////////////////////////////////////////////////////////////////////////////////
//
//  File: MeshGraphIOXml.cpp
//
//  For more information, please see: http://www.nektar.info/
//
//  The MIT License
//
//  Copyright (c) 2006 Division of Applied Mathematics, Brown University (USA),
//  Department of Aeronautics, Imperial College London (UK), and Scientific
//  Computing and Imaging Institute, University of Utah (USA).
//
//  Permission is hereby granted, free of charge, to any person obtaining a
//  copy of this software and associated documentation files (the "Software"),
//  to deal in the Software without restriction, including without limitation
//  the rights to use, copy, modify, merge, publish, distribute, sublicense,
//  and/or sell copies of the Software, and to permit persons to whom the
//  Software is furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included
//  in all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
//  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
//  THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
//  DEALINGS IN THE SOFTWARE.
//
//  Description:
//
//
////////////////////////////////////////////////////////////////////////////////

#include <iomanip>

#include <SpatialDomains/MeshGraphIOXml.h>
#include <SpatialDomains/MeshPartition.h>
#include <SpatialDomains/Movement/Movement.h>

#include <LibUtilities/BasicUtils/FieldIOXml.h>
#include <LibUtilities/BasicUtils/Filesystem.hpp>
#include <LibUtilities/BasicUtils/ParseUtils.h>
#include <LibUtilities/Interpreter/Interpreter.h>

#include <boost/format.hpp>

#include <tinyxml.h>

namespace Nektar::SpatialDomains
{

std::string MeshGraphIOXml::className =
    GetMeshGraphIOFactory().RegisterCreatorFunction(
        "Xml", MeshGraphIOXml::create, "IO with Xml geometry");

void MeshGraphIOXml::v_PartitionMesh(
    const LibUtilities::SessionReaderSharedPtr session)
{
    // Get row of comm, or the whole comm if not split
    LibUtilities::CommSharedPtr comm     = session->GetComm();
    LibUtilities::CommSharedPtr commMesh = comm->GetRowComm();
    const bool isRoot                    = comm->TreatAsRankZero();

    m_session = session;

    int meshDimension;

    // Load file for root process only (since this is always needed)
    // and determine if the provided geometry has already been
    // partitioned. This will be the case if the user provides the
    // directory of mesh partitions as an input. Partitioned geometries
    // have the attribute
    //    PARTITION=X
    // where X is the number of the partition (and should match the
    // process rank). The result is shared with all other processes.
    int isPartitioned = 0;
    if (isRoot)
    {
        if (m_session->DefinesElement("Nektar/Geometry"))
        {
            if (m_session->GetElement("Nektar/Geometry")
                    ->Attribute("PARTITION"))
            {
                std::cout << "Using pre-partitioned mesh." << std::endl;
                isPartitioned = 1;
            }
            m_session->GetElement("NEKTAR/GEOMETRY")
                ->QueryIntAttribute("DIM", &meshDimension);
        }
    }
    comm->Bcast(isPartitioned, 0);
    comm->Bcast(meshDimension, 0);

    if (m_meshGraph->GetDomainRange() &&
        m_meshGraph->GetDomainRange()->m_compElmts)
    {
        m_meshGraph->GetDomainRange()->m_compElmts = meshDimension;
    }

    SetupCompositeRange(m_meshGraph->GetDomainRange());

    // If the mesh is already partitioned, we are done. Remaining
    // processes must load their partitions.
    if (isPartitioned)
    {
        if (!isRoot)
        {
            m_session->InitSession();
        }
    }
    else
    {
        // Default partitioner to use is Scotch, if it is installed.
        bool haveScotch = GetMeshPartitionFactory().ModuleExists("Scotch");
        bool haveMetis  = GetMeshPartitionFactory().ModuleExists("Metis");

        std::string partitionerName = "Scotch";
        if (!haveScotch && haveMetis)
        {
            partitionerName = "Metis";
        }

        // Override default with command-line flags if they are set.
        if (session->DefinesCmdLineArgument("use-metis"))
        {
            partitionerName = "Metis";
        }
        if (session->DefinesCmdLineArgument("use-scotch"))
        {
            partitionerName = "Scotch";
        }

        // Mesh has not been partitioned so do partitioning if required.  Note
        // in the serial case nothing is done as we have already loaded the
        // mesh.
        if (session->DefinesCmdLineArgument("part-only") ||
            session->DefinesCmdLineArgument("part-only-overlapping"))
        {
            // Perform partitioning of the mesh only. For this we insist the
            // code is run in serial (parallel execution is pointless).
            ASSERTL0(comm->GetSize() == 1,
                     "The 'part-only' option should be used in serial.");

            // Read 'lite' geometry information
            ReadGeometry(false);

            // Number of partitions is specified by the parameter.
            int nParts;
            auto comp = CreateCompositeDescriptor();

