use v5.12;
use warnings;
use Test::More;

my $escaped = qr/\\./;

my $quoted  =
  qr/
        (['"])                          # --- start-quote

        (?:                             # --- inside 
            $escaped                    #     any escape-pair
        |
            .                           #     anything else
        )*?                             # non-greedy 

        (?:                             # --- end
            \g{-1}                      #   same quote
        |
            $                           #   EOL ends missing pair
        )
    /x;

my $re =
  qr/
        (?:
            $escaped                    #   any escape pair
        |
            $quoted                     #   any quoted string
        |
            \S                          #   any none whitespace
        )+                              # at least once
    /x;


my $str = q{This "is so" very simple.};

my @tests = (
             #  q{all '- and "-quotes properly balanced},
             [ q{This is simple.},           [ q{This}, q{is}, q{simple.}               ] ],
             [ q{     This  is   simple. },  [ q{This}, q{is}, q{simple.}               ] ],
             [ q{This is "so very simple".}, [ q{This}, q{is}, q{"so very simple".}     ] ],
             [ q{This "is so" very simple.}, [ q{This}, q{"is so"}, q{very}, q{simple.} ] ],
             [ q{This 'isn\'t nice.'},       [ q{This}, q{'isn\'t nice.'}               ] ],
             [ q{This "isn\"t nice."},       [ q{This}, q{"isn\"t nice."}               ] ],
             [ q{This 'isn\\\\'t nice.'},    [ q{This}, q{'isn\\\\'t}, q{nice.'}        ] ],
             [ q{This "isn\\\\"t nice."},    [ q{This}, q{"isn\\\\"t}, q{nice."}        ] ],
             [ q{This 'is not unnice.'},     [ q{This}, q{'is not unnice.'}             ] ],
             [ q{This "is not unnice."},     [ q{This}, q{"is not unnice."}             ] ],
             [ q{a "bb cc" d},               [ q{a}, q{"bb cc"}, q{d}                   ] ],

             #  q{UNbalanced '- and "-quotes at absolute end of string},
             [ q{This is "so very simple}, [ q{This}, q{is}, q{"so very simple} ] ],
             [ q{This 'isn\'t nice.},      [ q{This}, q{'isn\'t nice.}          ] ],
             [ q{This "isn\"t nice.},      [ q{This}, q{"isn\"t nice.}          ] ],
             [ q{This 'isn\\\\'t nice.},   [ q{This}, q{'isn\\\\'t}, q{nice.}   ] ],
             [ q{This "isn\\\\"t nice.},   [ q{This}, q{"isn\\\\"t}, q{nice.}   ] ],
             [ q{This 'is not unnice.},    [ q{This}, q{'is not unnice.}        ] ],
             [ q{This "is not unnice.},    [ q{This}, q{"is not unnice.}        ] ],

             #  'what about these questionable cases?',
             [ q{is this"really so"simple now?}, [ q{is}, q{this"really so"simple}, q{now?} ] ],
             [ q{is this"really so"       now?}, [ q{is}, q{this"really so"},       q{now?} ] ],
             [ q{is     "really so"simple now?}, [ q{is}, q{"really so"simple},     q{now?} ] ],
             [ q{is this'really so'simple now?}, [ q{is}, q{this'really so'simple}, q{now?} ] ],
             [ q{is this'really so'       now?}, [ q{is}, q{this'really so'},       q{now?} ] ],
             [ q{is     'really so'simple now?}, [ q{is}, q{'really so'simple},     q{now?} ] ],

            );

plan tests => 0+@tests;

for my $test (@tests) {
    my ($str, $exp) = @$test;

    my $got;
    push @$got, $&
      while ($str =~ /$re/g);

    is_deeply($got, $exp, qq{<$str>: } . join('|', @$exp));
}