OhmmsElementBase.h

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//////////////////////////////////////////////////////////////////////////////////////
// This file is distributed under the University of Illinois/NCSA Open Source License.
// See LICENSE file in top directory for details.
//
// Copyright (c) 2016 Jeongnim Kim and QMCPACK developers.
//
// File developed by: Jeongnim Kim, jeongnim.kim@gmail.com, University of Illinois at Urbana-Champaign
//                    Jeremy McMinnis, jmcminis@gmail.com, University of Illinois at Urbana-Champaign
//                    Mark A. Berrill, berrillma@ornl.gov, Oak Ridge National Laboratory
//
// File created by: Jeongnim Kim, jeongnim.kim@gmail.com, University of Illinois at Urbana-Champaign
//////////////////////////////////////////////////////////////////////////////////////


#ifndef OHMMS_XMLDATA_H
#define OHMMS_XMLDATA_H
/**@file OhmmsElementBase.h
 *@brief Declaration of OhmmsElementBase and define xml-related macros.
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "OhmmsData/libxmldefs.h"

/**\class OhmmsElementBase
 *\brief Abstract class to provide xml-compatible I/O interfaces for the derived classes.
 *
 *Generic interfaces using std::iostream are much preferred. However,
 *there isn't any pure c++ xml parser that is based on std::iostream alone.
 *After evaluating several xml parsers, JK chose libxml
 *(The XML C parser and toolkit of gnome, http://www.xmlsoft.org)
 *based on its performance and availability on many platforms.
 *
 *The base class is written to be able to handle DTD or Schema in
 *future.  Current implementation assumes that each OhmmsElementBase
 *object handles a node and its child nodes. However, it does not
 *specify how the derived classes hanlde the child nodes.
 */
class OhmmsElementBase
{
public:
  ///enumeration to choose the xml parser
  enum
  {
    useLIBXML = 0, /*!< using libxml2 library */
    useLIBXMLPP,   /*!< using libxml++ library */
    usePLAIN       /*!< using ascii parser */
  };

  ///constructor with a name
  OhmmsElementBase(const char* aname = "none") : myIOMode(useLIBXML), myName(aname) {}

  ///destructor
  virtual ~OhmmsElementBase() {}

  ///return the name
  inline const std::string& getName() const { return myName; }

  ///set name
  inline void setName(const std::string& aname) { myName = aname; }

  ///set iomode
  inline void setIOMode(int imode) { myIOMode = imode; }

  ///write to a std::ostream
  virtual bool get(std::ostream&) const = 0;

  ///read from std::istream
  virtual bool put(std::istream&) = 0;

  ///read from an xmlNode
  virtual bool put(xmlNodePtr cur) = 0;

  ///reset member data
  virtual void reset() = 0;

  ///add a xmlNode to the children list of parent
  virtual bool add(xmlNodePtr parent) { return true; }

  ///read from string
  void put(const std::string& s)
  {
    std::istringstream stream(s);
    put(stream);
  }

  ///write the start of a node
  virtual void begin_node(std::ostream& os) const {}

  ///write the end of a node
  virtual void end_node(std::ostream& os) const {}

protected:
  ///the type of IO mode: default is useLIBXML
  int myIOMode;

  ///the name of the node, corresponds to the xml tag
  std::string myName;
};

#endif