/*
 * This is the implementation file for the XML file driver
 * for NeXus
 *
 *   Copyright (C) 2006 Mark Koennecke
 * 
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  Lesser General Public License for more details.
 *
 *  You should have received a copy of the GNU Lesser General Public
 *  License along with this library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  For further information, see <http://www.nexusformat.org>
 */


#ifdef NXXML 

#include <stdio.h>
#include <assert.h>
#include <stdint.h>
#include <mxml.h>
#include <napi.h>
#include <nxxml.h>
#include "nxio.h"
#include "nxdataset.h"

#ifdef _MSC_VER
#define snprintf _snprintf
#endif /* _MSC_VER */

extern  void *NXpData;
extern int validNXName(const char* name, int allow_colon); /* from napi.c */
char *nxitrim(char *str); /* from napi.c */

/*----------------------- our data structures --------------------------
  One might wonder why a node stack is still needed even if this API
  operates on top of a tree API. The reason for this are the links.
  Following a link on any NXopenpath, data means a jump through the
  whole tree. In order to correctly return from such adventures,
  a stack is needed. Moreover we need it in order to keep track of the
  state of search operations.

  The true NXroot node is always at stack[0]. The root in the data
  structure is the ?xml element. The latter one is needed to store
  the tree.
-----------------------------------------------------------------------*/
typedef struct {
    mxml_node_t *current;
    mxml_node_t *currentChild;
    int currentAttribute;
    int options; /**< additional information about the node */
}xmlStack;

/*
 * Freddie Akeroyd, 19/03/2008
 *
 * Add in support for table style data writing - this is 
 * indicated internally via the XMLSTACK_OPTION_TABLE flag
 * and separates the dimensions and data into separate nodes contained
 * in DIMS_NODE_NAME and DATA_NODE_NAME. This is a first commit and 
 * involves some code duplication that will need to be cleaned up later.
 * Also writing in table style is only enabled for 1D arrays as
 * I haven't done slab writing yet which the nexus test program uses
 * for writing 2D arrays. 
 *
 * Table output is enabled by opening a file with (NXACC_CREATEXML | NXACC_TABLE)
 *
 * See http://trac.nexusformat.org/code/ticket/111 for further details
 */
#define XMLSTACK_OPTION_TABLE 		0x1 /**< indicates table option in xmlStack */


/*---------------------------------------------------------------------*/
typedef struct {
  mxml_node_t *root;           /* root node */
  int readOnly;                /* read only flag */
  int tableStyle;              /**< whether to output data in XML table style */
  int stackPointer;            /* stack pointer */
  char filename[1024];         /* file name, for NXflush, NXclose */
  xmlStack stack[NXMAXSTACK];  /* stack */
}XMLNexus, *pXMLNexus;
/*===================== support functions ===============================*/
extern char *stptok(char *s, char *tok, size_t toklen, char *brk);
/*----------------------------------------------------------------------*/
static mxml_node_t *getLinkTarget(pXMLNexus xmlHandle, const char *target){
  mxml_node_t *node = NULL;
  mxml_node_t *testNode = NULL;
  char path[132], *pPtr;

  pPtr = (char *)target + 1;
  node = xmlHandle->stack[0].current;
  while((pPtr = stptok(pPtr,path,131,"/")) != NULL){
    /*
      search for group node
    */
    testNode = mxmlFindElement(node,node,NULL,"name",path,MXML_DESCEND_FIRST);
    if(testNode == NULL){
      /*
	it can still be a data node
      */
      testNode = mxmlFindElement(node,node,path,NULL,NULL,MXML_DESCEND_FIRST);
    }
    if(testNode == NULL){
      NXReportError("Cannot follow broken link");
      return NULL;
    } else {
      node = testNode;
    }
  }
  return node;
}
/*==================== file functions ===================================*/
static void errorCallbackForMxml(const char *txt){
  NXReportError((char *)txt);
}
/*-----------------------------------------------------------------------*/
NXstatus  NXXopen(CONSTCHAR *filename, NXaccess am, 
			       NXhandle* pHandle) {
  pXMLNexus xmlHandle = NULL;
  FILE *fp = NULL;
  char *time_buffer = NULL;
  mxml_node_t *current;

  /*
    allocate data
  */
  xmlHandle = (pXMLNexus)malloc(sizeof(XMLNexus));
  if(!xmlHandle){
    NXReportError( "Out of memory allocating XML file handle");
    return NX_ERROR;
  }
  memset(xmlHandle,0,sizeof(XMLNexus));

  /*
    initialize mxml XML parser
  */
  mxmlSetCustomHandlers(nexusLoadCallback, nexusWriteCallback);
  initializeNumberFormats();
  mxmlSetErrorCallback(errorCallbackForMxml);

  xmlHandle->tableStyle = ((am & NXACC_TABLE) ? 1 : 0);
  /*
    open file
  */
  strncpy(xmlHandle->filename,filename,1023);
  switch(am & NXACCMASK_REMOVEFLAGS){
  case NXACC_READ:
    xmlHandle->readOnly = 1;
  case NXACC_RDWR:
    fp = fopen(filename,"r");
    if(fp == NULL){
      NXReportError("Failed to open file:");
      NXReportError((char *)filename);
      free(xmlHandle);
      return NX_ERROR;
    }
    xmlHandle->root = mxmlLoadFile(NULL,fp,nexusTypeCallback);
    xmlHandle->stack[0].current = mxmlFindElement(xmlHandle->root,
						  xmlHandle->root,
						  "NXroot",
						  NULL,NULL,
						  MXML_DESCEND);
    xmlHandle->stack[0].currentChild = NULL;
    xmlHandle->stack[0].currentAttribute = 0;
    xmlHandle->stack[0].options = 0;
    fclose(fp);
    break;
  case NXACC_CREATEXML:
    xmlHandle->root = mxmlNewElement(NULL,
		   "?xml version=\"1.0\" encoding=\"UTF-8\"?");
    current = mxmlNewElement(xmlHandle->root,"NXroot");
    mxmlElementSetAttr(current,"NeXus_version",NEXUS_VERSION);
    mxmlElementSetAttr(current,"XML_version","mxml");
    mxmlElementSetAttr(current,"file_name",filename);
    mxmlElementSetAttr(current,"xmlns", NEXUS_SCHEMA_NAMESPACE);
    mxmlElementSetAttr(current,"xmlns:xsi","http://www.w3.org/2001/XMLSchema-instance");
    mxmlElementSetAttr(current,"xsi:schemaLocation",
	NEXUS_SCHEMA_NAMESPACE " " NEXUS_SCHEMA_URL);
    time_buffer = NXIformatNeXusTime();
    if(time_buffer != NULL){
      mxmlElementSetAttr(current,"file_time",time_buffer);
      free(time_buffer);
    } 
    xmlHandle->stack[0].current = current;
    xmlHandle->stack[0].currentChild = NULL;
    xmlHandle->stack[0].currentAttribute = 0;
    xmlHandle->stack[0].options = 0;
    break;
  default:
    NXReportError("Bad access parameter specified in NXXopen");
    return NX_ERROR;
  }
  if(xmlHandle->stack[0].current == NULL){
      NXReportError(
		     "No NXroot element in XML-file, no NeXus-XML file");
      return NX_ERROR;
  }

