feat(cdcl): add solver statistics

src/Sift/Stats.hs

@@ -0,0 +1,27 @@
+module Sift.Stats
+  ( Stats(..)
+  , emptyStats
+  , renderStats
+  ) where
+
+data Stats = Stats
+  { statsDecisions    :: Int
+  , statsConflicts    :: Int
+  , statsPropagations :: Int
+  , statsRestarts     :: Int
+  , statsLearned      :: Int
+  , statsRemoved      :: Int
+  } deriving (Eq, Show)
+
+emptyStats :: Stats
+emptyStats = Stats 0 0 0 0 0 0
+
+renderStats :: Stats -> [String]
+renderStats st =
+  [ "c decisions    " ++ show (statsDecisions st)
+  , "c conflicts     " ++ show (statsConflicts st)
+  , "c propagations  " ++ show (statsPropagations st)
+  , "c restarts      " ++ show (statsRestarts st)
+  , "c learned       " ++ show (statsLearned st)
+  , "c removed       " ++ show (statsRemoved st)
+  ]