Module:String: Difference between revisions

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--[[
--[[


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


Most of the functions provided here can be invoked with named parameters,  
Most of the functions provided here can be invoked with named parameters,
unnamed parameters, or a mixture.  If named parameters are used, Mediawiki will  
unnamed parameters, or a mixture.  If named parameters are used, Mediawiki will
automatically remove any leading or trailing whitespace from the parameter.
automatically remove any leading or trailing whitespace from the parameter.
Depending on the intended use, it may be advantageous to either preserve or
Depending on the intended use, it may be advantageous to either preserve or
remove such whitespace.
remove such whitespace.


Global options
Global options
     ignore_errors: If set to 'true' or 1, any error condition will result in  
     ignore_errors: If set to 'true' or 1, any error condition will result in
         an empty string being returned rather than an error message.
         an empty string being returned rather than an error message.
       
 
     error_category: If an error occurs, specifies the name of a category to  
     error_category: If an error occurs, specifies the name of a category to
         include with the error message.  The default category is
         include with the error message.  The default category is
         [Category:Errors reported by Module String].
         [Category:Errors reported by Module String].
       
 
     no_category: If set to 'true' or 1, no category will be added if an error
     no_category: If set to 'true' or 1, no category will be added if an error
         is generated.
         is generated.
       
 
Unit tests for this module are available at Module:String/tests.
Unit tests for this module are available at Module:String/tests.
]]
]]
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If invoked using named parameters, Mediawiki will automatically remove any leading or
If invoked using named parameters, Mediawiki will automatically remove any leading or
trailing whitespace from the target string.
trailing whitespace from the target string.
]]
]]
function str.len( frame )
function str.len( frame )
    local new_args = str._getParameters( frame.args, {'s'} );
local new_args = str._getParameters( frame.args, {'s'} )
    local s = new_args['s'] or '';
local s = new_args['s'] or ''
    return mw.ustring.len( s )
return mw.ustring.len( s )
end
end


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     i: The fist index of the substring to return, defaults to 1.
     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.
     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
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  
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  
counting from the end of the string.  Hence, a value of -1 is the same as
selecting the last character of the string.
selecting the last character of the string.


If the requested indices are out of range for the given string, an error is  
If the requested indices are out of range for the given string, an error is
reported.
reported.
]]
]]
function str.sub( frame )
function str.sub( frame )
    local new_args = str._getParameters( frame.args, { 's', 'i', 'j' } );
local new_args = str._getParameters( frame.args, { 's', 'i', 'j' } )
    local s = new_args['s'] or '';
local s = new_args['s'] or ''
    local i = tonumber( new_args['i'] ) or 1;
local i = tonumber( new_args['i'] ) or 1
    local j = tonumber( new_args['j'] ) or -1;
local j = tonumber( new_args['j'] ) or -1
   
 
    local len = mw.ustring.len( s );
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


    -- Convert negatives for range checking
return mw.ustring.sub( s, i, j )
    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
end


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]]
]]
function str.sublength( frame )
function str.sublength( frame )
    local i = tonumber( frame.args.i ) or 0
local i = tonumber( frame.args.i ) or 0
    local len = tonumber( frame.args.len )
local len = tonumber( frame.args.len )
    return mw.ustring.sub( frame.args.s, i + 1, len and ( i + len ) )
return mw.ustring.sub( frame.args.s, i + 1, len and ( i + len ) )
end
end


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match
match


This function returns a substring from the source string that matches a  
This function returns a substring from the source string that matches a
specified pattern.
specified pattern.