  *pHandle = xmlHandle;
  return NX_OK;
}
/*----------------------------------------------------------------------*/
NXstatus  NXXclose (NXhandle* fid){
  pXMLNexus xmlHandle = NULL;
  FILE *fp = NULL;

  xmlHandle = (pXMLNexus)*fid;
  assert(xmlHandle);
  
  if(xmlHandle->readOnly == 0) {
    fp = fopen(xmlHandle->filename,"w");
    if(fp == NULL){
      NXReportError("Failed to open NeXus XML file for writing");
      return NX_ERROR;
    }
    mxmlSaveFile(xmlHandle->root,fp,NXwhitespaceCallback);
    fclose(fp);
  }
  mxmlDelete(xmlHandle->root);
  free(xmlHandle);
  *fid = NULL;
  return NX_OK;
}
/*----------------------------------------------------------------------*/
NXstatus  NXXflush(NXhandle *fid){
  pXMLNexus xmlHandle = NULL;
  FILE *fp = NULL;

  xmlHandle = (pXMLNexus)*fid;
  assert(xmlHandle);
  
  if(xmlHandle->readOnly == 0) {
    fp = fopen(xmlHandle->filename,"w");
    if(fp == NULL){
      NXReportError("Failed to open NeXus XML file for writing");
      return NX_ERROR;
    }
    mxmlSaveFile(xmlHandle->root,fp,NXwhitespaceCallback);
    fclose(fp);
  }
  return NX_OK;
}
/*=======================================================================
                   Group functions
=========================================================================*/
NXstatus  NXXmakegroup (NXhandle fid, CONSTCHAR *name, 
				     CONSTCHAR *nxclass){
  char buffer[256];
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *newGroup = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if (!validNXName(name, 0))
  {
    sprintf(buffer, "ERROR: invalid characters in group name \"%s\"", name);
    NXReportError(buffer);
    return NX_ERROR;
  }

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("Close dataset before trying to create a group");
    return NX_ERROR;
  }

  newGroup = mxmlNewElement(xmlHandle->stack[xmlHandle->stackPointer].current,
			    nxclass);
  if(!newGroup){
    NXReportError("failed to allocate new group");
    return NX_ERROR;
  }
  mxmlElementSetAttr(newGroup,"name",name);
  return NX_OK;
} 
/*----------------------------------------------------------------------*/
static mxml_node_t *searchGroupLinks(pXMLNexus xmlHandle, CONSTCHAR *name, 
				CONSTCHAR *nxclass){
  mxml_node_t *linkNode = NULL;
  mxml_node_t *current;
  mxml_node_t *test = NULL;
  const char *linkTarget;
  const char *linkName = NULL;

  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  linkNode = current;
  while((linkNode = mxmlFindElement(linkNode,current,"NAPIlink",NULL,NULL,
				    MXML_DESCEND_FIRST)) != NULL){
    linkTarget = mxmlElementGetAttr(linkNode,"target");
    test = getLinkTarget(xmlHandle,linkTarget);
    if(test != NULL){
      if(strcmp(test->value.element.name,nxclass) == 0){
	if(strcmp(mxmlElementGetAttr(test,"name"),name) == 0){
	  return test;
	}
      }
    }
    /*
      test for named links
    */
    linkName = mxmlElementGetAttr(linkNode,"name");
    if(test != NULL && linkName != NULL){
      if(strcmp(test->value.element.name,nxclass) == 0){
	if(strcmp(linkName, name) == 0){
	  return test;
	}
      }
    }
  }
  return NULL;
}
/*------------------------------------------------------------------------*/
NXstatus  NXXopengroup (NXhandle fid, CONSTCHAR *name, 
				     CONSTCHAR *nxclass){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *newGroup = NULL;
  char error[1024];

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("Close dataset before trying to open a group");
    return NX_ERROR;
  }
  newGroup = mxmlFindElement(xmlHandle->stack[xmlHandle->stackPointer].current,
			     xmlHandle->stack[xmlHandle->stackPointer].current,
			     nxclass,
			     "name",
			     name,
			     MXML_DESCEND_FIRST);
  if(newGroup == NULL){
    newGroup = searchGroupLinks(xmlHandle,name,nxclass);
  }
  if(!newGroup){
    snprintf(error,1023,"Failed to open %s, %s",name,nxclass);
    NXReportError(error);
    return NX_ERROR;
  }
  xmlHandle->stackPointer++;
  xmlHandle->stack[xmlHandle->stackPointer].current = newGroup;
  xmlHandle->stack[xmlHandle->stackPointer].currentChild = NULL;
  xmlHandle->stack[xmlHandle->stackPointer].currentAttribute = 0;
  xmlHandle->stack[xmlHandle->stackPointer].options = 0;
  return NX_OK;
}
/*----------------------------------------------------------------------*/
NXstatus  NXXclosegroup (NXhandle fid){
  pXMLNexus xmlHandle = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    /*
      silently fix this
    */
    NXXclosedata(fid);
  }
  if(xmlHandle->stackPointer > 0){
    xmlHandle->stackPointer--;
  }
  return NX_OK;
}
/*=========================================================================
         dataset functions
=========================================================================*/
NXstatus  NXXcompmakedata64 (NXhandle fid, CONSTCHAR *name, 
					int datatype, 
					int rank, 
					int64_t dimensions[],
					int compress_type, int64_t chunk_size[]){
  /*
    compression does not relly make sense with XML
  */
  return NXXmakedata64(fid,name,datatype,rank,dimensions);
}
/*-----------------------------------------------------------------------*/
static char *buildTypeString(int datatype, int rank, int64_t dimensions[]){
  char *typestring = NULL;
  char pNumber[20];
  int i;

  /*
    allocate data
  */
  typestring = (char *)malloc(132*sizeof(char));
  if(!typestring){
    NXReportError("Failed to allocate typestring");
    return NULL;
  }
  memset(typestring,0,132*sizeof(char));

  getNumberText(datatype,typestring,130);
  if(rank > 1 || datatype == NX_CHAR || dimensions[0] > 1) {
    strcat(typestring,"[");
    snprintf(pNumber,19,"%lld", (long long)dimensions[0]);
    strncat(typestring,pNumber,130-strlen(typestring));
    for(i = 1; i < rank; i++){
      snprintf(pNumber,19,",%lld", (long long)dimensions[i]);
      strncat(typestring,pNumber,130-strlen(typestring));
    }
    strcat(typestring,"]");
  }
  return typestring;
}

/*------------------------------------------------------------------------*/
NXstatus  NXXmakedatatable64 (NXhandle fid, 
				    CONSTCHAR *name, int datatype, 
				    int rank, int64_t dimensions[]){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *dataNode = NULL, *dataNodeRoot = NULL, *dimsNode = NULL, *dimsNodeRoot = NULL;
  mxml_node_t *newData = NULL;
  mxml_node_t *current;
  char *typestring;
  int i, ndata; 
  char buffer[256];
  static int64_t one = 1;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);
  if (!validNXName(name, 0))
  {
    sprintf(buffer, "ERROR: invalid characters in dataset name \"%s\"", name);
    NXReportError(buffer);
    return NX_ERROR;
  }

