I am currently working on a simple template engine. In a template, if-statements can be used. An if block looks like this

{% name IF: a EQUALS b %}

content

{% name ENDIF %}

I want to identify these blocks via regex.
The Problem is I need a regex pattern which contains two unknown but equal parts.
This is the pattern which matches to all blocks:

/{% +(.*) +IF: +(.*) +%}([\s\S]*){% +(.*) +ENDIF +%}/gm

To make it clarify which ENDIF marker belongs to which IF the first and the last capture group needs to be the same.
Is there a way to do this?

>Solution :

You may use this regex:

{%\s+(\S+)\s+IF:[^}]+%}(?s)(.+?){%\s+\1\s+ENDIF\s+%}

RegEx Demo

RegEx Details:

• {%: Match {%
• \s+: Match 1+ whitespaces
• (\S+):
• \s+: Match 1+ whitespaces
• IF:: Match IF:
• [^}]+: Match 1+ of any character that is not a }
• %}: Match %}
• (?s): Enable DOTALL mode so that dot matches line break
• (.+?): 1st capture group to match 1+ of any characters
• {%: Match {%
• \s+: Match 1+ whitespaces
• \1: Match same value as what we captured in capture group #1
• \s+: Match 1+ whitespaces
• ENDIF: Match ENDIF
• \s+: Match 1+ whitespaces
• %}: Match closing %}