Module:String: Difference between revisions

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local str = {}
--[[ 


-- Cannot include null byte.
This module is intended to provide access to basic string functions.
local UTF8_char = "[\1-\127\194-\244][\128-\191]*"


--[[
Most of the functions provided here can be invoked with named parameters,
ulen
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.


Counts UTF-8 characters. Faster than mw.ustring.len.
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.
]]


Assumes that the encoding is correct. Unlike mw.ustring.len, does not return nil
local str = {}
if encoding is invalid.
 
Does not count the bytes 192, 193, and 245-255. They are not used in UTF-8 and
will not occur if the string is valid. They are replaced with the replacement
character (U+FFFD) on MediaWiki pages.
--]]
function str.ulen(text)
local _, length = string.gsub(text, UTF8_char, "")
return length
end


--[[
--[[
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Usage:
Usage:
{{#invoke:string|len|target_string|}}
{{#invoke:String|len|target_string|}}
OR
OR
{{#invoke:string|len|s=target_string}}
{{#invoke:String|len|s=target_string}}


Parameters
Parameters
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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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Usage:
Usage:
{{#invoke:string|sub|target_string|start_index|end_index}}
{{#invoke:String|sub|target_string|start_index|end_index}}
OR
OR
{{#invoke:string|sub|s=target_string|i=start_index|j=end_index}}
{{#invoke:String|sub|s=target_string|i=start_index|j=end_index}}


Parameters
Parameters
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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
    -- Convert negatives for range checking
if i < 0 then
    if i < 0 then
i = len + i + 1;
        i = len + i + 1;
end
    end
if j < 0 then
    if j < 0 then
j = len + j + 1;
        j = len + j + 1;
end
    end
   
if i > len or j > len or i < 1 or j < 1 then
    if i > len or j > len or i < 1 or j < 1 then
return str._error('String subset index out of range');
        return str._error( 'String subset index out of range' );
end
    end
if j < i then
    if j < i then
return str._error('String subset indices out of order');
        return str._error( 'String subset indices out of order' );
end
    end
   
return mw.ustring.sub(s, i, j)
    return mw.ustring.sub( s, i, j )
end
end


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to maintain these older templates.
to maintain these older templates.
]]
]]
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.


Usage:
Usage:
{{#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|pos|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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]]
]]
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
    if s == '' then
return str._error('Target string is empty');
        return str._error( 'Target string is empty' );
end
    end
if pattern == '' then
    if pattern == '' then
return str._error('Pattern string is empty');
        return str._error( 'Pattern string is empty' );
end
    end
if math.abs(start) < 1 or math.abs(start) > mw.ustring.len(s) then
    if math.abs(start) < 1 or math.abs(start) > mw.ustring.len( s ) then
return str._error('Requested start is out of range');
        return str._error( 'Requested start is out of range' );
end
    end
if match_index == 0 then
    if match_index == 0 then
return str._error('Match index is out of range');
        return str._error( 'Match index is out of range' );
end
    end
if plain_flag then
    if plain_flag then
pattern = str.pattern_escape(pattern);
        pattern = str._escapePattern( pattern );
end
    end
   
local result
    local result
if match_index == 1 then
    if match_index == 1 then
-- Find first match is simple case
        -- Find first match is simple case
result = mw.ustring.match(s, pattern, start)
        result = mw.ustring.match( s, pattern, start )
else
    else
if start > 1 then
        if start > 1 then
s = mw.ustring.sub(s, start);
            s = mw.ustring.sub( s, start );
end
        end
       
local iterator = mw.ustring.gmatch(s, pattern);
        local iterator = mw.ustring.gmatch(s, pattern);
if match_index > 0 then
        if match_index > 0 then
-- Forward search
            -- Forward search
for w in iterator do
            for w in iterator do
match_index = match_index - 1;
                match_index = match_index - 1;
if match_index == 0 then
                if match_index == 0 then
result = w;
                    result = w;
break;
                    break;
end
                end
end
            end  
else
        else
-- Reverse search
            -- Reverse search
local result_table = {};
            local result_table = {};
local count = 1;
            local count = 1;
for w in iterator do
            for w in iterator do
result_table[count] = w;
                result_table[count] = w;
count = count + 1;
                count = count + 1;
end
            end
           
