Regex to find sequence of words that can repeat : <p>I would like to identify the following pattern on a string (all words are separated by comma)<br>
1. The string starts with RO,TA,PR<br>
2. The string ends with TA,TO<br>
3. After RO,TA,PR it can have multiples TA,PR<br></p>

<p>Example of valid patterns:<br>
 - RO,TA,PR,TA,TO<br>
 - RO,TA,PR,TA,PR,TA,TO<br>
 - RO,TA,PR,TA,PR,TA,PR,TA,TO<br>
 - RO,TA,PR,TA,PR,TA,PR,TA,PR,TA,TO<br>
 - RO,TA,PR,TA,PR,TA,PR,TA,PR,TA,TO<br></p>

<p>Example of invalid patterns:<br>
 - RO,PR,TA,TO<br>
 - RO,TA,TO,PR,TA,TO<br>
 - RO,TA,RO,TA,TO<br>
 - RO,TA,PR,TO<br></p>
