Module:String

Documentation for this module may be created at Module:String/doc

--[[

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|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

]]
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

--[[
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', 'trim', 'default' } )
	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
	local trim = new_args[ 'trim' ] or false
	local default = new_args[ 'default' ]
	if default == 'empty' then default = '' else default = tonumber( default ) or 0 end

	if source_str == '' or pattern == '' then
		return 0
	end

	plain = str._getBoolean( plain )
	trim = str._getBoolean( trim )

	if trim then source_str = mw.text.trim( source_str ) end

	local start = mw.ustring.find( source_str, pattern, start_pos, plain )
	if start == nil then
		start = default
	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

--[[
rep

Cette fonction retourne la concaténation de son premier paramètre n fois où n est le deuxième paramètre (fonction "rep" ou "repeat")

Usage :
{{#invoke:String|rep|s|n}}

Paramètres :
	la chaîne 's' dont on veut répeter
	l'entier 'n' le nombre d'itération
]]
function str.rep( frame )
	local new_args = str._getParameters( frame.args, { 's', 'n' } )
	local s = new_args[ 's' ] or ''
	local n = tonumber( new_args[ 'n' ] ) or 1
	if not s or s == '' then
		return ''
	end
	if not n or n <0 then
		return s
	end
	return mw.ustring.rep( s, n )
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

--[[
non_latin
Retire tous les caractères latins d'une chaîne de caractères. Rend la chaîne vide "" si le paramètre est un texte entièrement latin.
Paramètre : source
]]
function str.non_latin( frame )
	local args = str._getParameters( frame.args, { 'source' } )
    local s = args.source or ''
    s = mw.text.decode( s, true )
    s = mw.ustring.lower( mw.ustring.gsub( mw.ustring.toNFD( s ), "[^%w]", "" ) )
    s = mw.ustring.gsub( s, "[!-˿Ḁ-ỿ]", "" ) -- U+0021-02FF, U+1E00-1EFF
    return s
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

	for i = 1, #arg_list do
		local arg = arg_list[ i ]
		local 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