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|
#!/usr/local/bin/perl
package TiedHash;
use strict;
use warnings;
use DB_File;
use Carp;
=example
my $tied_hash = new TiedHash( { create => "$pfam_db.inx" } );
my $acc = "";
while (<$fh>) {
chomp;
my ($token, $rest) = split (/\s+/, $_, 2);
if ($token eq 'NAME') {
$acc = $rest;
}
elsif ($token =~ /^(NC|TC|DESC|ACC)$/) {
my $key = "$acc$;$token";
$tied_hash->store_key_value($key, $rest);
print STDERR "storing: $key, $rest\n";
}
=cut
sub new {
my $packagename = shift;
my $prefs_href = shift;
if ($prefs_href && ! ref $prefs_href) {
confess "Error, need hash reference with opts in constructor.\n";
}
my $self = {
index_filename => undef,
tied_index => {},
tie_invoked => 0,
};
bless ($self, $packagename);
if (ref $prefs_href eq "HASH") {
if (my $index_file = $prefs_href->{"create"}) {
$self->create_index_file($index_file);
}
elsif ($index_file = $prefs_href->{"use"}) {
$self->use_index_file($index_file);
}
}
return ($self);
}
####
sub tie_invoked {
my $self = shift;
return ($self->{tie_invoked});
}
####
sub DESTROY {
my $self = shift;
if ($self->{index_filename}) {
# hash must have been tied
# so, untie it
untie (%{$self->{tied_index}});
}
}
####
sub create_index_file {
my $self = shift;
return ($self->make_index_file(@_));
}
####
sub make_index_file {
my $self = shift;
my $filename = shift;
unless ($filename) {
confess "need filename as parameter";
}
if (-e $filename) {
unlink $filename or confess "cannot remove existing index filename $filename";
}
$self->{index_filename} = $filename;
tie (%{$self->{tied_index}}, 'DB_File', $filename, O_CREAT|O_RDWR, 0666, $DB_BTREE);
$self->{tie_invoked} = 1;
return;
}
####
sub use_index_file {
my $self = shift;
my $filename = shift;
unless ($filename) {
confess "need filename as parameter";
}
unless (-s $filename) {
confess "Error, cannot locate file: $filename\n";
}
$self->{index_filename} = $filename;
tie (%{$self->{tied_index}}, 'DB_File', $filename, O_RDONLY, 0, $DB_BTREE);
$self->{tie_invoked} = 1;
#my @keys = $self->get_keys();
#unless (@keys) {
# confess "Error, tried using $filename db, but couldn't perform retrievals.\n";
#}
return;
}
####
sub store_key_value {
my ($self, $identifier, $value) = @_;
#my $num_keys = scalar ($self->get_keys());
unless ($self->tie_invoked()) {
confess "Error, cannot store key/value pair since tied hash not created.\n";
}
my $found = 0;
while (! $found) {
$self->{tied_index}->{$identifier} = $value;
my $val = $self->get_value($identifier);
if (defined $val) {
$found = 1;
}
else {
warn "Berkeley DB had trouble storing ($identifier); trying again.\n";
}
}
return;
}
####
sub get_value {
my $self = shift;
my $identifier = shift;
unless ($self->tie_invoked()) {
confess "Error, cannot retrieve value from untied hash\n";
}
my $value = $self->{tied_index}->{$identifier};
return ($value);
}
##
sub get_keys {
my $self = shift;
unless ($self->tie_invoked()) {
confess "Error, cannot retrieve values from untied hash\n";
}
return (keys %{$self->{tied_index}});
}
1; #EOM
|
