Initial Commit

database/perl/lib/Memoize/SDBM_File.pm

@@ -0,0 +1,75 @@
+package Memoize::SDBM_File;
+
+=head1 NAME
+
+Memoize::SDBM_File - glue to provide EXISTS for SDBM_File for Storable use
+
+=head1 DESCRIPTION
+
+See L<Memoize>.
+
+=cut
+
+use SDBM_File;
+@ISA = qw(SDBM_File);
+$VERSION = '1.03';
+
+$Verbose = 0;
+
+sub AUTOLOAD {
+  warn "Nonexistent function $AUTOLOAD invoked in Memoize::SDBM_File\n";
+}
+
+sub import {
+  warn "Importing Memoize::SDBM_File\n" if $Verbose;
+}
+
+
+my %keylist;
+
+# This is so ridiculous...
+sub _backhash {
+  my $self = shift;
+  my %fakehash;
+  my $k; 
+  for ($k = $self->FIRSTKEY(); defined $k; $k = $self->NEXTKEY($k)) {
+    $fakehash{$k} = undef;
+  }
+  $keylist{$self} = \%fakehash;
+}
+
+sub EXISTS {
+  warn "Memoize::SDBM_File EXISTS (@_)\n" if $Verbose;
+  my $self = shift;
+  _backhash($self)  unless exists $keylist{$self};
+  my $r = exists $keylist{$self}{$_[0]};
+  warn "Memoize::SDBM_File EXISTS (@_) ==> $r\n" if $Verbose;
+  $r;
+}
+
+sub DEFINED {
+  warn "Memoize::SDBM_File DEFINED (@_)\n" if $Verbose;
+  my $self = shift;
+  _backhash($self)  unless exists $keylist{$self};
+  defined $keylist{$self}{$_[0]};
+}
+
+sub DESTROY {
+  warn "Memoize::SDBM_File DESTROY (@_)\n" if $Verbose;
+  my $self = shift;
+  delete $keylist{$self};   # So much for reference counting...
+  $self->SUPER::DESTROY(@_);
+}
+
+# Maybe establish the keylist at TIEHASH time instead?
+
+sub STORE {
+  warn "Memoize::SDBM_File STORE (@_)\n" if $VERBOSE;
+  my $self = shift;
+  $keylist{$self}{$_[0]} = undef;
+  $self->SUPER::STORE(@_);
+}
+
+# Inherit FETCH and TIEHASH
+
+1;