import "http://www.eclipse.org/emf/2002/Ecore" as ecore
generate protobuf "http://www.google.com/eclipse/protobuf/Protobuf"

Protobuf:
  (syntax=Syntax)?	
  (package=Package)?
  (imports+=Import)*
  (options+=Option)*
  (elements+=ProtobufElement)*;

Syntax:
  'syntax' '=' name=STRING ';';  
  
Package:
  'package' name=QualifiedName ';';

Import: 
  'import' importURI=STRING ';';

QualifiedName:
  ID ('.' ID)*;

Option:
  'option' name=ID '=' value=ValueRef ';';

ProtobufElement:
  Type | ExtendMessage | Service;