            MeshPartitionSharedPtr partitioner =
                GetMeshPartitionFactory().CreateInstance(
                    partitionerName, session, session->GetComm(), meshDimension,
                    CreateMeshEntities(), comp);

            if (session->DefinesCmdLineArgument("part-only"))
            {
                nParts = session->GetCmdLineArgument<int>("part-only");
                partitioner->PartitionMesh(nParts, true);
            }
            else
            {
                nParts =
                    session->GetCmdLineArgument<int>("part-only-overlapping");
                partitioner->PartitionMesh(nParts, true, true);
            }

            std::vector<std::set<unsigned int>> elmtIDs;
            std::vector<unsigned int> parts(nParts);
            for (int i = 0; i < nParts; ++i)
            {
                std::vector<unsigned int> elIDs;
                std::set<unsigned int> tmp;
                partitioner->GetElementIDs(i, elIDs);
                tmp.insert(elIDs.begin(), elIDs.end());
                elmtIDs.push_back(tmp);
                parts[i] = i;
            }

            this->WriteXMLGeometry(m_session->GetSessionName(), elmtIDs, parts);

            if (isRoot && session->DefinesCmdLineArgument("part-info"))
            {
                partitioner->PrintPartInfo(std::cout);
            }

            session->Finalise();
            exit(0);
        }

        if (commMesh->GetSize() > 1)
        {
            ASSERTL0(haveScotch || haveMetis,
                     "Valid partitioner not found! Either Scotch or METIS "
                     "should be used.");

            int nParts = commMesh->GetSize();

            if (session->GetSharedFilesystem())
            {
                std::vector<unsigned int> keys, vals;
                int i;

                if (isRoot)
                {
                    // Read 'lite' geometry information
                    ReadGeometry(false);

                    // Store composite ordering and boundary information.
                    m_compOrder = CreateCompositeOrdering();
                    m_meshGraph->SetCompositeOrdering(m_compOrder);
                    auto comp = CreateCompositeDescriptor();

                    // Create mesh partitioner.
                    MeshPartitionSharedPtr partitioner =
                        GetMeshPartitionFactory().CreateInstance(
                            partitionerName, session, session->GetComm(),
                            meshDimension, CreateMeshEntities(), comp);

                    partitioner->PartitionMesh(nParts, true);

                    std::vector<std::set<unsigned int>> elmtIDs;
                    std::vector<unsigned int> parts(nParts);
                    for (i = 0; i < nParts; ++i)
                    {
                        std::vector<unsigned int> elIDs;
                        std::set<unsigned int> tmp;
                        partitioner->GetElementIDs(i, elIDs);
                        tmp.insert(elIDs.begin(), elIDs.end());
                        elmtIDs.push_back(tmp);
                        parts[i] = i;
                    }

                    // Call WriteGeometry to write out partition files. This
                    // will populate m_bndRegOrder.
                    this->WriteXMLGeometry(m_session->GetSessionName(), elmtIDs,
                                           parts);

                    // Communicate orderings to the other processors.

                    // First send sizes of the orderings and boundary
                    // regions to allocate storage on the remote end.
                    keys.resize(2);
                    keys[0] = m_compOrder.size();
                    keys[1] = m_bndRegOrder.size();
                    comm->Bcast(keys, 0);

                    // Construct the keys and sizes of values for composite
                    // ordering
                    keys.resize(m_compOrder.size());
                    vals.resize(m_compOrder.size());

                    i = 0;
                    for (auto &cIt : m_compOrder)
                    {
                        keys[i]   = cIt.first;
                        vals[i++] = cIt.second.size();
                    }

                    // Send across data.
                    comm->Bcast(keys, 0);
                    comm->Bcast(vals, 0);
                    for (auto &cIt : m_compOrder)
                    {
                        comm->Bcast(cIt.second, 0);
                    }
                    m_meshGraph->SetCompositeOrdering(m_compOrder);

                    // Construct the keys and sizes of values for composite
                    // ordering
                    keys.resize(m_bndRegOrder.size());
                    vals.resize(m_bndRegOrder.size());

                    i = 0;
                    for (auto &bIt : m_bndRegOrder)
                    {
                        keys[i]   = bIt.first;
                        vals[i++] = bIt.second.size();
                    }

                    // Send across data.
                    if (!keys.empty())
                    {
                        comm->Bcast(keys, 0);
                    }
                    if (!vals.empty())
                    {
                        comm->Bcast(vals, 0);
                    }
                    for (auto &bIt : m_bndRegOrder)
                    {
                        comm->Bcast(bIt.second, 0);
                    }
                    m_meshGraph->SetBndRegionOrdering(m_bndRegOrder);

                    if (session->DefinesCmdLineArgument("part-info"))
                    {
                        partitioner->PrintPartInfo(std::cout);
                    }
                }
                else
                {
                    keys.resize(2);
                    comm->Bcast(keys, 0);

                    int cmpSize = keys[0];
                    int bndSize = keys[1];

                    keys.resize(cmpSize);
                    vals.resize(cmpSize);
                    comm->Bcast(keys, 0);
                    comm->Bcast(vals, 0);

                    for (int i = 0; i < keys.size(); ++i)
                    {
                        std::vector<unsigned int> tmp(vals[i]);
                        comm->Bcast(tmp, 0);
                        m_compOrder[keys[i]] = tmp;
                    }
                    m_meshGraph->SetCompositeOrdering(m_compOrder);

                    keys.resize(bndSize);
                    vals.resize(bndSize);
                    if (!keys.empty())
                    {
                        comm->Bcast(keys, 0);
                    }
                    if (!vals.empty())
                    {
                        comm->Bcast(vals, 0);
                    }
                    for (int i = 0; i < keys.size(); ++i)
                    {
                        std::vector<unsigned int> tmp(vals[i]);
                        comm->Bcast(tmp, 0);
                        m_bndRegOrder[keys[i]] = tmp;
                    }
                    m_meshGraph->SetBndRegionOrdering(m_bndRegOrder);
                }
            }
            else
            {
                m_session->InitSession();
                ReadGeometry(false);

                m_compOrder = CreateCompositeOrdering();
                m_meshGraph->SetCompositeOrdering(m_compOrder);
                auto comp = CreateCompositeDescriptor();

