[tag-expressions] Fix Perl handling of backslash escaping in tags

The escaping backslash was added to the tag and if the escaped character
was a space, it was skipped even though being escaped.

Re #1778.

tag-expressions/perl/lib/Cucumber/TagExpressions.pm

@@ -71,11 +71,12 @@ sub _get_token {
                 _save_token( $state, $char );
                 return $token;
             }
-            $token .= $char unless $char =~ /\s/;
-
             if ( $char eq "\\" ) {
                 $token .= _consume_char( $state );
             }
+            else {
+                $token .= $char;
+            }
         }
     }
 }

tag-expressions/perl/t/02-evaluate.t

@@ -9,6 +9,13 @@ use Cucumber::TagExpressions;
 
 
 my @good = (
+    { expr => '@a\  or @b',
+      tests => [ { tags => [ '@a\ ' ],    outcome => !!0 },
+                 { tags => [ '@a '  ],    outcome => 1 },
+                 { tags => [ '@b'   ],    outcome => 1 },
+                 { tags => [ '@a'   ],    outcome => !!0 },
+          ] },
+    { expr => "\@a\\\\", tests => [] },
     { expr => '@a',
       tests => [ { tags => [ qw/@a/ ],    outcome => 1 },
                  { tags => [ qw/@b/ ],    outcome => !!0 },
@@ -70,11 +77,16 @@ my @good = (
                  { tags => [ qw/@b @d/ ], outcome => 1 },
                  { tags => [ qw/@q/ ],    outcome => !!0 },
           ] },
-    { expr => '@a\b',
-      tests => [ { tags => [ qw/@a\b/ ],  outcome => 1 },
+    { expr => "\@a\\b",
+      tests => [ { tags => [ "\@a\\b" ],  outcome => !!0 },
+                 { tags => [ '@ab' ],     outcome => 1 },
+                 { tags => [ qw/@a/ ],    outcome => !!0 },
+          ] },
+    { expr => "\@a\\\\b",
+      tests => [ { tags => [ "\@a\\b" ],  outcome => 1 },
+                 { tags => [ '@ab' ],     outcome => !!0 },
                  { tags => [ qw/@a/ ],    outcome => !!0 },
           ] },
-
     );
 
 for my $ex (@good) {
@@ -102,6 +114,7 @@ my %bad_syntax = (
     '@'          => 'Tag must be longer than the at-sign',
     '@a or @'    => 'Tag must be longer than the at-sign',
     '@a and @b)' => 'Junk at end of expression',
+    "\@a\\"      => 'Unexpected end of string parsing tag expression',
     );
 
 for my $expr (keys %bad_syntax) {