* Subtitle::SSA::Record : add error() method

lib/Subtitle/SSA/Record.pm

@@ -10,6 +10,15 @@ use overload
   '""' => \&to_string,
 ;
 
+sub error {
+  my ($self, $text) = @_;
+  if (defined $text) {
+    $self->{_error} = $text;
+    return;
+  }
+  return $self->{_error};
+}
+
 sub set {
   my ($self, $field, $value) = @_;
   return unless $field;
@@ -22,7 +31,8 @@ sub set {
 sub parse_format_line {
   my ($self, $line) = @_;
 
-  return unless $line and $line =~ m{^Format:}oi;
+  return $self->error("not looks like Format line")
+    unless $line and $line =~ m{^Format:}oi;
 
   chomp $line;
   $line =~ s{^Format:\s*}{}oi;
@@ -30,7 +40,8 @@ sub parse_format_line {
   my @fields;
   foreach my $field (split(/,\s*/o, $line)) {
     $field = lc($field);
-    return unless exists $self->{_fields}->{$field};
+    return $self->error("unknown field: $field")
+      unless exists $self->{_fields}->{$field};
     push @fields, $field;
   }
 
@@ -49,15 +60,18 @@ sub parse {
   $format //= $self->{_format};
 
   my $PREFIX = $self->{_prefix};
-  return unless $line and $line =~ m{^$PREFIX:}oi;
+  return $self->error("not looks like $PREFIX line")
-  return unless $format and ref($format) eq 'ARRAY';
+    unless $line and $line =~ m{^$PREFIX:}oi;
+  return $self->error("passed custom fields order not ARRAY ref")
+    unless $format and ref($format) eq 'ARRAY';
 
   chomp $line;
   $line =~ s{^$PREFIX:\s*}{}oi;
   my $fieldcnt = scalar @{ $format };
   my @values = split /,\s*/o, $line, $fieldcnt;
   # check that values count match fields count
-  return if scalar @values != $fieldcnt;
+  return $self->error("number of fields less than expected count")
+    if scalar @values < $fieldcnt;
 
   foreach my $field (@{ $format }) {
     my $d = $self->{_fields}->{$field};
@@ -66,7 +80,8 @@ sub parse {
       $value = hex($1);
     } elsif ($d->{type} eq 't') {
       $value = parse_timing($value);
-      return if $value < 0; # parsing failure
+      return $self->error("can't parse timing: $value")
+        if $value < 0; # parsing failure
     }
     $self->set($field => $value);
   }