result = result_table[count + match_index];
            result = result_table[ count + match_index ];          
end
        end
end
    end      
   
if result == nil then
    if result == nil then
if nomatch == nil then
        if nomatch == nil then
return str._error('Match not found');
            return str._error( 'Match not found' );
else
        else
return nomatch;
            return nomatch;
end
        end
else
    else
return result;
        return result;
end
    end
end
end


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Usage:
Usage:
{{#invoke:string|pos|target_string|index_value}}
{{#invoke:String|pos|target_string|index_value}}
OR
OR
{{#invoke:string|pos|target=target_string|pos=index_value}}
{{#invoke:String|pos|target=target_string|pos=index_value}}


Parameters
Parameters
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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.


A requested value of zero, or a value greater than the length of the string returns an error.
A requested value of zero, or a value greater than the length of the string returns an error.
]]
]]
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
    if pos == 0 or math.abs(pos) > mw.ustring.len( target_str ) then
return str._error('String index out of range');
        return str._error( 'String index out of range' );
end
    end  
   
return mw.ustring.sub(target_str, pos, pos);
    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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separatetly.
separatetly.
]]
]]
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
    if target_str == '' then
return 1;
        return 1;
end
    end  
   
local start = mw.ustring.find(source_str, target_str, 1, true)
    local start = mw.ustring.find( source_str, target_str, 1, true )
if start == nil then
    if start == nil then
start = -1
        start = -1
end
    end
   
return start
    return start
end
end


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


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


This function should be safe for UTF-8 strings.
This function should be safe for UTF-8 strings.
]]
]]
function str.find(frame)
function str.find( frame )
local params = {
    local new_args = str._getParameters( frame.args, {'source', 'target', 'start', 'plain' } );
[1] = { required = true },
    local source_str = new_args['source'] or '';
[2] = { required = true },
    local pattern = new_args['target'] or '';
[3] = { type = "number" },
    local start_pos = tonumber(new_args['start']) or 1;
[4] = { type = "boolean" },
    local plain = new_args['plain'] or true;
}
       
    if source_str == '' or pattern == '' then
local args = require("Module:parameters").process(frame.args, params)
        return 0;
    end   
return mw.ustring.find(args[1], args[2], args[3], args[4])
   
    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
end


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Usage:
Usage:
{{#invoke:string|replace|source_str|pattern_string|replace_string|replacement_count|plain_flag}}
{{#invoke:String|replace|source_str|pattern_string|replace_string|replacement_count|plain_flag}}
OR
OR
{{#invoke:string|replace|source=source_string|pattern=pattern_string|replace=replace_string|
{{#invoke:String|replace|source=source_string|pattern=pattern_string|replace=replace_string|
   count=replacement_count|plain=plain_flag}}
   count=replacement_count|plain=plain_flag}}


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


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


function str.gsub(frame)
    return result;
local params = {
[1] = { required = true, allow_empty = true },
[2] = { required = true, allow_empty = true },
[3] = { required = true, allow_empty = true },
[4] = { type = "number" },
}
local args = require("Module:parameters").process(frame.args, params)
return (mw.ustring.gsub(args[1], args[2], args[3], args[4]))
end
end


 
--[[  
--[[
     simple function to pipe string.rep to templates.
     simple function to pipe string.rep to templates.
]]
]]


function str.rep(frame)
function str.rep( frame )
local repetitions = tonumber(frame.args[2])
    local repetitions = tonumber( frame.args[2] )
if not repetitions then
    if not repetitions then  
return str._error('function rep expects a number as second parameter, received "' .. (frame.args[2] or '') .. '"')
        return str._error( 'function rep expects a number as second parameter, received "' .. ( frame.args[2] or '' ) .. '"' )
end
    end
return string.rep(frame.args[1] or '', repetitions)
    return string.rep( frame.args[1] or '', repetitions )
end
 
function str.lower(frame)
local text = frame.args[1] or ''
return mw.ustring.lower(text)
end
end
str.lc = str.lower


