Module:String: Difference between revisions

Line 1:

--[[

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.

]]

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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

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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 )

-- 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

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]]

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

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match

This function returns a substring from the source string that matches a

specified pattern.

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{{#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

{{#invoke:String|pos|s=source_string|pattern=pattern_string|start=start_index

|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

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.

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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:

* ~~https~~://www.lua.org/manual/5.1/manual.html#5.4.1

* http://www.lua.org/manual/5.1/manual.html#5.4.1

* ~~https~~://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns

* http://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Patterns

* ~~https~~://www.mediawiki.org/wiki/Extension:Scribunto/Lua_reference_manual#Ustring_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

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

if result == nil then

if nomatch == nil then

return str._error( 'Match not found' );

else

return nomatch;

end

else

return result;

end

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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.

Line 242:

]]

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

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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.

Line 268:

]]

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

Line 303:

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.

Line 314:

]]

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 );

if source_str == '' or pattern == '' then

local start = mw.ustring.find( source_str, pattern, start_pos, plain )

return 0;

if start == nil then

end

start = 0

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

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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

if source_str == '' or pattern == '' then

return source_str;

pattern = str._escapePattern( pattern );

end

replace = mw.ustring.gsub( replace, "%%", "%%%%" ); --Only need to escape replacement sequences.

plain = str._getBoolean( plain );

end

local result;

if ~~count ~= nil~~ then

if plain then

~~result~~ = mw.~~ustring.gsub~~( ~~source_str,~~ pattern~~, replace, count~~ );

pattern = str._escapePattern( pattern );

replace = mw.ustring.gsub( replace, "%%", "%%%%" ); --Only need to escape replacement sequences.

else

end

result = mw.ustring.gsub( source_str, pattern, replace );

end

~~return~~ 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

--[[

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:

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

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]]

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

--[[

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]]

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

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]]

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