src/Darcs/Patch/Set.lhs

   1 %  Copyright (C) 2003 David Roundy
   2 %
   3 %  This program is free software; you can redistribute it and/or modify
   4 %  it under the terms of the GNU General Public License as published by
   5 %  the Free Software Foundation; either version 2, or (at your option)
   6 %  any later version.
   7 %
   8 %  This program is distributed in the hope that it will be useful,
   9 %  but WITHOUT ANY WARRANTY; without even the implied warranty of
  10 %  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11 %  GNU General Public License for more details.
  12 %
  13 %  You should have received a copy of the GNU General Public License
  14 %  along with this program; see the file COPYING.  If not, write to
  15 %  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  16 %  Boston, MA 02110-1301, USA.
  17
  18
  19 \begin{code}
  20 {-# OPTIONS_GHC -cpp #-}
  21 {-# LANGUAGE CPP #-}
  22
  23 #include "gadts.h"
  24
  25 module Darcs.Patch.Set ( PatchSet, SealedPatchSet ) where
  26
  27 import Darcs.Hopefully ( PatchInfoAnd )
  28 import Darcs.Ordered ( RL )
  29 import Darcs.Sealed ( Sealed )
  30
  31 -- | A PatchSet is in reverse order, plus has information about which
  32 -- tags are clean, meaning all patches applied prior to them are in
  33 -- the tag itself, so we can stop reading at that point.  Just to
  34 -- clarify, the first patch in a PatchSet is the one most recently
  35 -- applied to the repo.
  36 --
  37 -- 'PatchSet's have the property that if
  38 -- @
  39 -- (info $ last $ head a) == (info $ last $ head b)
  40 -- @
  41 -- then @(tail a)@ and @(tail b)@ are identical repositories
  42 --
  43 -- Questions:
  44 --
  45 -- Does this mean that in a patch set such as @[[a b t1 c d e t2][f g
  46 -- t3] [h i]]@, t1, t2 and t3 are tags, and t2 and t3 are clean?
  47 --
  48 -- Can we have PatchSet with length at least 3?
  49 -- Florent
  50 type PatchSet p C(x) = RL (RL (PatchInfoAnd p)) C(() x)
  51
  52 type SealedPatchSet p = Sealed (RL (RL (PatchInfoAnd p)) C(()))
  53 \end{code}
  54