:Module:String

--[[

This module is intended to provide access to basic string functions.

Most of the functions provided here can be invoked with named parameters,

unnamed parameters, or a mixture. If named parameters are used, Mediawiki will

automatically remove any leading or trailing whitespace from the parameter.

Depending on the intended use, it may be advantageous to either preserve or

remove such whitespace.

Global options

ignore_errors: If set to 'true' or 1, any error condition will result in

an empty string being returned rather than an error message.

error_category: If an error occurs, specifies the name of a category to

include with the error message. The default category is

[Category:Errors reported by Module String].

no_category: If set to 'true' or 1, no category will be added if an error

is generated.

Unit tests for this module are available at Module:String/tests.

]]

local str = {}

--[[

len

This function returns the length of the target string.

Usage:

Parameters

s: The string whose length to report

If invoked using named parameters, Mediawiki will automatically remove any leading or

trailing whitespace from the target string.

]]

function str.len( frame )

local new_args = str._getParameters( frame.args, {'s'} )

local s = new_args['s'] or ''

return mw.ustring.len( s )

end

--[[

sub

This function returns a substring of the target string at specified indices.

Usage:

Parameters

s: The string to return a subset of

i: The first index of the substring to return, defaults to 1.

j: The last index of the string to return, defaults to the last character.

The first character of the string is assigned an index of 1. If either i or j

is a negative value, it is interpreted the same as selecting a character by

counting from the end of the string. Hence, a value of -1 is the same as

selecting the last character of the string.

If the requested indices are out of range for the given string, an error is

reported.

]]

function str.sub( frame )

local new_args = str._getParameters( frame.args, { 's', 'i', 'j' } )

local s = new_args['s'] or ''

local i = tonumber( new_args['i'] ) or 1

local j = tonumber( new_args['j'] ) or -1

local len = mw.ustring.len( s )

-- Convert negatives for range checking

if i < 0 then

i = len + i + 1

end

if j < 0 then

j = len + j + 1

end

if i > len or j > len or i < 1 or j < 1 then

return str._error( 'String subset index out of range' )

end

if j < i then

return str._error( 'String subset indices out of order' )

end

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

end

--[[

This function implements that features of {{str sub old}} and is kept in order

to maintain these older templates.

]]

function str.sublength( frame )

local i = tonumber( frame.args.i ) or 0

local len = tonumber( frame.args.len )

return mw.ustring.sub( frame.args.s, i + 1, len and ( i + len ) )

end

--[[

_match

This function returns a substring from the source string that matches a

specified pattern. It is exported for use in other modules

Usage:

strmatch = require("Module:String")._match

sresult = strmatch( s, pattern, start, match, plain, nomatch )

Parameters

s: The string to search

pattern: The pattern or string to find within the string

start: The index within the source string to start the search. The first

character of the string has index 1. Defaults to 1.

match: In some cases it may be possible to make multiple matches on a single

string. This specifies which match to return, where the first match is

match= 1. If a negative number is specified then a match is returned

counting from the last match. Hence match = -1 is the same as requesting

the last match. Defaults to 1.

plain: A flag indicating that the pattern should be understood as plain

text. Defaults to false.

nomatch: If no match is found, output the "nomatch" value rather than an error.

For information on constructing Lua patterns, a form of [regular expression], see:

http://www.lua.org/manual/5.1/manual.html#5.4.1
http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Ustring_patterns

]]

-- This sub-routine is exported for use in other modules

function str._match( s, pattern, start, match_index, plain_flag, nomatch )

if s == '' then

return str._error( 'Target string is empty' )

end

if pattern == '' then

return str._error( 'Pattern string is empty' )

end

start = tonumber(start) or 1

if math.abs(start) < 1 or math.abs(start) > mw.ustring.len( s ) then

return str._error( 'Requested start is out of range' )

end

if match_index == 0 then

return str._error( 'Match index is out of range' )

end

if plain_flag then

pattern = str._escapePattern( pattern )

end

local result

if match_index == 1 then

-- Find first match is simple case

result = mw.ustring.match( s, pattern, start )

else

if start > 1 then

s = mw.ustring.sub( s, start )

end

local iterator = mw.ustring.gmatch(s, pattern)

if match_index > 0 then

-- Forward search

for w in iterator do

match_index = match_index - 1

if match_index == 0 then

result = w

break

end

else

-- Reverse search

local result_table = {}

local count = 1

for w in iterator do

result_table[count] = w

count = count + 1

end

result = result_table[ count + match_index ]

end

if result == nil then

if nomatch == nil then

return str._error( 'Match not found' )

else

return nomatch

end

else

return result

end

--[[

match

This function returns a substring from the source string that matches a

specified pattern.

