Returns a string containing either U+200E (the left-to-right mark) or U+200F (the right-to-left mark), depending on the directionality of the language and whether opposite is a true or false value.

mw.language:getDirMarkEntity

lang:getDirMarkEntity( opposite )

Returns "&lrm;" or "&rlm;", depending on the directionality of the language and whether opposite is a true or false value.

mw.language:getDurationIntervals

lang:getDurationIntervals( seconds )
lang:getDurationIntervals( seconds, allowedIntervals )

Breaks a duration in seconds into more human-readable units, e.g. 12345 to 3 hours, 25 minutes and 45 seconds, returning the result as a table mapping unit names to numbers.

allowedIntervals, if given, is a table with values naming the interval units to use in the response. These include 'millennia', 'centuries', 'decades', 'years', 'days', 'hours', 'minutes', and 'seconds'.

Message library

This library is an interface to the localisation messages and the MediaWiki: namespace.

Functions documented as mw.message.name are available on the global mw.message table; functions documented as mw.message:name and msg:name are methods of a message object (see mw.message.new).

mw.message.new

mw.message.new( key, ... )

Creates a new message object for the given message key.

The message object has no properties, but has several methods documented below.

mw.message.newFallbackSequence

mw.message.newFallbackSequence( ... )

Creates a new message object for the given messages (the first one that exists will be used).

The message object has no properties, but has several methods documented below.

mw.message.newRawMessage

mw.message.newRawMessage( msg, ... )

Creates a new message object, using the given text directly rather than looking up an internationalized message. The remaining parameters are passed to the new object's params() method.

The message object has no properties, but has several methods documented below.

mw.message.rawParam

mw.message.rawParam( value )

Wraps the value so that it will not be parsed as wikitext by msg:parse().

mw.message.numParam

mw.message.numParam( value )

Wraps the value so that it will automatically be formatted as by lang:formatNum(). Note this does not depend on the Language library actually being available.

mw.message.getDefaultLanguage

mw.message.getDefaultLanguage()

Returns a Language object for the default language.

mw.message:params

msg:params( ... )
msg:params( params )

Add parameters to the message, which may be passed as individual arguments or as a sequence table. Parameters must be numbers, strings, or the special values returned by mw.message.numParam() or mw.message.rawParam(). If a sequence table is used, parameters must be directly present in the table; references using the __index metamethod will not work.

Returns the msg object, to allow for call chaining.

mw.message:rawParams

msg:rawParams( ... )
msg:rawParams( params )

Like :params(), but has the effect of passing all the parameters through mw.message.rawParam() first.

Returns the msg object, to allow for call chaining.

mw.message:numParams

msg:numParams( ... )
msg:numParams( params )

Like :params(), but has the effect of passing all the parameters through mw.message.numParam() first.

Returns the msg object, to allow for call chaining.

mw.message:inLanguage

msg:inLanguage( lang )

Specifies the language to use when processing the message. lang may be a string or a table with a getCode() method (i.e. a Language object).

The default language is the one returned by mw.message.getDefaultLanguage().

Returns the msg object, to allow for call chaining.

mw.message:useDatabase

msg:useDatabase( bool )

Specifies whether to look up messages in the MediaWiki: namespace (i.e. look in the database), or just use the default messages distributed with MediaWiki.

The default is true.

Returns the msg object, to allow for call chaining.

mw.message:plain

msg:plain()

Substitutes the parameters and returns the message wikitext as-is. Template calls and parser functions are intact.

mw.message:exists

msg:exists()

Returns a boolean indicating whether the message key exists.

mw.message:isBlank

msg:isBlank()

Returns a boolean indicating whether the message key has content. Returns true if the message key does not exist or the message is the empty string.

mw.message:isDisabled

msg:isDisabled()

Returns a boolean indicating whether the message key is disabled. Returns true if the message key does not exist or if the message is the empty string or the string "-".

Site library

mw.site.currentVersion

A string holding the current version of MediaWiki.

mw.site.scriptPath

The value of $wgScriptPath.

mw.site.server

The value of $wgServer.

mw.site.siteName

The value of $wgSitename.

mw.site.stylePath

The value of $wgStylePath.

mw.site.namespaces

Table holding data for all namespaces, indexed by number.

The data available is:

  • id: Namespace number.
  • name: Local namespace name.
  • canonicalName: Canonical namespace name.
  • displayName: Set on namespace 0, the name to be used for display (since the name is often the empty string).
  • hasSubpages: Whether subpages are enabled for the namespace.
  • hasGenderDistinction: Whether the namespace has different aliases for different genders.
  • isCapitalized: Whether the first letter of pages in the namespace is capitalized.
  • isContent: Whether this is a content namespace.
  • isIncludable: Whether pages in the namespace can be transcluded.
  • isMovable: Whether pages in the namespace can be moved.
  • isSubject: Whether this is a subject namespace.
  • isTalk: Whether this is a talk namespace.
  • defaultContentModel: The default content model for the namespace, as a string.
  • aliases: List of aliases for the namespace.
  • subject: Reference to the corresponding subject namespace's data.
  • talk: Reference to the corresponding talk namespace's data.
  • associated: Reference to the associated namespace's data.