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("Close dataset before trying to create a dataset");
    return NX_ERROR;
  }
  if(dimensions[0] < 0){
    dimensions[0] = 1;
  }

  current = xmlHandle->stack[xmlHandle->stackPointer].current;

  dimsNodeRoot = mxmlFindElement(current, current, DIMS_NODE_NAME, NULL, NULL, MXML_DESCEND_FIRST);
  if (dimsNodeRoot == NULL)
  {
      dimsNodeRoot = mxmlNewElement(current, DIMS_NODE_NAME);
  }
  dimsNode = mxmlNewElement(dimsNodeRoot, name);
  mxmlNewOpaque(dimsNode, "");
  typestring = buildTypeString(datatype,rank,dimensions);
  if(typestring != NULL){
    mxmlElementSetAttr(dimsNode,TYPENAME,typestring);
    free(typestring);
  } else {
    NXReportError("Failed to allocate typestring");
    return NX_ERROR;
  }
  ndata = 1;
  for(i=0; i<rank; i++)
  {
     ndata *= dimensions[i];
  }
  dataNodeRoot = current;
  for(i=0; i<ndata; i++)
  {
      dataNodeRoot = mxmlFindElement(dataNodeRoot, current, DATA_NODE_NAME, NULL, NULL, (i == 0 ? MXML_DESCEND_FIRST : MXML_NO_DESCEND) );
      if (dataNodeRoot == NULL)
      {
          dataNodeRoot = mxmlNewElement(current, DATA_NODE_NAME);
      }
      dataNode = mxmlNewElement(dataNodeRoot,name);
      newData = (mxml_node_t *)malloc(sizeof(mxml_node_t));
      if(!newData){
        NXReportError("Failed to allocate space for dataset");
        return NX_ERROR;
      }
      memset(newData,0,sizeof(mxml_node_t));
      mxmlAdd(dataNode, MXML_ADD_AFTER, MXML_ADD_TO_PARENT, newData);
      newData->type = MXML_CUSTOM;
/*        newData->value.custom.data = createNXDataset(rank,datatype,dimensions); */
      newData->value.custom.data = createNXDataset(1,datatype,&one);
      if(!newData->value.custom.data){
        NXReportError("Failed to allocate space for dataset");
        return NX_ERROR;
      }
      newData->value.custom.destroy = destroyDataset;
  }
  return NX_OK;
}

NXstatus  NXXmakedata64 (NXhandle fid, 
				    CONSTCHAR *name, int datatype, 
				    int rank, int64_t dimensions[]){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *dataNode = NULL;
  mxml_node_t *newData = NULL;
  mxml_node_t *current;
  char *typestring;
  char buffer[256];


  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);
  if (!validNXName(name, 0))
  {
    sprintf(buffer, "ERROR: invalid characters in dataset name \"%s\"", name);
    NXReportError(buffer);
    return NX_ERROR;
  }

  if (xmlHandle->tableStyle && datatype != NX_CHAR && dimensions[0] != NX_UNLIMITED && rank == 1)
  {
      return NXXmakedatatable64(fid,name,datatype,rank,dimensions);
  }

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("Close dataset before trying to create a dataset");
    return NX_ERROR;
  }
  if(dimensions[0] < 0){
    dimensions[0] = 1;
  }

  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  dataNode = mxmlNewElement(current,name);
  typestring = buildTypeString(datatype,rank,dimensions);
  if(typestring != NULL){
    mxmlElementSetAttr(dataNode,TYPENAME,typestring);
    free(typestring);
  } else {
    NXReportError("Failed to allocate typestring");
    return NX_ERROR;
  }
  /*
    NX_CHAR maps to MXML_OPAQUE datasets
  */
  if(datatype == NX_CHAR){
    newData = mxmlNewOpaque(dataNode,"");
    return NX_OK;
  } else {
    newData = (mxml_node_t *)malloc(sizeof(mxml_node_t));
    if(!newData){
      NXReportError("Failed to allocate space for dataset");
      return NX_ERROR;
    }
    memset(newData,0,sizeof(mxml_node_t));
    mxmlAdd(dataNode, MXML_ADD_AFTER, MXML_ADD_TO_PARENT, newData);
    newData->type = MXML_CUSTOM;
    newData->value.custom.data = createNXDataset(rank,datatype,dimensions);
    if(!newData->value.custom.data){
      NXReportError("Failed to allocate space for dataset");
      return NX_ERROR;
    }
    newData->value.custom.destroy = destroyDataset;
  }
  return NX_OK;
}
/*----------------------------------------------------------------------*/
static mxml_node_t *searchSDSLinks(pXMLNexus xmlHandle, CONSTCHAR *name){
  mxml_node_t *linkNode = NULL;
  mxml_node_t *current;
  mxml_node_t *test = NULL;
  const char *linkTarget;
  const char *linkName = NULL;

  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  linkNode = current;
  while((linkNode = mxmlFindElement(linkNode,current,"NAPIlink",NULL,NULL,
				    MXML_DESCEND_FIRST)) != NULL){
    linkTarget = mxmlElementGetAttr(linkNode,"target");
    test = getLinkTarget(xmlHandle,linkTarget);
    if(test != NULL){
      if(strcmp(test->value.element.name,name) == 0){
	return test;
      }
    }
    /*
      test for named links
    */
    linkName = mxmlElementGetAttr(linkNode,"name");
    if(test != NULL && linkName != NULL){
      if(strcmp(linkName,name) == 0){
	return test;
      }
    }
  }
  return NULL;
}
/*-----------------------------------------------------------------------*/
NXstatus  NXXopendatatable (NXhandle fid, CONSTCHAR *name){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *dataNode = NULL, *dimsNode = NULL;
  char error[1024];

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);


  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    /*
      silently fix this
    */
    xmlHandle->stackPointer--;
    if(xmlHandle->stackPointer < 0){
      xmlHandle->stackPointer = 0;
    }
  }
  
  dimsNode = mxmlFindElement(xmlHandle->stack[xmlHandle->stackPointer].current,
			     xmlHandle->stack[xmlHandle->stackPointer].current,
			     DIMS_NODE_NAME,
			     NULL,
			     NULL,
			     MXML_DESCEND_FIRST);

  if(!dimsNode){
    snprintf(error,1023,"Failed to open dataset %s",name);
    NXReportError(error);
    return NX_ERROR;
  }

  dataNode = mxmlFindElement(dimsNode,
			     dimsNode,
			     name,
			     NULL,
			     NULL,
			     MXML_DESCEND_FIRST);
  if(dataNode == NULL){
    dataNode = searchSDSLinks(xmlHandle,name);
  }
  if(!dataNode){
    snprintf(error,1023,"Failed to open dataset %s",name);
    NXReportError(error);
    return NX_ERROR;
  }
  xmlHandle->stackPointer++;
  xmlHandle->stack[xmlHandle->stackPointer].current = dataNode;
  xmlHandle->stack[xmlHandle->stackPointer].currentChild = NULL;
  xmlHandle->stack[xmlHandle->stackPointer].currentAttribute = 0;
  xmlHandle->stack[xmlHandle->stackPointer].options = XMLSTACK_OPTION_TABLE;
  return NX_OK;
}


NXstatus  NXXopendata (NXhandle fid, CONSTCHAR *name){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *dataNode = NULL, *current = NULL;
  char error[1024];

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  /* is this a table style node ? */
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  dataNode = mxmlFindElement(current,
			     current,
			     DATA_NODE_NAME,
			     NULL,
			     NULL,
			     MXML_DESCEND_FIRST);
  if (dataNode != NULL)
  {
      dataNode = mxmlFindElement(dataNode,
			     dataNode,
			     name,
			     NULL,
			     NULL,
			     MXML_DESCEND_FIRST);
  }
  if (dataNode != NULL)
  {
	return NXXopendatatable(fid, name);
  }

