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{-|
Module : VeriFuzz.Graph.Random
Description : Random generation for DAG
Copyright : (c) 2018-2019, Yann Herklotz Grave
License : BSD-3
Maintainer : ymherklotz [at] gmail [dot] com
Stability : experimental
Portability : POSIX
Define the random generation for the directed acyclic graph.
-}
module VeriFuzz.Graph.Random where
import Data.Graph.Inductive (Context, LEdge)
import qualified Data.Graph.Inductive as G
import Data.Graph.Inductive.PatriciaTree (Gr)
import Data.List (nub)
import Test.QuickCheck (Arbitrary, Gen)
import qualified Test.QuickCheck as QC
dupFolder :: (Eq a, Eq b) => Context a b -> [Context a b] -> [Context a b]
dupFolder cont ns = unique cont : ns where unique (a, b, c, d) = (nub a, b, c, nub d)
-- | Remove duplicates.
rDups :: (Eq a, Eq b) => Gr a b -> Gr a b
rDups g = G.buildGr $ G.ufold dupFolder [] g
-- | Gen instance to create an arbitrary edge, where the edges are limited by
-- `n` that is passed to it.
arbitraryEdge :: (Arbitrary e) => Int -> Gen (LEdge e)
arbitraryEdge n = do
x <- with $ \a -> a < n && a > 0 && a /= n - 1
y <- with $ \a -> x < a && a < n && a > 0
z <- QC.arbitrary
return (x, y, z)
where with = QC.suchThat $ QC.resize n QC.arbitrary
-- | Gen instance for a random acyclic DAG.
randomDAG :: (Arbitrary l, Arbitrary e, Eq l, Eq e) => Gen (Gr l e) -- ^ The generated graph. It uses Arbitrary to
-- generate random instances of each node
randomDAG = do
list <- QC.infiniteListOf QC.arbitrary
l <- QC.infiniteListOf aE
QC.sized (\n -> return . G.mkGraph (nodes list n) $ take (10 * n) l)
where
nodes l n = zip [0 .. n] $ take n l
aE = QC.sized arbitraryEdge
-- | Generate a random acyclic DAG with an IO instance.
genRandomDAG :: (Arbitrary l, Arbitrary e, Eq l, Eq e) => IO (Gr l e)
genRandomDAG = QC.generate randomDAG
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