What's the most robust way to parse a source package's debian/changelog file (or debian/control?) to get the package's version number? Something like:

pkgver=$(dpkg-parsechangelog | magic_goes_here)

I want to extract the version number (and only the version number) so that I can manipulate it in a script.

I was expecting to find a dpkg-* utility for this purpose, but I haven't found one yet.