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 willautomatically remove any leading or trailing whitespace from the parameter.Depending on the intended use, it may be advantageous to either preserve orremove 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 = {}--[[lenThis function returns the length of the target string.Usage:{{#invoke:String|len|target_string|}}OR{{#invoke:String|len|s=target_string}}Parameters    s: The string whose length to reportIf invoked using named parameters, Mediawiki will automatically remove any leading ortrailing 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--[[subThis function returns a substring of the target string at specified indices.Usage:{{#invoke:String|sub|target_string|start_index|end_index}}OR{{#invoke:String|sub|s=target_string|i=start_index|j=end_index}}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 jis a negative value, it is interpreted the same as selecting a character bycounting from the end of the string.  Hence, a value of -1 is the same asselecting the last character of the string.If the requested indices are out of range for the given string, an error isreported.]]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 1local j = tonumber( new_args['j'] ) or -1local len = mw.ustring.len( s )-- Convert negatives for range checkingif i < 0 theni = len + i + 1endif j < 0 thenj = len + j + 1endif i > len or j > len or i < 1 or j < 1 thenreturn str._error( 'String subset index out of range' )endif j < i thenreturn str._error( 'String subset indices out of order' )endreturn mw.ustring.sub( s, i, j )end--[[This function implements that features of {{str sub old}} and is kept in orderto maintain these older templates.]]function str.sublength( frame )local i = tonumber( frame.args.i ) or 0local len = tonumber( frame.args.len )return mw.ustring.sub( frame.args.s, i + 1, len and ( i + len ) )end--[[_matchThis function returns a substring from the source string that matches aspecified pattern. It is exported for use in other modulesUsage:strmatch = require("Module:String")._matchsresult = 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 modulesfunction str._match( s, pattern, start, match_index, plain_flag, nomatch )if s == '' thenreturn str._error( 'Target string is empty' )endif pattern == '' thenreturn str._error( 'Pattern string is empty' )endstart = tonumber(start) or 1if math.abs(start) < 1 or math.abs(start) > mw.ustring.len( s ) thenreturn str._error( 'Requested start is out of range' )endif match_index == 0 thenreturn str._error( 'Match index is out of range' )endif plain_flag thenpattern = str._escapePattern( pattern )endlocal resultif match_index == 1 then-- Find first match is simple caseresult = mw.ustring.match( s, pattern, start )elseif start > 1 thens = mw.ustring.sub( s, start )endlocal iterator = mw.ustring.gmatch(s, pattern)if match_index > 0 then-- Forward searchfor w in iterator domatch_index = match_index - 1if match_index == 0 thenresult = wbreakendendelse-- Reverse searchlocal result_table = {}local count = 1for w in iterator doresult_table[count] = wcount = count + 1endresult = result_table[ count + match_index ]endendif result == nil thenif nomatch == nil thenreturn str._error( 'Match not found' )elsereturn nomatchendelsereturn resultendend--[[matchThis function returns a substring from the source string that matches aspecified pattern.Usage:{{#invoke:String|match|source_string|pattern_string|start_index|match_number|plain_flag|nomatch_output}}OR{{#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 ortrailing whitespace from each string.  In some circumstances this is desirable, inother cases one may want to preserve the whitespace.If the match_number or start_index are out of range for the string being queried, thenthis 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 andan 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|matchfunction 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 1local 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--[[posThis function returns a single character from the target string at position pos.Usage:{{#invoke:String|pos|target_string|index_value}}OR{{#invoke:String|pos|target=target_string|pos=index_value}}Parameters    target: The string to search    pos: The index for the character to returnIf invoked using named parameters, Mediawiki will automatically remove any leading ortrailing whitespace from the target string.  In some circumstances this is desirable, inother 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 backwardsfrom 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 0if pos == 0 or math.abs(pos) > mw.ustring.len( target_str ) thenreturn str._error( 'String index out of range' )endreturn mw.ustring.sub( target_str, pos, pos )end--[[str_findThis 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 fornew 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 avalue of "1", which is generally unexpected behavior, and must be accounted forseparatetly.]]