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{{#invoke:String|match|source_string|pattern_string|start_index|match_number|plain_flag|nomatch_output}}
{{#invoke:String|match|source_string|pattern_string|start_index|match_number|plain_flag|nomatch_output}}
OR
OR
{{#invoke:String|pos|s=source_string|pattern=pattern_string|start=start_index
{{#invoke:String|match|s=source_string|pattern=pattern_string|start=start_index
     |match=match_number|plain=plain_flag|nomatch=nomatch_output}}
     |match=match_number|plain=plain_flag|nomatch=nomatch_output}}


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     start: The index within the source string to start the search.  The first
     start: The index within the source string to start the search.  The first
         character of the string has index 1.  Defaults to 1.
         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  
     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  
         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  
         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
         counting from the last match.  Hence match = -1 is the same as requesting
         the last match.  Defaults to 1.
         the last match.  Defaults to 1.
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If invoked using named parameters, Mediawiki will automatically remove any leading or
If invoked using named parameters, Mediawiki will automatically remove any leading or
trailing whitespace from each string.  In some circumstances this is desirable, in  
trailing whitespace from each string.  In some circumstances this is desirable, in
other cases one may want to preserve the whitespace.
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
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.
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  
If one adds the parameter ignore_errors=true, then the error will be suppressed and
an empty string will be returned on any failure.
an empty string will be returned on any failure.


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]]
]]
-- 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 )
function str.match( frame )
    local new_args = str._getParameters( frame.args, {'s', 'pattern', 'start', 'match', 'plain', 'nomatch'} );
local new_args = str._getParameters( frame.args, {'s', 'pattern', 'start', 'match', 'plain', 'nomatch'} )
    local s = new_args['s'] or '';
local s = new_args['s'] or ''
    local start = tonumber( new_args['start'] ) or 1;
local start = tonumber( new_args['start'] ) or 1
    local plain_flag = str._getBoolean( new_args['plain'] or false );
local plain_flag = str._getBoolean( new_args['plain'] or false )
    local pattern = new_args['pattern'] or '';
local pattern = new_args['pattern'] or ''
    local match_index = math.floor( tonumber(new_args['match']) or 1 );
local match_index = math.floor( tonumber(new_args['match']) or 1 )
    local nomatch = new_args['nomatch'];
local nomatch = new_args['nomatch']
   
 
    if s == '' then
return str._match( s, pattern, start, match_index, plain_flag, nomatch )
        return str._error( 'Target string is empty' );
    end
    if pattern == '' then
        return str._error( 'Pattern string is empty' );
    end
    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
end


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If invoked using named parameters, Mediawiki will automatically remove any leading or
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  
trailing whitespace from the target string.  In some circumstances this is desirable, in
other cases one may want to preserve the whitespace.
other cases one may want to preserve the whitespace.


The first character has an index value of 1.
The first character has an index value of 1.


If one requests a negative value, this function will select a character by counting backwards  
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.
from the end of the string.  In other words pos = -1 is the same as asking for the last character.


Line 242: Line 248:
]]
]]
function str.pos( frame )
function str.pos( frame )
    local new_args = str._getParameters( frame.args, {'target', 'pos'} );
local new_args = str._getParameters( frame.args, {'target', 'pos'} )
    local target_str = new_args['target'] or '';
local target_str = new_args['target'] or ''
    local pos = tonumber( new_args['pos'] ) or 0;
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


    if pos == 0 or math.abs(pos) > mw.ustring.len( target_str ) then
return mw.ustring.sub( target_str, pos, pos )
        return str._error( 'String index out of range' );
    end   
   
    return mw.ustring.sub( target_str, pos, pos );
end
end


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This function duplicates the behavior of {{str_find}}, including all of its quirks.
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  
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.
new code and templates.  New code is recommended to use the "find" function instead.


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]]
]]
function str.str_find( frame )
function str.str_find( frame )
    local new_args = str._getParameters( frame.args, {'source', 'target'} );
local new_args = str._getParameters( frame.args, {'source', 'target'} )
    local source_str = new_args['source'] or '';
local source_str = new_args['source'] or ''
    local target_str = new_args['target'] 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


    if target_str == '' then
return start
        return 1;
    end   
   
    local start = mw.ustring.find( source_str, target_str, 1, true )
    if start == nil then
        start = -1
    end
   
    return start
end
end


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If invoked using named parameters, Mediawiki will automatically remove any leading or
If invoked using named parameters, Mediawiki will automatically remove any leading or
trailing whitespace from the parameter.  In some circumstances this is desirable, in  
trailing whitespace from the parameter.  In some circumstances this is desirable, in
other cases one may want to preserve the whitespace.
other cases one may want to preserve the whitespace.