                // Partitioner now operates in parallel. Each process receives
                // partitioning over interconnect and writes its own session
                // file to the working directory.
                MeshPartitionSharedPtr partitioner =
                    GetMeshPartitionFactory().CreateInstance(
                        partitionerName, session, session->GetComm(),
                        meshDimension, CreateMeshEntities(), comp);

                partitioner->PartitionMesh(nParts, false);

                std::vector<unsigned int> parts(1), tmp;
                parts[0] = commMesh->GetRank();
                std::vector<std::set<unsigned int>> elIDs(1);
                partitioner->GetElementIDs(parts[0], tmp);
                elIDs[0].insert(tmp.begin(), tmp.end());

                // if (comm->GetTimeComm()->GetRank() == 0) // FIXME
                // (OpenMPI 3.1.3)
                {
                    this->WriteXMLGeometry(session->GetSessionName(), elIDs,
                                           parts);
                }

                if (m_session->DefinesCmdLineArgument("part-info") && isRoot)
                {
                    partitioner->PrintPartInfo(std::cout);
                }
            }

            // Wait for all processors to finish their writing activities.
            comm->Block();

            std::string dirname = m_session->GetSessionName() + "_xml";
            fs::path pdirname(dirname);
            boost::format pad("P%1$07d.xml");
            pad % comm->GetRowComm()->GetRank();
            fs::path pFilename(pad.str());
            fs::path fullpath = pdirname / pFilename;

            std::vector<std::string> filenames = {
                LibUtilities::PortablePath(fullpath)};
            m_session->InitSession(filenames);
        }
        else if (!isRoot)
        {
            // No partitioning, non-root processors need to read the session
            // file -- handles case where --npz is the same as number of
            // processors.
            m_session->InitSession();
        }
    }
}

void MeshGraphIOXml::SetupCompositeRange(LibUtilities::DomainRangeShPtr &rng)
{
    // Get row of comm, or the whole comm if not split
    LibUtilities::CommSharedPtr comm     = m_session->GetComm();
    LibUtilities::CommSharedPtr commMesh = comm->GetRowComm();
    const bool isRoot                    = comm->TreatAsRankZero();

    if (!rng || rng->m_compElmts == 0)
    {
        return; // composite rangge not being used.
    }

    TiXmlElement *field = nullptr;

    if (isRoot)
    {
        /// Look for elements in ELEMENT block.
        if (m_session->DefinesElement("NEKTAR/GEOMETRY/COMPOSITE"))
        {

            field = m_session->GetElement("NEKTAR/GEOMETRY/COMPOSITE");
        }
        else
        {
            return; // composite not defined
        }

        ASSERTL0(field, "Unable to find COMPOSITE tag in file.");

        TiXmlElement *node = field->FirstChildElement("C");

        while (node)
        {
            /// All elements are of the form: "<? ID="#"> ... </?>", with
            /// ? being the element type.
            int indx;
            int err = node->QueryIntAttribute("ID", &indx);
            ASSERTL0(err == TIXML_SUCCESS, "Unable to read attribute ID.");
            // check to see if we need to add this composite
            if (rng->m_comps.count(indx))
            {

                TiXmlNode *compositeChild = node->FirstChild();
                // This is primarily to skip comments that may be present.
                // Comments appear as nodes just like elements.
                // We are specifically looking for text in the body
                // of the definition.
                while (compositeChild &&
                       compositeChild->Type() != TiXmlNode::TINYXML_TEXT)
                {
                    compositeChild = compositeChild->NextSibling();
                }

                ASSERTL0(compositeChild,
                         "Unable to read composite definition body.");
                std::string compositeStr = compositeChild->ToText()->ValueStr();

                /// Parse out the element components corresponding to type of
                /// element.
                std::istringstream compositeDataStrm(compositeStr.c_str());

                try
                {
                    while (!compositeDataStrm.fail())
                    {
                        std::string compStr;
                        compositeDataStrm >> compStr;

                        if (compStr.length() > 0)
                        {
                            // extract setquence of values
                            std::string::size_type indxBeg =
                                compStr.find_first_of('[') + 1;
                            std::string::size_type indxEnd =
                                compStr.find_last_of(']') - 1;

                            ASSERTL0(indxBeg <= indxEnd,
                                     (std::string(
                                          "Error reading index definition:") +
                                      compStr)
                                         .c_str());

                            std::string indxStr =
                                compStr.substr(indxBeg, indxEnd - indxBeg + 1);
                            std::vector<unsigned int> seqVector;
                            bool err = ParseUtils::GenerateSeqVector(
                                indxStr.c_str(), seqVector);
                            ASSERTL0(err, "Error reading composite elements: " +
                                              indxStr);

                            for (auto it : seqVector) // add ids to Traceid
                            {
                                rng->m_traceIDs.insert(it);
                            }
                        }
                    }
                }
                catch (...)
                {
                    NEKERROR(ErrorUtil::efatal,
                             (std::string("Unable to read COMPOSITE data in "
                                          "composite range setup: ") +
                              compositeStr)
                                 .c_str());
                }
            }
            /// Keep looking for additional composite definitions.
            node = node->NextSiblingElement("C");
        }

        std::vector<unsigned> traceIDs;
        unsigned nTraceIDs = rng->m_traceIDs.size();

        comm->Bcast(nTraceIDs, 0);

        for (auto &It : rng->m_traceIDs)
        {
            traceIDs.push_back(It);
        }

        // Send across data.
        if (!traceIDs.empty())
        {
            comm->Bcast(traceIDs, 0);
        }
    }
    else // share TraceIDs from root
    {
        unsigned nTraceIDs;
        comm->Bcast(nTraceIDs, 0);

        std::vector<unsigned> traceIDs;
        traceIDs.resize(nTraceIDs);
        comm->Bcast(traceIDs, 0);
        for (auto &It : traceIDs)
        {
            rng->m_traceIDs.insert(It);
        }
    }
}

void MeshGraphIOXml::v_ReadGeometry(bool fillGraph)
{
    // Reset member variables.
    m_meshGraph->Clear();
    m_xmlGeom = m_session->GetElement("NEKTAR/GEOMETRY");

    int err; /// Error value returned by TinyXML.