A metatable is also set that allows for looking up namespaces by name (localized or canonical). For example, both mw.site.namespaces[4] and mw.site.namespaces.Project will return information about the Project namespace.

mw.site.contentNamespaces

Table holding just the content namespaces, indexed by number. See mw.site.namespaces for details.

mw.site.subjectNamespaces

Table holding just the subject namespaces, indexed by number. See mw.site.namespaces for details.

mw.site.talkNamespaces

Table holding just the talk namespaces, indexed by number. See mw.site.namespaces for details.

mw.site.stats

Table holding site statistics. Available statistics are:

  • pages: Number of pages in the wiki.
  • articles: Number of articles in the wiki.
  • files: Number of files in the wiki.
  • edits: Number of edits in the wiki.
  • users: Number of users in the wiki.
  • activeUsers: Number of active users in the wiki.
  • admins: Number of users in group 'sysop' in the wiki.

mw.site.stats.pagesInCategory

mw.site.stats.pagesInCategory( category, which )

This function is expensive

Gets statistics about the category. If which is unspecified, nil, or "*", returns a table with the following properties:

  • all: Total pages, files, and subcategories.
  • subcats: Number of subcategories.
  • files: Number of files.
  • pages: Number of pages.

If which is one of the above keys, just the corresponding value is returned instead.

Each new category queried will increment the expensive function count.

mw.site.stats.pagesInNamespace

mw.site.stats.pagesInNamespace( ns )

Returns the number of pages in the given namespace (specify by number).

mw.site.stats.usersInGroup

mw.site.stats.usersInGroup( group )

Returns the number of users in the given group.

mw.site.interwikiMap

mw.site.interwikiMap( filter )

Returns a table holding data about available interwiki prefixes. If filter is the string "local", then only data for local interwiki prefixes is returned. If filter is the string "!local", then only data for non-local prefixes is returned. If no filter is specified, data for all prefixes is returned. A "local" prefix in this context is one that is for the same project. For example, on the English Wikipedia, other-language Wikipedias are considered local, while Wiktionary and such are not.

Keys in the table returned by this function are interwiki prefixes, and the values are subtables with the following properties:

  • prefix - the interwiki prefix.
  • url - the URL that the interwiki points to. The page name is represented by the parameter $1.
  • isProtocolRelative - a boolean showing whether the URL is protocol-relative.
  • isLocal - whether the URL is for a site in the current project.
  • isCurrentWiki - whether the URL is for the current wiki.
  • isTranscludable - whether pages using this interwiki prefix are transcludable. This requires scary transclusion, which is disabled on Wikimedia wikis.
  • isExtraLanguageLink - whether the interwiki is listed in $wgExtraInterlanguageLinkPrefixes.
  • displayText - for links listed in $wgExtraInterlanguageLinkPrefixes, this is the display text shown for the interlanguage link. Nil if not specified.
  • tooltip - for links listed in $wgExtraInterlanguageLinkPrefixes, this is the tooltip text shown when users hover over the interlanguage link. Nil if not specified.

Text library

The text library provides some common text processing functions missing from the String library and the Ustring library. These functions are safe for use with UTF-8 strings.

mw.text.decode

mw.text.decode( s )
mw.text.decode( s, decodeNamedEntities )

Replaces HTML entities in the string with the corresponding characters.

If decodeNamedEntities is omitted or false, the only named entities recognized are '&lt;', '&gt;', '&amp;', '&quot;', and '&nbsp;'. Otherwise, the list of HTML5 named entities to recognize is loaded from PHP's get_html_translation_table function.

mw.text.encode

mw.text.encode( s )
mw.text.encode( s, charset )

Replaces characters in a string with HTML entities. Characters '<', '>', '&', '"', and the non-breaking space are replaced with the appropriate named entities; all others are replaced with numeric entities.

If charset is supplied, it should be a string as appropriate to go inside brackets in a Ustring pattern, i.e. the "set" in [set]. The default charset is '<>&"\' ' (the space at the end is the non-breaking space, U+00A0).

mw.text.jsonDecode

mw.text.jsonDecode( s )
mw.text.jsonDecode( s, flags )

Decodes a JSON string. flags is 0 or a combination (use +) of the flags mw.text.JSON_PRESERVE_KEYS and mw.text.JSON_TRY_FIXING.

Normally JSON's zero-based arrays are renumbered to Lua one-based sequence tables; to prevent this, pass mw.text.JSON_PRESERVE_KEYS.

To relax certain requirements in JSON, such as no terminal comma in arrays or objects, pass mw.text.JSON_TRY_FIXING. This is not recommended.

Limitations:

  • Decoded JSON arrays may not be Lua sequences if the array contains null values.
  • JSON objects will drop keys having null values.
  • It is not possible to directly tell whether the input was a JSON array or a JSON object with sequential integer keys.
  • A JSON object having sequential integer keys beginning with 1 will decode to the same table structure as a JSON array with the same values, despite these not being at all equivalent, unless mw.text.JSON_PRESERVE_KEYS is used.

mw.text.jsonEncode

mw.text.jsonEncode( value )
mw.text.jsonEncode( value, flags )

Encode a JSON string. Errors are raised if the passed value cannot be encoded in JSON. flags is 0 or a combination (use +) of the flags mw.text.JSON_PRESERVE_KEYS and mw.text.JSON_PRETTY.

Normally Lua one-based sequence tables are encoded as JSON zero-based arrays; when mw.text.JSON_PRESERVE_KEYS is set in flags, zero-based sequence tables are encoded as JSON arrays.

Limitations:

  • Empty tables are always encoded as empty arrays ([]), not empty objects ({}).
  • Sequence tables cannot be encoded as JSON objects without adding a "dummy" element.
  • To produce objects or arrays with nil values, a tricky implementation of the __pairs metamethod is required.
  • A Lua table having sequential integer keys beginning with 0 will encode as a JSON array, the same as a Lua table having integer keys beginning with 1, unless mw.text.JSON_PRESERVE_KEYS is used.
  • When both a number and the string representation of that number are used as keys in the same table, behavior is unspecified.

mw.text.killMarkers

mw.text.killMarkers( s )

Removes all MediaWiki strip markers from a string.

mw.text.listToText

mw.text.listToText( list )
mw.text.listToText( list, separator, conjunction )

Join a list, prose-style. In other words, it's like table.concat() but with a different separator before the final item.

