multiline regex match pattern in brackets ignoring escaped brackets

Question

I finally managed to find out how to do this, see https://regex101.com/r/Zls9Kq/5/

(?!\\)[{](.|\n)*?(?<!\\)[}]

Trying to match

sometext {
 blah \{
\}
\{
 \}
}

But that expression can't be used in flex.

Anyone know if it can be transformed in a way that will work in flex?

Answer 1

I'm going to assume a limited regex engine and give you this to try out

([^\\]|^)[{]([^\\}]|\\(.|\n))*[}]

https://regex101.com/r/WBFbWw/1

**

 ( [^\\] | ^ )      # (1), Before the opening {, match not an escape or the beginning of the string
 [{]                # Opening brace
 (                  # (2 start)
      [^\\}]             # Not an escape nor a closing brace
   |  \\                 # Or, an escape anything
      ( . | \n )         # (3)
 )*                 # (2 end), 0 to many times
 [}]                # Closing brace