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    /*
      silently fix this
    */
    xmlHandle->stackPointer--;
    if(xmlHandle->stackPointer < 0){
      xmlHandle->stackPointer = 0;
    }
  }
  
  dataNode = mxmlFindElement(xmlHandle->stack[xmlHandle->stackPointer].current,
			     xmlHandle->stack[xmlHandle->stackPointer].current,
			     name,
			     NULL,
			     NULL,
			     MXML_DESCEND_FIRST);
  if(dataNode == NULL){
    dataNode = searchSDSLinks(xmlHandle,name);
  }
  if(!dataNode){
    snprintf(error,1023,"Failed to open dataset %s",name);
    NXReportError(error);
    return NX_ERROR;
  }
  xmlHandle->stackPointer++;
  xmlHandle->stack[xmlHandle->stackPointer].current = dataNode;
  xmlHandle->stack[xmlHandle->stackPointer].currentChild = NULL;
  xmlHandle->stack[xmlHandle->stackPointer].currentAttribute = 0;
  xmlHandle->stack[xmlHandle->stackPointer].options = 0;
  return NX_OK;
}
/*----------------------------------------------------------------------*/

NXstatus  NXXclosedata (NXhandle fid){
  pXMLNexus xmlHandle = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    if(xmlHandle->stackPointer > 0){
      xmlHandle->stackPointer--;
    }
    return NX_OK;
  }
  return NX_OK;
}
/*----------------------------------------------------------------------*/
static mxml_node_t *findData(mxml_node_t *node){
  mxml_node_t *baby = node;
  
  while( (baby = mxmlWalkNext(baby,node,MXML_DESCEND_FIRST)) != NULL){
    if(baby->type == MXML_OPAQUE || baby->type == MXML_CUSTOM){
      return baby;
    }
  }
  return NULL;
}

/* we only havv to deal with non-character data here */
NXstatus  NXXputdatatable (NXhandle fid, const void *data){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *userData = NULL;
  mxml_node_t *current = NULL;
  mxml_node_t *nodeRoot = NULL;
  mxml_node_t *dataNodeRoot = NULL;
  mxml_node_t *dataNode = NULL;
  const char* name;
  pNXDS dataset;
  int i, offset, length;
  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);
  /* current points at the Idims node as done in NXXopendatatable */
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  name = current->value.element.name;
  /* we want to walk all Idata nodes and set name */
  nodeRoot =  current->parent->parent;
  dataNodeRoot = nodeRoot;
  offset = 0;
  for(i=0; dataNodeRoot != NULL; i++)
  {
      dataNodeRoot = mxmlFindElement(dataNodeRoot, nodeRoot, DATA_NODE_NAME, NULL, NULL, (i == 0 ? MXML_DESCEND_FIRST : MXML_NO_DESCEND) );
      if (dataNodeRoot != NULL)
      {
	dataNode = mxmlFindElement(dataNodeRoot,dataNodeRoot,name,NULL,NULL,MXML_DESCEND_FIRST);
	if (dataNode != NULL)
	{
	    userData = findData(dataNode);
  	    assert(userData != NULL);
            dataset = (pNXDS)userData->value.custom.data;
            assert(dataset);
            length = getNXDatasetByteLength(dataset);
            memcpy(dataset->u.ptr,(char*)data + offset,length);
	    offset += length;
	}
      }
    } 
    return NX_OK;
}

/*------------------------------------------------------------------------*/
NXstatus  NXXputdata (NXhandle fid, const void *data){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *userData = NULL;
  mxml_node_t *current = NULL;
  pNXDS dataset;
  int i, length, type, rank; 
  int64_t dim[NX_MAXRANK];
  char *pPtr = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if (xmlHandle->stack[xmlHandle->stackPointer].options & XMLSTACK_OPTION_TABLE)
  {
      return NXXputdatatable(fid,data);
  }

  if(!isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No dataset open");
    return NX_ERROR;
  }
  
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  userData = findData(current);
  assert(userData != NULL);
  if(userData->type == MXML_OPAQUE){
    /*
      Text data. We have to make sure that the text is \0 terminated. 
      Some language bindings do not ensure that this is the case.
    */
    if(NXXgetinfo64(fid,&rank, dim, &type) == NX_OK){
      length = 1;
      for(i=0; i<rank; i++)
      {
	length *= dim[i];
      }
      /* we seem to have trouble reading an empty node back (no userData), so make sure we have at least a single space present even for empty strings */
      if (length == 0)
      {
	mxmlSetOpaque(userData," ");
      }
      else
      {
        pPtr = (char *)malloc((length+1)*sizeof(char));
        if(pPtr != NULL){
          memcpy(pPtr,data,length);
          pPtr[length] = '\0';
	  mxmlSetOpaque(userData,(const char *)pPtr);
          free(pPtr);
        }
      }
    }
    else
    {
        NXReportError("Unable to determine size of character dataset");
        return NX_ERROR;
    }
  } else {
    dataset = (pNXDS)userData->value.custom.data;
    assert(dataset);
    length = getNXDatasetByteLength(dataset);
    memcpy(dataset->u.ptr,data,length);
  }
  return NX_OK;
}

NXstatus  NXXgetdatatable (NXhandle fid, void *data){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *userData = NULL;
  mxml_node_t *current = NULL;
  mxml_node_t *nodeRoot = NULL;
  mxml_node_t *dataNodeRoot = NULL;
  mxml_node_t *dataNode = NULL;
  const char* name;
  pNXDS dataset;
  int i, offset, length;
  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  /* current points at the Idims node as done in NXXopendatatable */
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  name = current->value.element.name;
  /* we want to walk all Idata nodes and set name */
  nodeRoot =  current->parent->parent;
  dataNodeRoot = nodeRoot;
  offset = 0;
  for(i=0; dataNodeRoot != NULL; i++)
  {
      dataNodeRoot = mxmlFindElement(dataNodeRoot, nodeRoot, DATA_NODE_NAME, NULL, NULL, (i == 0 ? MXML_DESCEND_FIRST : MXML_NO_DESCEND) );
      if (dataNodeRoot != NULL)
      {
	dataNode = mxmlFindElement(dataNodeRoot,dataNodeRoot,name,NULL,NULL,MXML_DESCEND_FIRST);
	if (dataNode != NULL)
	{
	    userData = findData(dataNode);
  	    assert(userData != NULL);
            dataset = (pNXDS)userData->value.custom.data;
            assert(dataset);
            length = getNXDatasetByteLength(dataset);
            memcpy((char*)data + offset, dataset->u.ptr, length);
	    offset += length;
	}
      }
    } 
    return NX_OK;
}


/*------------------------------------------------------------------------*/
NXstatus  NXXgetdata (NXhandle fid, void *data){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *userData = NULL;
  mxml_node_t *current = NULL;
  pNXDS dataset;
  int i, length, type, rank; 
  int64_t dim[NX_MAXRANK];

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if (xmlHandle->stack[xmlHandle->stackPointer].options & XMLSTACK_OPTION_TABLE)
  {
      return NXXgetdatatable(fid,data);
  }

  if(!isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No dataset open");
    return NX_ERROR;
  }
  
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  userData = findData(current);
  assert(userData != NULL);
  if(userData->type == MXML_OPAQUE){
    /*
      text data
    */
    if(NXXgetinfo64(fid,&rank, dim, &type) == NX_OK){
      length = 1;
      for(i=0; i<rank; i++)
      {
          length *= dim[i];
      }
      strncpy((char *)data,userData->value.opaque,length);
    } else {
      strcpy((char *)data,nxitrim(userData->value.opaque));
    }

  } else {
    dataset = (pNXDS)userData->value.custom.data;
    assert(dataset);
    length = getNXDatasetByteLength(dataset);
    memcpy(data,dataset->u.ptr,length);
  }
  return NX_OK;
}
/*------------------------------------------------------------------------*/
NXstatus  NXXgetinfo64 (NXhandle fid, int *rank, 
				   int64_t dimension[], int *iType){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *userData = NULL;
  mxml_node_t *current = NULL;
  pNXDS dataset;
  int myRank, i;
  const char *attr = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(!isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No dataset open");
    return NX_ERROR;
  }
  
