Split FlagAssignment printer/parser out of UserConstraint ones

We want to reuse the FlagAssignment printer/parser for the config files.

(cherry picked from commit d0fb249e)

cabal-install/Distribution/Client/Targets.hs

@@ -44,7 +44,9 @@ module Distribution.Client.Targets (
   UserConstraint(..),
   userConstraintPackageName,
   readUserConstraint,
-  userToPackageConstraint
+  userToPackageConstraint,
+  dispFlagAssignment,
+  parseFlagAssignment,
 
   ) where
 
@@ -758,12 +760,6 @@ instance Text UserConstraint where
                                                     <+> Disp.text "source"
   disp (UserConstraintFlags     pkgname flags)    = disp pkgname
                                                     <+> dispFlagAssignment flags
-    where
-      dispFlagAssignment = Disp.hsep . map dispFlagValue
-      dispFlagValue (f, True)   = Disp.char '+' <> dispFlagName f
-      dispFlagValue (f, False)  = Disp.char '-' <> dispFlagName f
-      dispFlagName (FlagName f) = Disp.text f
-
   disp (UserConstraintStanzas   pkgname stanzas)  = disp pkgname
                                                     <+> dispStanzas stanzas
     where
@@ -773,37 +769,51 @@ instance Text UserConstraint where
 
   parse = parse >>= parseConstraint
     where
-      spaces = Parse.satisfy isSpace >> Parse.skipSpaces
-
       parseConstraint pkgname =
             ((parse >>= return . UserConstraintVersion pkgname)
-        +++ (do spaces
+        +++ (do skipSpaces1
                 _ <- Parse.string "installed"
                 return (UserConstraintInstalled pkgname))
-        +++ (do spaces
+        +++ (do skipSpaces1
                 _ <- Parse.string "source"
                 return (UserConstraintSource pkgname))
-        +++ (do spaces
+        +++ (do skipSpaces1
                 _ <- Parse.string "test"
                 return (UserConstraintStanzas pkgname [TestStanzas]))
-        +++ (do spaces
+        +++ (do skipSpaces1
                 _ <- Parse.string "bench"
                 return (UserConstraintStanzas pkgname [BenchStanzas])))
-        <++ (parseFlagAssignment >>= (return . UserConstraintFlags pkgname))
-
-      parseFlagAssignment = Parse.many1 (spaces >> parseFlagValue)
-      parseFlagValue =
-            (do Parse.optional (Parse.char '+')
-                f <- parseFlagName
-                return (f, True))
-        +++ (do _ <- Parse.char '-'
-                f <- parseFlagName
-                return (f, False))
-      parseFlagName = liftM FlagName ident
-
-      ident :: Parse.ReadP r String
-      ident = Parse.munch1 identChar >>= \s -> check s >> return s
-        where
-          identChar c   = isAlphaNum c || c == '_' || c == '-'
-          check ('-':_) = Parse.pfail
-          check _       = return ()
+        <++ (do skipSpaces1
+                flags <- parseFlagAssignment
+                return (UserConstraintFlags pkgname flags))
+
+--TODO: [code cleanup] move these somewhere else
+dispFlagAssignment :: FlagAssignment -> Disp.Doc
+dispFlagAssignment = Disp.hsep . map dispFlagValue
+  where
+    dispFlagValue (f, True)   = Disp.char '+' <> dispFlagName f
+    dispFlagValue (f, False)  = Disp.char '-' <> dispFlagName f
+    dispFlagName (FlagName f) = Disp.text f
+
+parseFlagAssignment :: Parse.ReadP r FlagAssignment
+parseFlagAssignment = Parse.sepBy1 parseFlagValue skipSpaces1
+  where
+    parseFlagValue =
+          (do Parse.optional (Parse.char '+')
+              f <- parseFlagName
+              return (f, True))
+      +++ (do _ <- Parse.char '-'
+              f <- parseFlagName
+              return (f, False))
+    parseFlagName = liftM (FlagName . lowercase) ident
+
+    ident :: Parse.ReadP r String
+    ident = Parse.munch1 identChar >>= \s -> check s >> return s
+      where
+        identChar c   = isAlphaNum c || c == '_' || c == '-'
+        check ('-':_) = Parse.pfail
+        check _       = return ()
+
+skipSpaces1 :: Parse.ReadP r ()
+skipSpaces1 = Parse.satisfy isSpace >> Parse.skipSpaces
+