--[[
--[[
Line 411: Line 401:
we sometimes want to either preserve or remove that whitespace depending on the application.
we sometimes want to either preserve or remove that whitespace depending on the application.
]]
]]
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 _, arg in ipairs(arg_list) do
    for i,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      


--[[
--[[
Helper function to handle error messages.
Helper function to handle error messages.
]]
]]
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 452: Line 442:
Helper Function to interpret boolean strings
Helper Function to interpret boolean strings
]]
]]
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 – ().%+-*?[^$] – so that they will be treated
Helper function that escapes all pattern characters so that they will be treated  
as plain text.
as plain text.
]]
]]
function str.pattern_escape(pattern_str)
function str._escapePattern( pattern_str )
local invoked = false
    return mw.ustring.gsub( pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1" );
if type(pattern_str) == "table" then
if pattern_str.args then
local frame = pattern_str
invoked = true
if frame.args[1] then
pattern_str = frame.args[1]
else
pattern_str = frame:getParent().args[1]
end
else
error("First argument to pattern_escape should be a string, a number, or a frame object.")
end
elseif not (type(pattern_str) == "string" or type(pattern_str) == "number") then
error("First argument to pattern_escape should be a string or a number.")
end
if invoked then
local escaped = mw.ustring.gsub(pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1")
return escaped
else
return mw.ustring.gsub(pattern_str, "([%(%)%.%%%+%-%*%?%[%^%$%]])", "%%%1");
end
end
 
function str.count(text, pattern, plain)
if not (type(text) == "string" or type(text) == "number") then
error('The first argument to the function "count" must be a string or a number, not a ' .. type(text) .. '.')
end
if not (type(pattern) == "string" or type(pattern) == "number") then
error('The first argument to the function "count" must be a string or a number, not a ' .. type(text) .. '.')
end
if plain then
pattern = str.pattern_escape(pattern)
end
local _, count = mw.ustring.gsub(text, pattern, "")
return count
end
 
function str.plain_gsub(text, pattern, replacement)
local invoked = false
if type(text) == "table" then
invoked = true
if text.args then
local frame = text
local params = {
[1] = {},
[2] = {},
[3] = { allow_empty = true },
}
local args = require("Module:parameters").process(frame.args, params)
text = args[1]
pattern = args[2]
replacement = args[3]
else
error("If the first argument to plain_gsub is a table, it should be a frame object.")
end
else
if not (type(pattern) == "string" or type(pattern) == "number") then
error("The second argument to plain_gsub should be a string or a number.")
end
if not (type(replacement) == "string" or type(replacement) == "number") then
error("The third argument to plain_gsub should be a string or a number.")
end
end
pattern = str.pattern_escape(pattern)
if invoked then
text = mw.ustring.gsub(text, pattern, replacement)
return text
else
return mw.ustring.gsub(text, pattern, replacement)
end
end
 
function str.matchToArray(text, pattern)
local invoked = false
if type(text) == "table" then
invoked = true
if text.args then
local frame = text
local params = {
[1] = { required = true },
[2] = { required = true },
}
local args = require("Module:parameters").process(frame.args, params)
text = args[1]
pattern = args[2]
else
error("If the first argument to plain_gsub is a table, it should be a frame object.")
end
else
if not (type(pattern) == "string" or type(pattern) == "number") then
error("The second argument to plain_gsub should be a string or a number.")
end
end
local matches = {}
local i = 0
for match in mw.ustring.gmatch(text, pattern) do
i = i + 1
matches[i] = match
end
if i > 0 then
if invoked then
return table.concat(matches, ", ")
else
return matches
end
else
if invoked then
return ""
else
return nil
end
end
end
 
