模块:String：修订间差异

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（创建页面，内容为“--[[ 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' o…”）
 
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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
-- 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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]]
]]
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
 
--[[
_match
 
This function returns a substring from the source string that matches a
specified pattern. It is exported for use in other modules
 
Usage:
strmatch = require("Module:String")._match
sresult = strmatch( s, pattern, start, match, plain, nomatch )
 
Parameters
    s: The string to search
    pattern: The pattern or string to find within the string
    start: The index within the source string to start the search.  The first
        character of the string has index 1.  Defaults to 1.
    match: In some cases it may be possible to make multiple matches on a single
        string.  This specifies which match to return, where the first match is
        match= 1.  If a negative number is specified then a match is returned
        counting from the last match.  Hence match = -1 is the same as requesting
        the last match.  Defaults to 1.
    plain: A flag indicating that the pattern should be understood as plain
        text.  Defaults to false.
    nomatch: If no match is found, output the "nomatch" value rather than an error.
 
For information on constructing Lua patterns, a form of [regular expression], see:
 
* http://www.lua.org/manual/5.1/manual.html#5.4.1
* http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
* http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Ustring_patterns
 
]]
-- This sub-routine is exported for use in other 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
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 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.


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]]
]]
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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]]
]]
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.
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]]
]]
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
if plain then
        pattern = str._escapePattern( 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;


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


    return 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
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


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]]
]]
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


--[[
--[[
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]]
]]
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


第443行： 第560行：
]]
]]
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

2023年12月10日 (日) 00:45的版本

模板:Lmd

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 mw.ustring.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.}}" → "A%.D%."
  • "{{#invoke:String|escapePattern|10%}}" → "10%%"

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}}" → "2"
  • Count occurrences of 'aba': "{{#invoke:String|count|ababababab|aba}}" → "2"
  • Count of "either 'a' or 'c' ":"{{#invoke:String|count|aabbcc|[ac]|plain=false}}" → "4"
  • Count of "not 'a' ": "{{#invoke:String|count|aaabaaac|[^a]|plain=false}}" → "2"
  • Count of "starts with 'a' ": "{{#invoke:String|count|aaabaaac|^a|plain=false}}" → "1"

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}}" → "fooxbarxbaz"
  • "{{#invoke:String|join||a|b|c|d|e|f|g}}" → "abcdefg"
  • "{{#invoke:String|join|,|a|b|c|d|e|f|g}}" → "a,b,c,d,e,f,g"
  • "{{#invoke:String|join|, |a|b|c|d|e|f|g}}" → "a, b, c, d, e, f, g"
  • "{{#invoke:String|join| – |a|b|c|d|e|f|g}}" → "a – b – c – d – e – f – g"

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

endswith

WikimediaUI-ArticleDisambiguation-ltr.svg
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}}" → "yes"
  • "{{#invoke:String|endswith|xxxyyy|z}}" → ""

See also

模板:String handling templates 

--[[

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. It is exported for use in other modules

Usage:
strmatch = require("Module:String")._match
sresult = strmatch( s, pattern, start, match, plain, nomatch )

Parameters
    s: The string to search
    pattern: The pattern or string to find within the string
    start: The index within the source string to start the search.  The first
        character of the string has index 1.  Defaults to 1.
    match: In some cases it may be possible to make multiple matches on a single
        string.  This specifies which match to return, where the first match is
        match= 1.  If a negative number is specified then a match is returned
        counting from the last match.  Hence match = -1 is the same as requesting
        the last match.  Defaults to 1.
    plain: A flag indicating that the pattern should be understood as plain
        text.  Defaults to false.
    nomatch: If no match is found, output the "nomatch" value rather than an error.

For information on constructing Lua patterns, a form of [regular expression], see:

* http://www.lua.org/manual/5.1/manual.html#5.4.1
* http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
* http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Ustring_patterns

]]
-- This sub-routine is exported for use in other 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

--[[
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: A flag indicating that the pattern should be understood as plain
        text.  Defaults to false.
    nomatch: If no match is found, output the "nomatch" value rather than an error.

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

If the match_number or start_index are out of range for the string being queried, then
this function generates an error.  An error is also generated if no match is found.
If one adds the parameter ignore_errors=true, then the error will be suppressed and
an empty string will be returned on any failure.

For information on constructing Lua patterns, a form of [regular expression], see:

* http://www.lua.org/manual/5.1/manual.html#5.4.1
* http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
* http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Ustring_patterns

]]
-- This 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:
{{#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

--[[
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

Join all non empty arguments together; the first argument is the separator.
Usage:
{{#invoke:String|join|sep|one|two|three}}
]]
function str.join(frame)
	local args = {}
	local 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 = '<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
取自“https://wiki.statsape.com/index.php?title=模块:String&oldid=3547”