What kind of Regex does tasker use?

[Cliff Karlsson]

I am a bit confused why some of my regex examples does not work in tasker but work when regexbuddy.

I have tried this:

data= <div id="clock-days">016<span class="timedesc">days&nbsp;</span></div>
Regex= (?<=<div id="clock-.*)\d.+(?=<span class="timedesc">)

I want to get the number 016

[Bob Hansen]

Tasker uses javascript "flavor" of regex.

Try:

(?<=<div id="clock-.+)\d+(?=<span class="timedesc">)

[Bob Hansen]

Actually that change wouldn't make a difference. Make sure you are using Save Matches To: %match (for example) and checking for the result in %match(1) (Tasker puts the matches in an array).

[Cliff Karlsson]

Are you sure that the regex is correct? When I switch to javascript in regexbuddy I can't match either.

[Cliff Karlsson]

Ok, I gave up on that one. Found something simpler that worked instead. >\d{2,3}<

[Bob Hansen]

Even simpler \d+

Tasker didn't like the clock-.*

I think it failed because it made the capture group variable length, but that is speculation. 

(?<=<div id="clock-.*)\d.+(?=<span class="timedesc">) 

this below works.

(?<=<div id="clock-days">)\d+(?=<span class="timedesc">) 

[Matt R]

Most regex don't allow variable length lookbehind strings.

Matt

[Pent]

I think it failed because it made the capture group variable length, but that is speculation. 

I remember hitting that in specifying the regex for variable name matching. Limitation of
Android regex.

Pent

[Nate French]

"The maximum length of possible matches for look-behind patterns must not be unbounded." 
Source: http://developer.android.com/reference/java/util/regex/Pattern.html (section: Look-around assertions)

I think it's not due to a variable length, but rather an unbounded length.  The expression .*  or .+ will match greedily (and .*? or .+? sparingly) off to an unspecified length.  By contrast, the expression .{1,10}? has a bounded length, variable from 1 to 10 characters.

[Matt R]

I can confirm that you can use "bounded" variable length expressions in regex in Tasker ... except you can't use repetition (curly braces) above 10 for some reason. Even a fixed, non-variable {11}. Strange...

Matt