The default separator is taken from MediaWiki:comma-separator in the wiki's content language, and the default conjuction is MediaWiki:and concatenated with MediaWiki:word-separator.

Examples, using the default values for the messages:

 -- Returns the empty string
 mw.text.listToText( {} )
 
 -- Returns "1"
 mw.text.listToText( { 1 } )
 
 -- Returns "1 and 2"
 mw.text.listToText( { 1, 2 } )
 
 -- Returns "1, 2, 3, 4 and 5"
 mw.text.listToText( { 1, 2, 3, 4, 5 } )
 
 -- Returns "1; 2; 3; 4 or 5"
 mw.text.listToText( { 1, 2, 3, 4, 5 }, '; ', ' or ' )

mw.text.nowiki

mw.text.nowiki( s )

Replaces various characters in the string with HTML entities to prevent their interpretation as wikitext. This includes:

  • The following characters: '"', '&', "'", '<', '=', '>', '[', ']', '{', '|', '}'
  • The following characters at the start of the string or immediately after a newline: '#', '*', ':', ';', space, tab ('\t')
  • Blank lines will have one of the associated newline or carriage return characters escaped
  • "----" at the start of the string or immediately after a newline will have the first '-' escaped
  • "__" will have one underscore escaped
  • "://" will have the colon escaped
  • A whitespace character following "ISBN", "RFC", or "PMID" will be escaped

mw.text.split

mw.text.split( s, pattern, plain )

Splits the string into substrings at boundaries matching the Ustring pattern pattern. If plain is specified and true, pattern will be interpreted as a literal string rather than as a Lua pattern (just as with the parameter of the same name for mw.ustring.find()). Returns a table containing the substrings.

For example, mw.text.split( 'a b\tc\nd', '%s' ) would return a table { 'a', 'b', 'c', 'd' }.

If pattern matches the empty string, s will be split into individual characters.

mw.text.gsplit

mw.text.gsplit( s, pattern, plain )

Returns an iterator function that will iterate over the substrings that would be returned by the equivalent call to mw.text.split().

mw.text.tag

mw.text.tag( name, attrs, content )
mw.text.tag{ name = string, attrs = table, content = string|false }

Note the use of named arguments.

Generates an HTML-style tag for name.

If attrs is given, it must be a table with string keys. String and number values are used as the value of the attribute; boolean true results in the key being output as an HTML5 valueless parameter; boolean false skips the key entirely; and anything else is an error.

If content is not given (or is nil), only the opening tag is returned. If content is boolean false, a self-closed tag is returned. Otherwise it must be a string or number, in which case that content is enclosed in the constructed opening and closing tag. Note the content is not automatically HTML-encoded; use mw.text.encode() if needed.

For properly returning extension tags such as <ref>, use frame:extensionTag() instead.

mw.text.trim

mw.text.trim( s )
mw.text.trim( s, charset )

Remove whitespace or other characters from the beginning and end of a string.

If charset is supplied, it should be a string as appropriate to go inside brackets in a Ustring pattern, i.e. the "set" in [set]. The default charset is ASCII whitespace, "\t\r\n\f ".

mw.text.truncate

mw.text.truncate( text, length )
mw.text.truncate( text, length, ellipsis )
mw.text.truncate( text, length, ellipsis, adjustLength )

Truncates text to the specified length, adding ellipsis if truncation was performed. If length is positive, the end of the string will be truncated; if negative, the beginning will be removed. If adjustLength is given and true, the resulting string including ellipsis will not be longer than the specified length.

The default value for ellipsis is taken from MediaWiki:ellipsis in the wiki's content language.

Examples, using the default "..." ellipsis:

 -- Returns "foobarbaz"
 mw.text.truncate( "foobarbaz", 9 )
 
 -- Returns "fooba..."
 mw.text.truncate( "foobarbaz", 5 )
 
 -- Returns "...arbaz"
 mw.text.truncate( "foobarbaz", -5 )
 
 -- Returns "foo..."
 mw.text.truncate( "foobarbaz", 6, nil, true )
 
 -- Returns "foobarbaz", because that's shorter than "foobarba..."
 mw.text.truncate( "foobarbaz", 8 )

mw.text.unstripNoWiki

mw.text.unstripNoWiki( s )

Replaces MediaWiki <nowiki> strip markers with the corresponding text. Other types of strip markers are not changed.

mw.text.unstrip

mw.text.unstrip( s )

Equivalent to mw.text.killMarkers( mw.text.unstripNoWiki( s ) ).

This no longer reveals the HTML behind special page transclusion, <ref> tags, and so on as it did in earlier versions of Scribunto.

Title library

mw.title.equals

mw.title.equals( a, b )

Test for whether two titles are equal. Note that fragments are ignored in the comparison.

mw.title.compare

mw.title.compare( a, b )

Returns -1, 0, or 1 to indicate whether the title a is less than, equal to, or greater than title b.

This compares titles by interwiki prefix (if any) as strings, then by namespace number, then by the unprefixed title text as a string. These string comparisons use Lua's standard < operator.

mw.title.getCurrentTitle

mw.title.getCurrentTitle()

Returns the title object for the current page.

mw.title.new

mw.title.new( text, namespace )
mw.title.new( id )

This function is expensive when called with an ID

Creates a new title object.