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  userData = findData(current);
  assert(userData != NULL);
  if(userData->type == MXML_OPAQUE){
    /*
      text data
    */
    attr = mxmlElementGetAttr(current, TYPENAME);
    if(attr == NULL){
      *rank = 1;
      *iType = NX_CHAR;
      dimension[0]= strlen(userData->value.opaque);
    } else {
      *iType = translateTypeCode(attr);
      analyzeDim(attr,rank,dimension,iType);
      if (dimension[0] == -1) /* 1D strings are NX_CHAR not NX_CHAR[] so length will not be correct */
      {
        dimension[0] = strlen(userData->value.opaque);
      }
      
    }
  } else { 
    dataset = (pNXDS)userData->value.custom.data;
    assert(dataset);
    myRank = getNXDatasetRank(dataset);
    *rank = myRank;
    *iType = getNXDatasetType(dataset);
    for(i = 0; i < myRank; i++){
      dimension[i] = getNXDatasetDim(dataset,i);
    }
  }
  return NX_OK;
}
/*---------------------------------------------------------------------
  clone the dataset and set the data pointer. This in order to use
  the addressing and type conversion implemented in nxdataset
---------------------------------------------------------------------*/ 
static pNXDS makeSlabData(pNXDS dataset, const void *data, const int64_t size[]){
  pNXDS slabData = NULL;
  int rank, i;
  
  slabData = (pNXDS)malloc(sizeof(NXDS));
  if(slabData == NULL){
    return NULL;
  }

  rank = getNXDatasetRank(dataset);
  slabData->rank = rank;
  slabData->dim = (int64_t *)malloc(rank*sizeof(int64_t));
  for(i = 0; i < rank; i++){
    slabData->dim[i] = size[i];
  }
  slabData->type = getNXDatasetType(dataset);
  slabData->u.ptr = (void*)data;
  slabData->magic = dataset->magic;
  return slabData;
} 
/*--------------------------------------------------------------------
  This goes by recursion
----------------------------------------------------------------------*/
static void putSlabData(pNXDS dataset, pNXDS slabData, int dim,
			const int64_t start[], 
			int64_t sourcePos[], int64_t targetPos[]){
  int64_t i, rank, length;

  rank = getNXDatasetRank(slabData);
  length = getNXDatasetDim(slabData,dim);
  if(dim != rank-1){
    for(i = 0; i < length; i++){
      targetPos[dim] = start[dim] +i;
      sourcePos[dim] = i;
      putSlabData(dataset,slabData, dim+1,start,
		  sourcePos,targetPos);
    }
  } else {
    for(i = 0; i < length; i++){
      targetPos[dim] = start[dim] +i;
      sourcePos[dim] = i;
      putNXDatasetValue(dataset,targetPos,
			getNXDatasetValue(slabData,sourcePos));
    }
  }
}
/*----------------------------------------------------------------------
 This is in order to support unlimited dimensions along the first axis
 -----------------------------------------------------------------------*/
static int checkAndExtendDataset(mxml_node_t *node, pNXDS dataset, 
				 const int64_t start[], const int64_t size[]){
  int64_t dim0, byteLength;
  void *oldData = NULL;
  char *typestring = NULL;

  dim0 = start[0] + size[0];
  if(dim0 > dataset->dim[0]){
    byteLength = getNXDatasetByteLength(dataset);
    oldData = dataset->u.ptr;
    dataset->dim[0] = dim0;
    dataset->u.ptr = malloc(getNXDatasetByteLength(dataset));
    if(dataset->u.ptr == NULL){
      return 0;
    }
    memset(dataset->u.ptr,0,getNXDatasetByteLength(dataset));
    memcpy(dataset->u.ptr,oldData,byteLength);
    free(oldData);
    typestring = buildTypeString(dataset->type,dataset->rank,dataset->dim);
    if(typestring != NULL){
      mxmlElementSetAttr(node,TYPENAME,typestring);
      free(typestring);
    } else {
      NXReportError("Failed to allocate typestring");
      return 0;
    }
  }
  return 1;
}

NXstatus  NXXputslabtable (NXhandle fid, const void *data, 
				   const int64_t iStart[], const int64_t iSize[]){
    return NX_OK;
}
/*----------------------------------------------------------------------*/
NXstatus  NXXputslab64 (NXhandle fid, const void *data, 
				   const int64_t iStart[], const int64_t iSize[]){
  
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *userData = NULL;
  mxml_node_t *current = NULL;
  pNXDS dataset, slabData;
  int64_t sourcePos[NX_MAXRANK], targetPos[NX_MAXRANK];
  int status;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if (xmlHandle->stack[xmlHandle->stackPointer].options & XMLSTACK_OPTION_TABLE)
  {
      return NXXputslabtable(fid,data,iStart,iSize);
  }

  if(!isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No dataset open");
    return NX_ERROR;
  }
  
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  userData = findData(current);
  assert(userData != NULL);
  if(userData->type == MXML_OPAQUE){
    NXReportError("This API does not support slabs on text data");
    return NX_ERROR;
  }
  dataset = (pNXDS)userData->value.custom.data;
  assert(dataset);

  status = checkAndExtendDataset(current,dataset,iStart,iSize);
  if(status == 0){
    NXReportError("Out of memory extending dataset");
    return NX_ERROR;
  }

  slabData = makeSlabData(dataset, data, iSize);
  if(slabData == NULL){
    NXReportError("Failed to allocate slab data");
    return NX_ERROR;
  }
  

  putSlabData(dataset,slabData,0,iStart,sourcePos,targetPos);
  free(slabData->dim);
  free(slabData);
  
  return NX_OK;
}
/*--------------------------------------------------------------------
  This goes by recursion
----------------------------------------------------------------------*/
static void getSlabData(pNXDS dataset, pNXDS slabData, int dim,
			const int64_t start[], 
			int64_t sourcePos[],int64_t targetPos[]){
  int64_t i, rank, length;

  rank = getNXDatasetRank(slabData);
  length = getNXDatasetDim(slabData,dim);
  if(dim != rank-1){
    for(i = 0; i < length; i++){
      sourcePos[dim] = start[dim] +i;
      targetPos[dim] = i;
      getSlabData(dataset,slabData, dim+1,start,
		  sourcePos,targetPos);
    }
  } else {
    for(i = 0; i < length; i++){
      sourcePos[dim] = start[dim] +i;
      targetPos[dim] = i;
      putNXDatasetValue(slabData,targetPos,
			getNXDatasetValue(dataset,sourcePos));
    }
  }
}
/*----------------------------------------------------------------------*/
NXstatus  NXXgetslab64 (NXhandle fid, void *data, 
				   const int64_t iStart[], const int64_t iSize[]){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *userData = NULL;
  mxml_node_t *current = NULL;
  pNXDS dataset, slabData;
  int64_t sourcePos[NX_MAXRANK], targetPos[NX_MAXRANK];

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(!isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No dataset open");
    return NX_ERROR;
  }
  
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  userData = findData(current);
  assert(userData != NULL);
  if(userData->type == MXML_OPAQUE){
    NXReportError("This API does not support slabs on text data");
    return NX_ERROR;
  }
  dataset = (pNXDS)userData->value.custom.data;
  assert(dataset);
  slabData = makeSlabData(dataset, data, iSize);
  if(slabData == NULL){
    NXReportError("Failed to allocate slab data");
    return NX_ERROR;
  }
  getSlabData(dataset,slabData,0,iStart,sourcePos,targetPos);
  free(slabData->dim);
  free(slabData);
  
  return NX_OK;
}
/*----------------------------------------------------------------------*/
static NXstatus  NXXsetnumberformat(NXhandle fid,
						 int type, char *format){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL;
  mxml_node_t *userData = NULL;
  pNXDS dataset;
  