--[=[
Similar to gmatch, but it returns the count of the match in addition to the
list of captures, something like ipairs().
If the pattern doesn't contain any captures, the whole match is returned.
Invoke thus:
for i, whole_match in require("Module:string").imatch(text, pattern) do
[ do something with i and whole_match ]
end
or
for i, capture1[, capture2[, capture3[, ...]]] in require("Module:string").imatch(text, pattern) do
[ do something with i and capture1 ]
end
For example, this code
for i, whole_match in require("Module:string").imatch("a b c", "[a-z]") do
mw.log(i, whole_match)
end
will log
1 a
2 b
3 c
]=]
function str.imatch(text, pattern, pos, plain, use_basic_Lua_function)
local i = 0
pos = pos or 0
if not string.find(pattern, "%b()") then
pattern = "(" .. pattern .. ")"
end
local find = use_basic_Lua_function and string.find or mw.ustring.find
return function()
i = i + 1
local return_values = { find(text, pattern, pos, plain) }
local j = return_values[2]
if return_values[3] then
pos = j + 1
-- Skip the first two returned values, which are the indices of the
-- whole match.
return i, unpack(return_values, 3)
end
end
end
 
function str.escapebytes(s)
return (string.gsub(s,
'.',
function(char)
return ('\\%03d'):format(string.byte(char))
end))
end
 
function str.URIdecode(frame)
return mw.uri.decode(frame.args[1], frame.args[2] or "PATH")
end
end


return str
return str

Revision as of 14:04, 4 March 2019

Module:String (edit | talk | history | links | watch | logs)

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 (0).
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/testcases.

len

This 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 report

Examples:

  • {{#invoke:String|len| abcdefghi }} → 11
  • {{#invoke:String|len|s= abcdefghi }} → 9

sub

This function returns a substring of the target string at specified inclusive, one-indexed 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 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. To avoid error messages, use {{#invoke:ustring|sub}} instead.

Examples:

  • "{{#invoke:String|sub| abcdefghi }}" → " abcdefghi "
  • "{{#invoke:String|sub|s= abcdefghi }}" → "abcdefghi"
  • "{{#invoke:String|sub| abcdefghi | 3 }}" → "bcdefghi "
  • "{{#invoke:String|sub|s= abcdefghi |i= 3 }}" → "cdefghi"
  • "{{#invoke:String|sub| abcdefghi | 3 | 4 }}" → "bc"
  • "{{#invoke:String|sub|s= abcdefghi |i= 3 |j= 4 }}" → "cd"

sublength

This function implements the features of {{str sub old}} and is kept in order to maintain these older templates. It returns a substring of the target string starting at a specified index and of a specified length.

Usage:

{{#invoke:String|sublength|s= target_string |i= start_index |len= length }}

Parameters:

s
The string
i
The starting index of the substring to return. The first character of the string is assigned an index of 0.
len
The length of the string to return, defaults to the last character.

Examples:

  • {{#invoke:String|sublength|s= abcdefghi }} → abcdefghi
  • {{#invoke:String|sublength|s= abcdefghi |i= 3 }} → defghi
  • {{#invoke:String|sublength|s= abcdefghi |i= 3 |len= 4 }} → defg

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}}

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
Boolean flag indicating that pattern should be understood as plain text and not as a Scribunto ustring pattern (a unicode-friendly Lua-style regular expression). Defaults to false (to change: plain=true)
nomatch
If no match is found, output the "nomatch" value rather than an error.
ignore_errors
If no match is found and ignore_errors=true, output an empty string rather than an error.