If a number id is given, an object is created for the title with that page_id. The title referenced will be counted as linked from the current page. If the page_id does not exist, returns nil. The expensive function count will be incremented if the title object created is not for a title that has already been loaded.

If a string text is given instead, an object is created for that title (even if the page does not exist). If the text string does not specify a namespace, namespace (which may be any key found in mw.site.namespaces) will be used. If the text is not a valid title, nil is returned.

mw.title.makeTitle

mw.title.makeTitle( namespace, title, fragment, interwiki )

Creates a title object with title title in namespace namespace, optionally with the specified fragment and interwiki prefix. namespace may be any key found in mw.site.namespaces. If the resulting title is not valid, returns nil.

Note that, unlike mw.title.new(), this method will always apply the specified namespace. For example, mw.title.makeTitle( 'Template', 'Module:Foo' ) will create an object for the page Template:Module:Foo, while mw.title.new( 'Module:Foo', 'Template' ) will create an object for the page Module:Foo.

Title objects

A title object has a number of properties and methods. Most of the properties are read-only.

Note that fields ending with text return titles as string values whereas the fields ending with title return title objects.

  • id: The page_id. 0 if the page does not exist. This may be expensive.
  • interwiki: The interwiki prefix, or the empty string if none.
  • namespace: The namespace number.
  • fragment: The fragment, or the empty string. May be assigned.
  • nsText: The text of the namespace for the page.
  • subjectNsText: The text of the subject namespace for the page.
  • text: The title of the page, without the namespace or interwiki prefixes.
  • prefixedText: The title of the page, with the namespace and interwiki prefixes.
  • fullText: The title of the page, with the namespace and interwiki prefixes and the fragment. Interwiki is not returned if equal to the current.
  • rootText: If this is a subpage, the title of the root page without prefixes. Otherwise, the same as title.text.
  • baseText: If this is a subpage, the title of the page it is a subpage of without prefixes. Otherwise, the same as title.text.
  • subpageText: If this is a subpage, just the subpage name. Otherwise, the same as title.text.
  • canTalk: Whether the page for this title could have a talk page.
  • exists: Whether the page exists. Alias for file.exists for Media-namespace titles. For File-namespace titles this checks the existence of the file description page, not the file itself. This may be expensive.
  • file, fileExists: See #File metadata below.
  • isContentPage: Whether this title is in a content namespace.
  • isExternal: Whether this title has an interwiki prefix.
  • isLocal: Whether this title is in this project. For example, on the English Wikipedia, any other Wikipedia is considered "local" while Wiktionary and such are not.
  • isRedirect: Whether this is the title for a page that is a redirect. This may be expensive.
  • isSpecialPage: Whether this is the title for a possible special page (i.e. a page in the Special: namespace).
  • isSubpage: Whether this title is a subpage of some other title.
  • isTalkPage: Whether this is a title for a talk page.
  • isSubpageOf( title2 ): Whether this title is a subpage of the given title.
  • inNamespace( ns ): Whether this title is in the given namespace. Namespaces may be specified by anything that is a key found in mw.site.namespaces.
  • inNamespaces( ... ): Whether this title is in any of the given namespaces. Namespaces may be specified by anything that is a key found in mw.site.namespaces.
  • hasSubjectNamespace( ns ): Whether this title's subject namespace is in the given namespace. Namespaces may be specified by anything that is a key found in mw.site.namespaces.
  • contentModel: The content model for this title, as a string. This may be expensive.
  • basePageTitle: The same as mw.title.makeTitle( title.namespace, title.baseText ).
  • rootPageTitle: The same as mw.title.makeTitle( title.namespace, title.rootText ).
  • talkPageTitle: The same as mw.title.makeTitle( mw.site.namespaces[title.namespace].talk.id, title.text ), or nil if this title cannot have a talk page.
  • subjectPageTitle: The same as mw.title.makeTitle( mw.site.namespaces[title.namespace].subject.id, title.text ).
  • redirectTarget: Returns a title object of the target of the redirect page if the page is a redirect and the page exists, returns false otherwise.
  • protectionLevels: The page's protection levels. This is a table with keys corresponding to each action (e.g., "edit" and "move"). The table values are arrays, the first item of which is a string containing the protection level. If the page is unprotected, either the table values or the array items will be nil. This is expensive.
  • subPageTitle( text ): The same as mw.title.makeTitle( title.namespace, title.text .. '/' .. text ).
  • partialUrl(): Returns title.text encoded as it would be in a URL.
  • fullUrl( query, proto ): Returns the full URL (with optional query table/string) for this title. proto may be specified to control the scheme of the resulting url: "http", "https", "relative" (the default), or "canonical".
  • localUrl( query ): Returns the local URL (with optional query table/string) for this title.
  • canonicalUrl( query ): Returns the canonical URL (with optional query table/string) for this title.
  • getContent(): Returns the (unparsed) content of the page, or nil if there is no page. The page will be recorded as a transclusion.

Title objects may be compared using relational operators. tostring( title ) will return title.prefixedText.

Since people find the fact surprising, note that accessing any expensive field on a title object records a "link" to the page (as shown on Special:WhatLinksHere, for example). Using the title object's getContent() method or accessing the redirectTarget field records it as a "включение", and accessing the title object's file or fileExists fields records it as a "файловая ссылка".

