This code is a mess, but works. Can you refactor it?

The nastiest thing is $flag, but it's open season on the rest of it too.

It's deliberately unrunnable, as you don't have the code for f1() or f2() or any sample data. Does that make it too hard?

{
    my( $indent, $depth ) = ( "\t", 0 );
    sub pp {
        my $flag;
        my( $pos1, $first ) = f1( $str );
        if( defined $first ) {
            if( $first eq CONST1 ) {
                $pos1++;
                $depth++;
            }
            else {
                my $pos2 = f2( $str, $first );
                if( defined $pos2 ) {
                    $pos1 = $pos2 + 2;
                }
                else {
                    $flag = 1;
                }
            }
        }
        print $indent x $depth, substr( $str, 0, $pos1 );
        $str =~ s[^.{$pos1}\s*][];
        $depth++ if $flag;
        return;
    }
}
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