--[[  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:  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 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  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.  Usage:  OR  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 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 			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 	end  	if result == nil then 		if nomatch == nil then 			return str._error( 'Match not found' ) 		else 			return nomatch 		end 	else 		return result 	end end -- 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:  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 = mw.ustring.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 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 	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 mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" ) end  return str