nested_string_escapes.pl

#!/usr/bin/perl

use strict;
use warnings;

use Test::More;

# Increase this number as your sanity allows
use constant PAREN_DEPTH => 5;

my $nested_string_escape_regex = '\\\\\(' . '(?:[^()]|\(' x PAREN_DEPTH . '[^()]*' . '\))*' x PAREN_DEPTH . '\)';

my @test_cases = (
  '(one)' => [],
  '\(one)' => [ '\(one)' ],
  '(one \\(two))' => [ '\\(two)' ],
  '(one \\(two (three (four))))' => [ '\\(two (three (four)))' ],
  '(one (two \(three (four))))' => [ '\\(three (four))' ],
  '(one (two \(three (four)))) five \(six (seven (eight (nine))) ten)' => [ '\\(three (four))', '\\(six (seven (eight (nine))) ten)' ],
);

plan tests => @test_cases / 2;

for (my $i = 0; $i < @test_cases; $i += 2) {
  my $string = $test_cases[$i];
  my $expect = $test_cases[$i + 1];

  my @match = ($string =~ /.*?($nested_string_escape_regex)/g);
  
  is_deeply(\@match, $expect, $string);
}