Added missing file

diff --git a/lib/DBM/Deep/Engine.pm b/lib/DBM/Deep/Engine.pm
new file mode 100644 (file)
index 0000000..a144e47
--- /dev/null
+++ b/lib/DBM/Deep/Engine.pm
@@ -0,0 +1,54 @@
+package DBM::Deep::Engine;
+
+use 5.006_000;
+
+use strict;
+use warnings FATAL => 'all';
+
+use DBM::Deep::Iterator ();
+
+# File-wide notes:
+# * Every method in here assumes that the storage has been appropriately
+#   safeguarded. This can be anything from flock() to some sort of manual
+#   mutex. But, it's the caller's responsability to make sure that this has
+#   been done.
+
+# Setup file and tag signatures.  These should never change.
+sub SIG_FILE     () { 'DPDB' }
+sub SIG_HEADER   () { 'h'    }
+sub SIG_HASH     () { 'H'    }
+sub SIG_ARRAY    () { 'A'    }
+sub SIG_NULL     () { 'N'    }
+sub SIG_DATA     () { 'D'    }
+sub SIG_INDEX    () { 'I'    }
+sub SIG_BLIST    () { 'B'    }
+sub SIG_FREE     () { 'F'    }
+sub SIG_SIZE     () {  1     }
+
+=head2 get_next_key( $obj, $prev_key )
+
+This takes an object that provides _base_offset() and an optional string
+representing the prior key returned via a prior invocation of this method.
+
+This method delegates to C<< DBM::Deep::Iterator->get_next_key() >>.
+
+=cut
+
+# XXX Add staleness here
+sub get_next_key {
+    my $self = shift;
+    my ($obj, $prev_key) = @_;
+
+    # XXX Need to add logic about resetting the iterator if any key in the reference has changed
+    unless ( $prev_key ) {
+        $obj->{iterator} = DBM::Deep::Iterator->new({
+            base_offset => $obj->_base_offset,
+            engine      => $self,
+        });
+    }
+
+    return $obj->{iterator}->get_next_key( $obj );
+}
+
+1;
+__END__