  Planets open gaps in discs. Gap opening is typically modeled by considering
the planetary Lindblad torque which repels disc gas away from the planet's
orbit. But gaps also clear because the planet consumes local material. We
present a simple, easy-to-use, analytic framework for calculating how gaps
deplete and how the disc's structure as a whole changes by the combined action
of Lindblad repulsion and planetary consumption. The final mass to which a
gap-embedded gas giant grows is derived in tandem. The analytics are tested
against 1D numerical experiments and calibrated using published
multi-dimensional simulations. In viscous alpha discs, the planet, while
clearing a gap, initially accretes practically all of the gas that tries to
diffuse past, rapidly achieving super-Jupiter if not brown dwarf status. By
contrast, in inviscid discs---that may still accrete onto their central stars
by, say, magnetized winds---planets open deep, repulsion-dominated gaps. Then
only a small fraction of the disc accretion flow is diverted onto the planet,
which grows to a fraction of a Jupiter mass. Transitional disc cavities might
be cleared by families of such low-mass objects opening inviscid,
repulsion-dominated, overlapping gaps which allow most of the outer disc gas to
flow unimpeded onto host stars.