Usage:

{{#invoke:String|match|source_string|pattern_string|start_index|match_number|plain_flag|nomatch_output}}

{{#invoke:String|match|s=source_string|pattern=pattern_string|start=start_index

|match=match_number|plain=plain_flag|nomatch=nomatch_output}}

Parameters

s: The string to search

pattern: The pattern or string to find within the string

start: The index within the source string to start the search. The first

character of the string has index 1. Defaults to 1.

match: In some cases it may be possible to make multiple matches on a single

string. This specifies which match to return, where the first match is

match= 1. If a negative number is specified then a match is returned

counting from the last match. Hence match = -1 is the same as requesting

the last match. Defaults to 1.

plain: A flag indicating that the pattern should be understood as plain

text. Defaults to false.

nomatch: If no match is found, output the "nomatch" value rather than an error.

If invoked using named parameters, Mediawiki will automatically remove any leading or

trailing whitespace from each string. In some circumstances this is desirable, in

other cases one may want to preserve the whitespace.

If the match_number or start_index are out of range for the string being queried, then

this function generates an error. An error is also generated if no match is found.

If one adds the parameter ignore_errors=true, then the error will be suppressed and

an empty string will be returned on any failure.

For information on constructing Lua patterns, a form of [regular expression], see:

http://www.lua.org/manual/5.1/manual.html#5.4.1
http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Ustring_patterns

]]

-- This is the entry point for #invoke:String|match

function str.match( frame )

local new_args = str._getParameters( frame.args, {'s', 'pattern', 'start', 'match', 'plain', 'nomatch'} )

local s = new_args['s'] or ''

local start = tonumber( new_args['start'] ) or 1

local plain_flag = str._getBoolean( new_args['plain'] or false )

local pattern = new_args['pattern'] or ''

local match_index = math.floor( tonumber(new_args['match']) or 1 )

local nomatch = new_args['nomatch']

return str._match( s, pattern, start, match_index, plain_flag, nomatch )

end

--[[

pos

This function returns a single character from the target string at position pos.

Usage:

Parameters

target: The string to search

pos: The index for the character to return

If invoked using named parameters, Mediawiki will automatically remove any leading or

trailing whitespace from the target string. In some circumstances this is desirable, in

other cases one may want to preserve the whitespace.

The first character has an index value of 1.

If one requests a negative value, this function will select a character by counting backwards

from the end of the string. In other words pos = -1 is the same as asking for the last character.

A requested value of zero, or a value greater than the length of the string returns an error.

]]

function str.pos( frame )

local new_args = str._getParameters( frame.args, {'target', 'pos'} )

local target_str = new_args['target'] or ''

local pos = tonumber( new_args['pos'] ) or 0

if pos == 0 or math.abs(pos) > mw.ustring.len( target_str ) then

return str._error( 'String index out of range' )

end

return mw.ustring.sub( target_str, pos, pos )

end

--[[

str_find

This function duplicates the behavior of {{str_find}}, including all of its quirks.

This is provided in order to support existing templates, but is NOT RECOMMENDED for

new code and templates. New code is recommended to use the "find" function instead.

Returns the first index in "source" that is a match to "target". Indexing is 1-based,

and the function returns -1 if the "target" string is not present in "source".

Important Note: If the "target" string is empty / missing, this function returns a

value of "1", which is generally unexpected behavior, and must be accounted for

separatetly.

]]

function str.str_find( frame )

local new_args = str._getParameters( frame.args, {'source', 'target'} )

local source_str = new_args['source'] or ''

local target_str = new_args['target'] or ''

if target_str == '' then

return 1

end

local start = mw.ustring.find( source_str, target_str, 1, true )

if start == nil then

start = -1

end

return start

end

--[[

find

This function allows one to search for a target string or pattern within another

string.

Usage:

{{#invoke:String|find|source_str|target_string|start_index|plain_flag}}

{{#invoke:String|find|source=source_str|target=target_str|start=start_index|plain=plain_flag}}

Parameters

source: The string to search

target: The string or pattern to find within source

start: The index within the source string to start the search, defaults to 1

plain: Boolean flag indicating that target should be understood as plain

text and not as a Lua style regular expression, defaults to true

If invoked using named parameters, Mediawiki will automatically remove any leading or

trailing whitespace from the parameter. In some circumstances this is desirable, in

other cases one may want to preserve the whitespace.

This function returns the first index >= "start" where "target" can be found

within "source". Indices are 1-based. If "target" is not found, then this

function returns 0. If either "source" or "target" are missing / empty, this

function also returns 0.

This function should be safe for UTF-8 strings.

]]

function str.find( frame )

local new_args = str._getParameters( frame.args, {'source', 'target', 'start', 'plain' } )

local source_str = new_args['source'] or ''

local pattern = new_args['target'] or ''

local start_pos = tonumber(new_args['start']) or 1

local plain = new_args['plain'] or true

if source_str == or pattern == then

return 0

end

plain = str._getBoolean( plain )

local start = mw.ustring.find( source_str, pattern, start_pos, plain )

if start == nil then

start = 0

end

return start

end

--[[

replace

This function allows one to replace a target string or pattern within another

string.

