Mass Deface [1]; $self; } sub CLEAR { local($self) = @_; $$self[0] = "\0" x ($$self[4] * $$self[3]->[1]); $$self[5] = 0; $$self[6] = -1; } sub FETCH { local($self,$key) = @_; local($klen, $vlen, $tsize, $rlen) = @$self[1..4]; &hashkey; for (;;) { $offset = $hash * $rlen; $record = substr($$self[0], $offset, $rlen); if (ord($record) == 0) { return undef; } elsif (ord($record) == 1) { } elsif (substr($record, 1, $klen) eq $key) { return substr($record, 1+$klen, $vlen); } &rehash; } } sub STORE { local($self,$key,$val) = @_; local($klen, $vlen, $tsize, $rlen) = @$self[1..4]; croak("Table is full ($tsize->[0] elements)") if $$self[5] > $tsize->[0]; croak(qq/Value "$val" is not $vlen characters long/) if length($val) != $vlen; my $writeoffset; &hashkey; for (;;) { $offset = $hash * $rlen; $record = substr($$self[0], $offset, $rlen); if (ord($record) == 0) { $record = "\2". $key . $val; die "panic" unless length($record) == $rlen; $writeoffset = $offset unless defined $writeoffset; substr($$self[0], $writeoffset, $rlen) = $record; ++$$self[5]; return; } elsif (ord($record) == 1) { $writeoffset = $offset unless defined $writeoffset; } elsif (substr($record, 1, $klen) eq $key) { $record = "\2". $key . $val; die "panic" unless length($record) == $rlen; substr($$self[0], $offset, $rlen) = $record; return; } &rehash; } } sub DELETE { local($self,$key) = @_; local($klen, $vlen, $tsize, $rlen) = @$self[1..4]; &hashkey; for (;;) { $offset = $hash * $rlen; $record = substr($$self[0], $offset, $rlen); if (ord($record) == 0) { return undef; } elsif (ord($record) == 1) { } elsif (substr($record, 1, $klen) eq $key) { substr($$self[0], $offset, 1) = "\1"; return substr($record, 1+$klen, $vlen); --$$self[5]; } &rehash; } } sub FIRSTKEY { local($self) = @_; $$self[6] = -1; &NEXTKEY; } sub NEXTKEY { local($self) = @_; local($klen, $vlen, $tsize, $rlen, $entries, $iterix) = @$self[1..6]; for (++$iterix; $iterix < $tsize->[1]; ++$iterix) { next unless substr($$self[0], $iterix * $rlen, 1) eq "\2"; $$self[6] = $iterix; return substr($$self[0], $iterix * $rlen + 1, $klen); } $$self[6] = -1; undef; } sub EXISTS { croak "Tie::SubstrHash does not support exists()"; } sub hashkey { croak(qq/Key "$key" is not $klen characters long/) if length($key) != $klen; $hash = 2; for (unpack('C*', $key)) { $hash = $hash * 33 + $_; &_hashwrap if $hash >= 1e13; } &_hashwrap if $hash >= $tsize->[1]; $hash = 1 unless $hash; $hashbase = $hash; } sub _hashwrap { $hash -= int($hash / $tsize->[1]) * $tsize->[1]; } sub rehash { $hash += $hashbase; $hash -= $tsize->[1] if $hash >= $tsize->[1]; } # using POSIX::ceil() would be too heavy, and not all platforms have it. sub ceil { my $num = shift; $num = int($num + 1) unless $num == int $num; return $num; } # See: # # http://www-groups.dcs.st-andrews.ac.uk/~history/HistTopics/Prime_numbers.html # sub findgteprime { # find the smallest prime integer greater than or equal to use integer; my $num = ceil(shift); return 2 if $num <= 2; $num++ unless $num % 2; my $i; my $sqrtnum = int sqrt $num; my $sqrtnumsquared = $sqrtnum * $sqrtnum; NUM: for (;; $num += 2) { if ($sqrtnumsquared < $num) { $sqrtnum++; $sqrtnumsquared = $sqrtnum * $sqrtnum; } for ($i = 3; $i <= $sqrtnum; $i += 2) { next NUM unless $num % $i; } return $num; } } 1;