[RFC] Add Schema Definition to IDL.

src/language/__tests__/schema-kitchen-sink.graphql

@@ -5,6 +5,11 @@
 # LICENSE file in the root directory of this source tree. An additional grant
 # of patent rights can be found in the PATENTS file in the same directory.
 
+schema {
+  query: QueryType
+  mutation: MutationType
+}
+
 type Foo implements Bar {
   one: Type
   two(argument: InputType!): Type

src/language/__tests__/schema-printer.js

@@ -51,7 +51,12 @@ describe('Printer', () => {
 
     /* eslint-disable max-len */
     expect(printed).to.equal(
-`type Foo implements Bar {
+`schema {
+  query: QueryType
+  mutation: MutationType
+}
+
+type Foo implements Bar {
   one: Type
   two(argument: InputType!): Type
   three(argument: InputType, other: String): Int

src/language/ast.js

@@ -47,12 +47,14 @@ export type Node = Name
                  | NamedType
                  | ListType
                  | NonNullType
+                 | SchemaDefinition
+                 | OperationTypeDefinition
+                 | ScalarTypeDefinition
                  | ObjectTypeDefinition
                  | FieldDefinition
                  | InputValueDefinition
                  | InterfaceTypeDefinition
                  | UnionTypeDefinition
-                 | ScalarTypeDefinition
                  | EnumTypeDefinition
                  | EnumValueDefinition
                  | InputObjectTypeDefinition
@@ -77,19 +79,21 @@ export type Document = {
 
 export type Definition = OperationDefinition
                        | FragmentDefinition
-                       | TypeSystemDefinition
+                       | TypeSystemDefinition // experimental non-spec addition.
 
 export type OperationDefinition = {
   kind: 'OperationDefinition';
   loc?: ?Location;
-  // Note: subscription is an experimental non-spec addition.
-  operation: 'query' | 'mutation' | 'subscription';
+  operation: OperationType;
   name?: ?Name;
   variableDefinitions?: ?Array<VariableDefinition>;
   directives?: ?Array<Directive>;
   selectionSet: SelectionSet;
 }
 
+// Note: subscription is an experimental non-spec addition.
+export type OperationType = 'query' | 'mutation' | 'subscription';
+
 export type VariableDefinition = {
   kind: 'VariableDefinition';
   loc?: ?Location;
@@ -256,10 +260,24 @@ export type NonNullType = {
 
 // Type System Definition
 
-export type TypeSystemDefinition = TypeDefinition
+export type TypeSystemDefinition = SchemaDefinition
+                                 | TypeDefinition
                                  | TypeExtensionDefinition
                                  | DirectiveDefinition
 
+export type SchemaDefinition = {
+  kind: 'SchemaDefinition';
+  loc?: ?Location;
+  operationTypes: Array<OperationTypeDefinition>;
+}
+
+export type OperationTypeDefinition = {
+  kind: 'OperationTypeDefinition';
+  loc?: ?Location;
+  operation: OperationType;
+  type: NamedType;
+}
+
 export type TypeDefinition = ScalarTypeDefinition
                            | ObjectTypeDefinition
                            | InterfaceTypeDefinition

src/language/kinds.js

@@ -50,6 +50,9 @@ export const NON_NULL_TYPE = 'NonNullType';
 
 // Type System Definitions
 
+export const SCHEMA_DEFINITION = 'SchemaDefinition';
+export const OPERATION_TYPE_DEFINITION = 'OperationTypeDefinition';
+
 // Type Definitions
 
 export const SCALAR_TYPE_DEFINITION = 'ScalarTypeDefinition';

src/language/parser.js

@@ -19,6 +19,7 @@ import type {
   Document,
   Definition,
   OperationDefinition,
+  OperationType,
   VariableDefinition,
   SelectionSet,
   Selection,
@@ -41,6 +42,9 @@ import type {
 
   TypeSystemDefinition,
 
+  SchemaDefinition,
+  OperationTypeDefinition,
+
   ScalarTypeDefinition,
   ObjectTypeDefinition,
   FieldDefinition,
@@ -86,6 +90,9 @@ import {
   LIST_TYPE,
   NON_NULL_TYPE,
 
+  SCHEMA_DEFINITION,
+  OPERATION_TYPE_DEFINITION,
+
   SCALAR_TYPE_DEFINITION,
   OBJECT_TYPE_DEFINITION,
   FIELD_DEFINITION,
@@ -203,6 +210,7 @@ function parseDefinition(parser: Parser): Definition {
       case 'fragment': return parseFragmentDefinition(parser);
 
