Commit cc0213f3 authored by Duncan Coutts's avatar Duncan Coutts
Browse files

Add PackageIndex.reverseDependencyClosure

It's similar to dependencyClosure but looks at reverse dependencies.
For example it's useful to find all packages that depend on broken
packages and are thus themselves broken.
parent 32939559
......@@ -42,6 +42,7 @@ module Distribution.Simple.PackageIndex (
-- ** Special queries
......@@ -51,12 +52,13 @@ import Prelude hiding (lookup)
import Control.Exception (assert)
import qualified Data.Map as Map
import Data.Map (Map)
import qualified Data.Tree as Tree
import qualified Data.Graph as Graph
import qualified Data.Array as Array
import Data.Array ((!))
import Data.List (nubBy, group, sort, groupBy, sortBy, find)
import Data.Monoid (Monoid(..))
import Data.Maybe (isNothing)
import Data.Maybe (isNothing, fromMaybe)
import Distribution.Package
( PackageIdentifier, Package(..), packageName, packageVersion
......@@ -285,6 +287,25 @@ dependencyClosure index pkgids0 = case closure mempty [] pkgids0 of
where completed' = insert pkg completed
pkgids' = depends pkg ++ pkgids
-- | Takes the transative closure of the packages reverse dependencies.
-- * The given 'PackageIdentifier's must be in the index.
reverseDependencyClosure :: PackageFixedDeps pkg
=> PackageIndex pkg
-> [PackageIdentifier]
-> [PackageIdentifier]
reverseDependencyClosure index =
map vertexToPkgId
. concatMap Tree.flatten
. Graph.dfs reverseDepGraph
. map (fromMaybe noSuchPkgId . pkgIdToVertex)
(depGraph, vertexToPkgId, pkgIdToVertex) = dependencyGraph index
reverseDepGraph = Graph.transposeG depGraph
noSuchPkgId = error "reverseDependencyClosure: package is not in the graph"
-- | Given a package index where we assume we want to use all the packages
-- (use 'dependencyClosure' if you need to get such a index subset) find out
-- if the dependencies within it use consistent versions of each package.
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