Difference between revisions of "Module:String"
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adds updated match support with wider parameter choices, whitespace handling, etc.
>Dragons flight (fix pattern escape in replace function) |
>Dragons flight (adds updated match support with wider parameter choices, whitespace handling, etc.) |
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end | end | ||
--[[ | |||
This function implements that features of {{str sub old}} and is kept in order | |||
to maintain these older templates. | |||
]] | |||
function str.sublength( frame ) | function str.sublength( frame ) | ||
local i = tonumber( frame.args.i ) or 0 | local i = tonumber( frame.args.i ) or 0 | ||
| Line 102: | Line 106: | ||
end | 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}} | |||
OR | |||
{{#invoke:String|pos|s=source_string|pattern=pattern_string|start=start_index | |||
|match=match_number|plain=plain_flag}} | |||
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_flag: A flag indicating that the pattern should be understood as plain | |||
text. Defaults to false. | |||
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 ) | function str.match( frame ) | ||
return mw.ustring.match | local new_args = str._getParameters( frame.args, {'s', 'pattern', 'start', 'match', 'plain'} ); | ||
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 ); | |||
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 | |||
return str._error( 'Match not found' ); | |||
else | |||
return result; | |||
end | |||
end | end | ||