Fix watching specific files on windows

When you are only watching specific file paths, you
get change events for all files in the same directory.
On linux only changes to watched files get reported.

Author: mgreter

lib/Filesys/Notify/Simple.pm

@@ -119,6 +119,8 @@ sub mk_wait_win32 {
     return sub {
         my @path = @_;
 
+        my %watched = map { ( $_ => 1 ) }
+            grep defined, map { Cwd::abs_path($_) } @path;
         my $fs = _full_scan(@path);
         my (@notify, @fskey);
         for my $path (keys %$fs) {
@@ -133,11 +135,35 @@ sub mk_wait_win32 {
 
             my @events;
             while(1) {
-                my $idx = Win32::ChangeNotify::wait_any(\@notify);
+                my $idx = Win32::ChangeNotify::wait_any(\@notify); 
                 Carp::croak("Can't wait notifications, maybe ".scalar(@notify)." directories exceeds limitation.") if ! defined $idx;
                 if($idx > 0) {
                     --$idx;
+                    # get all file changes in path
                     my $new_fs = _full_scan($fskey[$idx]);
+                    foreach my $root (keys %{$new_fs}) {
+                        # on windows we can only watch folders
+                        # therefore we need to filter unwanted
+                        # events for files we are not looking for
+                        unless (exists $watched{$root}) {
+                            # process all reported file changes in path
+                            foreach my $file (keys %{$new_fs->{$root}}) {
+                                # don't remove if we watch particular file
+                                unless (exists $fs->{$root}->{$file}) {
+                                    # we are not interested in this event
+                                    delete $new_fs->{$root}->{$file};
+                                }
+                            }
+                        }
+                        # but only if we don't watch folder itself
+                        else {
+                            # check if we watch particular root
+                            unless (exists $fs->{$root}) {
+                                # remove paths not watched by us
+                                delete $new_fs->{$root};
+                            }
+                        }
+                    }
                     $notify[$idx]->reset;
                     my $old_fs = +{ map { ($_ => $fs->{$_}) } keys %$new_fs };
                     _compare_fs($old_fs, $new_fs, sub { push @events, { path => $_[0] } });
@@ -210,7 +236,7 @@ sub _full_scan {
 
         # remove root entry
         # NOTE: On MSWin32, realpath and rel2abs disagree with path separator.
-        delete $map{$fp}{File::Spec->rel2abs($fp)};
+        delete $map{$fp}{File::Spec->rel2abs($fp)} if exists $map{$fp};
     }
 
     return \%map;