Module:string

---

The followingdocumentationis located atModule:string/documentation.^[edit]

Useful links:subpage list•links•transclusions•testcases•sandbox

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.

A very few templates are provided to enable the functions to be freely used in entries in main space:

Function	Template
replace	{{replace}}

Global options

ignore_errors

If set totrueor1,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 isErrors reported by Module String.

no_category

If set totrueor1,no category will be added if an error is generated.

See also

• Module:string utilities– main module for string manipulation

localm_string_utils=require("Module:string utilities")

localstr={}

localdecode_uri=m_string_utils.decode_uri
localgsub=string.gsub
localpattern_escape=m_string_utils.pattern_escape
localprocess_params=require("Module:parameters").process
localreplacement_escape=m_string_utils.replacement_escape
localreverse=string.reverse
localufind=m_string_utils.find
localugmatch=m_string_utils.gmatch
localugsub=m_string_utils.gsub
localulen=m_string_utils.len
localulower=m_string_utils.lower
localumatch=m_string_utils.match
localunpack=unpack
localusub=m_string_utils.sub

--[[
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.
]]
functionstr.len(frame)
returnulen(str._getParameters(frame.args,{"s"}).sor"")
end

--[[
len_visible

This function returns the length of the target string, excluding the text encompassed in <... >

Usage: exactly as len, above.
]]
functionstr.len_visible(frame)
returnulen(ugsub(str._getParameters(frame.args,{"s"}).sor"","<[^<>]+>",""))
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.
]]
functionstr.sub(frame)
localnew_args=str._getParameters(frame.args,{"s","i","j"});
locals=new_args["s"]or"";
locali=tonumber(new_args["i"])or1;
localj=tonumber(new_args["j"])or-1;

locallen=ulen(s);

-- Convert negatives for range checking
ifi<0then
i=len+i+1;
end
ifj<0then
j=len+j+1;
end

ifi>lenorj>lenthen
returnstr._error('String subset index out of range');
end
ifj<ithen
returnstr._error('String subset indices out of order');
end

returnusub(s,i,j)
end

--[[
This function implements that features of {{str sub old}} and is kept in order
to maintain these older templates.
]]
functionstr.sublength(frame)
locali=tonumber(frame.args.i)or0
locallen=tonumber(frame.args.len)
returnusub(frame.args.s,i+1,lenand(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:// lua.org/manual/5.1/manual.html#5.4.1
* http:// mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns
* http:// mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Ustring_patterns

]]
functionstr.match(frame)
localnew_args=str._getParameters(frame.args,{'s','pattern','start','match','plain','nomatch'});
locals=new_args['s']or'';
localstart=tonumber(new_args['start'])or1;
localplain_flag=str._getBoolean(new_args['plain']orfalse);
localpattern=new_args['pattern']or'';
localmatch_index=math.floor(tonumber(new_args['match'])or1);
localnomatch=new_args['nomatch'];

ifs==''then
returnstr._error('Target string is empty');
end
ifpattern==''then
returnstr._error('Pattern string is empty');
end
ifmath.abs(start)<1ormath.abs(start)>ulen(s)then
returnstr._error('Requested start is out of range');
end
ifmatch_index==0then
returnstr._error('Match index is out of range');
end
ifplain_flagthen
pattern=pattern_escape(pattern);
end

localresult
ifmatch_index==1then
-- Find first match is simple case
result=umatch(s,pattern,start)
else
ifstart>1then
s=usub(s,start);
end

localiterator=ugmatch(s,pattern);
ifmatch_index>0then
-- Forward search
forwiniteratordo
match_index=match_index-1;
ifmatch_index==0then
result=w;
break;
end
end
else
-- Reverse search
localresult_table={};
localcount=1;
forwiniteratordo
result_table[count]=w;
count=count+1;
end

result=result_table[count+match_index];
end
end

ifresult==nilthen
ifnomatch==nilthen
returnstr._error('Match not found');
else
returnnomatch;
end
else
returnresult;
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.
]]
functionstr.pos(frame)
localnew_args=str._getParameters(frame.args,{'target','pos'});
localtarget_str=new_args['target']or'';
localpos=tonumber(new_args['pos'])or0;

ifpos==0ormath.abs(pos)>ulen(target_str)then
returnstr._error('String index out of range');
end

returnusub(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". Inde xing 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.
]]
functionstr.str_find(frame)
localnew_args=str._getParameters(frame.args,{'source','target'});
localsource_str=new_args['source']or'';
localtarget_str=new_args['target']or'';

iftarget_str==''then
return1;
end

localstart=ufind(source_str,target_str,1,true)
ifstart==nilthen
start=-1
end

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

This function should be safe for UTF-8 strings.
]]
functionstr.find(frame)
localmain_param={required=true,allow_empty=true}
returnufind(unpack(process_params(frame.args,{
[1]=main_param,
[2]=main_param,
[3]={type="number"},
[4]={type="boolean"},
})))
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
]]
functionstr.replace(frame)
localnew_args=str._getParameters(frame.args,{'source','pattern','replace','count','plain'});
localsource_str=new_args['source']or'';
localpattern=new_args['pattern']or'';
localreplace=new_args['replace']or'';
localcount=tonumber(new_args['count']);
localplain=new_args['plain']ortrue;

ifsource_str==''orpattern==''then
returnsource_str;
end
plain=str._getBoolean(plain);

ifplainthen
pattern=pattern_escape(pattern);
replace=replacement_escape(replace);
end

localresult;

result=ugsub(source_str,pattern,replace,count);

returnresult;
end


functionstr.gsub(frame)
localmain_param={required=true,allow_empty=true,no_trim=true}
return(ugsub(unpack(process_params(frame.args,{
[1]=main_param,
[2]=main_param,
[3]=main_param,
[4]={type="number"},
}))))
end


