User:Gechy/lua-scripting

Overview

Lua is a programming language implemented on Wikipedia with some substantial restrictions via Scribunto. Its purpose is to allow you to process the data which is available on Wikipedia content pages to allow various sorts of customized display of information. Lua is supported as a scripting language in all Wikimedia Foundation sites (since March 2013), via the Scribunto extension. for example. See also Lua tutorial.

The Scribunto (Latin: "they shall write/let them write (in the future)") extension allows for embedding scripting languages in MediaWiki.

Currently, the only supported scripting language is Lua.

Why Lua Scripting

Templates and ParserFunctions were introduced to allow end-users of MediaWiki to replicate content easily and build tools using basic logic, effectively turning wikitext into a limited programming language.

This project aims to make it possible for MediaWiki end-users to use a proper scripting language that will be more powerful and efficient than ad-hoc ParserFunctions-based logic.

Initially MediaWiki templates were pieces of wikitext that were substituted into pages instead of copy-pasting. By 2005, any other use was rare and, to some extent, controversial. In 2006, ParserFunctions were enabled, allowing users to use constructions such as {{#if}} and {{#switch}}, essentially turning wikitext into a purely functional programming language (i.e., a language that has no concept of state at any level and one part of the code may not affect any other part, it can only change its own output). This eventually caused several problems, including performance (some pages are overloaded with templates and require 40 seconds or more to parse/render) and readability (just take a look at this).

However, complex templates have caused performance issues and bottlenecks.

Installation and configuration

Scribunto comes bundled with Lua binary distributions for Linux (x86 and x86-64), Mac OS X Lion, and Windows (32- and 64-bit). For detailed explanation see Scribunto Extension.

Check out the Lua.org demo if you don't want to download Scribunto just yet.

Deep dive on Lua(Scribunto) Scripting

Setting up

The software used by Wikipedia, called MediaWiki, has an extension that provides a version of Lua that can be used within Wikipedia pages. The extension is called Scribunto.

On a MediaWiki wiki with Scribunto enabled, create a page with a title starting with "Module:", for example "Module:Bananas". Into this new page, copy the following text:

local p = {} -- p stands for package
function p.hello( frame )
    return "Hello, world!"
end

return p

Save that, then on another(non-module) page, type:

{{#invoke:Bananas|hello}}  -- Replace "Bananas" with the name of your module.

The "hello" function is exported from the module, and the result of the function is returned.

It's generally a good idea to invoke Lua code from the context of a template. This means that from the perspective of a calling page, the syntax is independent of whether the template logic is implemented in Lua or in wikitext.

For Hands-on see Setting up really fast.

Working with modules

The module itself must return a Lua table containing the functions that may be called by{{#invoke:}}. Generally, as shown above, a local variable is declared holding a table, functions are added to this table, and the table is returned at the end of the module code.

Any functions that are not added to this table, whether local or global, will not be accessible by {{#invoke:}}, but globals might be accessible from other modules loaded using require(). It is generally good style for the module to declare all functions and variables local.

Wrap up this session by creating your own lua module

Accessing parameters from wiki

Functions called by {{#invoke:}} will be passed a single parameter, that being a frame object. To access the parameters passed to the {{#invoke:}}, code will typically use the args table of that frame object. It's also possible to access the parameters passed to the template containing the {{#invoke:}} by using frame:getParent() and accessing that frame's args.

local p = {}
function p.hello(frame)
    return 'Hello, my ' .. frame.args[1] .. ' is ' .. frame.args[2]
end
return p

Such a function can access the frame object to get access to the parameters that the template was invoked with.

For detailed examples on passing data to your Lua module

Loops and tables

Lua has several control structures if, while, repeat, for.Control structures let your program make choices, or to run the same piece of code many times.

See control statement and loop and table examples for more elaborate use cases.

Lua libraries

Lua has a number of built-in libraries, such as the table library and the math library, and you can read about them at Standard Libraries. These supply variants of many of the standard features found in other popular programming languages like PHP and Python, such as regular expressions and string handling functions. Because Lua can access libraries written in C, custom extensions can be implemented.

See Lua standard libraries and Lua libraries tasks for more details.

MediaWiki libraries

All Scribunto libraries are located in the table mw.

Base functions

mw.allToString (mw.allToString( ... ))

Calls tostring() on all arguments, then concatenates them with tabs as separators.

mw.clearLogBuffer(mw.clearLogBuffer())

Removes all data logged with mw.log().

mw.clone (mw.clone( value ))

Creates a deep copy of a value. All tables (and their metatables) are reconstructed from scratch. Functions are still shared, however.

mw.executeFunction(mw.executeFunction( func ))

This creates a new copy of the frame object, calls the function with that as its parameter, then calls tostring() on all results and concatenates them (no separator) and returns the resulting string.

Note this will not work correctly from the debug console, as there is no frame object to copy.

mw.executeModule(mw.executeModule( func ))

Executes the function in a sandboxed environment; the function cannot affect anything in the current environment, with the exception of side effects of calling any existing closures.

The name "executeModule" is because this is the function used when a module is loaded from the Module: namespace.