  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    current = xmlHandle->stack[xmlHandle->stackPointer].current;
    userData = findData(current);
    assert(userData != NULL);
    if(userData->type == MXML_OPAQUE){
      return NX_OK;
    }
    dataset = (pNXDS)userData->value.custom.data;
    assert(dataset);
    if(dataset->format != NULL){
      free(dataset->format);
    }
    dataset->format = strdup(format);
  } else {
    setNumberFormat(type, format);
  }
  return NX_OK;
}
/*============================ Attributes ============================*/
static char *formatAttributeData(const void *data, int datalen, int iType){
  int intData = 0;
  long iValue = -99999;
  double dValue = -1e38;
  char type[20];
  char *number;


  if(iType == NX_CHAR){
/* data may not be NULL terminated */
    number = (char*)malloc((datalen+1) * sizeof(char));
    memcpy(number, data, datalen * sizeof(char));
    number[datalen] = '\0';
    return number;
  }

  number = (char *)malloc(132*sizeof(char));
  if(!number){
    NXReportError("Failed to allocate attribute number buffer");
    return NULL;
  }
  
  if(datalen > 1){
    return NULL;
  }
  type[0] = '\0';
  switch(iType){
  case NX_INT32:
    iValue = ((int *)data)[0];
    intData = 1;
    strcpy(type,"NX_INT32:");
    break;
  case NX_UINT32:
    iValue = ((unsigned int *)data)[0];
    intData = 1;
    strcpy(type,"NX_UINT32:");
    break;
  case NX_INT16:
    iValue = ((short *)data)[0];
    intData = 1;
    strcpy(type,"NX_INT16:");
    break;
  case NX_UINT16:
    iValue = ((unsigned short *)data)[0];
    intData = 1;
    strcpy(type,"NX_UINT16:");
    break;
  case NX_INT8:
    iValue = (int)((char *)data)[0];
    intData = 1;
    strcpy(type,"NX_INT8:");
    break;
  case NX_UINT8:
    intData = 1;
    iValue = (int)((unsigned char *)data)[0];
    strcpy(type,"NX_UINT8:");
    break;
  case NX_FLOAT32:
    dValue = ((float *)data)[0];
    strcpy(type,"NX_FLOAT32:");
    intData = 0;
    break;
  case NX_FLOAT64:
    dValue = ((double *)data)[0];
    strcpy(type,"NX_FLOAT64:");
    intData = 0;
    break;
  }
  if(intData){
    snprintf(number,79,"%s%ld",type,iValue);
  } else {
    snprintf(number,79,"%s%f",type,dValue);
  }
  return number;
}
/*---------------------------------------------------------------------*/
NXstatus  NXXputattr (NXhandle fid, CONSTCHAR *name, const void *data, 
				   int datalen, int iType){
  char buffer[256];
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL;
  char *numberData = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);
  if (!validNXName(name, 1))
  {
    sprintf(buffer, "ERROR: invalid characters in attribute name \"%s\"", name);
    NXReportError(buffer);
    return NX_ERROR;
  }

  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    if(strcmp(name,TYPENAME) == 0){
      NXReportError("type is a reserved attribute name, rejected");
      return  NX_ERROR;
    }
  }

  numberData = formatAttributeData(data,datalen,iType);
  if(numberData == NULL){
    NXReportError("This API does not support non number arrays");
    return NX_ERROR;
  } else {
    mxmlElementSetAttr(current,name,numberData);
    free(numberData);
  }
  return NX_OK;
}
/*--------------------------------------------------------------------------*/
NXstatus  NXXgetattr (NXhandle fid, char *name, 
				   void *data, int* datalen, int* iType){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL;
  const char *attribute = NULL;
  char error[1024];
  const char *attData = NULL;
  int nx_type;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  current = xmlHandle->stack[xmlHandle->stackPointer].current;

  attribute = mxmlElementGetAttr(current,name);
  if(!attribute){
    snprintf(error,1023,"Attribute %s not found", name);
    NXReportError(error);
    return NX_ERROR;
  }
  nx_type = translateTypeCode((char *)attribute);
  if(nx_type < 0) {
    /*
      no type code == text attribute
    */
    nx_type = NX_CHAR;
  } else {
    /*
      We need to find the number after the type code. However, there is
      the complication of the datatype type attribute ...
    */
    if(strcmp(name,TYPENAME) == 0){
      nx_type = NX_CHAR;
    } else {
      attData = strchr(attribute,(int)':');
      if(attData == NULL){
	NXReportError("ERROR: bad attribute string, : missing");
	return NX_ERROR;
      }
      attData++;
    }
  }
  *iType = nx_type;
  switch(nx_type){
  case NX_CHAR:
    /* enforce NULL termination regardless of length of datalen */
    strncpy((char *)data, attribute, *datalen-1);
    ((char*)data)[*datalen-1] = '\0';
    /* *datalen = strlen(attribute); */
    *datalen = strlen((char*)data);
    *iType = NX_CHAR;
    break;
  case NX_INT32:
    ((int *)data)[0] = atoi(attData);
    *datalen = 1;
    break;
  case NX_UINT32:
    ((unsigned int *)data)[0] = atoi(attData);
    *datalen = 1;
    break;
  case NX_INT16:
    ((short *)data)[0] = atoi(attData);
    *datalen = 1;
    break;
  case NX_UINT16:
    ((unsigned short *)data)[0] = atoi(attData);
    *datalen = 1;
    break;
  case NX_INT8:
    ((char *)data)[0] = atoi(attData);
    *datalen = 1;
    break;
  case NX_UINT8:
    ((unsigned char *)data)[0] = atoi(attData);
    *datalen = 1;
    break;
  case NX_FLOAT32:
    ((float *)data)[0] = atof(attData);
    *datalen = 1;
    break;
  case NX_FLOAT64:
    ((double *)data)[0] = atof(attData);
    *datalen = 1;
    break;
  }

  return NX_OK;
}

/* find the next node, ignoring Idata */
static mxml_node_t* find_node(mxml_node_t* node, int next)
{
  int done = 0;
  mxml_node_t* parent_next = NULL; /* parent to use if we are in an Idims  search */
   if (node == NULL)
   {
	return NULL;
   }
   if ( (node->parent != NULL)  && !strcmp(node->parent->value.element.name, DIMS_NODE_NAME) )
   {
	parent_next = node->parent->next;
   }
   else
   {
	parent_next = NULL;
   }
   if (next)
   {
       if (node->next != NULL)
       {
	    node = node->next;
       }
       else
       {
	    node = parent_next;
       }
   }
   while(node != NULL && !done)
   {
     if ( (node->parent != NULL)  && !strcmp(node->parent->value.element.name, DIMS_NODE_NAME) )
     {
	parent_next = node->parent->next;
     }
     else
     {
        parent_next = NULL;
     }
     if ( (node->type != MXML_ELEMENT) || !strcmp(node->value.element.name, DATA_NODE_NAME) )
     {
	if (node->next != NULL)
	{
	    node = node->next;
	}
	else
	{
	    node = parent_next;
	}
	continue;
     }
     if (!strcmp(node->value.element.name, DIMS_NODE_NAME))
     {
	node = node->child;
	continue;
     }
     done = 1;
  }
  return node;
}

