Delimiting-a-macro-with-itself-chain

Reading this question and the answer of @Werner made me think about if it is possible to have chains of self-delimiting macros like \XX abc \XX def \XX xyz or lets say

\begin{someenv}
  \XX abc
  \XX def
  \XX xyz
\end{someenv}

The original definition will obviously fail here - insufficent number fo \XXs. So, a first step towards an easy redefinition of \XX could be to say

\def\XX#1\XX{do sth with #1\\ \XX}

The problem now is to terminate this chain in an elegant way. A rather rude and not desiderable way is shown in the MWE below.

\documentclass{article}

\def\XX#1\XX{do sth with #1\\ \XX}

\newenvironment{someenv}{\center}{\endcenter}

\def\abc{def}

\begin{document}
\begin{someenv}
  \XX xyz
  \XX abc
  \XX \abc
  \let\XX\empty %this is the bad guy that needs to be busted
\end{someenv}
\end{document}