    TiXmlAttribute *attr = m_xmlGeom->FirstAttribute();

    // Initialize the mesh and space dimensions to 3 dimensions.
    // We want to do this each time we read a file, so it should
    // be done here and not just during class initialization.
    int meshDimension  = m_meshGraph->GetMeshDimension();
    int spaceDimension = m_meshGraph->GetSpaceDimension();
    m_meshPartitioned  = false;
    meshDimension      = 3;
    spaceDimension     = 3;

    while (attr)
    {
        std::string attrName(attr->Name());
        if (attrName == "DIM")
        {
            err = attr->QueryIntValue(&meshDimension);
            ASSERTL0(err == TIXML_SUCCESS, "Unable to read mesh dimension.");
        }
        else if (attrName == "SPACE")
        {
            err = attr->QueryIntValue(&spaceDimension);
            ASSERTL0(err == TIXML_SUCCESS, "Unable to read space dimension.");
        }
        else if (attrName == "PARTITION")
        {
            err = attr->QueryIntValue(&m_partition);
            ASSERTL0(err == TIXML_SUCCESS, "Unable to read partition.");
            m_meshPartitioned = true;
            m_meshGraph->SetMeshPartitioned(true);
        }
        else
        {
            std::string errstr("Unknown attribute: ");
            errstr += attrName;
            ASSERTL0(false, errstr.c_str());
        }

        // Get the next attribute.
        attr = attr->Next();
    }

    m_meshGraph->SetMeshDimension(meshDimension);
    m_meshGraph->SetSpaceDimension(spaceDimension);

    ASSERTL0(meshDimension <= spaceDimension,
             "Mesh dimension greater than space dimension");

    v_ReadVertices();
    v_ReadCurves();
    if (meshDimension >= 2)
    {
        v_ReadEdges();
        if (meshDimension == 3)
        {
            v_ReadFaces();
        }
    }
    ReadElements();
    ReadComposites();
    ReadDomain();

    if (fillGraph)
    {
        m_meshGraph->FillGraph();
    }
}

void MeshGraphIOXml::v_ReadVertices()
{
    int spaceDimension = m_meshGraph->GetSpaceDimension();

    // Now read the vertices
    TiXmlElement *element = m_xmlGeom->FirstChildElement("VERTEX");
    ASSERTL0(element, "Unable to find mesh VERTEX tag in file.");

    NekDouble xscale, yscale, zscale;

    // check to see if any scaling parameters are in
    // attributes and determine these values
    LibUtilities::Interpreter expEvaluator;
    const char *xscal = element->Attribute("XSCALE");
    if (!xscal)
    {
        xscale = 1.0;
    }
    else
    {
        std::string xscalstr = xscal;
        int expr_id          = expEvaluator.DefineFunction("", xscalstr);
        xscale               = expEvaluator.Evaluate(expr_id);
    }

    const char *yscal = element->Attribute("YSCALE");
    if (!yscal)
    {
        yscale = 1.0;
    }
    else
    {
        std::string yscalstr = yscal;
        int expr_id          = expEvaluator.DefineFunction("", yscalstr);
        yscale               = expEvaluator.Evaluate(expr_id);
    }

    const char *zscal = element->Attribute("ZSCALE");
    if (!zscal)
    {
        zscale = 1.0;
    }
    else
    {
        std::string zscalstr = zscal;
        int expr_id          = expEvaluator.DefineFunction("", zscalstr);
        zscale               = expEvaluator.Evaluate(expr_id);
    }

    NekDouble xmove, ymove, zmove;

    // check to see if any moving parameters are in
    // attributes and determine these values

    const char *xmov = element->Attribute("XMOVE");
    if (!xmov)
    {
        xmove = 0.0;
    }
    else
    {
        std::string xmovstr = xmov;
        int expr_id         = expEvaluator.DefineFunction("", xmovstr);
        xmove               = expEvaluator.Evaluate(expr_id);
    }

    const char *ymov = element->Attribute("YMOVE");
    if (!ymov)
    {
        ymove = 0.0;
    }
    else
    {
        std::string ymovstr = ymov;
        int expr_id         = expEvaluator.DefineFunction("", ymovstr);
        ymove               = expEvaluator.Evaluate(expr_id);
    }

    const char *zmov = element->Attribute("ZMOVE");
    if (!zmov)
    {
        zmove = 0.0;
    }
    else
    {
        std::string zmovstr = zmov;
        int expr_id         = expEvaluator.DefineFunction("", zmovstr);
        zmove               = expEvaluator.Evaluate(expr_id);
    }

    NekDouble zrotate;

    const char *zrot = element->Attribute("ZROT");
    if (!zrot)
    {
        zrotate = 0.0;
    }
    else
    {
        std::string zrotstr = zrot;
        int expr_id         = expEvaluator.DefineFunction("", zrotstr);
        zrotate             = expEvaluator.Evaluate(expr_id);
    }

