// EventId.h

#ifndef EventId_H
#define EventId_H

// David Adams
// June 2002
//
// Event Identifier
//
// We assume a specifiic implementation: long run number plus
// long event number.
//
// Ordering is included to allow sorted containers.
//
// Increment is included to allow contiguous ranges.
//
// XML format:
//
// EventId
//   run = 123
//   event = 246
//
// Run and event are integers with value greater than zero.
//

#include <iosfwd>
#include "dataset_util/Text.h"

class XmlElement;

class EventId {

public:  // typedefs

  typedef unsigned long RunNumber;
  typedef unsigned long EventNumber;

public:  // static methods

  static const char* xml_name() { return "EventId"; }

  // XML DTD.
  static const Text& dtd();

private:

  // Run number (must be greater than zero)
  RunNumber _run;

  // Event number within the run.
  EventNumber _evt;

public:

  // Default constructor.
  // Leaves ID in an invalid state.
  EventId();

  // Constructor.
  EventId(RunNumber run, EventNumber evt);

  // XML constructor.
  explicit EventId(const XmlElement& ele);

  // Validity.
  bool is_valid() const;

  // Run.
  RunNumber run() const { return _run; }

  // Event.
  EventNumber event() const { return _evt; }

  // Increment.
  EventId& operator++();

  // Convert to XML.
  const XmlElement* xml() const;

};

// Ordering.
bool operator<(const EventId& lhs, const EventId& rhs);

// Equality.
bool operator==(const EventId& lhs, const EventId& rhs);

// Inequality.
bool operator!=(const EventId& lhs, const EventId& rhs);

// Output stream.
std::ostream& operator<<(std::ostream& lhs, const EventId& rhs);

#endif