simple_xml_settings.cpp

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#include <QMap>
#include <QList>
#include <QSharedPointer>
#include <QStringList>
#include <QXmlStreamReader>
#include <QXmlStreamWriter>
#include "utilities/simple_xml_settings.h"

namespace utilities
{
const QSettings::Format SimpleXmlSettings::format = QSettings::registerFormat("xml",
  SimpleXmlSettings::read, SimpleXmlSettings::write);

bool SimpleXmlSettings::read(QIODevice& device, QSettings::SettingsMap& map) {
  QXmlStreamReader xmlReader(&device);

  QStringList groups;

  while (!xmlReader.atEnd()) {
    xmlReader.readNext();

    if (xmlReader.isStartElement())
      groups.append(xmlReader.name().toString());
    else if (xmlReader.isCharacters() && !xmlReader.isWhitespace())
      map[groups.join("/")] = xmlReader.text().toString();
    else if (xmlReader.isEndElement())
      groups.removeLast();
  }

  return !xmlReader.hasError();
}

bool SimpleXmlSettings::write(QIODevice& device, const QSettings::SettingsMap& map) {
  struct NestedMap;
  struct NestedMap : QMap<QString, QSharedPointer<NestedMap> > {};

  QSharedPointer<NestedMap> nestedMap(new NestedMap());

  for (QSettings::SettingsMap::const_iterator it= map.begin();
      it != map.end(); ++it) {
    QSharedPointer<NestedMap> currentMap = nestedMap;

    QStringList groups = it.key().split("/");

    for (QStringList::const_iterator jt = groups.begin();
        jt != groups.end(); ++jt) {
      NestedMap::iterator kt = currentMap->find(*jt);

      if (kt == currentMap->end()) {
        kt = currentMap->insert(*jt, QSharedPointer<NestedMap>(
          new NestedMap()));
        currentMap = kt.value();
      }
      else
        currentMap = kt.value();
    }
  }

  QXmlStreamWriter xmlWriter(&device);

  xmlWriter.setAutoFormatting(true);
  xmlWriter.writeStartDocument();

  QStringList groups;
  QList<QSharedPointer<NestedMap> > nestedMaps;
  QList<NestedMap::iterator> nestedMapIterators;

  nestedMaps.append(nestedMap);
  nestedMapIterators.append(nestedMap->begin());

  while (!nestedMaps.isEmpty()) {
    QSharedPointer<NestedMap> currentMap = nestedMaps.last();
    NestedMap::iterator it = nestedMapIterators.last();

    if (it != currentMap->end()) {
      xmlWriter.writeStartElement(it.key());

      groups.append(it.key());
      nestedMaps.append(it.value());
      nestedMapIterators.append(it.value()->begin());
    }
    else {
      if (currentMap->isEmpty())
        xmlWriter.writeCharacters(map[groups.join("/")].toString());

      xmlWriter.writeEndElement();

      if (!groups.isEmpty())
        groups.removeLast();
      nestedMaps.removeLast();
      nestedMapIterators.removeLast();

      if (!nestedMaps.isEmpty())
        ++nestedMapIterators.last();
    }
  }

  xmlWriter.writeEndDocument();

  return true;
}

}