    TiXmlElement *vertex = element->FirstChildElement("V");

    int indx;

    while (vertex)
    {
        TiXmlAttribute *vertexAttr = vertex->FirstAttribute();
        std::string attrName(vertexAttr->Name());

        ASSERTL0(attrName == "ID",
                 (std::string("Unknown attribute name: ") + attrName).c_str());

        int err = vertexAttr->QueryIntValue(&indx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read attribute ID.");

        // Now read body of vertex
        std::string vertexBodyStr;

        TiXmlNode *vertexBody = vertex->FirstChild();

        while (vertexBody)
        {
            // Accumulate all non-comment body data.
            if (vertexBody->Type() == TiXmlNode::TINYXML_TEXT)
            {
                vertexBodyStr += vertexBody->ToText()->Value();
                vertexBodyStr += " ";
            }

            vertexBody = vertexBody->NextSibling();
        }

        ASSERTL0(!vertexBodyStr.empty(),
                 "Vertex definitions must contain vertex data.");

        // Get vertex data from the data string.
        NekDouble xval, yval, zval;
        std::istringstream vertexDataStrm(vertexBodyStr.c_str());

        try
        {
            while (!vertexDataStrm.fail())
            {
                vertexDataStrm >> xval >> yval >> zval;

                xval = xval * xscale + xmove;
                yval = yval * yscale + ymove;
                zval = zval * zscale + zmove;

                if (zrotate != 0.0)
                {
                    NekDouble xval_tmp =
                        xval * cos(zrotate) - yval * sin(zrotate);
                    yval = xval * sin(zrotate) + yval * cos(zrotate);
                    xval = xval_tmp;
                }

                // Need to check it here because we may not be
                // good after the read indicating that there
                // was nothing to read.
                if (!vertexDataStrm.fail())
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<PointGeom>::AllocateUniquePtr(
                                  spaceDimension, indx, xval, yval, zval));
                }
            }
        }
        catch (...)
        {
            ASSERTL0(false, "Unable to read VERTEX data.");
        }

        vertex = vertex->NextSiblingElement("V");
    }
}

void MeshGraphIOXml::v_ReadCurves()
{
    auto &curvedEdges = m_meshGraph->GetCurvedEdges();
    auto &curvedFaces = m_meshGraph->GetCurvedFaces();
    auto &curveNodes  = m_meshGraph->GetAllCurveNodes();
    int meshDimension = m_meshGraph->GetMeshDimension();

    // check to see if any scaling parameters are in
    // attributes and determine these values
    TiXmlElement *element = m_xmlGeom->FirstChildElement("VERTEX");
    ASSERTL0(element, "Unable to find mesh VERTEX tag in file.");

    NekDouble xscale, yscale, zscale;

    LibUtilities::Interpreter expEvaluator;
    const char *xscal = element->Attribute("XSCALE");
    if (!xscal)
    {
        xscale = 1.0;
    }
    else
    {
        std::string xscalstr = xscal;
        int expr_id          = expEvaluator.DefineFunction("", xscalstr);
        xscale               = expEvaluator.Evaluate(expr_id);
    }

    const char *yscal = element->Attribute("YSCALE");
    if (!yscal)
    {
        yscale = 1.0;
    }
    else
    {
        std::string yscalstr = yscal;
        int expr_id          = expEvaluator.DefineFunction("", yscalstr);
        yscale               = expEvaluator.Evaluate(expr_id);
    }

    const char *zscal = element->Attribute("ZSCALE");
    if (!zscal)
    {
        zscale = 1.0;
    }
    else
    {
        std::string zscalstr = zscal;
        int expr_id          = expEvaluator.DefineFunction("", zscalstr);
        zscale               = expEvaluator.Evaluate(expr_id);
    }

    NekDouble xmove, ymove, zmove;

    // check to see if any moving parameters are in
    // attributes and determine these values

    const char *xmov = element->Attribute("XMOVE");
    if (!xmov)
    {
        xmove = 0.0;
    }
    else
    {
        std::string xmovstr = xmov;
        int expr_id         = expEvaluator.DefineFunction("", xmovstr);
        xmove               = expEvaluator.Evaluate(expr_id);
    }

    const char *ymov = element->Attribute("YMOVE");
    if (!ymov)
    {
        ymove = 0.0;
    }
    else
    {
        std::string ymovstr = ymov;
        int expr_id         = expEvaluator.DefineFunction("", ymovstr);
        ymove               = expEvaluator.Evaluate(expr_id);
    }

    const char *zmov = element->Attribute("ZMOVE");
    if (!zmov)
    {
        zmove = 0.0;
    }
    else
    {
        std::string zmovstr = zmov;
        int expr_id         = expEvaluator.DefineFunction("", zmovstr);
        zmove               = expEvaluator.Evaluate(expr_id);
    }

    NekDouble zrotate;

    const char *zrot = element->Attribute("ZROT");
    if (!zrot)
    {
        zrotate = 0.0;
    }
    else
    {
        std::string zrotstr = zrot;
        int expr_id         = expEvaluator.DefineFunction("", zrotstr);
        zrotate             = expEvaluator.Evaluate(expr_id);
    }

    int err;

    /// Look for elements in CURVE block.
    TiXmlElement *field = m_xmlGeom->FirstChildElement("CURVED");

    if (!field) // return if no curved entities
    {
        return;
    }

    /// All curves are of the form: "<? ID="#" TYPE="GLL OR other
    /// points type" NUMPOINTS="#"> ... </?>", with ? being an
    /// element type (either E or F).

