Add flag to format not .cabal file

Like cabal.project or cabal.haskell-ci

Makefile

@@ -10,6 +10,9 @@ self-test :
 self-test-2 :
 	cabal v2-run cabal-fmt -- --no-tabular cabal-fmt.cabal
 
+self-test-3 :
+	cabal v2-run cabal-fmt -- --no-cabal-file cabal.project
+
 self-test-raw :
 	$$(cabal-plan list-bin cabal-fmt) cabal-fmt.cabal
 

cli/Main.hs

@@ -90,6 +90,8 @@ optsP = (,)
         , indentP
         , tabularP
         , noTabularP
+        , cabalFileP
+        , noCabalFileP
         , stdoutP
         , inplaceP
         , checkP
@@ -110,6 +112,12 @@ optsP = (,)
     noTabularP = O.flag' (mkOptionsMorphism $ \opts -> opts { optTabular = False })
         $ O.long "no-tabular"
 
+    cabalFileP = O.flag' (mkOptionsMorphism $ \opts -> opts { optCabalFile = True })
+        $ O.long "cabal-file"
+
+    noCabalFileP = O.flag' (mkOptionsMorphism $ \opts -> opts { optCabalFile = False })
+        $ O.short 'n' <> O.long "no-cabal-file" <> O.help "Don't parse as .cabal file"
+
     stdoutP = O.flag' (mkOptionsMorphism $ \opts -> opts { optMode = ModeStdout })
         $ O.long "stdout" <> O.help "Write output to stdout (default)"
 

src/CabalFmt.hs

@@ -48,7 +48,6 @@ import CabalFmt.Refactoring
 
 cabalFmt :: MonadCabalFmt r m => FilePath -> BS.ByteString -> m String
 cabalFmt filepath contents = do
-    gpd          <- parseGpd filepath contents
     inputFields' <- parseFields contents
     let (inputFieldsC, endComments) = attachComments contents inputFields'
 
@@ -62,16 +61,23 @@ cabalFmt filepath contents = do
     inputFieldsR  <- foldM (&) inputFieldsP refactorings
 
     -- options morphisms
-    let pragmas = foldMap (foldMap snd) inputFieldsR <> endCommentsPragmas
+    let pragmas :: [Pragma]
+        pragmas = foldMap (foldMap snd) inputFieldsR <> endCommentsPragmas
+
         optsEndo :: OptionsMorphism
         optsEndo = foldMap pragmaToOM pragmas
 
-    let v = C.cabalSpecFromVersionDigits
-          $ C.versionNumbers
-          $ C.specVersion
-          $ C.packageDescription gpd
-
-    local (over options $ \o -> runOptionsMorphism optsEndo $ o { optSpecVersion = v }) $ do
+    cabalFile <- asks (optCabalFile . view options)
+    csv <- case cabalFile of
+        False -> return C.cabalSpecLatest
+        True  -> do
+            gpd <- parseGpd filepath contents
+            return $ C.cabalSpecFromVersionDigits
+              $ C.versionNumbers
+              $ C.specVersion
+              $ C.packageDescription gpd
+
+    local (over options $ \o -> runOptionsMorphism optsEndo $ o { optSpecVersion = csv }) $ do
         indentWith <- asks (optIndent . view options)
         let inputFields = fmap (fmap fst) inputFieldsR
 

src/CabalFmt/Options.hs

@@ -23,6 +23,7 @@ data Options = Options
     { optError       :: !Bool
     , optIndent      :: !Int
     , optTabular     :: !Bool
+    , optCabalFile   :: !Bool
     , optSpecVersion :: !C.CabalSpecVersion
     , optMode        :: !Mode
     }
@@ -33,6 +34,7 @@ defaultOptions = Options
     { optError       = False
     , optIndent      = 2
     , optTabular     = True
+    , optCabalFile   = True
     , optSpecVersion = C.cabalSpecLatest
     , optMode        = ModeStdout
     }