File metadata

Title objects representing a page in the File or Media namespace will have a property called file. This is expensive. This is a table, structured as follows:

  • exists: Whether the file exists. It will be recorded as an image usage. The fileExists property on a Title object exists for backwards compatibility reasons and is an alias for this property. If this is false, all other file properties will be nil.
  • width: The width of the file. If the file contains multiple pages, this is the width of the first page.
  • height: The height of the file. If the file contains multiple pages, this is the height of the first page.
  • pages: If the file format supports multiple pages, this is a table containing tables for each page of the file; otherwise, it is nil. The # operator can be used to get the number of pages in the file. Each individual page table contains a width and height property.
  • size: The size of the file in bytes.
  • mimeType: The MIME type of the file.
Expensive properties

The properties id, isRedirect, exists, and contentModel require fetching data about the title from the database. For this reason, the expensive function count is incremented the first time one of them is accessed for a page other than the current page. Subsequent accesses of any of these properties for that page will not increment the expensive function count again.

Other properties marked as expensive will always increment the expensive function count the first time they are accessed for a page other than the current page.

URI library

mw.uri.encode

mw.uri.encode( s, enctype )

Percent-encodes the string. The default type, "QUERY", encodes spaces using '+' for use in query strings; "PATH" encodes spaces as %20; and "WIKI" encodes spaces as '_'.

Note that the "WIKI" format is not entirely reversible, as both spaces and underscores are encoded as '_'.

mw.uri.decode

mw.uri.decode( s, enctype )

Percent-decodes the string. The default type, "QUERY", decodes '+' to space; "PATH" does not perform any extra decoding; and "WIKI" decodes '_' to space.

mw.uri.anchorEncode

mw.uri.anchorEncode( s )

Encodes a string for use in a MediaWiki URI fragment.

mw.uri.buildQueryString

mw.uri.buildQueryString( table )

Encodes a table as a URI query string. Keys should be strings; values may be strings or numbers, sequence tables, or boolean false.

mw.uri.parseQueryString

mw.uri.parseQueryString( s, i, j )

Decodes the query string s to a table. Keys in the string without values will have a value of false; keys repeated multiple times will have sequence tables as values; and others will have strings as values.

The optional numerical arguments i and j can be used to specify a substring of s to be parsed, rather than the entire string. i is the position of the first character of the substring, and defaults to 1. j is the position of the last character of the substring, and defaults to the length of the string. Both i and j can be negative, as in string.sub.

mw.uri.canonicalUrl

mw.uri.canonicalUrl( page, query )

Returns a URI object for the canonical URL for a page, with optional query string/table.

mw.uri.fullUrl

mw.uri.fullUrl( page, query )

Returns a URI object for the full URL for a page, with optional query string/table.

mw.uri.localUrl

mw.uri.localUrl( page, query )

Returns a URI object for the local URL for a page, with optional query string/table.

mw.uri.new

mw.uri.new( s )

Constructs a new URI object for the passed string or table. See the description of URI objects for the possible fields for the table.

mw.uri.validate

mw.uri.validate( table )

Validates the passed table (or URI object). Returns a boolean indicating whether the table was valid, and on failure a string explaining what problems were found.

URI object

The URI object has the following fields, some or all of which may be nil:

  • protocol: String protocol/scheme
  • user: String user
  • password: String password
  • host: String host name
  • port: Integer port
  • path: String path
  • query: A table, as from mw.uri.parseQueryString
  • fragment: String fragment.

The following properties are also available:

  • userInfo: String user and password
  • hostPort: String host and port
  • authority: String user, password, host, and port
  • queryString: String version of the query table
  • relativePath: String path, query string, and fragment

tostring() will give the URI string.

Methods of the URI object are:

mw.uri:parse

uri:parse( s )

Parses a string into the current URI object. Any fields specified in the string will be replaced in the current object; fields not specified will keep their old values.

mw.uri:clone

uri:clone()

Makes a copy of the URI object.

mw.uri:extend

uri:extend( parameters )

Merges the parameters table into the object's query table.

Ustring library

The ustring library is intended to be a direct reimplementation of the standard String library, except that the methods operate on characters in UTF-8 encoded strings rather than bytes.

Most functions will raise an error if the string is not valid UTF-8; exceptions are noted.

mw.ustring.maxPatternLength

The maximum allowed length of a pattern, in bytes.

mw.ustring.maxStringLength

The maximum allowed length of a string, in bytes.

mw.ustring.byte

mw.ustring.byte( s, i, j )

Returns individual bytes; identical to string.byte().

mw.ustring.byteoffset

mw.ustring.byteoffset( s, l, i )

Returns the byte offset of a character in the string. The default for both l and i is 1. i may be negative, in which case it counts from the end of the string.

The character at l == 1 is the first character starting at or after byte i; the character at l == 0 is the first character starting at or before byte i. Note this may be the same character. Greater or lesser values of l are calculated relative to these.

mw.ustring.char

mw.ustring.char( ... )

Much like string.char(), except that the integers are Unicode codepoints rather than byte values.

local value = mw.ustring.char( 0x41f, 0x440, 0x438, 0x432, 0x435, 0x442, 0x21 ) -- value is now 'Привет!'

mw.ustring.codepoint

mw.ustring.codepoint( s, i, j )

Much like string.byte(), except that the return values are codepoints and the offsets are characters rather than bytes.

mw.ustring.find

mw.ustring.find( s, pattern, init, plain )

Much like string.find(), except that the pattern is extended as described in Ustring patterns and the init offset is in characters rather than bytes.

mw.ustring.format

mw.ustring.format( format, ... )

Identical to string.format(). Widths and precisions for strings are expressed in bytes, not codepoints.

mw.ustring.gcodepoint

mw.ustring.gcodepoint( s, i, j )

Returns three values for iterating over the codepoints in the string. i defaults to 1, and j to -1. This is intended for use in the iterator form of for:

for codepoint in mw.ustring.gcodepoint( s ) do
     -- block
end

mw.ustring.gmatch

mw.ustring.gmatch( s, pattern )

Much like string.gmatch(), except that the pattern is extended as described in Ustring patterns.

mw.ustring.gsub

mw.ustring.gsub( s, pattern, repl, n )

Much like string.gsub(), except that the pattern is extended as described in Ustring patterns.

mw.ustring.isutf8

mw.ustring.isutf8( s )

Returns true if the string is valid UTF-8, false if not.

mw.ustring.len

mw.ustring.len( s )

Returns the length of the string in codepoints, or nil if the string is not valid UTF-8.

