Something like seqsplit that prioritizes separators?

Question

I'm trying to show a url with a long parameter list, and I'd like to prioritize some breakpoints over others, eg:

http://example.com/endpoint/?longsequence=\seqsplit{[100,200,300,400,5000,60000,70000,80000,9000000,1000000000,110000000,120000000,13000000,14000000,1500000,1600000,1700000,1800000,19000000,2000000000]&another=asdasdasdasdasdasdasdasdasdasdasdasdasdasdasdasad}

My problem here is that seqsplit is often choosing to break in the middle of the integers, just as frequently as anywhere else. I understand I can prevent this by using \seqsplit{[{100},{200},{300}...]} but for a long list, grouping manually becomes quite cumbersome.

Ideally, I could say something like:

\seqsplit[\& ,]{...}

To suggest that seqsplit prioritize the & and , as good breakpoints.

Answer 1

I can propose a different solution:

\documentclass{article}
\usepackage{xparse}

\ExplSyntaxOn
\NewDocumentCommand{\longstring}{O{}m}
 {
  \tl_map_inline:nn { #2 }
   {
    ##1
    \tl_if_in:nnTF { #1 } { ##1 } { \penalty -100 } { \penalty 0 }
    \skip_horizontal:n { 0pt plus 1pt }
   }
 }
\ExplSyntaxOff

\begin{document}

http://example.com/endpoint/?longsequence=\longstring[\&,]{[100,200,300,%
  400,5000,60000,70000,80000,9000000,1000000000,110000000,120000000,%
  13000000,14000000,1500000,1600000,1700000,1800000,19000000,%
  2000000000]\&another=asdasdasdasdasdasdasdasdasdasdasdasdasdasdasdasad}

\end{document}

A slightly stretchable space is added after , and \& in order to help filling lines.