Javascript regexp templates: only match when string inside brackets is equal

Question

I'm working with a javascript templating system for a website I'm building and I'm having a bit a of problem.

I'm using the following regex to match with sections within my string:

 /(\{\{(#|\^)(.*?)\?\}\}(.*?)\{\{\/(.*?)\?\}\})/

Feeding this a string such as:

 {{#is_user?}} The user is an user {{/user?}}

While stating "user"=true, displays the string. When "is_user" is set to false, the string is not shown. However I've found that this allows no room for nesting as such that:

 {{#is_user?}} The user is an user {{#has_picture?}} and has a picture{{/has_picture?}} {{/user?}}

This will result in the following:

The user is an user  {#is_user?}} The user is an user{{/user?}}   

Thus meaning the the match is found between {{#is_user?}} and {{/has_picture?}} as the regex just checks for a match between {{# anystring ?}} and {{/ anystring? }}.

Now my question is if its possible to say that there's only a match if the two strings between the brackets are equal so that a match is only found when {{#stirngA?}} {{/stringA?}}.

Answer 1

You can make your regex only match the corresponding opening tag by using backreferences.

Eg:

/(\{\{(#|\^)(.*?)\?\}\}(.*?)\{\{\/(\3)\?\}\})/

or without capturing all groups:

/(?:\{\{(?:#|\^)(.*?)\?\}\}(.*)\{\{\/(?:\1)\?\}\})/

The \\3 (or \\1) will contain the value of the first (.*?).

See it on rubular .

But this might not fully solve your problem of nested matches. Although you could use the result and apply the regex again. Maybe thats enough for your specific case.