Add option to switch between Z3 and CVC4

src/Options.hs

 {-# LANGUAGE TupleSections #-}
 
 module Options
-    (InputFormat(..),OutputFormat(..),RefinementType(..),RefinementOption(..),
+    (InputFormat(..),OutputFormat(..),RefinementType(..),RefinementOption(..),BackendSolver(..),
      PropertyOption(..),Options(..),startOptions,options,parseArgs,
      usageInformation)
 where
@@ -20,6 +20,9 @@ instance Show InputFormat where
 instance Show OutputFormat where
         show OutDOT = "DOT"
 
+data BackendSolver = Z3
+                   | CVC4
+
 data RefinementType = TrapRefinement
                     | SiphonRefinement
                     | UTrapRefinement
@@ -37,6 +40,7 @@ data Options = Options { inputFormat :: InputFormat
                        , optVerbosity :: Int
                        , optShowHelp :: Bool
                        , optShowVersion :: Bool
+                       , optSolver :: BackendSolver
                        , optProperties :: PropertyOption
                        , optRefinementType :: RefinementOption
                        , optMinimizeRefinement :: Int
@@ -52,6 +56,7 @@ startOptions = Options { inputFormat = InPP
                        , optVerbosity = 1
                        , optShowHelp = False
                        , optShowVersion = False
+                       , optSolver = Options.Z3
                        , optProperties = PropDefault
                        , optRefinementType = RefDefault
                        , optMinimizeRefinement = 0
@@ -88,6 +93,16 @@ options =
         (NoArg (\opt -> Right opt { optInvariant = True }))
         "Generate an invariant"
 
+        , Option "" ["solver"]
+        (ReqArg (\arg opt ->
+            case arg of
+                        "z3" -> Right opt { optSolver = Options.Z3 }
+                        "cvc4" -> Right opt { optSolver = Options.CVC4 }
+                        _ -> Left ("invalid argument for refinement method: " ++ arg)
+                )
+                "SOLVER")
+        ("Use backend solver SOLVER (z3, cvc4)")
+
         , Option "r" ["refinement"]
         (ReqArg (\arg opt ->
                     let addRef ref =

src/Solver.hs

@@ -32,15 +32,22 @@ symConstraints vars exVars allVars constraint = do
         allSyms <- mapM forall allVars
         return $ constraint $ val $ M.fromList $ (vars `zip` syms) ++ (exVars `zip` exSyms) ++ (allVars `zip` allSyms)
 
-getSolverConfig :: Bool -> SMTConfig
-getSolverConfig verbose = z3{ verbose=verbose }
+getSolverConfig :: BackendSolver -> Bool -> SMTConfig
+getSolverConfig Options.Z3 verbose = z3 { verbose=verbose }
+getSolverConfig Options.CVC4 verbose =
+        cvc4 {
+            verbose=verbose,
+            solverSetOptions = [],
+            solver = (solver cvc4) { Data.SBV.options = const ["--lang", "smt", "--incremental", "--no-interactive-prompt"] }
+        }
 
 checkSat :: (SatModel a, SymWord a, Show a, Show b) =>
         ConstraintProblem a b -> OptIO (Maybe b)
 checkSat (problemName, resultName, vars, exVars, allVars, constraint, interpretation) = do
         verbosePut 2 $ "Checking SAT of " ++ problemName
         verbosity <- opt optVerbosity
-        result <- liftIO (satWith (getSolverConfig (verbosity >= 4))
+        solver <- opt optSolver
+        result <- liftIO (satWith (getSolverConfig solver (verbosity >= 4))
                     (symConstraints vars exVars allVars constraint))
         case rebuildModel vars (getModelAssignment result) of
             Nothing -> do