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:

Examples:

  • {{#invoke:String|match| abc123def456 |%d+}} → 123
  • {{#invoke:String|match|s= abc123def456 |pattern= %d+ }} → 123
  • {{#invoke:String|match| abc123def456 |%d+|6}} → 23
  • {{#invoke:String|match|s= abc123def456 |pattern= %d+ |start= 6 }} → 3
  • {{#invoke:String|match|s= abc123def456 |pattern= %d+ |start= 6 |match= 2 }} → 456
  • {{#invoke:String|match|s= abc123%d+ |pattern= %d+ }} → 123
  • {{#invoke:String|match|s= abc123%d+ |pattern= %d+ |plain= true }} → %d+
  • {{#invoke:String|match|s= abc |pattern= %d }} → String Module Error: Match not found
  • {{#invoke:String|match|s= abc |pattern= %d |nomatch= No numeric characters in string }} → No numeric characters in string
  • {{#invoke:String|match|s= abc |pattern= %d |ignore_errors= true }} →
  • {{#invoke:String|match|s= 0012001200 |pattern= 0*(%d*) }} → 12001200

pos

This 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 return

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.

Examples:

  • {{#invoke:String|pos| abcdefghi | 4 }} → c
  • {{#invoke:String|pos|target= abcdefghi |pos= 4 }} → d

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 separately.

Usage:

{{#invoke:String|str_find|source_string|target_string}}

OR

{{#invoke:String|str_find|source= source_string |target= target_string }}

Parameters:

source
The string to search
target
The string to find within source

Examples:

  • {{#invoke:String|str_find| abc123def }} → 1
  • {{#invoke:String|str_find|source= abc123def }} → 1
  • {{#invoke:String|str_find| abc123def |123}} → 5
  • {{#invoke:String|str_find|source= abc123def |target= 123 }} → 4
  • {{#invoke:String|str_find| abc123def |not}} → -1

find

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

Usage:

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

OR

{{#invoke:String|find|source= source_string |target= target_string |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 Scribunto ustring pattern (a unicode-friendly Lua-style regular expression); defaults to true

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.

Examples:

  • {{#invoke:String|find|abc123def|12}} → 4
  • {{#invoke:String|find|source=abc123def|target=12}} → 4
  • {{#invoke:String|find|source=abc123def|target=pqr}} → 0
  • {{#invoke:String|find| abc123def |123}} → 5
  • {{#invoke:String|find|source= abc123def |target= 123 }} → 4
  • {{#invoke:String|find|source=abc123def|target=%d |start=3 |plain=false }} → 4

When using unnamed parameters, preceding and trailing spaces are kept and counted:

  • {{#invoke:String|find| abc123def |c|false}} → 5
  • {{#invoke:String|find|source= abc123def |target=c|plain=false}} → 3
  • {{#invoke:string|find|abc 123 def|%s|plain=false}} → 4

Testing for the presence of a string:

  • {{#ifexpr:{{#invoke:string|find|haystack|needle}}|Found needle|Didn't find needle}} → Didn't find needle

replace (gsub)

This function allows one to replace a target string or pattern within another string. To Lua programmers: this function works internally by calling string.gsub.

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 occurrences to replace; defaults to all
plain
Boolean flag indicating that pattern should be understood as plain text and not as a Scribunto ustring pattern (a unicode-friendly Lua-style regular expression); defaults to true

Examples:

  • "{{#invoke:String|replace| abc123def456 |123|XYZ}}" → " abcXYZdef456 "
  • "{{#invoke:String|replace|source= abc123def456 |pattern= 123 |replace= XYZ }}" → "abcXYZdef456"
  • "{{#invoke:String|replace| abc123def456 |%d+|XYZ|1|false}}" → " abcXYZdef456 "
  • "{{#invoke:String|replace|source= abc123def456 |pattern= %d+ |replace= XYZ |count=1 |plain= false }}" → "abcXYZdef456"
  • "{{#invoke:String|replace|source= abc123def456 |pattern= %d+ |replace= XYZ |plain= false }}" → "abcXYZdefXYZ"
  • {{#invoke:String|replace|source= 0012001200 |pattern= ^0* |plain= false }} → 12001200

rep

Repeats a string n times. A simple function to pipe string.rep to templates.

Usage:

{{#invoke:String|rep|source|count}}

Parameters:

source
The string to repeat
count
The number of repetitions.