       // Note: the Type System IDL is an experimental non-spec addition.
+      case 'schema':
       case 'scalar':
       case 'type':
       case 'interface':
@@ -224,8 +232,6 @@ function parseDefinition(parser: Parser): Definition {
  * OperationDefinition :
  *  - SelectionSet
  *  - OperationType Name? VariableDefinitions? Directives? SelectionSet
- *
- * OperationType : one of query mutation
  */
 function parseOperationDefinition(parser: Parser): OperationDefinition {
   const start = parser.token.start;
@@ -240,12 +246,7 @@ function parseOperationDefinition(parser: Parser): OperationDefinition {
       loc: loc(parser, start)
     };
   }
-  const operationToken = expect(parser, TokenKind.NAME);
-  const operation =
-    operationToken.value === 'mutation' ? 'mutation' :
-    operationToken.value === 'subscription' ? 'subscription' :
-    operationToken.value === 'query' ? 'query' :
-    (() => { throw unexpected(parser, operationToken); })();
+  const operation = parseOperationType(parser);
   let name;
   if (peek(parser, TokenKind.NAME)) {
     name = parseName(parser);
@@ -261,6 +262,21 @@ function parseOperationDefinition(parser: Parser): OperationDefinition {
   };
 }
 
+/**
+ * OperationType : one of query mutation subscription
+ */
+function parseOperationType(parser: Parser): OperationType {
+  const operationToken = expect(parser, TokenKind.NAME);
+  switch (operationToken.value) {
+    case 'query': return 'query';
+    case 'mutation': return 'mutation';
+    // Note: subscription is an experimental non-spec addition.
+    case 'subscription': return 'subscription';
+  }
+
+  throw unexpected(parser, operationToken);
+}
+
 /**
  * VariableDefinitions : ( VariableDefinition+ )
  */
@@ -666,6 +682,7 @@ export function parseNamedType(parser: Parser): NamedType {
 function parseTypeSystemDefinition(parser: Parser): TypeSystemDefinition {
   if (peek(parser, TokenKind.NAME)) {
     switch (parser.token.value) {
+      case 'schema': return parseSchemaDefinition(parser);
       case 'scalar': return parseScalarTypeDefinition(parser);
       case 'type': return parseObjectTypeDefinition(parser);
       case 'interface': return parseInterfaceTypeDefinition(parser);
@@ -680,6 +697,40 @@ function parseTypeSystemDefinition(parser: Parser): TypeSystemDefinition {
   throw unexpected(parser);
 }
 
+/**
+ * SchemaDefinition : schema { OperationTypeDefinition+ }
+ *
+ * OperationTypeDefinition : OperationType : NamedType
+ */
+function parseSchemaDefinition(parser: Parser): SchemaDefinition {
+  const start = parser.token.start;
+  expectKeyword(parser, 'schema');
+  const operationTypes = many(
+    parser,
+    TokenKind.BRACE_L,
+    parseOperationTypeDefinition,
+    TokenKind.BRACE_R
+  );
+  return {
+    kind: SCHEMA_DEFINITION,
+    operationTypes,
+    loc: loc(parser, start),
+  };
+}
+
+function parseOperationTypeDefinition(parser: Parser): OperationTypeDefinition {
+  const start = parser.token.start;
+  const operation = parseOperationType(parser);
+  expect(parser, TokenKind.COLON);
+  const type = parseNamedType(parser);
+  return {
+    kind: OPERATION_TYPE_DEFINITION,
+    operation,
+    type,
+    loc: loc(parser, start),
+  };
+}
+
 /**
  * ScalarTypeDefinition : scalar Name
  */

src/language/printer.js

@@ -94,6 +94,12 @@ const printDocASTReducer = {
 
   // Type System Definitions
 
+  SchemaDefinition: ({ operationTypes }) =>
+    'schema ' + block(operationTypes),
+
+  OperationTypeDefinition: ({ operation, type }) =>
+    operation + ': ' + type,
+
   ScalarTypeDefinition: ({ name }) =>
     `scalar ${name}`,
 

src/language/visitor.js

@@ -38,16 +38,21 @@ export const QueryDocumentKeys = {
   ListType: [ 'type' ],
   NonNullType: [ 'type' ],
 
+  SchemaDefinition: [ 'operationTypes' ],
+  OperationTypeDefinition: [ 'type' ],
+
+  ScalarTypeDefinition: [ 'name' ],
   ObjectTypeDefinition: [ 'name', 'interfaces', 'fields' ],
   FieldDefinition: [ 'name', 'arguments', 'type' ],
   InputValueDefinition: [ 'name', 'type', 'defaultValue' ],
   InterfaceTypeDefinition: [ 'name', 'fields' ],
   UnionTypeDefinition: [ 'name', 'types' ],
-  ScalarTypeDefinition: [ 'name' ],
   EnumTypeDefinition: [ 'name', 'values' ],
   EnumValueDefinition: [ 'name' ],
   InputObjectTypeDefinition: [ 'name', 'fields' ],
+
   TypeExtensionDefinition: [ 'definition' ],
+
   DirectiveDefinition: [ 'name', 'arguments', 'locations' ],
 };