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// This file contains the definition of the ObjectIdParserObserver class.

#ifndef KML_ENGINE_OBJECT_ID_PARSER_OBSERVER_H__
#define KML_ENGINE_OBJECT_ID_PARSER_OBSERVER_H__

#include <map>
#include <string>
#include "kml/dom.h"
#include "kml/dom/parser_observer.h"
#include "kml/engine/engine_types.h"

namespace kmlengine {

// The ObjectIdParserObserver is a kmldom::ParserObserver which gathers all
// all Objects with id's into the given map.  An Object whose id is already
// in the map causes NewElement() to return false if strict parsing is enabled.
// Duplicate id attributes are illegal and _should_ cause the parse to fail.
// However, Google Earth never enforced this in its KML ingest and thus the
// web has a lot of invalid KML. Clients who want to successfully parse unknown
// KML from the wider web should attempt to parse this by default.
class ObjectIdParserObserver : public kmldom::ParserObserver {
 public:
  ObjectIdParserObserver(ObjectIdMap* object_id_map, bool strict_parsing)
    : object_id_map_(object_id_map),
      strict_parse_(strict_parsing) {}  // TODO: NULL check, or use reference

  virtual ~ObjectIdParserObserver() {}

  // This is ParserObserver::NewElement().  If the Element is an Object with an
  // id and a mapping for this id already exists and strict parsing has been
  // enabled, return false. Else add this id to Object mapping to the
  // object_id_map and return true.
  virtual bool NewElement(const kmldom::ElementPtr& element) {
    if (kmldom::ObjectPtr object = kmldom::AsObject(element)) {
      if (object->has_id()) {
        if (object_id_map_->find(object->get_id()) != object_id_map_->end()
            && strict_parse_) {
          // TODO: create an error message
          return false;  // Duplicate id, fail parse.
        }
        (*object_id_map_)[object->get_id()] = object;  // Last one wins.
      }
    }
    // Not a duplicate id, or strict parsing not enabled, keep parsing.
    return true;  
  }

  // The default implementation of Parser::AddChild() is essentially a nop.
 
 private:
  // An ObjectIdParserObserver only exists for a short time and operates
  // on a persistent ObjectIdMap.
  ObjectIdMap* object_id_map_;
  bool strict_parse_;
};

}  // end namespace kmlengine

#endif  // KML_ENGINE_OBJECT_ID_PARSER_OBSERVER_H__
