From adffa185bb249394ef651392b41b7a20b26031cc Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Sat, 11 Jan 2020 08:32:25 +0100
Subject: [PATCH] Parse interface type definition

---
 semaphoreci.sh                           |  6 +++---
 src/Language/GraphQL/AST/Parser.hs       | 10 ++++++++++
 src/Language/GraphQL/Schema.hs           |  2 +-
 tests/Language/GraphQL/AST/ParserSpec.hs |  7 +++++++
 4 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/semaphoreci.sh b/semaphoreci.sh
index eb9ef38..d7c8a93 100755
--- a/semaphoreci.sh
+++ b/semaphoreci.sh
@@ -10,10 +10,10 @@ setup() {
 	fi
 	if [ -e "$SEMAPHORE_CACHE_DIR/graphql.cabal" ]
 	then
-            cp -a $SEMAPHORE_CACHE_DIR/graphql.cabal graphql.cabal
-        fi
+		cp -a $SEMAPHORE_CACHE_DIR/graphql.cabal graphql.cabal
+	fi
 	$STACK --no-terminal setup
-        cp -a graphql.cabal $SEMAPHORE_CACHE_DIR/graphql.cabal
+	cp -a graphql.cabal $SEMAPHORE_CACHE_DIR/graphql.cabal
 }
 
 setup_test() {
diff --git a/src/Language/GraphQL/AST/Parser.hs b/src/Language/GraphQL/AST/Parser.hs
index 274045d..41748b2 100644
--- a/src/Language/GraphQL/AST/Parser.hs
+++ b/src/Language/GraphQL/AST/Parser.hs
@@ -38,6 +38,7 @@ typeSystemDefinition = schemaDefinition
 typeDefinition :: Parser TypeDefinition
 typeDefinition = scalarTypeDefinition
     <|> objectTypeDefinition
+    <|> interfaceTypeDefinition
     <|> unionTypeDefinition
     <?> "TypeDefinition"
 
@@ -83,6 +84,15 @@ unionMemberTypes sepBy' = UnionMemberTypes
     <*> name `sepBy'` pipe
     <?> "UnionMemberTypes"
 
+interfaceTypeDefinition :: Parser TypeDefinition
+interfaceTypeDefinition = InterfaceTypeDefinition
+    <$> description
+    <* symbol "interface"
+    <*> name
+    <*> opt directives
+    <*> braces (many fieldDefinition)
+    <?> "InterfaceTypeDefinition"
+
 implementsInterfaces ::
     Foldable t =>
     (Parser Text -> Parser Text -> Parser (t NamedType)) ->
diff --git a/src/Language/GraphQL/Schema.hs b/src/Language/GraphQL/Schema.hs
index 8bdf605..661e452 100644
--- a/src/Language/GraphQL/Schema.hs
+++ b/src/Language/GraphQL/Schema.hs
@@ -94,7 +94,7 @@ resolveFieldValue f resolveRight fld@(Field _ _ args _) = do
             _ <- addErrMsg err
             return $ HashMap.singleton (aliasOrName fld) Aeson.Null
 
--- | Helper function to facilitate 'Argument' handling.
+-- | Helper function to facilitate error handling and result emitting.
 withField :: (MonadIO m, Aeson.ToJSON a)
     => CollectErrsT m a -> Field -> CollectErrsT m (HashMap Text Aeson.Value)
 withField v fld
diff --git a/tests/Language/GraphQL/AST/ParserSpec.hs b/tests/Language/GraphQL/AST/ParserSpec.hs
index e1b48d8..efb5b63 100644
--- a/tests/Language/GraphQL/AST/ParserSpec.hs
+++ b/tests/Language/GraphQL/AST/ParserSpec.hs
@@ -74,3 +74,10 @@ spec = describe "Parser" $ do
         parse document "" `shouldSucceedOn` [r|
             union SearchResult = Photo | Person
         |]
+
+    it "parses minimal interface type definition" $
+        parse document "" `shouldSucceedOn` [r|
+            interface NamedEntity {
+              name: String
+            }
+        |]