allow keywords in aggregate option values, issue emicklei#76

option.go

@@ -197,7 +197,7 @@ func parseAggregateConstants(p *Parser, container interface{}) (list []*NamedLit
 			}
 			continue
 		}
-		if tIDENT != tok {
+		if tIDENT != tok && !isKeyword(tok) {
 			err = p.unexpected(lit, "option aggregate key", container)
 			return
 		}

option_test.go

@@ -372,3 +372,15 @@ func TestMultiLineOptionAggregateValue(t *testing.T) {
 		t.Errorf("got [%v] want [%v]", got, want)
 	}
 }
+
+// issue #76
+func TestOptionAggregateCanUseKeyword(t *testing.T) {
+	src := `message User {
+		string email = 3 [(validate.field) = {required: true}];
+	}`
+	p := newParserOn(src)
+	_, err := p.Parse()
+	if err != nil {
+		t.Error(err)
+	}
+}