See string.len() for a similar function that uses byte length rather than codepoints.

mw.ustring.lower

mw.ustring.lower( s )

Much like string.lower(), except that all characters with lowercase to uppercase definitions in Unicode are converted.

If the Language library is also loaded, this will instead call lc() on the default language object.

mw.ustring.match

mw.ustring.match( s, pattern, init )

Much like string.match(), except that the pattern is extended as described in Ustring patterns and the init offset is in characters rather than bytes.

mw.ustring.rep

mw.ustring.rep( s, n )

Identical to string.rep().

mw.ustring.sub

mw.ustring.sub( s, i, j )

Much like string.sub(), except that the offsets are characters rather than bytes.

mw.ustring.toNFC

mw.ustring.toNFC( s )

Converts the string to Normalization Form C. Returns nil if the string is not valid UTF-8.

mw.ustring.toNFD

mw.ustring.toNFD( s )

Converts the string to Normalization Form D. Returns nil if the string is not valid UTF-8.

mw.ustring.upper

mw.ustring.upper( s )

Much like string.upper(), except that all characters with uppercase to lowercase definitions in Unicode are converted.

If the Language library is also loaded, this will instead call uc() on the default language object.

Ustring patterns

Patterns in the ustring functions use the same syntax as the String library patterns. The major difference is that the character classes are redefined in terms of Unicode character properties:

  • %a: represents all characters with General Category "Letter".
  • %c: represents all characters with General Category "Control".
  • %d: represents all characters with General Category "Number, decimal digit".
  • %l: represents all characters with General Category "Lowercase Letter".
  • %p: represents all characters with General Category "Punctuation".
  • %s: represents all characters with General Category "Separator", plus tab, linefeed, carriage return, vertical tab, and form feed.
  • %u: represents all characters with General Category "Uppercase Letter".
  • %w: represents all characters with General Category "Letter" or "Decimal Number".
  • %x: adds fullwidth character versions of the hex digits.

In all cases, characters are interpreted as Unicode characters instead of bytes, so ranges such as [0-9], patterns such as %b«», and quantifiers applied to multibyte characters will work correctly. Empty captures will capture the position in code points rather than bytes.

Loadable libraries

These libraries are not included by default, but if needed may be loaded using require().

bit32

This emulation of the Lua 5.2 bit32 library may be loaded using

bit32 = require( 'bit32' )

The bit32 library provides bitwise operations on unsigned 32-bit integers. Input numbers are truncated to integers (in an unspecified manner) and reduced modulo 232 so the value is in the range 0 to 232−1; return values are also in this range.

When bits are numbered (as in bit32.extract()), 0 is the least-significant bit (the one with value 20) and 31 is the most-significant (the one with value 231).

bit32.band

bit32.band( ... )

Returns the bitwise AND of its arguments: the result has a bit set only if that bit is set in all of the arguments.

If given zero arguments, the result has all bits set.

bit32.bnot

bit32.bnot( x )

Returns the bitwise complement of x.

bit32.bor

bit32.bor( ... )

Returns the bitwise OR of its arguments: the result has a bit set if that bit is set in any of the arguments.

If given zero arguments, the result has all bits clear.

bit32.btest

bit32.btest( ... )

Equivalent to bit32.band( ... ) ~= 0

bit32.bxor

bit32.bxor( ... )

Returns the bitwise XOR of its arguments: the result has a bit set if that bit is set in an odd number of the arguments.

If given zero arguments, the result has all bits clear.

bit32.extract

bit32.extract( n, field, width )

Extracts width bits from n, starting with bit field. Accessing bits outside of the range 0 to 31 is an error.

If not specified, the default for width is 1.

bit32.replace

bit32.replace( n, v, field, width )

Replaces width bits in n, starting with bit field, with the low width bits from v. Accessing bits outside of the range 0 to 31 is an error.

If not specified, the default for width is 1.

bit32.lshift

bit32.lshift( n, disp )

Returns the number n shifted disp bits to the left. This is a logical shift: inserted bits are 0. This is generally equivalent to multiplying by 2disp.

Note that a displacement over 31 will result in 0.

bit32.rshift

bit32.rshift( n, disp )

Returns the number n shifted disp bits to the right. This is a logical shift: inserted bits are 0. This is generally equivalent to dividing by 2disp.

Note that a displacement over 31 will result in 0.

bit32.arshift

bit32.arshift( n, disp )

Returns the number n shifted disp bits to the right. This is an arithmetic shift: if disp is positive, the inserted bits will be the same as bit 31 in the original number.

Note that a displacement over 31 will result in 0 or 4294967295.

bit32.lrotate

bit32.lrotate( n, disp )

Returns the number n rotated disp bits to the left.

Note that rotations are equivalent modulo 32: a rotation of 32 is the same as a rotation of 0, 33 is the same as 1, and so on.

bit32.rrotate

bit32.rrotate( n, disp )

Returns the number n rotated disp bits to the right.