Usage:

{{#invoke:String|replace|source_str|pattern_string|replace_string|replacement_count|plain_flag}}

{{#invoke:String|replace|source=source_string|pattern=pattern_string|replace=replace_string|

count=replacement_count|plain=plain_flag}}

Parameters

source: The string to search

pattern: The string or pattern to find within source

replace: The replacement text

count: The number of occurences to replace, defaults to all.

plain: Boolean flag indicating that pattern should be understood as plain

text and not as a Lua style regular expression, defaults to true

]]

function str.replace( frame )

local new_args = str._getParameters( frame.args, {'source', 'pattern', 'replace', 'count', 'plain' } )

local source_str = new_args['source'] or ''

local pattern = new_args['pattern'] or ''

local replace = new_args['replace'] or ''

local count = tonumber( new_args['count'] )

local plain = new_args['plain'] or true

if source_str == or pattern == then

return source_str

end

plain = str._getBoolean( plain )

if plain then

pattern = str._escapePattern( pattern )

replace = string.gsub( replace, "%%", "%%%%" ) --Only need to escape replacement sequences.

end

local result

if count ~= nil then

result = mw.ustring.gsub( source_str, pattern, replace, count )

else

result = mw.ustring.gsub( source_str, pattern, replace )

end

return result

end

--[[

simple function to pipe string.rep to templates.

]]

function str.rep( frame )

local repetitions = tonumber( frame.args[2] )

if not repetitions then

return str._error( 'function rep expects a number as second parameter, received "' .. ( frame.args[2] or '' ) .. '"' )

end

return string.rep( frame.args[1] or '', repetitions )

end

--[[

escapePattern

This function escapes special characters from a Lua string pattern. See [1]

for details on how patterns work.

[1] https://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns

Usage:

Parameters

pattern_string: The pattern string to escape.

]]

function str.escapePattern( frame )

local pattern_str = frame.args[1]

if not pattern_str then

return str._error( 'No pattern string specified' )

end

local result = str._escapePattern( pattern_str )

return result

end

--[[

count

This function counts the number of occurrences of one string in another.

]]

function str.count(frame)

local args = str._getParameters(frame.args, {'source', 'pattern', 'plain'})

local source = args.source or ''

local pattern = args.pattern or ''

local plain = str._getBoolean(args.plain or true)

if plain then

pattern = str._escapePattern(pattern)

end

local _, count = mw.ustring.gsub(source, pattern, '')

return count

end

--[[

endswith

This function determines whether a string ends with another string.

]]

function str.endswith(frame)

local args = str._getParameters(frame.args, {'source', 'pattern'})

local source = args.source or ''

local pattern = args.pattern or ''

if pattern == '' then

-- All strings end with the empty string.

return "yes"

end

if mw.ustring.sub(source, -mw.ustring.len(pattern), -1) == pattern then

return "yes"

else

return ""

end

--[[

join

Join all non empty arguments together; the first argument is the separator.

Usage:

]]

function str.join(frame)

local args = {}

local sep

for _, v in ipairs( frame.args ) do

if sep then

if v ~= '' then

table.insert(args, v)

end

else

sep = v

end

return table.concat( args, sep or '' )

end

--[[

Helper function that populates the argument list given that user may need to use a mix of

named and unnamed parameters. This is relevant because named parameters are not

identical to unnamed parameters due to string trimming, and when dealing with strings

we sometimes want to either preserve or remove that whitespace depending on the application.

]]

function str._getParameters( frame_args, arg_list )

local new_args = {}

local index = 1

local value

for _, arg in ipairs( arg_list ) do

value = frame_args[arg]

if value == nil then

value = frame_args[index]

index = index + 1

end

new_args[arg] = value

end

return new_args

end

--[[

Helper function to handle error messages.

]]

function str._error( error_str )

local frame = mw.getCurrentFrame()

local error_category = frame.args.error_category or 'Errors reported by Module String'

local ignore_errors = frame.args.ignore_errors or false

local no_category = frame.args.no_category or false

if str._getBoolean(ignore_errors) then

return ''

end

local error_str = 'String Module Error: ' .. error_str .. ''

if error_category ~= '' and not str._getBoolean( no_category ) then

error_str = 'Category:' .. error_category .. '' .. error_str

end

return error_str

end

--[[

Helper Function to interpret boolean strings

]]

function str._getBoolean( boolean_str )

local boolean_value

if type( boolean_str ) == 'string' then

boolean_str = boolean_str:lower()

if boolean_str == 'false' or boolean_str == 'no' or boolean_str == '0'

or boolean_str == '' then

boolean_value = false

else

boolean_value = true

end

elseif type( boolean_str ) == 'boolean' then

boolean_value = boolean_str

else

error( 'No boolean value found' )

end

return boolean_value

end

--[[

Helper function that escapes all pattern characters so that they will be treated

as plain text.

]]

function str._escapePattern( pattern_str )

return ( string.gsub( pattern_str, "[%(%)%.%%%+%-%*%?%[%^%$%]]", "%%%0" ) )

end

return str