Add methodOptions to HasMethodImpl to provide custom method optio…

…ns. (google#331)

We provide the whole proto message, rather than pulling off individual fields. The set of fields may change for different builds of proto-lens (or based on extensions, though we can't see those directly due to google#27).

Internally, we save the proto message in the source file as an encoded string, and decode it into a Haskell type lazily.

Changelog.md

@@ -5,6 +5,7 @@
 ### Breaking Changes
 - Reexport transitive definitions from modules generated for `.proto` files
   with `import public` statements (#329).
+- Add `methodOptions` to `HasMethodImpl` to provide custom method options.
 
 ### Backwards-Compatible Changes
 - Fix a potential naming conflict when message types and enum values

package.yaml

@@ -18,6 +18,7 @@ extra-source-files:
 
 dependencies:
   - base >= 4.9 && < 4.13
+  - bytestring == 0.10.*
   - containers >= 0.5 && < 0.7
   - lens-family == 1.2.*
   - proto-lens == 0.5.*
@@ -41,5 +42,4 @@ executables:
     main: protoc-gen-haskell.hs
     source-dirs: app
     dependencies:
-      - bytestring == 0.10.*
       - proto-lens-protoc

src/Data/ProtoLens/Compiler/Definitions.hs

@@ -70,6 +70,7 @@ import Proto.Google.Protobuf.Descriptor
     , FieldDescriptorProto'Type(..)
     , FileDescriptorProto
     , MethodDescriptorProto
+    , MethodOptions
     , ServiceDescriptorProto
     )
 import Proto.Google.Protobuf.Descriptor_Fields
@@ -160,6 +161,7 @@ data MethodInfo = MethodInfo
     , methodOutput :: Text
     , methodClientStreaming :: Bool
     , methodServerStreaming :: Bool
+    , methodOptions :: MethodOptions
     }
 
 -- | Information about a single field of a proto message,
@@ -352,6 +354,7 @@ collectServices fd = fmap (toServiceInfo $ fd ^. package) $ fd ^. service
             , methodOutput = fromString . T.unpack $ md ^. outputType
             , methodClientStreaming = md ^. clientStreaming
             , methodServerStreaming = md ^. serverStreaming
+            , methodOptions = md ^. options
             }
 
 messageAndEnumDefs ::

src/Data/ProtoLens/Compiler/Generate.hs

@@ -16,12 +16,14 @@ module Data.ProtoLens.Compiler.Generate(
 
 
 import Control.Arrow (second)
+import qualified Data.ByteString.Char8 as B
 import qualified Data.Foldable as F
 import qualified Data.List as List
 import qualified Data.Map as Map
 import Data.Maybe (isJust)
 import Data.Monoid ((<>))
 import Data.Ord (comparing)
+import Data.ProtoLens (encodeMessage)
 import qualified Data.Set as Set
 import Data.String (fromString)
 import Data.Text (unpack)
@@ -263,6 +265,14 @@ generateServiceDecls env si =
                      (True,  False) -> "Data.ProtoLens.Service.Types.ClientStreaming"
                      (False, True)  -> "Data.ProtoLens.Service.Types.ServerStreaming"
                      (True,  True)  -> "Data.ProtoLens.Service.Types.BiDiStreaming"
+        -- methodOptions _ _ = decodeMessageOrDie (pack "...")
+        -- (where "..." is the encoded version of the proto message).
+        , instMatch
+            [ match "methodOptions" [pWildCard, pWildCard]
+                $ "Data.ProtoLens.decodeMessageOrDie"
+                      @@ ("Data.ByteString.Char8.pack"
+                            @@ stringExp (B.unpack $ encodeMessage $ methodOptions m))
+            ]
         ]
     | m <- serviceMethods si
     , let instanceHead = tyPromotedString (T.unpack $ methodIdent m)