Model:
	'Program' name=ID ';'
	'START' 
		model+=(Student | Course | Enroll)* 
	'FINISH'
;
Student: 
	'Student' name=ID 
	// personal info
	'(' firstName=STRING lastName=STRING 'born' 'in' ageOfBirth=INT ')' 
	// student faculty - only fixed choices
	'studies' faculty=('Informatics' | 'Computing' | 'Electrotehnics') ';' 
; 
Course:
	'Course' name=ID '(' 'ECTS' ects=INT ')' (students+=[Student])?  ';'  
;
Enroll:
	'Enroll' students+=[Student](',' students+=[Student])* 'to' course=[Course] ';'
;

	@Check
	def checkDuplicateCourseEnrollement(Enroll enroll) {
		val names = newHashSet;
		for(i : enroll.students)
			if(!names.add(i.name))
				error("Duplicate entry: " + "\'" + i.name + "\'!",   
					MyDslPackage.Literals.ENROLL__STUDENTS, enroll.students.lastIndexOf(i));			
	}
}

Enroll John, Mark, Mark to Mathematics; // duplicate 'Mark'

Enroll John to English;
Enroll John, Mark to English;  // I would like to have error here since John is already enrolled to English course

	@Check
	def checkDuplicateCourseEnrollement(Model model) {
		val names = HashMultimap.<String,String>create;
		for (enroll : model.model.filter(Enroll))
			for (i : enroll.students)
				if (!names.put(enroll.course.name, i.name))
					error("Duplicate entry: " + "\'" + i.name + "\'!", enroll, MyDslPackage.Literals.ENROLL__STUDENTS,
						enroll.students.lastIndexOf(i));
	}

	override void doGenerate(Resource resource, IFileSystemAccess2 fsa, IGeneratorContext context) {
        fsa.generateFile("generator.txt", '''
            «FOR student : resource.allContents.filter(Student).toIterable»
            Student «student.name»("«student.firstName»", "«student.lastName»", «student.ageOfBirth», "«student.faculty»");
            «ENDFOR»
            «FOR course : resource.allContents.filter(Course).toIterable»
            Course «course.name»(«course.ects»«FOR student : course.students», «student.name»«ENDFOR»);
            «ENDFOR»
        ''')
	}

Program StudentDSL_Test; 
START 
	Course English (ECTS 6);  
	Student John ("John" "Johnston" born in 2000) studies Computing;
	Course Mathematics (ECTS 0) enroll John; 
	Student Mark ("Mark" "Markston" born in 2002) studies Informatics;
FINISH

Student John("John", "Johnston", 2000, "Computing");
Student Mark("Mark", "Markston", 2002, "Informatics");
Course English(6);
Course Mathematics(0, John);

Course English(6);
Student John("John", "Johnston", 2000, "Computing");
Course Mathematics(0, John);
Student Mark("Mark", "Markston", 2002, "Informatics");

	override void doGenerate(Resource resource, IFileSystemAccess2 fsa, IGeneratorContext context) {
		val root = resource.contents.get(0) as StudentDSL;
		fsa.generateFile("generator.txt", '''
            «FOR i : root.studentDSL»
            «i.eClass.name» 
            «ENDFOR»
            
        ''')
	}

StudentDSL:
	'Program' name=ID ';'
	'START' 
		studentDSL+=(Student | Course | Enroll)* 
	'FINISH'
;

Student: 
	'Student' name=ID 
	// personal info
	'(' firstName=STRING lastName=STRING 'born' 'in' ageOfBirth=INT ')' 
	// student faculty - only fixed choices
	'studies' faculty=('Informatics' | 'Computing' | 'Electrotehnics') ';' 
; 

Course:
	'Course' name=ID
	// how many ECTS? 
	'(' 'ECTS' ects=INT ')'
	// enroll students (optional)  
	('enroll' students+=[Student](',' students+=[Student])*)?  
	';'  
;

Enroll:
	'Enroll' students+=[Student](',' students+=[Student])* 'to' course=[Course] ';'
;

Program StudentDSL_Test; 
START 
	Student John ("John" "Johnston" born in 2000) studies Computing;
	Course English (ECTS 6);  
	Student Mark ("Mark" "Markston" born in 2002) studies Informatics;
	Course Mathematics (ECTS 0) enroll John; 
	Enroll John, Mark to Mathematics; 
FINISH

    Student John("John", "Johnston", 2000, "Computing");
    Course English(6);
    Student Mark("Mark", "Markston", 2002, "Informatics");
    Course Mathematics(0, John);
    Mathematics.Enroll(John, Mark);

	override void doGenerate(Resource resource, IFileSystemAccess2 fsa, IGeneratorContext context) {
		val root = resource.contents.get(0) as StudentDSL;
		fsa.generateFile("program_cpp.txt", '''
		«FOR item : root.studentDSL»
		«IF item instanceof Student»
		Student «item.name»("«item.firstName»", "«item.lastName»",«item.ageOfBirth»);
		«ELSEIF item instanceof Course»
		Course «item.name»(«item.ects»);
		«ELSEIF item instanceof Enroll»
		«item.course.name».Enroll(«FOR stud : item.students SEPARATOR ', '»«stud.name »«ENDFOR»);
		«ELSE»
		Unrecognized type: «item.eClass.name»
		«ENDIF»
		«ENDFOR»            
        ''')
	}