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

functionstr.rep(frame)
localrepetitions=tonumber(frame.args[2])
ifnotrepetitionsthen
returnstr._error('function rep expects a number as second parameter, received "'..(frame.args[2]or'')..' "')
end
returnstring.rep(frame.args[1]or'',repetitions)
end

functionstr.lower(frame)
returnulower(frame.args[1]or"")
end
str.lc=str.lower

--[[
format

This function allows one to format strings according to a template. This is a direct interface onto
str.format() in Lua, and works like the C printf() function.

For example:
{{#invoke:string|format|page_%04d.html|65}}
will produce the result
page_0065.html

Parameters
1: The format template. See https:// mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#string.format
2, 3,...: Arguments to be inserted into the template.

Note that leading and trailing whitespace is not removed from the arguments.
]]
functionstr.format(frame)
localfmt=frame.args[1]
-- You can't call unpack() directly on frame.args because it isn't really a
-- table, and doesn't support the # operator.
localargs={}
locali=2
whiletruedo
localval=frame.args[i]
ifnotvalthen
break
end
table.insert(args,val)
i=i+1
end
returnfmt:format(unpack(args))
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.
]]
functionstr._getParameters(frame_args,arg_list)
localnew_args={};
localindex=1;
localvalue;

for_,arginipairs(arg_list)do
value=frame_args[arg]
ifvalue==nilthen
value=frame_args[index];
index=index+1;
end
new_args[arg]=value;
end

returnnew_args;
end

--[[
Helper function to handle error messages.
]]
functionstr._error(error_str)
localframe=mw.getCurrentFrame();
localerror_category=frame.args.error_categoryor'Errors reported by Module String';
localignore_errors=frame.args.ignore_errorsorfalse;
localno_category=frame.args.no_categoryorfalse;

ifstr._getBoolean(ignore_errors)then
return'';
end

localerror_str='<strong class= "error" >String Module Error: '..error_str..'</strong>';
iferror_category~=''andnotstr._getBoolean(no_category)then
error_str='[[Category:'..error_category..']]'..error_str;
end

returnerror_str;
end

--[[
Helper Function to interpret boolean strings
]]
functionstr._getBoolean(boolean_str)
localboolean_value;

iftype(boolean_str)=='string'then
boolean_str=boolean_str:lower();
ifboolean_str=='false'orboolean_str=='no'orboolean_str=='0'
orboolean_str==''then
boolean_value=false;
else
boolean_value=true;
end
elseiftype(boolean_str)=='boolean'then
boolean_value=boolean_str;
else
error('No boolean value found');
end
returnboolean_value
end

functionstr.count(text,pattern,plain)
ifnot(type(text)=="string"ortype(text)=="number")then
error('The first argument to the function "count" must be a string or a number, not a '..type(text)..'.')
end

ifnot(type(pattern)=="string"ortype(pattern)=="number")then
error('The first argument to the function "count" must be a string or a number, not a '..type(text)..'.')
end

ifplainthen
pattern=pattern_escape(pattern)
end

local_,count=ugsub(text,pattern,"")

returncount
end

functionstr.matchToArray(text,pattern)
localinvoked=false

iftype(text)=="table"then
invoked=true

iftext.argsthen
localframe=text

localparams={
[1]={required=true},
[2]={required=true},
}

localargs=process_params(frame.args,params)

text=args[1]
pattern=args[2]
else
error("If the first argument to matchToArray is a table, it should be a frame object.")
end
else
ifnot(type(pattern)=="string"ortype(pattern)=="number")then
error("The second argument to matchToArray should be a string or a number.")
end
end

localmatches={}
locali=0
formatchinugmatch(text,pattern)do
i=i+1
matches[i]=match
end

ifi>0then
ifinvokedthen
returntable.concat(matches,",")
else
returnmatches
end
else
ifinvokedthen
return""
else
returnnil
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
]=]
functionstr.imatch(text,pattern,pos,plain,use_basic_Lua_function)
locali=0
pos=posor0
ifnotstring.find(pattern,"%b()")then
pattern="("..pattern..")"
end
localfind=use_basic_Lua_functionandstring.findorufind
returnfunction()
i=i+1
localreturn_values={find(text,pattern,pos,plain)}
localj=return_values[2]

ifreturn_values[3]then
pos=j+1
-- Skip the first two returned values, which are the indices of the
-- whole match.
returni,unpack(return_values,3)
end
end
end

functionstr.URIdecode(frame)
returndecode_uri(frame.args[1],frame.args[2]or"PATH")
end

functionstr:__index(k)
self[k]=package.loaders[2]("Module:string/"..k)()
returnself[k]
end

returnsetmetatable(str,str)