    TiXmlElement *edgelement = field->FirstChildElement("E");

    int edgeindx, edgeid;

    while (edgelement)
    {
        std::string edge(edgelement->ValueStr());
        ASSERTL0(edge == "E",
                 (std::string("Unknown 3D curve type:") + edge).c_str());

        /// Read id attribute.
        err = edgelement->QueryIntAttribute("ID", &edgeindx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read curve attribute ID.");

        /// Read edge id attribute.
        err = edgelement->QueryIntAttribute("EDGEID", &edgeid);
        ASSERTL0(err == TIXML_SUCCESS,
                 "Unable to read curve attribute EDGEID.");

        /// Read text edgelement description.
        std::string elementStr;
        TiXmlNode *elementChild = edgelement->FirstChild();

        while (elementChild)
        {
            // Accumulate all non-comment element data
            if (elementChild->Type() == TiXmlNode::TINYXML_TEXT)
            {
                elementStr += elementChild->ToText()->ValueStr();
                elementStr += " ";
            }
            elementChild = elementChild->NextSibling();
        }

        ASSERTL0(!elementStr.empty(), "Unable to read curve description body.");

        /// Parse out the element components corresponding to type of
        /// element.
        if (edge == "E")
        {
            int numPts = 0;
            // Determine the points type
            std::string typeStr = edgelement->Attribute("TYPE");
            ASSERTL0(!typeStr.empty(), "TYPE must be specified in "
                                       "points definition");

            LibUtilities::PointsType type;
            const std::string *begStr = LibUtilities::kPointsTypeStr;
            const std::string *endStr =
                LibUtilities::kPointsTypeStr + LibUtilities::SIZE_PointsType;
            const std::string *ptsStr = std::find(begStr, endStr, typeStr);

            ASSERTL0(ptsStr != endStr, "Invalid points type.");
            type = (LibUtilities::PointsType)(ptsStr - begStr);

            // Determine the number of points
            err = edgelement->QueryIntAttribute("NUMPOINTS", &numPts);
            ASSERTL0(err == TIXML_SUCCESS,
                     "Unable to read curve attribute NUMPOINTS.");

            auto curve = MemoryManager<Curve>::AllocateSharedPtr(edgeid, type);

            // Read points (x, y, z)
            NekDouble xval, yval, zval;
            std::istringstream elementDataStrm(elementStr.c_str());
            try
            {
                while (!elementDataStrm.fail())
                {
                    elementDataStrm >> xval >> yval >> zval;

                    xval = xval * xscale + xmove;
                    yval = yval * yscale + ymove;
                    zval = zval * zscale + zmove;

                    if (zrotate != 0.0)
                    {
                        NekDouble xval_tmp =
                            xval * cos(zrotate) - yval * sin(zrotate);
                        yval = xval * sin(zrotate) + yval * cos(zrotate);
                        xval = xval_tmp;
                    }
                    // Need to check it here because we may not be
                    // good after the read indicating that there
                    // was nothing to read.
                    if (!elementDataStrm.fail())
                    {
                        curveNodes.emplace_back(
                            ObjPoolManager<PointGeom>::AllocateUniquePtr(
                                meshDimension, edgeindx, xval, yval, zval));
                        curve->m_points.emplace_back(curveNodes.back().get());
                    }
                }
            }
            catch (...)
            {
                NEKERROR(ErrorUtil::efatal,
                         (std::string("Unable to read curve data for EDGE: ") +
                          elementStr)
                             .c_str());
            }

            ASSERTL0(curve->m_points.size() == numPts,
                     "Number of points specificed by attribute "
                     "NUMPOINTS is different from number of points "
                     "in list (edgeid = " +
                         std::to_string(edgeid));

            curvedEdges[edgeid] = curve;

            edgelement = edgelement->NextSiblingElement("E");

        } // end if-loop

    } // end while-loop

    TiXmlElement *facelement = field->FirstChildElement("F");
    int faceindx, faceid;

    while (facelement)
    {
        std::string face(facelement->ValueStr());
        ASSERTL0(face == "F",
                 (std::string("Unknown 3D curve type: ") + face).c_str());

        /// Read id attribute.
        err = facelement->QueryIntAttribute("ID", &faceindx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read curve attribute ID.");

        /// Read face id attribute.
        err = facelement->QueryIntAttribute("FACEID", &faceid);
        ASSERTL0(err == TIXML_SUCCESS,
                 "Unable to read curve attribute FACEID.");

        /// Read text face element description.
        std::string elementStr;
        TiXmlNode *elementChild = facelement->FirstChild();

        while (elementChild)
        {
            // Accumulate all non-comment element data
            if (elementChild->Type() == TiXmlNode::TINYXML_TEXT)
            {
                elementStr += elementChild->ToText()->ValueStr();
                elementStr += " ";
            }
            elementChild = elementChild->NextSibling();
        }

        ASSERTL0(!elementStr.empty(), "Unable to read curve description body.");

        /// Parse out the element components corresponding to type of
        /// element.
        if (face == "F")
        {
            std::string typeStr = facelement->Attribute("TYPE");
            ASSERTL0(!typeStr.empty(), "TYPE must be specified in "
                                       "points definition");
            LibUtilities::PointsType type;
            const std::string *begStr = LibUtilities::kPointsTypeStr;
            const std::string *endStr =
                LibUtilities::kPointsTypeStr + LibUtilities::SIZE_PointsType;
            const std::string *ptsStr = std::find(begStr, endStr, typeStr);

