mtFltXmlReader.h

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/*******************************************************************************
** Copyright (c) 2005 MAK Technologies, Inc.
** All rights reserved.
*******************************************************************************/
/*******************************************************************************
** $RCSfile: mtFltXmlReader.h,v $ $Revision: 1.8 $ $State: Exp $
*******************************************************************************/

#ifndef mtFltXmlReader_H_
#define mtFltXmlReader_H_

//
// \file mtFltXmlReader.h
// \brief Represents a reader class that interacts with libXml to read a Metaflight file
//

#include "mtflt/mtfltDefines.h"
#include <vlutil/vlString.h>
#include <libxml/xmlreader.h>

// \brief Represents a reader class that interacts with libXml to read a Metaflight file
// A Metaflight file is represented as a n-ary tree document in which the tags contained
// inside other tags are represented as parent-child relationships. For example, 
// \code
// <Ellipsoid name="WGS84">
//   <SemiMajorRadius>6378137</SemiMajorRadius>
//   <SemiMinorRadius>6356752.31424518</SemiMinorRadius>
// </Ellipsoid>
// \endcode
// is represented as a tree with the Ellipsoid node as the father and SemiMajorRadius and 
// SemiMinorRadius as children. Both SemiMajorRadius and SemiMinorRadius are considered
// atomic nodes since they have no child tags.

class DT_DLL_mtflt DtMtFltXmlReader
{
public:

   // Default constructor.
   DtMtFltXmlReader();

   DtMtFltXmlReader(xmlNodePtr root, xmlNodePtr node);

   // Destructor
   virtual ~DtMtFltXmlReader();
   
   // Copy constructor
   DtMtFltXmlReader(const DtMtFltXmlReader& node);
   
   // Assignment operator
   DtMtFltXmlReader& operator=(const DtMtFltXmlReader& orig);
   
   // Finds the first node whose tag matches the one given by \p nodeName.   
   // \param node Starting node for the search inside the xml document
   // \param nodeName Name of the node to be searched (e.g. "GridStructure")
   // \return 0 if no matches are found.
   virtual xmlNodePtr findNode(xmlNodePtr node, const char* nodeName);

   // Finds the node named as nodeName and that also has an attribute named 
   // attrName with a value of attrValue. For example, 
   // <tt>findNode(nodeptr, "GridStructure", "name", "abc")</tt> searches for a 
   // node that looks like <br> <br> <tt>
   // <GridStructure name="abc"> <br>
   // ... <br>
   // </GridStructure>
   // </tt>
   // \return 0 if no matches are found.
   virtual xmlNodePtr findNode(xmlNodePtr node, const char* nodeName, 
      const char* attrName, const char *attrValue);

   // Returns the value of the attribute attrname inside the node. Attributes
   // are specified inside the node like this <br><br> <tt>
   // <node \e attrname=\e value ...> <br>
   // ... <br>
   // </node>
   // </tt>
   // \param node Node to access
   // \param attrname Name of the attribute to be searched (e.g. "name")
   // \return The attribute's value if present or an empty DtSring otherwise.
   virtual DtString getAttrValue(xmlNodePtr node, const char* attrname) const;

   // Returns the value of an "atomic" node. Atomic nodes are the ones that 
   // have the following structure <tt><tag>value</tag></tt>. 
   // \param node Node to start the search of the atomic node
   // \param nodeName Name of the atomic node to be searched
   // \return It returns an empty DtString if the node has the form or <tag></tag>   
   virtual DtString getAtomicNodeValue(xmlNodePtr node, const char* nodeName);

   // \return the next node which is not a blank text node
   virtual void nextNode(xmlNodePtr& node);

   // \return the top root node of this reader
   virtual xmlNodePtr getRootNode() { return myRootNode; };

protected:

   xmlNodePtr myRootNode;
   xmlNodePtr myCurNode;

   // Returns the value of an "atomic" node. Atomic nodes are the ones that 
   // have the following structure <tag>value</tag>. It returns the empty
   // string if the node has the form or <tag></tag>
   virtual DtString getAtomicNodeValue(xmlNodePtr node) const;

   // Returns a pointer to the first child of the node or NULL if not defined
   // The reason for this method is because libXml also includes blank text
   // nodes sometimes, so they need to be filtered out. This function 
   // guarantees you get an actual child node as the first node
   virtual xmlNodePtr getChildren(xmlNodePtr node) const;

};

#endif