Note that rotations are equivalent modulo 32: a rotation of 32 is the same as a rotation of 0, 33 is the same as 1, and so on.

libraryUtil

This library contains methods useful when implementing Scribunto libraries. It may be loaded using

libraryUtil = require( 'libraryUtil' )

libraryUtil.checkType

libraryUtil.checkType( name, argIdx, arg, expectType, nilOk )

Raises an error if type( arg ) does not match expectType. In addition, no error will be raised if arg is nil and nilOk is true.

name is the name of the calling function, and argIdx is the position of the argument in the argument list. These are used in formatting the error message.

libraryUtil.checkTypeMulti

libraryUtil.checkTypeMulti( name, argIdx, arg, expectTypes )

Raises an error if type( arg ) does not match any of the strings in the array expectTypes.

This is for arguments that have more than one valid type.

libraryUtil.checkTypeForIndex

libraryUtil.checkTypeForIndex( index, value, expectType )

Raises an error if type( value ) does not match expectType.

This is intended for use in implementing a __newindex metamethod.

libraryUtil.checkTypeForNamedArg

libraryUtil.checkTypeForNamedArg( name, argName, arg, expectType, nilOk )

Raises an error if type( arg ) does not match expectType. In addition, no error will be raised if arg is nil and nilOk is true.

This is intended to be used as an equivalent to libraryUtil.checkType() in methods called using Lua's "named argument" syntax, func{ name = value }.

libraryUtil.makeCheckSelfFunction

libraryUtil.makeCheckSelfFunction( libraryName, varName, selfObj, selfObjDesc )

This is intended for use in implementing "methods" on object tables that are intended to be called with the obj:method() syntax. It returns a function that should be called at the top of these methods with the self argument and the method name, which will raise an error if that self object is not selfObj.

This function will generally be used in a library's constructor function, something like this:

 function myLibrary.new()
     local obj = {}
     local checkSelf = libraryUtil.makeCheckSelfFunction( 'myLibrary', 'obj', obj, 'myLibrary object' )
 
     function obj:method()
         checkSelf( self, 'method' )
     end
 
     function obj:method2()
         checkSelf( self, 'method2' )
     end
 
     return obj
 end

luabit

The luabit library modules "bit" and "hex" may be loaded using

bit = require( 'luabit.bit' )
hex = require( 'luabit.hex' )

Note that the bit32 library contains the same operations as "luabit.bit", and the operations in "luabit.hex" may be performed using string.format() and tonumber().

The luabit module "noki" is not available, as it is entirely useless in Scribunto. The luabit module "utf8" is also not available, as it was considered redundant to the Ustring library.

ustring

The pure-Lua backend to the Ustring library may be loaded using

ustring = require( 'ustring' )

In all cases the Ustring library (mw.ustring) should be used instead, as that replaces many of the slower and more memory-intensive operations with callbacks into PHP code.

Extension libraries (mw.ext)

The following MediaWiki extensions provide additional Scribunto libraries:

See also the lists of extensions using the ScribuntoExternalLibraries and ScribuntoExternalLibraryPaths hooks.

Planned Scribunto libraries

These libraries are planned, or are in Gerrit pending review.

(none at this time)

Differences from standard Lua

Changed functions

The following functions have been modified:

setfenv()
getfenv()
May not be available, depending on the configuration. If available, attempts to access parent environments will fail.
getmetatable()
Works on tables only to prevent unauthorized access to parent environments.
tostring()
Pointer addresses of tables and functions are not provided. This is to make memory corruption vulnerabilities more difficult to exploit.
pairs()
ipairs()
Support for the __pairs and __ipairs metamethods (added in Lua 5.2) has been added.
pcall()
xpcall()
Certain internal errors cannot be intercepted.
require()
Can fetch certain built-in modules distributed with Scribunto, as well as modules present in the Module namespace of the wiki. To fetch wiki modules, use the full page name including the namespace. Cannot otherwise access the local filesystem.

Removed functions and packages

The following packages are mostly removed. Only those functions listed are available:

package.*
Filesystem and C library access has been removed. Available functions and tables are:
package.loaded
package.preload
package.loaders
Loaders which access the local filesystem or load C libraries are not present. A loader for Module-namespace pages is added.
package.seeall()
os.*
There are some insecure functions in here, such as os.execute(), which can't be allowed. Available functions are:
os.clock()
os.date()
os.difftime()
os.time()
debug.*
Most of the functions are insecure. Available functions are:
debug.traceback()

The following functions and packages are not available:

collectgarbage()
module()
coroutine.*
No application is known for us, so it has not been reviewed for security.
dofile()
loadfile()
io.*, file.*
Allows local filesystem access, which is insecure.
load()
loadstring()
These were omitted to allow for static analysis of the Lua source code. Also, allowing these would allow Lua code to be added directly to article and template pages, which was not desired for usability reasons.
print()
This was discussed on wikitech-l and it was decided that it should be omitted in favour of return values, to improve code quality. If necessary, mw.log() may be used to output information to the debug console.
string.dump()
May expose private data from parent environments.

Additional caveats

Referential data structures
Circular data structures and data structures where the same node may be reached by more than one path cannot be correctly sent to PHP. Attempting to do so will cause undefined behavior. This includes (but is not limited to) returning such data structures from the module called by {{#invoke:}} and passing such data structures as parameters to Scribunto library functions that are implemented as callbacks into PHP.

Such data structures may be used freely within Lua, including as the return values of modules loaded with mw.loadData().