            ASSERTL0(ptsStr != endStr, "Invalid points type.");
            type = (LibUtilities::PointsType)(ptsStr - begStr);

            std::string numptsStr = facelement->Attribute("NUMPOINTS");
            ASSERTL0(!numptsStr.empty(),
                     "NUMPOINTS must be specified in points definition");
            int numPts = 0;
            std::stringstream s;
            s << numptsStr;
            s >> numPts;

            curvedFaces[faceid] =
                MemoryManager<Curve>::AllocateSharedPtr(faceid, type);

            ASSERTL0(numPts >= 3, "NUMPOINTS for face must be greater than 2");

            if (numPts == 3)
            {
                ASSERTL0(ptsStr != endStr, "Invalid points type.");
            }

            // Read points (x, y, z)
            NekDouble xval, yval, zval;
            std::istringstream elementDataStrm(elementStr.c_str());
            try
            {
                while (!elementDataStrm.fail())
                {
                    elementDataStrm >> xval >> yval >> zval;

                    // Need to check it here because we
                    // may not be good after the read
                    // indicating that there was nothing
                    // to read.
                    if (!elementDataStrm.fail())
                    {
                        curveNodes.emplace_back(
                            ObjPoolManager<PointGeom>::AllocateUniquePtr(
                                meshDimension, faceindx, xval, yval, zval));
                        curvedFaces[faceid]->m_points.emplace_back(
                            curveNodes.back().get());
                    }
                }
            }
            catch (...)
            {
                NEKERROR(ErrorUtil::efatal,
                         (std::string("Unable to read curve data for FACE: ") +
                          elementStr)
                             .c_str());
            }

            facelement = facelement->NextSiblingElement("F");
        }
    }
}

void MeshGraphIOXml::ReadDomain()
{
    auto &domain = m_meshGraph->GetDomain();

    TiXmlElement *element = nullptr;
    /// Look for data in DOMAIN block.
    element = m_xmlGeom->FirstChildElement("DOMAIN");

    ASSERTL0(element, "Unable to find DOMAIN tag in file.");

    /// Elements are of the form: "<D ID = "N"> ... </D>".
    /// Read the ID field first.
    TiXmlElement *multidomains = element->FirstChildElement("D");

    if (multidomains)
    {
        while (multidomains)
        {
            int indx;
            int err = multidomains->QueryIntAttribute("ID", &indx);
            ASSERTL0(err == TIXML_SUCCESS,
                     "Unable to read attribute ID in Domain.");

            TiXmlNode *elementChild = multidomains->FirstChild();
            while (elementChild &&
                   elementChild->Type() != TiXmlNode::TINYXML_TEXT)
            {
                elementChild = elementChild->NextSibling();
            }

            ASSERTL0(elementChild, "Unable to read DOMAIN body.");
            std::string elementStr = elementChild->ToText()->ValueStr();

            elementStr = elementStr.substr(elementStr.find_first_not_of(" "));

            std::string::size_type indxBeg = elementStr.find_first_of('[') + 1;
            std::string::size_type indxEnd = elementStr.find_last_of(']') - 1;
            std::string indxStr =
                elementStr.substr(indxBeg, indxEnd - indxBeg + 1);

            ASSERTL0(
                !indxStr.empty(),
                "Unable to read domain's composite index (index missing?).");

            // Read the domain composites.
            // Parse the composites into a list.
            std::map<int, CompositeSharedPtr> unrollDomain;
            m_meshGraph->GetCompositeList(indxStr, unrollDomain);
            domain[indx] = unrollDomain;

            ASSERTL0(!domain[indx].empty(),
                     (std::string(
                          "Unable to obtain domain's referenced composite: ") +
                      indxStr)
                         .c_str());

            /// Keep looking
            multidomains = multidomains->NextSiblingElement("D");
        }
    }
    else // previous definition of just one composite
    {

        // find the non comment portion of the body.
        TiXmlNode *elementChild = element->FirstChild();
        while (elementChild && elementChild->Type() != TiXmlNode::TINYXML_TEXT)
        {
            elementChild = elementChild->NextSibling();
        }

        ASSERTL0(elementChild, "Unable to read DOMAIN body.");
        std::string elementStr = elementChild->ToText()->ValueStr();

        elementStr = elementStr.substr(elementStr.find_first_not_of(" "));

        std::string::size_type indxBeg = elementStr.find_first_of('[') + 1;
        std::string::size_type indxEnd = elementStr.find_last_of(']') - 1;
        std::string indxStr = elementStr.substr(indxBeg, indxEnd - indxBeg + 1);

        ASSERTL0(!indxStr.empty(),
                 "Unable to read domain's composite index (index missing?).");

        // Read the domain composites.
        // Parse the composites into a list.
        std::map<int, CompositeSharedPtr> fullDomain;
        m_meshGraph->GetCompositeList(indxStr, fullDomain);
        domain[0] = fullDomain;

        ASSERTL0(
            !domain[0].empty(),
            (std::string("Unable to obtain domain's referenced composite: ") +
             indxStr)
                .c_str());
    }
}

void MeshGraphIOXml::v_ReadEdges()
{
    auto &curvedEdges  = m_meshGraph->GetCurvedEdges();
    int spaceDimension = m_meshGraph->GetSpaceDimension();

    CurveMap::iterator it;

    /// Look for elements in ELEMENT block.
    TiXmlElement *field = m_xmlGeom->FirstChildElement("EDGE");