/*====================== search functions =================================*/
NXstatus  NXXgetnextentry (NXhandle fid,NXname name, 
					NXname nxclass, int *datatype){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *next = NULL, *userData, *node = NULL;
  int stackPtr;
  const char *target = NULL, *attname = NULL;
  pNXDS dataset;
  char pBueffel[256];
  const char *linkName = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    /*
      be nice to user: silently fix this problem
    */
    NXXclosedata(fid);
  }

  stackPtr = xmlHandle->stackPointer;
  if(xmlHandle->stack[stackPtr].currentChild == NULL){
    /*
      initialization of search
    */
      node = find_node(xmlHandle->stack[stackPtr].current->child, 0);
  } else {
    /*
      proceed
    */
    node = find_node(xmlHandle->stack[stackPtr].currentChild, 1);
  }
  xmlHandle->stack[stackPtr].currentChild = node;
  next = node;
  if(next == NULL){
    return NX_EOD;
  }
  if(strcmp(next->value.element.name,"NAPIlink") == 0){
    target = mxmlElementGetAttr(next,"target");
    linkName = mxmlElementGetAttr(next,"name");
    if(target == NULL){
      NXReportError("Corrupted file, NAPIlink without target");
      return NX_ERROR;
    }
    next = getLinkTarget(xmlHandle,target);
    if(next == NULL){
      NXReportError("Corrupted file, broken link");
      return NX_ERROR;
    }
  }

  if(isDataNode(next)){
    strcpy(name,next->value.element.name);
    strcpy(nxclass,"SDS");
    userData = findData(next);
    if(userData == NULL){
	snprintf(pBueffel,255,"Corrupted file, userData for %s not found",
		 name);
      NXReportError(pBueffel);
      return NX_ERROR;
    }
    if(userData->type == MXML_OPAQUE){
      *datatype = NX_CHAR;
    } else {
      dataset = (pNXDS)userData->value.custom.data;
      assert(dataset);
      *datatype = getNXDatasetType(dataset);
    }
  } else {
    strcpy(nxclass,next->value.element.name);
    attname = mxmlElementGetAttr(next,"name");
    strcpy(name,attname);
  }
  /*
    this is for named links
  */
  if(linkName != NULL){
    strcpy(name,linkName);
  }
  return NX_OK;
}
/*----------------------------------------------------------------------*/
extern  NXstatus NXXinitgroupdir(NXhandle fid){
  pXMLNexus xmlHandle = NULL;
  int stackPtr;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("Cannot search datasets");
    return NX_ERROR;
  }

  stackPtr = xmlHandle->stackPointer;
  xmlHandle->stack[stackPtr].currentChild = NULL;
  return NX_OK;
}
/*-------------------------------------------------------------------------*/
NXstatus  NXXgetnextattr (NXhandle fid, NXname pName,
					  int *iLength, int *iType){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL;
  int stackPtr, currentAtt, nx_type;
  char *attVal; 

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  stackPtr = xmlHandle->stackPointer;

  current = xmlHandle->stack[stackPtr].current;
  currentAtt = xmlHandle->stack[stackPtr].currentAttribute;
  if(currentAtt >= 
     current->value.element.num_attrs ){
    xmlHandle->stack[stackPtr].currentAttribute = 0;
    return NX_EOD;
  }

  /*
    hide group name attribute
  */
  if(strcmp(current->value.element.attrs[currentAtt].name,"name") == 0
     && !isDataNode(current) ){
    xmlHandle->stack[stackPtr].currentAttribute++;
    return NXXgetnextattr(fid,pName,iLength,iType);
  }

  /*
    hide type attribute
  */
  if(strcmp(current->value.element.attrs[currentAtt].name,TYPENAME) == 0
     && isDataNode(current)){
    xmlHandle->stack[stackPtr].currentAttribute++;
    return NXXgetnextattr(fid,pName,iLength,iType);
  }

  strcpy(pName,current->value.element.attrs[currentAtt].name);
  attVal = current->value.element.attrs[currentAtt].value;
  nx_type = translateTypeCode((char *)attVal);
  if(nx_type < 0 || strcmp(pName,TYPENAME) == 0){
    /*
      no type == NX_CHAR
    */
    *iLength = strlen(attVal);
    *iType = NX_CHAR;
  } else {
    *iLength = 1;
    *iType = nx_type;
  }

  xmlHandle->stack[stackPtr].currentAttribute++;
  return NX_OK;
}
/*-------------------------------------------------------------------------*/
extern  NXstatus  NXXinitattrdir(NXhandle fid){
  pXMLNexus xmlHandle = NULL;
  int stackPtr;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  stackPtr = xmlHandle->stackPointer;
  xmlHandle->stack[stackPtr].currentAttribute = 0;
  return NX_OK;
}
/*-------------------------------------------------------------------------*/
NXstatus  NXXgetgroupinfo (NXhandle fid, int *iN, 
					NXname pName, NXname pClass){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *node = NULL, *child = NULL;
  mxml_node_t *current = NULL;
  const char *nameAtt = NULL;
  int childCount;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No group open");
    return NX_ERROR;
  } 
  current = xmlHandle->stack[xmlHandle->stackPointer].current;

  nameAtt = mxmlElementGetAttr(current,"name");
  if(nameAtt !=  NULL){
    strcpy(pName,nameAtt);
  }
  strcpy(pClass,current->value.element.name);

/* count all child nodes, but need to ignore DATA_NODE_NAME and
 * descend into DIMS_NODE_NAME 
 */
  childCount = 0;
  node = current->child;
  while(node != NULL)
  {
	if (!strcmp(node->value.element.name, DATA_NODE_NAME))
	{
	    ;	/* names also exist in DIMS_NODE_NAME so do nothing here */
	}
	else if (!strcmp(node->value.element.name, DIMS_NODE_NAME))
	{
	    child = node->child;
	    while(child != NULL)
	    {
		/* not sure why this check is needed, but you double count otherwise */
		if (child->type == MXML_ELEMENT) 
		{
		    childCount++;
		}
		child = child->next;
	    }
	}
	else
	{
    	    childCount++;
	}
	node = node->next;
  }
  *iN = childCount;
  return NX_OK;
}
/*----------------------------------------------------------------------*/
NXstatus  NXXgetattrinfo (NXhandle fid, int *iN){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL;
  int stackPtr, skip;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  stackPtr = xmlHandle->stackPointer;

  current = xmlHandle->stack[stackPtr].current;

  /*
    hide type and group name attributes
  */
  skip=0;
  if(isDataNode(current)) {
    /* data nodes may have type */
    if(mxmlElementGetAttr(current,TYPENAME) != NULL) skip=1;
  } else {
    /* group nodes (except root) have name */
    if(mxmlElementGetAttr(current,"name") != NULL) skip=1;
  }
  *iN = current->value.element.num_attrs - skip;
  return NX_OK;
}
/*================= Linking functions =================================*/
static int countPathChars(mxml_node_t *path[], int stackPtr){
  int count = 1;
  const char *name = NULL;

  while(stackPtr >= 0) {
    if(isDataNode(path[stackPtr])){
      count += strlen(path[stackPtr]->value.element.name);
    } else {
      name = mxmlElementGetAttr(path[stackPtr],"name");
      if(name != NULL){
	count += strlen(name);
      }
    }
    stackPtr--;
    count += 1;
  }
  return count;
}
/*-------------------------------------------------------------------*/
static char *buildPathString(mxml_node_t *path[], int stackPtr){
  int count = 0;
  const char *name = NULL;
  char *pathString = NULL;

  count = countPathChars(path,stackPtr);
  pathString = (char *)malloc((count+10)*sizeof(char));
  if(pathString == NULL){
    return NULL;
  }
  memset(pathString,0,(count+10)*sizeof(char));

  while(stackPtr >= 0) {
    if(isDataNode(path[stackPtr])){
      strcat(pathString,"/");
      strcat(pathString,path[stackPtr]->value.element.name);
    } else {
      name = mxmlElementGetAttr(path[stackPtr],"name");
      if(name != NULL){
	strcat(pathString,"/");
	strcat(pathString,name);
      }
    }
    stackPtr--;
  }
  return pathString;
}
/*--------------------------------------------------------------------*/
static char *findLinkPath(mxml_node_t *node){
  mxml_node_t **path = NULL;
  int stackPtr;
  mxml_node_t *current = NULL;
  char *result = NULL;

  path = (mxml_node_t **)malloc(NXMAXSTACK*sizeof(mxml_node_t *));
  if(path == NULL){
    NXReportError("ERROR: out of memory following link path");
    return NULL;
  }
  memset(path,0,NXMAXSTACK*sizeof(mxml_node_t *));

