Perl尝试理解regex调试输出

use strict;
use warnings;

my $text = "Hello, World!";
if ($text =~ /(\w+), (\w+)!/) {
    print "Matched: $1, $2\n";
} else {
    print "No match\n";
}

use strict;
use warnings;

my $text = "Hello, World!";
if ($text =~ /(?p)(\w+), (\w+)!/) {
    print "Matched: $1, $2\n";
} else {
    print "No match\n";
}

Compiling REx "(?p)(\w+), (\w+)!"
Final program:
   1: EXACT <Hello, > (4)
   4: OPEN1 (6)
   6: PLUS (8)
   7:   ALNUM (0)
   8: CLOSE1 (10)
  10: EXACT <, > (13)
 13: OPEN2 (15)
 15: PLUS (17)
 16:   ALNUM (0)
 17: CLOSE2 (19)
 19: EXACT <!> (22)
 22: END (0)
anchored "Hello, " at 0 floating "!" at 7..2147483647 (checking floating) minlen 7 
Guessing start of match in sv for REx "(?p)(\w+), (\w+)!" against "Hello, World!"...
Found anchored substr "Hello, " at offset 0...
start_shift: 0 check_at: 7 s: 0 endpos: 13
Does not contradict STCLASS...
Guessed: match at offset 0
Matching REx "(?p)(\w+), (\w+)!" against "Hello, World!"
   0 <> <Hello, >              |  1:EXACT <Hello, >(4)
   4 <Hello, > <World>         |  4:OPEN1(6)
   4 <Hello, > <World>         |  6:PLUS(8)
                                  EXACT <, >(13)
  13 <Hello, World> <>         | 13:OPEN2(15)
  13 <Hello, World> <>         | 15:PLUS(17)
                                  ALNUM(0)
  14 <Hello, World> < >        | 17:CLOSE2(19)
  14 <Hello, World> < >        | 19:EXACT <!>(22)
  14 <Hello, World> < >        | 22:END(0)
Match successful!
Matched: Hello, World