NAME¶
Stone::Cursor - Traverse tags and values of a Stone
SYNOPSIS¶
use Boulder::Store;
$store = Boulder::Store->new('./soccer_teams');
my $stone = $store->get(28);
$cursor = $stone->cursor;
while (my ($key,$value) = $cursor->each) {
print "$value: Go Bluejays!\n" if $key eq 'State' and $value eq 'Katonah';
}
DESCRIPTION¶
Boulder::Cursor is a utility class that allows you to create one or more
iterators across a Stone object. This is used for traversing large Stone
objects in order to identify or modify portions of the record.
CLASS METHODS¶
- Boulder::Cursor->new($stone)
- Return a new Boulder::Cursor over the specified Stone
object. This will return an error if the object is not a Stone or a
descendent. This method is usually not called directly, but rather
indirectly via the Stone cursor() method:
my $cursor = $stone->cursor;
OBJECT METHODS¶
- $cursor->each()
- Iterate over the attached Stone. Each iteration will
return a two-valued list consisting of a tag path and a value. The tag
path is of a form that can be used with
Stone::index() (in fact, a cursor is used
internally to implement the Stone::dump()
method. When the end of the Stone is reached, "each()"
will return an empty list, after which it will start over again from the
beginning. If you attempt to insert or delete from the stone while
iterating over it, all attached cursors will reset to the beginnning.
For example:
$cursor = $s->cursor;
while (($key,$value) = $cursor->each) {
print "$value: BOW WOW!\n" if $key=~/pet/;
}
- $cursor->reset()
- This resets the cursor back to the beginning of the
associated Stone.
AUTHOR¶
Lincoln D. Stein <lstein@cshl.org>.
COPYRIGHT¶
Copyright 1997-1999, Cold Spring Harbor Laboratory, Cold Spring Harbor NY. This
module can be used and distributed on the same terms as Perl itself.
SEE ALSO¶
Boulder, Stone