  /*
    first path:  walk up the tree untill NXroot is found
  */
  current = node;
  stackPtr = 0;
  while(current != NULL && 
	strcmp(current->value.element.name,"NXroot") != 0){
    path[stackPtr] = current;
    stackPtr++;
    current = current->parent;
  }
  stackPtr--;

  /*
    path now contains the nodes to the root node in reverse order.
    From this build the path string
  */
  result = buildPathString(path,stackPtr);
  free(path);
  return result;
}
/*--------------------------------------------------------------------*/
NXstatus  NXXgetdataID (NXhandle fid, NXlink* sRes){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL;
  char *linkPath = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(!isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    return NX_ERROR;
  } 
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  
  linkPath = findLinkPath(current);
  if(!linkPath){
    NXReportError("Failed to allocate link path string");
    return NX_ERROR;
  }
  strncpy(sRes->targetPath,linkPath,1023);
  free(linkPath);
  return NX_OK;
}
/*--------------------------------------------------------------------*/
NXstatus  NXXgetgroupID (NXhandle fid, NXlink* sRes){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL;
  char *linkPath = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No group open");
    return NX_ERROR;
  } 
  current = xmlHandle->stack[xmlHandle->stackPointer].current;

  if(xmlHandle->stackPointer == 0){
    return NX_ERROR;
  }

  linkPath = findLinkPath(current);
  if(!linkPath){
    NXReportError("Failed to allocate link path string");
    return NX_ERROR;
  }
  strncpy(sRes->targetPath,linkPath,1023);
  free(linkPath);
  return NX_OK;
}

/*-----------------------------------------------------------------------*/
  NXstatus  NXXprintlink (NXhandle fid, NXlink* sLink)
  {
    pXMLNexus xmlHandle = NULL;
    xmlHandle = (pXMLNexus)fid;
    assert(xmlHandle);

    printf("XML link: target=\"%s\"\n", sLink->targetPath);
    return NX_OK;
  }
  
/*-----------------------------------------------------------------------*/
NXstatus  NXXmakelink (NXhandle fid, NXlink* sLink){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL, *linkNode = NULL;
  mxml_node_t *linkedNode = NULL;

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No group to link to open");
    return NX_ERROR;
  } 
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  linkNode = mxmlNewElement(current,"NAPIlink");
  if(!linkNode){
    NXReportError("Failed to allocate new link element");
    return NX_ERROR;
  }
  mxmlElementSetAttr(linkNode,"target",sLink->targetPath);
  linkedNode = getLinkTarget(xmlHandle,sLink->targetPath);
  if(linkedNode != NULL){
    mxmlElementSetAttr(linkedNode,"target",sLink->targetPath);
  }
  return NX_OK;
}
  
/*-----------------------------------------------------------------------*/
NXstatus  NXXmakenamedlink (NXhandle fid, CONSTCHAR *name, NXlink* sLink){
  pXMLNexus xmlHandle = NULL;
  mxml_node_t *current = NULL, *linkNode = NULL;
  mxml_node_t *linkedNode = NULL;
  char buffer[256];

  xmlHandle = (pXMLNexus)fid;
  assert(xmlHandle);
  if (!validNXName(name, 0))
  {
    sprintf(buffer, "ERROR: invalid characters in link name \"%s\"", name);
    NXReportError(buffer);
    return NX_ERROR;
  }

  if(isDataNode(xmlHandle->stack[xmlHandle->stackPointer].current)){
    NXReportError("No group to link to open");
    return NX_ERROR;
  } 
  current = xmlHandle->stack[xmlHandle->stackPointer].current;
  linkNode = mxmlNewElement(current,"NAPIlink");
  if(!linkNode){
    NXReportError("Failed to allocate new link element");
    return NX_ERROR;
  }
  mxmlElementSetAttr(linkNode,"target",sLink->targetPath);
  mxmlElementSetAttr(linkNode,"name",name);
  linkedNode = getLinkTarget(xmlHandle,sLink->targetPath);
  if(linkedNode != NULL){
    mxmlElementSetAttr(linkedNode,"target",sLink->targetPath);
  }
  return NX_OK;
}
/*----------------------------------------------------------------------*/
NXstatus  NXXsameID (NXhandle fileid, NXlink* pFirstID, 
				  NXlink* pSecondID){
  if(strcmp(pFirstID->targetPath,pSecondID->targetPath) == 0) {
    return NX_OK;
  } else {
    return NX_ERROR;
  }
}
/*--------------------------------------------------------------------*/
int  NXXcompress(NXhandle fid, int comp){
  /* that will throw an exception in the Java API, errors have to be fatal */
  /* NXReportError("NXcompress is deprecated, IGNORED"); */
  return NX_OK;
}
/*----------------------------------------------------------------------*/
void NXXassignFunctions(pNexusFunction fHandle){
      fHandle->nxclose=NXXclose;
	  fHandle->nxreopen=NULL;
      fHandle->nxflush=NXXflush;
      fHandle->nxmakegroup=NXXmakegroup;
      fHandle->nxopengroup=NXXopengroup;
      fHandle->nxclosegroup=NXXclosegroup;
      fHandle->nxmakedata64=NXXmakedata64;
      fHandle->nxcompmakedata64=NXXcompmakedata64;
      fHandle->nxcompress=NXXcompress;
      fHandle->nxopendata=NXXopendata;
      fHandle->nxclosedata=NXXclosedata;
      fHandle->nxputdata=NXXputdata;
      fHandle->nxputattr=NXXputattr;
      fHandle->nxputslab64=NXXputslab64;    
      fHandle->nxgetdataID=NXXgetdataID;
      fHandle->nxmakelink=NXXmakelink;
      fHandle->nxmakenamedlink=NXXmakenamedlink;
      fHandle->nxgetdata=NXXgetdata;
      fHandle->nxgetinfo64=NXXgetinfo64;
      fHandle->nxgetnextentry=NXXgetnextentry;
      fHandle->nxgetslab64=NXXgetslab64;
      fHandle->nxgetnextattr=NXXgetnextattr;
      fHandle->nxgetattr=NXXgetattr;
      fHandle->nxgetattrinfo=NXXgetattrinfo;
      fHandle->nxgetgroupID=NXXgetgroupID;
      fHandle->nxgetgroupinfo=NXXgetgroupinfo;
      fHandle->nxsameID=NXXsameID;
      fHandle->nxinitgroupdir=NXXinitgroupdir;
      fHandle->nxinitattrdir=NXXinitattrdir;
      fHandle->nxsetnumberformat=NXXsetnumberformat;
      fHandle->nxprintlink=NXXprintlink;
      fHandle->nxnativeexternallink=NULL;
}



#endif /*NXXML*/