Module:String: Difference between revisions

This function implements that features of {{subr|s|skip|max}} and

is kept in order to maintain these older templates.

Uses only numbered paramameters to preserve spaces (caller may trim

whitespaces by passing the parameter explicitly by numbering the

parameters).

Accepts negative values as relative to strng length.

No error is returned if attempting to read past end of string or

before start of string.

Currently does not parse and replace placeholders for nowiki tags.

local s = frame.args[1] or '';

local skip = tonumber( frame.args[2] ) or 0;

local max = tonumber( frame.args[3] ) or 0;

local len = mw.ustring.len( s );

-- convert negative values of max and skip as relative to string length

if max < 0 then

max = len + max

end

if skip < 0 then

skip = len + skip

end

-- check boundaries to reduce the requested max

if skip < 0 then -- if before start of string

max = max + skip

skip = 0 -- skip can't underflow now

end

if max > len - skip then -- if past end of string

max = len - skip -- max can't overflow now

end

if max <= 0 then

return '' -- nothing left to return

end

return mw.ustring.sub( s, skip + 1, skip + max )