Writing Scribunto libraries

This information is useful to developers writing additional Scribunto libraries, whether for inclusion in Scribunto itself or for providing an interface for their own extensions.

A Scribunto library will generally consist of five parts:

  • The PHP portion of the library.
  • The Lua portion of the library.
  • The PHP portion of the test cases.
  • The Lua portion of the test cases.
  • The documentation.

Existing libraries serve as a good example.

Library

The PHP portion of the library is a class that must extend Scribunto_LuaLibraryBase. See the documentation for that class for implementation details. In the Scribunto extension, this file should be placed in engines/LuaCommon/NameLibrary.php, and a mapping added to Scribunto_LuaEngine::$libraryClasses. Other extensions should use the ScribuntoExternalLibraries hook. In either case, the key should match the Lua module name ("mw.name" for libraries in Scribunto, or "mw.ext.name" for extension libraries).

The Lua portion of the library sets up the table containing the functions that can be called from Lua modules. In the Scribunto extension, the file should be placed in engines/LuaCommon/lualib/mw.name.lua. This file should generally include boilerplate something like this:

local object = {}
local php

function object.setupInterface( options )
    -- Remove setup function
    object.setupInterface = nil

    -- Copy the PHP callbacks to a local variable, and remove the global
    php = mw_interface
    mw_interface = nil

    -- Do any other setup here

    -- Install into the mw global
    mw = mw or {}
    mw.ext = mw.ext or {}
    mw.ext.NAME = object

    -- Indicate that we're loaded
    package.loaded['mw.ext.NAME'] = object
end

return object

The module in engines/LuaCommon/lualib/libraryUtil.lua (load this with local util = require 'libraryUtil') contains some functions that may be helpful.

Be sure to run the Scribunto test cases with your library loaded, even if your library doesn't itself provide any test cases. The standard test cases include tests for things like libraries adding unexpected global variables. Also, if the library is loaded with PHP, any upvalues that its Lua functions have will not be reset between #invoke's. Care must be taken to ensure that modules can't abuse this to transfer information between #invoke's.

Test cases

The Scribunto extension includes a base class for test cases, Scribunto_LuaEngineTestBase, which will run the tests against both the LuaSandbox and LuaStandalone engines. The library's test case should extend this class, and should not override static function suite(). In the Scribunto extension, the test case should be in tests/engines/LuaCommon/NameLibraryTest.php and added to the array in ScribuntoHooks::unitTestsList() (in common/Hooks.php); extensions should add the test case in their own UnitTestsList hook function, probably conditional on whether $wgAutoloadClasses['Scribunto_LuaEngineTestBase'] is set.

Most of the time, all that is needed to make the test case is this:

class ClassNameTest extends Scribunto_LuaEngineTestBase {
    protected static $moduleName = 'ClassNameTest';

    function getTestModules() {
         return parent::getTestModules() + array(
             'ClassNameTest' => __DIR__ . '/ClassNameTests.lua';
         );
    }
}

This will load the file ClassNameTests.lua as if it were the page "Module:ClassNameTests", expecting it to return an object with the following properties:

  • count: Integer, number of tests
  • provide( n ): Function that returns three values: n, the name of test n, and a string that is the expected output for test n.
  • run( n ): Function that runs test n and returns one string.

If getTestModules() is declared as shown, "Module:TestFramework" is available which provides many useful helper methods. If this is used, ClassNameTests.lua would look something like this:

local testframework = require 'Module:TestFramework'

return testframework.getTestProvider( {
    -- Tests go here
} )

Each test is itself a table, with the following properties:

  • name: The name of the test.
  • func: The function to execute.
  • args: Optional table of arguments to pass to the function.
  • expect: Results to expect.
  • type: Optional "type" of the test, default is "Normal".

The type controls the format of expect and how func is called. Included types are:

  • Normal: expect is a table of return values, or a string if the test should raise an error. func is simply called.
  • Iterator: expect is a table of tables of return values. func is called as with an iterated for loop, and each iteration's return values are accumulated.
  • ToString: Like "Normal", except each return value is passed through tostring().

Test cases in another extension

There are (at least) two ways to run PHPUnit tests:

  1. Run phpunit against core, allowing the tests/phpunit/suites/ExtensionsTestSuite.php to find the extension's tests using the UnitTestsList hook. If your extension's test class names all contain a unique component (e.g. the extension's name), the --filter option may be used to run only your extension's tests.
  2. Run phpunit against the extension directory, where it will pick up any file ending in "Test.php".

Either of these will work fine if Scribunto is loaded in LocalSettings.php. And it is easy for method #1 to work if Scribunto is not loaded, as the UnitTestsList hook can easily be written to avoid returning the Scribunto test when $wgAutoloadClasses['Scribunto_LuaEngineTestBase'] is not set.

But Jenkins uses method #2. For Jenkins to properly run the tests, you will need to add Scribunto as a dependency for your extension. See Gerrit change 56570 for an example of how this is done.

If for some reason you need the tests to be able to run using method #2 without Scribunto loaded, one workaround is to add this check to the top of your unit test file:

 if ( !isset( $GLOBALS['wgAutoloadClasses']['Scribunto_LuaEngineTestBase'] ) ) {
     return;
 }

Documentation

Modules included in Scribunto should include documentation in the Scribunto libraries section above. Extension libraries should include documentation in a subpage of their own Extension page, and link to that documentation from #Extension libraries (mw.ext).

See also

License

This manual is derived from the Lua 5.1 reference manual, which is available under the MIT license.

This derivative manual may also be copied under the terms of the same license.

  1. Пространство имён модулей может иметь локализованный синоним, например, Модуль:.