Examples:

  • "{{#invoke:String|rep|hello|3}}" → "hellohellohello"
  • "{{#invoke:String|rep| hello | 3 }}" → " hello hello hello "

escapePattern

In a Lua pattern, changes a class character into a literal character. For example: in a pattern, character . catches "any character"; escapePattern will convert it to %., catching just the literal character ".".

Usage:

  • {{#invoke:String|escapePattern|pattern_string}}

Parameters:

pattern_string
The pattern string to escape

Examples:

  • "{{#invoke:String|escapePattern|A.D.}}" → "Script error: The function "escapePattern" does not exist."
  • "{{#invoke:String|escapePattern|10%}}" → "Script error: The function "escapePattern" does not exist."

count

Counts the number of times a given pattern appears in the arguments that get passed on to this module. Counts disjoint matches only.

Usage:

{{#invoke:String|count|source_str|pattern_string|plain_flag}}

OR

{{#invoke:String|count|source= source_string |pattern= pattern_string|plain= plain_flag }}

Parameters:

source_string
The string to count occurrences in
pattern
The string or pattern to count occurrences of within source
plain
Boolean flag indicating that pattern should be understood as plain text and not as a Scribunto ustring pattern (a unicode-friendly Lua-style regular expression); defaults to true

Examples:

  • Count of 'a': "{{#invoke:String|count|aabbcc|a}}" → "Script error: The function "count" does not exist."
  • Count occurrences of 'aba': "{{#invoke:String|count|ababababab|aba}}" → "Script error: The function "count" does not exist."
  • Count of "either 'a' or 'c' ":"{{#invoke:String|count|aabbcc|[ac]|plain=false}}" → "Script error: The function "count" does not exist."
  • Count of "not 'a' ": "{{#invoke:String|count|aaabaaac|[^a]|plain=false}}" → "Script error: The function "count" does not exist."
  • Count of "starts with 'a' ": "{{#invoke:String|count|aaabaaac|^a|plain=false}}" → "Script error: The function "count" does not exist."

join

Joins all strings passed as arguments into one string, treating the first argument as a separator

Usage:

{{#invoke:String|join|separator|string1|string2|...}}

Parameters:

separator
String that separates each string being joined together
Note that leading and trailing spaces are not stripped from the separator.
string1/string2/...
Strings being joined together

Examples:

  • "{{#invoke:String|join|x|foo|bar|baz}}" → "Script error: The function "join" does not exist."
  • "{{#invoke:String|join||a|b|c|d|e|f|g}}" → "Script error: The function "join" does not exist."
  • "{{#invoke:String|join|,|a|b|c|d|e|f|g}}" → "Script error: The function "join" does not exist."
  • "{{#invoke:String|join|, |a|b|c|d|e|f|g}}" → "Script error: The function "join" does not exist."
  • "{{#invoke:String|join| – |a|b|c|d|e|f|g}}" → "Script error: The function "join" does not exist."

The preceding example uses the html entity &ndash; but the unicode character also works.

endswith

For the startswith function, see Module:String2 § startswith.

Usage:

{{#invoke:String|endswith|source_str|search_string}}

OR

{{#invoke:String|endswith|source= source_string |pattern= search_string}}

Returns "yes" if the source string ends with the search string. Use named parameters to have the strings trimmed before use. Despite the parameter name, search_string is not a Lua pattern, it is interpreted literally.

  • "{{#invoke:String|endswith|xxxyyy|y}}" → "Script error: The function "endswith" does not exist."
  • "{{#invoke:String|endswith|xxxyyy|z}}" → "Script error: The function "endswith" does not exist."

See also

--[[  

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:
{{#invoke:String|len|target_string|}}
OR
{{#invoke:String|len|s=target_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:
{{#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 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.

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

]]
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'];
    
    if s == '' then
        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

--[[
pos

This 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 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}}
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 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}}
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 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

--[[
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;
    local no_category = frame.args.no_category or false;
    
    if str._getBoolean(ignore_errors) then
        return '';
    end
    
    local error_str = '<strong class="error">String Module Error: ' .. error_str .. '</strong>';
    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
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