module Distribution.Client.Dependency.Modular.Assignment where
import Control.Applicative
import Control.Monad
import Data.Array as A
import Data.List as L
import Data.Map as M
import Data.Maybe
import Data.Graph
import Prelude hiding (pi)
import Distribution.PackageDescription (FlagAssignment) -- from Cabal
import Distribution.Client.Types (OptionalStanza)
import Distribution.Client.Dependency.Modular.Configured
import Distribution.Client.Dependency.Modular.Dependency
import Distribution.Client.Dependency.Modular.Flag
import Distribution.Client.Dependency.Modular.Index
import Distribution.Client.Dependency.Modular.Package
import Distribution.Client.Dependency.Modular.Version
-- | A (partial) package assignment. Qualified package names
-- are associated with instances.
type PAssignment = Map QPN I
-- | A (partial) package preassignment. Qualified package names
-- are associated with constrained instances. Constrained instances
-- record constraints about the instances that can still be chosen,
-- and in the extreme case fix a concrete instance.
type PPreAssignment = Map QPN (CI QPN)
type FAssignment = Map QFN Bool
type SAssignment = Map QSN Bool
-- | A (partial) assignment of variables.
data Assignment = A PAssignment FAssignment SAssignment
deriving (Show, Eq)
-- | A preassignment comprises knowledge about variables, but not
-- necessarily fixed values.
data PreAssignment = PA PPreAssignment FAssignment SAssignment
-- | Extend a package preassignment.
--
-- Takes the variable that causes the new constraints, a current preassignment
-- and a set of new dependency constraints.
--
-- We're trying to extend the preassignment with each dependency one by one.
-- Each dependency is for a particular variable. We check if we already have
-- constraints for that variable in the current preassignment. If so, we're
-- trying to merge the constraints.
--
-- Either returns a witness of the conflict that would arise during the merge,
-- or the successfully extended assignment.
extend :: Var QPN -> PPreAssignment -> [Dep QPN] -> Either (ConflictSet QPN, [Dep QPN]) PPreAssignment
extend var pa qa = foldM (\ a (Dep qpn ci) ->
let ci' = M.findWithDefault (Constrained []) qpn a
in case (\ x -> M.insert qpn x a) <$> merge ci' ci of
Left (c, (d, d')) -> Left (c, L.map (Dep qpn) (simplify (P qpn) d d'))
Right x -> Right x)
pa qa
where
-- We're trying to remove trivial elements of the conflict. If we're just
-- making a choice pkg == instance, and pkg => pkg == instance is a part
-- of the conflict, then this info is clear from the context and does not
-- have to be repeated.
simplify v (Fixed _ (Goal var' _)) c | v == var && var' == var = [c]
simplify v c (Fixed _ (Goal var' _)) | v == var && var' == var = [c]
simplify _ c d = [c, d]
-- | Delivers an ordered list of fully configured packages.
--
-- TODO: This function is (sort of) ok. However, there's an open bug
-- w.r.t. unqualification. There might be several different instances
-- of one package version chosen by the solver, which will lead to
-- clashes.
toCPs :: Assignment -> RevDepMap -> [CP QPN]
toCPs (A pa fa sa) rdm =
let
-- get hold of the graph
g :: Graph
vm :: Vertex -> ((), QPN, [QPN])
cvm :: QPN -> Maybe Vertex
-- Note that the RevDepMap contains duplicate dependencies. Therefore the nub.
(g, vm, cvm) = graphFromEdges (L.map (\ (x, xs) -> ((), x, nub xs))
(M.toList rdm))
tg :: Graph
tg = transposeG g
-- Topsort the dependency graph, yielding a list of pkgs in the right order.
-- The graph will still contain all the installed packages, and it might
-- contain duplicates, because several variables might actually resolve to
-- the same package in the presence of qualified package names.
ps :: [PI QPN]
ps = L.map ((\ (_, x, _) -> PI x (pa M.! x)) . vm) $
topSort g
-- Determine the flags per package, by walking over and regrouping the
-- complete flag assignment by package.
fapp :: Map QPN FlagAssignment
fapp = M.fromListWith (++) $
L.map (\ ((FN (PI qpn _) fn), b) -> (qpn, [(fn, b)])) $
M.toList $
fa
-- Stanzas per package.
sapp :: Map QPN [OptionalStanza]
sapp = M.fromListWith (++) $
L.map (\ ((SN (PI qpn _) sn), b) -> (qpn, if b then [sn] else [])) $
M.toList $
sa
-- Dependencies per package.
depp :: QPN -> [PI QPN]
depp qpn = let v :: Vertex
v = fromJust (cvm qpn)
dvs :: [Vertex]
dvs = tg A.! v
in L.map (\ dv -> case vm dv of (_, x, _) -> PI x (pa M.! x)) dvs
in
L.map (\ pi@(PI qpn _) -> CP pi
(M.findWithDefault [] qpn fapp)
(M.findWithDefault [] qpn sapp)
(depp qpn))
ps
-- | Finalize an assignment and a reverse dependency map.
--
-- This is preliminary, and geared towards output right now.
finalize :: Index -> Assignment -> RevDepMap -> IO ()
finalize idx (A pa fa _) rdm =
let
-- get hold of the graph
g :: Graph
vm :: Vertex -> ((), QPN, [QPN])
(g, vm) = graphFromEdges' (L.map (\ (x, xs) -> ((), x, xs)) (M.toList rdm))
-- topsort the dependency graph, yielding a list of pkgs in the right order
f :: [PI QPN]
f = L.filter (not . instPI) (L.map ((\ (_, x, _) -> PI x (pa M.! x)) . vm) (topSort g))
fapp :: Map QPN [(QFN, Bool)] -- flags per package
fapp = M.fromListWith (++) $
L.map (\ (qfn@(FN (PI qpn _) _), b) -> (qpn, [(qfn, b)])) $ M.toList $ fa
-- print one instance
ppi pi@(PI qpn _) = showPI pi ++ status pi ++ " " ++ pflags (M.findWithDefault [] qpn fapp)
-- print install status
status :: PI QPN -> String
status (PI (Q _ pn) _) =
case insts of
[] -> " (new)"
vs -> " (" ++ intercalate ", " (L.map showVer vs) ++ ")"
where insts = L.map (\ (I v _) -> v) $ L.filter isInstalled $
M.keys (M.findWithDefault M.empty pn idx)
isInstalled (I _ (Inst _ )) = True
isInstalled _ = False
-- print flag assignment
pflags = unwords . L.map (uncurry showFBool)
in
-- show packages with associated flag assignments
putStr (unlines (L.map ppi f))