feat: add implementation of std.thisFile

Fixes #65

Author: moleike

src/Language/Jsonnet/Eval.hs

@@ -56,6 +56,7 @@ rnf = whnf >=> manifest
 whnfV :: Value -> Eval Value
 whnfV (VIndir loc) = whnfIndir loc >>= whnfV
 whnfV (VThunk c e) = withEnv e (whnf c)
+whnfV (VThunk' v) = v
 whnfV v = pure v
 
 whnf :: Core -> Eval Value
@@ -417,6 +418,7 @@ manifest = \case
   VFun _ -> throwE (ManifestError "function")
   v@VThunk {} -> whnfV v >>= manifest
   v@VIndir {} -> whnfV v >>= manifest
+  v@VThunk' {} -> whnfV v >>= manifest
   _ -> throwE (ManifestError "impossible")
   where
     filterNonAssertionFields :: HashMap Text (JSON.Value, Bool) -> HashMap Text JSON.Value
@@ -517,6 +519,7 @@ showTy = \case
   VPrim _ -> pure "function"
   VThunk {} -> pure "thunk"
   VIndir {} -> pure "pointer"
+  VThunk' _ -> pure "thunk"
 
 --v@VThunk {} -> whnfV v >>= showTy
 --v@VIndir {} -> whnfV v >>= showTy
@@ -597,6 +600,10 @@ instance {-# OVERLAPS #-} (HasValue a, HasValue b, HasValue c) => HasValue (a ->
   {-# INLINE inj #-}
   proj = throwTypeMismatch "impossible"
 
+instance {-# OVERLAPS #-} HasValue a => HasValue (Eval a) where
+  inj a = VThunk' $ inj <$> a
+  proj = proj'
+
 instance {-# OVERLAPS #-} (HasValue a, HasValue b) => HasValue (a -> Eval b) where
   inj f = VFun $ proj' >=> fmap inj . f
   {-# INLINE inj #-}

src/Language/Jsonnet/Eval/Monad.hs

@@ -21,9 +21,10 @@ import qualified Data.Map.Lazy as M (union)
 import Language.Jsonnet.Common (Backtrace (..), StackFrame (..))
 import Language.Jsonnet.Core (Core)
 import Language.Jsonnet.Error (Error (EvalError), EvalError)
-import Language.Jsonnet.Parser.SrcSpan (SrcSpan)
+import Language.Jsonnet.Parser.SrcSpan (SrcSpan, spanBegin)
 import Unbound.Generics.LocallyNameless
 import Unbound.Generics.LocallyNameless.Name
+import Text.Megaparsec.Pos
 
 type Ctx a = Map (Name Core) a
 
@@ -107,3 +108,6 @@ getBacktrace = do
       case sequence sp of
         Just sp' -> zipWith StackFrame sc sp'
         Nothing -> []
+
+getFilename :: EvalM a (Maybe FilePath)
+getFilename = (sourceName . spanBegin <$>) <$> view currentPos

src/Language/Jsonnet/Std/Lib.hs

@@ -28,7 +28,7 @@ import Data.Word
 import Language.Jsonnet.Common
 import Language.Jsonnet.Error
 import Language.Jsonnet.Eval
-import Language.Jsonnet.Eval.Monad
+import Language.Jsonnet.Eval.Monad (getFilename, throwE)
 import Language.Jsonnet.Value
 import Unbound.Generics.LocallyNameless
 import Prelude hiding (length)
@@ -71,7 +71,8 @@ std extVars = VObj $ H.fromList $ map f xs
         ("objectHasEx", inj objectHasEx),
         ("objectFieldsEx", inj objectFieldsEx),
         ("parseJson", inj (JSON.decodeStrict @Value)),
-        ("extVar", inj (lookupExtVar extVars))
+        ("extVar", inj (lookupExtVar extVars)),
+        ("thisFile", inj thisFile)
       ]
 
 lookupExtVar :: ExtVars -> Text -> Eval Value
@@ -105,3 +106,6 @@ makeArray n f = traverse f (V.fromList [0 .. n - 1])
 
 hypot :: Double -> Double -> Double
 hypot a b = sqrt (a * a + b * b)
+
+thisFile :: Eval Value
+thisFile = inj <$> getFilename

src/Language/Jsonnet/Value.hs

@@ -44,6 +44,7 @@ data Value
   | VPrim !Prim
   | VClos !Lam !Env
   | VFun !Fun
+  | VThunk' !(Eval Value)
 
 instance FromJSON Value where
   parseJSON = \case