Note this will not work correctly from the debug console, as there is no frame object to copy.

mw.getCurrentFrame(mw.getCurrentFrame())

Note this will not work correctly from the debug console, as there is no frame object to copy.

Returns the current frame object.

mw.getLogBuffer(mw.getLogBuffer())

Returns the data logged by mw.log(), as a string.

mw.incrementExpensiveFunctionCount (mw.incrementExpensiveFunctionCount())

Adds one to the "expensive parser function" count, and throws an exception if it exceeds the limit(see $wgExpensiveParserFunctionLimit).

mw.loadData (mw.loadData( module ))

Sometimes a module needs large tables of data; for example, a general-purpose module to convert units of measure might need a large table of recognized units and their conversion factors. And sometimes these modules will be used many times on one page. Parsing the large data table for every {{#invoke:}} can use a significant amount of time. To avoid this issue, mw.loadData() is provided.

mw.loadData works like require(), with the following differences:

• The loaded module is evaluated only once per page, rather than once per {{#invoke:}} call.

• The loaded module is not recorded in package.loaded.
• The value returned from the loaded module must be a table. Other data types are not supported.
• The returned table (and all subtables) may contain only booleans, numbers, strings, and other tables. Other data types, particularly functions, are not allowed.
• The returned table (and all subtables) may not have a metatable.
• All table keys must be booleans, numbers, or strings.
• The table actually returned by mw.loadData() has metamethods that provide read-only access to the table returned by the module. Since it does not contain the data directly, pairs() and ipairs() will work but other methods, including #value, next(), and the functions in the Table library, will not work correctly.

The hypothetical unit-conversion module mentioned above might store its code in "Module:Convert" and its data in "Module:Convert/data", and "Module:Convert" would use local data = mw.loadData( 'Module:Convert/data' ) to efficiently load the data.

Global modules

Modules containing tables can also be retrieved from a global repository ( specifically dev.wikia.com). This uses a syntax such as:

local data = mw.loadData( 'Dev:Convert/data' )

The code above will load a table from a module stored in dev.wikia.com/wiki/Module:Convert/data (if it exists). Note: This is case sensitive.

mw.log(mw.log( ... ))

Passes the arguments to mw.allToString(), then appends the resulting string to the log buffer.

In the debug console, the function print() is an alias for this function.

Frame object

The frame object is the interface to the parameters passed to {{#invoke:}}, and to the parser.

frame.args

A table for accessing the arguments passed to the frame. For example, if a module is called from wikitext with

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

then frame.args[1] will return "arg1", frame.args[2] will return "arg2", and frame.args['name'] (or frame.args.name) will return "arg3". It is also possible to iterate over arguments using pairs( frame.args ) or ipairs( frame.args ).

Note that values in this table are always strings; tonumber() may be used to convert them to numbers, if necessary. Keys, however, are numbers even if explicitly supplied in the invocation: {{#invoke:module|function|1|2=2}} gives string values "1" and "2" indexed by numeric keys 1 and 2.

As in MediaWiki template invocations, named arguments will have leading and trailing whitespace removed from both the name and the value before they are passed to Lua, whereas unnamed arguments will not have whitespace stripped.

For performance reasons, frame.args is a metatable, not a real table of arguments. Argument values are requested from MediaWiki on demand. This means that most other table methods will not work correctly, including #frame.args, next( frame.args ), and the functions in the Table library.

If preprocessor syntax such as template invocations and triple-brace arguments are included within an argument to #invoke, they will be expanded before being passed to Lua. If certain special tags are written in XML notation, such as <pre>, <nowiki>, <gallery> and <ref>, are included as arguments to #invoke, then these tags will be converted to "strip markers" — special strings which begin with a delete character (ASCII 127), to be replaced with HTML after they are returned from #invoke.

frame:getParent (frame:getParent())

Called on the frame created by {{#invoke:}}, returns the frame for the page that called {{#invoke:}}. Called on that frame, returns nil. This lets you just put {{#invoke:ModuleName|method}} inside a template and the parameters passed to the template (i.e. {{Hello|we|are|foo=Wikians}}) will be passed straight to the Lua module, without having to include them directly (so, you don't have to do {{#invoke:ModuleName|method|{{{1|}}}|{{{2|}}}|{{{foo|}}}}}).

Example:

• Module:Hello

local p = {}

function p.hello( frame )
	return "Hello, " .. frame:getParent().args[1] .. "!"
end

return p

• Template:Hello

{{#invoke:Hello|hello}}

• Article

{{Hello|Fandom}}

• This will output "Hello, Fandom!".

frame:expandTemplate (frame:expandTemplate{ title=template, args=table })

Note the use of named args syntactic sugar; see Function calls for details.

