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]. If set to an empty string, no category will be added during an error. ]]

local str = {}

--[[ len

This function returns the length of the target string.

Usage:

OR

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:

OR

Parameters s: The string to return a subset of   i: The fist 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 j < i then return str._error( 'String subset indices out of order' ); end if i > len or j > len or i < 1 or j < 1 then return str._error( 'String subset index out of range' ); end return mw.ustring.sub( s, i, j ) end

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

function str.match( frame ) return mw.ustring.match( frame.args.s, frame.args.pattern, tonumber( frame.args.i ) ) end

--[[ pos

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

Usage:

OR

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, 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:

OR

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:

OR

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 = str._escapePattern( replace ); 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

-- 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 i,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; if str._getBoolean(ignore_errors) then return ''; end local error_str = ' String Module Error: ' .. error_str .. ' ';   if error_category ~= '' then error_str = '' .. 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' 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 mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" ); end

return str