Dpkg::parse contains utilities to parse the various files created by dpkg and turn them into helpful perl objects. current files understood by various dpkg::parse modules:

/var/lib/dpkg/status - dpkg::parse::status

/var/lib/dpkg/available - dpkg::parse::available

packages.gz - dpkg::parse::packages

see each module's documentation for particulars - you should not be calling dpkg::parse directly.