모듈:연습장/배우는사람/String

--  
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
--
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
--
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 i,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