This is transclusion. The call frame:expandTemplate{ title = 'template', args = { 'arg1', 'arg2', name = 'arg3' } } does roughly the same thing from Lua that {{arg1|arg2}} 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:preprocess

This can be represented as frame:preprocess( string ) frame:preprocess{ text = string }. It 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 wiki text string to pass to this method. It's faster and less prone to error if the arguments contain pipe characters or other wiki markups.

local p = {} 

function p.hello( frame )
	-- This will preprocess the wikitext and expand the template {{foo}}
	return frame:preprocess( "'''Bold''' and ''italics'' is {{Foo}}" )
end

return p

frame:getArgument

This is represented as frame:getArgument( arg ) , frame:getArgument{ name = arg }.

It 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.

local p = {} 

function p.hello( frame )
	-- {{#invoke:ModuleName|hello|''Foo'' bar|{{Foo}}|foo={{HelloWorld}}}}
	local varOne = frame:getArgument( 1 )
	local varTwo = frame.args[2]
	local varThree = frame:getArgument( 'foo' )
	return varOne:expand() .. varTwo .. varThree:expand()
end

return p

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 }

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.

frame:getTitle

Returns the title associated with the frame as a string.

Language library

Many of MediaWiki's [:mw:Manual:Language#Language_code | language code] is 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 are methods of a language object.

mw.language.fetchLanguageName

mw.language.fetchLanguageName( code )

The full name of the native language name (language autonym).

mw.language.getContentLanguage

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

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

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.

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.

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.

The methods below must all use the language object (e.g. lang).

local lang = mw.language.new("en")
local ucText = lang:uc("En Taro Adun executor")
mw.log (ucText)

mw.language:getCode

lang:getCode()

Returns the language code for this language object.

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

Converts the string to lowercase, honouring 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, honouring 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 , nocommafy)

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.

With the second parameter, one can prevent the output from containing commas, as shown below:

 local result = lang:formatNum(123123123, {noCommafy=true})
output: 123123123

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 server's local time rather than in UTC.

The timestamp is the actual date. It accepts dates with either a backslash or dash e.g. "2015/10/20" or "2015-10-20".

The format string and supported values for timestamp are identical to those for the #time parser function from Extension:ParserFunctions, as shown below:

--This outputs the current date with spaces between the month,day and year
lang:formatDate( 'y m d' )

--This outputs the inputted date using the specified format
lang:formatDate( 'y m d', "2015-02-01" )

Note that backslashes may need to be doubled in the Lua string where they wouldn't in wikitext:

-- This outputs a newline, where {{#time:\n}} would output a literal "n"
lang:formatDate( '\n' )

-- This outputs a literal "n", where {{#time:\\n}} would output a backslash
-- followed by the month number.
lang:formatDate( '\\n' )

-- This outputs a backslash followed by the month number, where {{#time:\\\\n}}
-- would output two backslashes followed by the month number.
lang:formatDate( '\\\\n' )

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().

This library allows one to do arithmetic in multiple supported languages (simultaneously), and is better than the {{#expr}} parser function:

local n1 = "١"
local n2 = "٣"
local lang = mw.language.new("ar")
local num1 = lang:parseFormattedNumber(n1) 
local num2 = lang:parseFormattedNumber(n2) 
local tot = lang:formatNum(num1 + num2)
mw.log(tot)

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.

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 mw:Help:Magic words#Localisation.

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

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.

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.
• 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 See mw.site.namespaces for details.

mw.site.sassParams

Table holding SASS utility parameters, including Theme Designer color variables.

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.
• views: Number of views 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 )

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.

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 '_'.

On Unified Community Platform wikis, the "WIKI" format matches the behaviour of Template:Urlencode - any symbol in the set [!$()*,./:;@~_-] will not be percent-encoded.

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; "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 )

Decodes a query string 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.

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 individual 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.

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.

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 "Decimal Number".
• %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.

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 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 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.

mw.html:wikitext

html:wikitext( ... )

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

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.

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.

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.

mw.html:cssText

html:cssText( css )

Add some raw css to the node's style attribute.

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.

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 '<', '>', '&', and '"'. 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 appropriately 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.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.

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 }

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.

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.

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.unstrip

mw.text.unstrip( s )

Replaces MediaWiki strip markers with the corresponding text. Note that the content of the strip marker does not necessarily correspond to the input, nor do they necessarily match the final page output.

Note that strip markers are typically used for a reason, and replacing them in Lua rather than allowing the parser to do so at the appropriate time may break things.

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

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 )

Creates a new title object. The expensive function count will be incremented if the title object created is not for the current page and is not for a title that has already been loaded.

• If a number id is given, an object is created for the title with that page_id. If the page_id does not exist, returns nil.
• 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. This function is expensive under the same conditions as mw.title.new(), and records a link just as does mw.title.new().

Note that mw.title.new( 'Module:Foo', 'Template' ) will create an object for the page Module:Foo, while mw.title.makeTitle( 'Template', 'Module:Foo' ) will create an object for the page Template:Module:Foo.

Note some of the properties below are methods and other are fields or variables in the title object, as shown in the example:

local titleobject = mw.title.new( 'Yoda' )
--Doesn't use a colon
local existspage = titleobject.exists
local pagecontent

if existspage then
-- Method uses a colon
  pagecontent = titleobject:getContent()
end

return pagecontent

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.

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

mw.message.rawParam

mw.message.numParam( 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: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 "-".