This function returns the first index >= "start" where "target" can be found  
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  
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 returns 0.  If either "source" or "target" are missing / empty, this
function also returns 0.
function also returns 0.
Line 314: Line 320:
]]
]]
function str.find( frame )
function str.find( frame )
    local new_args = str._getParameters( frame.args, {'source', 'target', 'start', 'plain' } );
local new_args = str._getParameters( frame.args, {'source', 'target', 'start', 'plain' } )
    local source_str = new_args['source'] or '';
local source_str = new_args['source'] or ''
    local pattern = new_args['target'] or '';
local pattern = new_args['target'] or ''
    local start_pos = tonumber(new_args['start']) or 1;
local start_pos = tonumber(new_args['start']) or 1
    local plain = new_args['plain'] or true;
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 source_str == '' or pattern == '' then
    if start == nil then
return 0
        start = 0
end
    end
 
   
plain = str._getBoolean( plain )
    return start
 
local start = mw.ustring.find( source_str, pattern, start_pos, plain )
if start == nil then
start = 0
end
 
return start
end
end


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     count: The number of occurences to replace, defaults to all.
     count: The number of occurences to replace, defaults to all.
     plain: Boolean flag indicating that pattern should be understood as plain
     plain: Boolean flag indicating that pattern should be understood as plain
         text and not as a Lua style regular expression, defaults to true  
         text and not as a Lua style regular expression, defaults to true
]]
]]
function str.replace( frame )
function str.replace( frame )
    local new_args = str._getParameters( frame.args, {'source', 'pattern', 'replace', 'count', 'plain' } );
local new_args = str._getParameters( frame.args, {'source', 'pattern', 'replace', 'count', 'plain' } )
    local source_str = new_args['source'] or '';
local source_str = new_args['source'] or ''
    local pattern = new_args['pattern'] or '';
local pattern = new_args['pattern'] or ''
    local replace = new_args['replace'] or '';
local replace = new_args['replace'] or ''
    local count = tonumber( new_args['count'] );
local count = tonumber( new_args['count'] )
    local plain = new_args['plain'] or true;
local plain = new_args['plain'] or true
       
 
    if source_str == '' or pattern == '' then
if source_str == '' or pattern == '' then
        return source_str;
return source_str
    end  
end
    plain = str._getBoolean( plain );
plain = str._getBoolean( plain )
 
if plain then
pattern = str._escapePattern( pattern )
replace = mw.ustring.gsub( replace, "%%", "%%%%" ) --Only need to escape replacement sequences.
end


    if plain then
local result
        pattern = str._escapePattern( pattern );
        replace = mw.ustring.gsub( replace, "%%", "%%%%" ); --Only need to escape replacement sequences.
    end
   
    local result;


    if count ~= nil then
if count ~= nil then
        result = mw.ustring.gsub( source_str, pattern, replace, count );
result = mw.ustring.gsub( source_str, pattern, replace, count )
    else
else
        result = mw.ustring.gsub( source_str, pattern, replace );
result = mw.ustring.gsub( source_str, pattern, replace )
    end      
end


    return result;
return result
end
end


--[[  
--[[
     simple function to pipe string.rep to templates.
     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:
{{#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 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


function str.rep( frame )
Join all non empty arguments together; the first argument is the separator.
    local repetitions = tonumber( frame.args[2] )
Usage:
    if not repetitions then  
{{#invoke:String|join|sep|one|two|three}}
        return str._error( 'function rep expects a number as second parameter, received "' .. ( frame.args[2] or '' ) .. '"' )
]]
    end
function str.join(frame)
    return string.rep( frame.args[1] or '', repetitions )
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
end


