Mô đun:String

--=  
Mô đun này nhằm cung cấp các hàm chuỗi cơ bản.
Phần nhiều hàm này cho phép gọi với các tham số có tên, các tham số không có
tên, hoặc pha trộn cả hai kiểu. Nếu sử dụng các tham số có tên, MediaWiki tự
động bỏ qua khoảng cách đằng truớc và đằng sau tham số. Tùy cách sử dụng, bạn có
thể cần giữ hoặc bỏ qua khoảng cách này.
Các tùy chọn toàn cục:
ignore_errors: Nếu là 'true' hoặc 1, bất cứ trạng thái lỗi nào sẽ cho ra
chuỗi rỗng thay vì thông báo lỗi.

error_category: Nếu xuất hiện lỗi, trang được tự động xếp vào thể loại này
và thông báo lỗi sẽ được hiển thị. Thể loại mặc định là
Thể loại:Trang gây lỗi trong mô đun String.

no_category: Nếu là 'true' hoặc 1, trang không được tự động xếp vào thể loại
khi xuất hiện lỗi.
Các trường hợp kiểm thử đơn vị cho mô đun này có sẵn tại Module:String/tests.
**
--
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:
OR
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:
OR
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  len or j > len or i  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_tablecount = 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:
OR
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:
OR
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 , 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:
OR
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:
OR
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.args2 )
	if not repetitions then
		return str._error( 'function rep expects a number as second parameter, received "' .. ( frame.args2 or  ) .. '"' )
	end
	return string.rep( frame.args1 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.args1
	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:
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_argsarg
		if value == nil then
			value = frame_argsindex
			index = index + 1
		end
		new_argsarg = 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 = 'String Module Error: ' .. error_str .. 
	if error_category ~=  and not str._getBoolean( no_category ) then
		error_str =  .. 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