Add "extend symbol" lexer to parse extensions

src/Language/GraphQL/AST/Document.hs

@@ -8,7 +8,7 @@ module Language.GraphQL.AST.Document
     ( Alias
     , Argument(..)
     , ArgumentsDefinition(..)
-    , Definition(ExecutableDefinition, TypeSystemDefinition)
+    , Definition(..)
     , Description(..)
     , Directive(..)
     , Document
@@ -26,6 +26,7 @@ module Language.GraphQL.AST.Document
     , OperationType(..)
     , OperationTypeDefinition(..)
     , OperationTypeDefinitions
+    , SchemaExtension(..)
     , Selection(..)
     , SelectionSet
     , SelectionSetOpt
@@ -34,6 +35,7 @@ module Language.GraphQL.AST.Document
     , TypeDefinition(..)
     , TypeExtension(..)
     , TypeSystemDefinition(..)
+    , TypeSystemExtension(..)
     , UnionMemberTypes(..)
     , Value(..)
     , VariableDefinition(..)

src/Language/GraphQL/AST/Lexer.hs

@@ -15,6 +15,7 @@ module Language.GraphQL.AST.Lexer
     , dollar
     , comment
     , equals
+    , extend
     , integer
     , float
     , lexeme
@@ -31,6 +32,7 @@ module Language.GraphQL.AST.Lexer
 import Control.Applicative (Alternative(..), liftA2)
 import Data.Char (chr, digitToInt, isAsciiLower, isAsciiUpper, ord)
 import Data.Foldable (foldl')
+import Data.Functor (($>))
 import Data.List (dropWhileEnd)
 import Data.Proxy (Proxy(..))
 import Data.Void (Void)
@@ -217,3 +219,7 @@ escapeSequence = do
 -- | Parser for the "Byte Order Mark".
 unicodeBOM :: Parser ()
 unicodeBOM = optional (char '\xfeff') >> pure ()
+
+-- | Parses "extend" followed by a 'symbol'. It is used by schema extensions.
+extend :: Text -> Parser ()
+extend token = symbol "extend" $> extend token >> pure ()

src/Language/GraphQL/AST/Parser.hs

@@ -215,7 +215,7 @@ schemaDefinition = SchemaDefinition
     <*> operationTypeDefinitions
     <?> "SchemaDefinition"
   where
-    operationTypeDefinitions  = braces $ NonEmpty.some operationTypeDefinition
+    operationTypeDefinitions = braces $ NonEmpty.some operationTypeDefinition
 
 operationTypeDefinition :: Parser OperationTypeDefinition
 operationTypeDefinition = OperationTypeDefinition