add support for repeatable directives

internal/schema/schema.go

@@ -2,6 +2,7 @@ package schema
 
 import (
 	"fmt"
+	"regexp"
 	"text/scanner"
 
 	"github.com/graph-gophers/graphql-go/errors"
@@ -511,10 +512,21 @@ func parseDirectiveDef(l *common.Lexer) *types.DirectiveDefinition {
 		l.ConsumeToken(')')
 	}
 
-	l.ConsumeKeyword("on")
+	switch x := l.ConsumeIdent(); x {
+	case "on":
+		// no-op; Go doesn't fallthrough by default
+	case "repeatable":
+		d.Repeatable = true
+		l.ConsumeKeyword("on")
+	default:
+		l.SyntaxError(fmt.Sprintf(`unexpected %q, expecting "on" or "repeatable"`, x))
+	}
 
 	for {
 		loc := l.ConsumeIdent()
+		if ok, err := regexp.MatchString("^[A-Z_]+$", loc); err != nil || !ok {
+			l.SyntaxError(fmt.Sprintf("expected directive location-spec to be SNAKE_CASE, but got %q", loc))
+		}
 		d.Locations = append(d.Locations, loc)
 		if l.Peek() != '|' {
 			break

internal/schema/schema_test.go

@@ -813,6 +813,7 @@ Second line of the description.
 				| ENUM_VALUE
 				| INPUT_OBJECT
 				| INPUT_FIELD_DEFINITION
+			directive @repeatabledirective repeatable on SCALAR
 
 			interface NamedEntity @directive { name: String }
 
@@ -834,6 +835,8 @@ Second line of the description.
 			}
 
 			union Union @uniondirective = Photo | Person
+
+			scalar Mass @repeatabledirective @repeatabledirective
 			`,
 			validateSchema: func(s *types.Schema) error {
 				namedEntityDirectives := s.Types["NamedEntity"].(*types.InterfaceTypeDefinition).Directives
@@ -864,6 +867,55 @@ Second line of the description.
 				if len(unionDirectives) != 1 || unionDirectives[0].Name.Name != "uniondirective" {
 					return fmt.Errorf("missing directive on Union union, expected @uniondirective but got %v", unionDirectives)
 				}
+
+				massDirectives := s.Types["Mass"].(*types.ScalarTypeDefinition).Directives
+				if len(massDirectives) != 2 || massDirectives[0].Name.Name != "repeatabledirective" || massDirectives[1].Name.Name != "repeatabledirective" {
+					return fmt.Errorf("missing directive on Repeatable scalar, expected @repeatabledirective @repeatabledirective but got %v", massDirectives)
+				}
+				return nil
+			},
+		},
+		{
+			name: "Sets Directive.Repeatable iff `repeatable` keyword is given",
+			sdl: `
+			directive @nonrepeatabledirective on SCALAR
+			directive @repeatabledirective repeatable on SCALAR
+			`,
+			validateSchema: func(s *types.Schema) error {
+				if dir := s.Directives["nonrepeatabledirective"]; dir.Repeatable {
+					return fmt.Errorf("did not expect directive to be repeatable: %v", dir)
+				}
+				if dir := s.Directives["repeatabledirective"]; !dir.Repeatable {
+					return fmt.Errorf("expected directive to be repeatable: %v", dir)
+				}
+				return nil
+			},
+		},
+		{
+			name: "Directive definition does not allow double-`repeatable`",
+			sdl: `
+			directive @mydirective repeatable repeatable SCALAR
+			scalar MyScalar @mydirective
+			`,
+			validateError: func(err error) error {
+				msg := `graphql: syntax error: unexpected "repeatable", expecting "on" (line 2, column 38)`
+				if err == nil || err.Error() != msg {
+					return fmt.Errorf("expected error %q, but got %q", msg, err)
+				}
+				return nil
+			},
+		},
+		{
+			name: "Directive definition does not allow double-`on` instead of `repeatable on`",
+			sdl: `
+			directive @mydirective on on SCALAR
+			scalar MyScalar @mydirective
+			`,
+			validateError: func(err error) error {
+				msg := `graphql: syntax error: expected directive location-spec to be SNAKE_CASE, but got "on" (line 2, column 33)`
+				if err == nil || err.Error() != msg {
+					return fmt.Errorf("expected error %q, but got %q", msg, err)
+				}
 				return nil
 			},
 		},

types/directive.go

@@ -14,11 +14,12 @@ type Directive struct {
 //
 // http://spec.graphql.org/draft/#sec-Type-System.Directives
 type DirectiveDefinition struct {
-	Name      string
-	Desc      string
-	Locations []string
-	Arguments ArgumentsDefinition
-	Loc       errors.Location
+	Name       string
+	Desc       string
+	Repeatable bool
+	Locations  []string
+	Arguments  ArgumentsDefinition
+	Loc        errors.Location
 }
 
 type DirectiveList []*Directive