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 == '' thenreturn 1endlocal start = mw.ustring.find( source_str, target_str, 1, true )if start == nil thenstart = -1endreturn startend--[[findThis function allows one to search for a target string or pattern within anotherstring.Usage:{{#invoke:String|find|source_str|target_string|start_index|plain_flag}}OR{{#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 trueIf invoked using named parameters, Mediawiki will automatically remove any leading ortrailing whitespace from the parameter.  In some circumstances this is desirable, inother cases one may want to preserve the whitespace.This function returns the first index >= "start" where "target" can be foundwithin "source".  Indices are 1-based.  If "target" is not found, then thisfunction returns 0.  If either "source" or "target" are missing / empty, thisfunction 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 1local plain = new_args['plain'] or trueif source_str == '' or pattern == '' thenreturn 0endplain = str._getBoolean( plain )local start = mw.ustring.find( source_str, pattern, start_pos, plain )if start == nil thenstart = 0endreturn startend--[[replaceThis function allows one to replace a target string or pattern within anotherstring.Usage:{{#invoke:String|replace|source_str|pattern_string|replace_string|replacement_count|plain_flag}}OR{{#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 trueif source_str == '' or pattern == '' thenreturn source_strendplain = str._getBoolean( plain )if plain thenpattern = str._escapePattern( pattern )replace = mw.ustring.gsub( replace, "%%", "%%%%" ) --Only need to escape replacement sequences.endlocal resultif count ~= nil thenresult = mw.ustring.gsub( source_str, pattern, replace, count )elseresult = mw.ustring.gsub( source_str, pattern, replace )endreturn resultend--[[    simple function to pipe string.rep to templates.]]function str.rep( frame )local repetitions = tonumber( frame.args[2] )if not repetitions thenreturn str._error( 'function rep expects a number as second parameter, received "' .. ( frame.args[2] or '' ) .. '"' )endreturn string.rep( frame.args[1] or '', repetitions )end--[[escapePatternThis 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#PatternsUsage:{{#invoke:String|escapePattern|pattern_string}}Parameters    pattern_string: The pattern string to escape.]]function str.escapePattern( frame )local pattern_str = frame.args[1]if not pattern_str thenreturn str._error( 'No pattern string specified' )endlocal result = str._escapePattern( pattern_str )return resultend--[[countThis 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 thenpattern = str._escapePattern(pattern)endlocal _, count = mw.ustring.gsub(source, pattern, '')return countend--[[endswithThis 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"endif mw.ustring.sub(source, -mw.ustring.len(pattern), -1) == pattern thenreturn "yes"elsereturn ""endend--[[joinJoin all non empty arguments together; the first argument is the separator.Usage:{{#invoke:String|join|sep|one|two|three}}]]function str.join(frame)local args = {}local sepfor _, v in ipairs( frame.args ) doif sep thenif v ~= '' thentable.insert(args, v)endelsesep = vendendreturn table.concat( args, sep or '' )end--[[Helper function that populates the argument list given that user may need to use a mix ofnamed and unnamed parameters.  This is relevant because named parameters are notidentical to unnamed parameters due to string trimming, and when dealing with stringswe 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 = 1local valuefor _, arg in ipairs( arg_list ) dovalue = frame_args[arg]if value == nil thenvalue = frame_args[index]index = index + 1endnew_args[arg] = valueendreturn new_argsend--[[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 falselocal no_category = frame.args.no_category or falseif str._getBoolean(ignore_errors) thenreturn ''endlocal error_str = '<strong class="error">String Module Error: ' .. error_str .. '</strong>'if error_category ~= '' and not str._getBoolean( no_category ) thenerror_str = '[[Category:' .. error_category .. ']]' .. error_strendreturn error_strend--[[Helper Function to interpret boolean strings]]function str._getBoolean( boolean_str )local boolean_valueif type( boolean_str ) == 'string' thenboolean_str = boolean_str:lower()if boolean_str == 'false' or boolean_str == 'no' or boolean_str == '0'or boolean_str == '' thenboolean_value = falseelseboolean_value = trueendelseif type( boolean_str ) == 'boolean' thenboolean_value = boolean_strelseerror( 'No boolean value found' )endreturn boolean_valueend--[[Helper function that escapes all pattern characters so that they will be treatedas plain text.]]function str._escapePattern( pattern_str )return mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" )endreturn str