+#
+# get the next key that matches, this assumes that you have done a 'get' first
+#
+#
+sub next
+{
+ my $key = shift;
+ my @out;
+ my @outref;
+ my $ref;
+ my $gotkey;
+
+ return () if $db->seq($gotkey, $ref, R_NEXT);
+ return () if $key ne substr $gotkey, 0, length $key;
+
+ @outref = map { $prefix_loc{$_} } split ',', $ref;
+ return ($gotkey, @outref);
+}
+
+#
+# extract a 'prefix' from a callsign, in other words the largest entity that will
+# obtain a result from the prefix table.
+#
+# This is done by repeated probing, callsigns of the type VO1/G1TLH or
+# G1TLH/VO1 (should) return VO1
+#
+
+sub extract
+{
+ my $call = uc shift;
+ my @out;
+ my @nout;
+ my $p;
+ my @parts;
+ my ($sp, $i);
+
+ # first check if the whole thing succeeds
+ @out = get($call);
+ return @out if @out > 0 && $out[0] eq $call;
+
+ # now split the call into parts if required
+ @parts = ($call =~ '/') ? split('/', $call) : ($call);
+
+ # remove any /0-9 /P /A /M /MM /AM suffixes etc
+ if (@parts > 1) {
+ $p = $parts[$#parts];
+ pop @parts if $p =~ /^(\d+|[PABM]|AM|MM|BCN|SIX|Q\w+)$/o;
+ $p = $parts[$#parts];
+ pop @parts if $p =~ /^(\d+|[PABM]|AM|MM|BCN|SIX|Q\w+)$/o;
+
+ # can we resolve them by direct lookup
+ foreach $p (@parts) {
+ @out = get($p);
+ return @out if @out > 0 && $out[0] eq $call;
+ }
+ }
+
+ # which is the shortest part (first if equal)?
+ $sp = $parts[0];
+ foreach $p (@parts) {
+ $sp = $p if length $sp > length $p;
+ }
+ # now start to resolve it from the left hand end
+ for (@out = (), $i = 1; $i <= length $sp; ++$i) {
+ @nout = get(substr($sp, 0, $i));
+ last if @nout > 0 && $nout[0] gt $sp;
+ last if @nout == 0;
+ @out = @nout;
+ }
+
+ # not found
+ return (@out > 0) ? @out : ();
+}
+
+my %valid = (
+ lat => '0,Latitude,slat',
+ long => '0,Longitude,slong',
+ dxcc => '0,DXCC',
+ name => '0,Name',
+ itu => '0,ITU',
+ cq => '0,CQ',
+ utcoff => '0,UTC offset',
+);
+
+no strict;
+sub AUTOLOAD
+{
+ my $self = shift;
+ my $name = $AUTOLOAD;
+
+ return if $name =~ /::DESTROY$/;
+ $name =~ s/.*:://o;
+
+ confess "Non-existant field '$AUTOLOAD'" if !$valid{$name};
+ if (@_) {
+ $self->{$name} = shift;
+ }
+ return $self->{$name};
+}
+use strict;
+
+#
+# return a prompt for a field
+#
+
+sub field_prompt
+{
+ my ($self, $ele) = @_;
+ return $valid{$ele};
+}