Line 402: Line 487:
]]
]]
function str._getParameters( frame_args, arg_list )
function str._getParameters( frame_args, arg_list )
    local new_args = {};
local new_args = {}
    local index = 1;
local index = 1
    local value;
local value
   
 
    for i,arg in ipairs( arg_list ) do
for _, arg in ipairs( arg_list ) do
        value = frame_args[arg]
value = frame_args[arg]
        if value == nil then
if value == nil then
            value = frame_args[index];
value = frame_args[index]
            index = index + 1;
index = index + 1
        end
end
        new_args[arg] = value;
new_args[arg] = value
    end
end
   
 
    return new_args;
return new_args
end      
end


--[[
--[[
Line 422: Line 507:
]]
]]
function str._error( error_str )
function str._error( error_str )
    local frame = mw.getCurrentFrame();
local frame = mw.getCurrentFrame()
    local error_category = frame.args.error_category or 'Errors reported by Module String';
local error_category = frame.args.error_category or 'Errors reported by Module String'
    local ignore_errors = frame.args.ignore_errors or false;
local ignore_errors = frame.args.ignore_errors or false
    local no_category = frame.args.no_category or false;
local no_category = frame.args.no_category or false
   
 
    if str._getBoolean(ignore_errors) then
if str._getBoolean(ignore_errors) then
        return '';
return ''
    end
end
   
 
    local error_str = '<strong class="error">String Module Error: ' .. error_str .. '</strong>';
local error_str = '<strong class="error">String Module Error: ' .. error_str .. '</strong>'
    if error_category ~= '' and not str._getBoolean( no_category ) then
if error_category ~= '' and not str._getBoolean( no_category ) then
        error_str = '[[Category:' .. error_category .. ']]' .. error_str;
error_str = '[[Category:' .. error_category .. ']]' .. error_str
    end      
end
   
 
    return error_str;
return error_str
end
end


Line 443: Line 528:
]]
]]
function str._getBoolean( boolean_str )
function str._getBoolean( boolean_str )
    local boolean_value;
local boolean_value
   
 
    if type( boolean_str ) == 'string' then
if type( boolean_str ) == 'string' then
        boolean_str = boolean_str:lower();
boolean_str = boolean_str:lower()
        if boolean_str == 'false' or boolean_str == 'no' or boolean_str == '0'  
if boolean_str == 'false' or boolean_str == 'no' or boolean_str == '0'
                or boolean_str == '' then
or boolean_str == '' then
            boolean_value = false;
boolean_value = false
        else
else
            boolean_value = true;
boolean_value = true
        end  
end
    elseif type( boolean_str ) == 'boolean' then
elseif type( boolean_str ) == 'boolean' then
        boolean_value = boolean_str;
boolean_value = boolean_str
    else
else
        error( 'No boolean value found' );
error( 'No boolean value found' )
    end  
end
    return boolean_value
return boolean_value
end
end


--[[
--[[
Helper function that escapes all pattern characters so that they will be treated  
Helper function that escapes all pattern characters so that they will be treated
as plain text.
as plain text.
]]
]]
function str._escapePattern( pattern_str )
function str._escapePattern( pattern_str )
    return mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" );
return mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" )
end
end


return str
return str

Latest revision as of 18:18, 23 August 2021

--[[

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: Script error: No such module "String". OR Script error: No such module "String".

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: Script error: No such module "String". OR Script error: No such module "String".

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 Script error: No such module "String". 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: Script error: No such module "String". OR Script error: No such module "String".

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:

]] -- 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: Script error: No such module "String". OR Script error: No such module "String".

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 Script error: No such module "String"., 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: Script error: No such module "String". OR Script error: No such module "String".

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: Script error: No such module "String". OR Script error: No such module "String".

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: Script error: No such module "String".

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: Script error: No such module "String". ]] 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 = .. 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

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