Regex Pattern with two equal but unknown parts-CodePudding

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?

CodePudding user response：

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 %}