    ASSERTL0(field, "Unable to find EDGE tag in file.");

    /// All elements are of the form: "<E ID="#"> ... </E>", with
    /// ? being the element type.
    /// Read the ID field first.
    TiXmlElement *edgeElement = field->FirstChildElement("E");

    /// Since all edge data is one big text block, we need to accumulate
    /// all TINYXML_TEXT data and then parse it.  This approach effectively
    /// skips
    /// all comments or other node types since we only care about the
    /// edge list.  We cannot handle missing edge numbers as we could
    /// with missing element numbers due to the text block format.
    std::string edgeStr;
    int indx;

    while (edgeElement)
    {
        int err = edgeElement->QueryIntAttribute("ID", &indx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read edge attribute ID.");

        TiXmlNode *child = edgeElement->FirstChild();
        edgeStr.clear();
        if (child->Type() == TiXmlNode::TINYXML_TEXT)
        {
            edgeStr += child->ToText()->ValueStr();
        }

        /// Now parse out the edges, three fields at a time.
        int vertex1, vertex2;
        std::istringstream edgeDataStrm(edgeStr.c_str());

        try
        {
            while (!edgeDataStrm.fail())
            {
                edgeDataStrm >> vertex1 >> vertex2;

                // Must check after the read because we
                // may be at the end and not know it.  If
                // we are at the end we will add a
                // duplicate of the last entry if we don't
                // check here.
                if (!edgeDataStrm.fail())
                {
                    std::array<PointGeom *, 2> vertices = {
                        m_meshGraph->GetPointGeom(vertex1),
                        m_meshGraph->GetPointGeom(vertex2)};
                    it = curvedEdges.find(indx);

                    if (it == curvedEdges.end())
                    {
                        m_meshGraph->AddGeom(
                            indx, ObjPoolManager<SegGeom>::AllocateUniquePtr(
                                      indx, spaceDimension, vertices));
                    }
                    else
                    {
                        m_meshGraph->AddGeom(
                            indx,
                            ObjPoolManager<SegGeom>::AllocateUniquePtr(
                                indx, spaceDimension, vertices, it->second));
                    }
                }
            }
        }
        catch (...)
        {
            NEKERROR(
                ErrorUtil::efatal,
                (std::string("Unable to read edge data: ") + edgeStr).c_str());
        }

        edgeElement = edgeElement->NextSiblingElement("E");
    }
}

void MeshGraphIOXml::v_ReadFaces()
{
    auto &curvedFaces = m_meshGraph->GetCurvedFaces();

    /// Look for elements in FACE block.
    TiXmlElement *field = m_xmlGeom->FirstChildElement("FACE");

    ASSERTL0(field, "Unable to find FACE tag in file.");

    /// All faces are of the form: "<? ID="#"> ... </?>", with
    /// ? being an element type (either Q or T).
    /// They might be in compressed format and so then need upacking.

    TiXmlElement *element = field->FirstChildElement();
    CurveMap::iterator it;

    while (element)
    {
        std::string elementType(element->ValueStr());

        ASSERTL0(elementType == "Q" || elementType == "T",
                 (std::string("Unknown 3D face type: ") + elementType).c_str());

        /// Read id attribute.
        int indx;
        int err = element->QueryIntAttribute("ID", &indx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read face attribute ID.");

        /// See if this face has curves.
        it = curvedFaces.find(indx);

        /// Read text element description.
        TiXmlNode *elementChild = element->FirstChild();
        std::string elementStr;
        while (elementChild)
        {
            if (elementChild->Type() == TiXmlNode::TINYXML_TEXT)
            {
                elementStr += elementChild->ToText()->ValueStr();
            }
            elementChild = elementChild->NextSibling();
        }

        ASSERTL0(!elementStr.empty(), "Unable to read face description body.");

        /// Parse out the element components corresponding to type of
        /// element.
        if (elementType == "T")
        {
            // Read three edge numbers
            int edge1, edge2, edge3;
            std::istringstream elementDataStrm(elementStr.c_str());

            try
            {
                elementDataStrm >> edge1;
                elementDataStrm >> edge2;
                elementDataStrm >> edge3;

                ASSERTL0(
                    !elementDataStrm.fail(),
                    (std::string("Unable to read face data for TRIANGLE: ") +
                     elementStr)
                        .c_str());

                /// Create a TriGeom to hold the new definition.
                std::array<SegGeom *, TriGeom::kNedges> edges = {
                    m_meshGraph->GetSegGeom(edge1),
                    m_meshGraph->GetSegGeom(edge2),
                    m_meshGraph->GetSegGeom(edge3)};

                if (it == curvedFaces.end())
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<TriGeom>::AllocateUniquePtr(
                                  indx, edges));
                }
                else
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<TriGeom>::AllocateUniquePtr(
                                  indx, edges, it->second));
                }
            }
            catch (...)
            {
                NEKERROR(
                    ErrorUtil::efatal,
                    (std::string("Unable to read face data for TRIANGLE: ") +
                     elementStr)
                        .c_str());
            }
        }
        else if (elementType == "Q")
        {
            // Read four edge numbers
            int edge1, edge2, edge3, edge4;
            std::istringstream elementDataStrm(elementStr.c_str());

            try
            {
                elementDataStrm >> edge1;
                elementDataStrm >> edge2;
                elementDataStrm >> edge3;
                elementDataStrm >> edge4;

                ASSERTL0(!elementDataStrm.fail(),
                         (std::string("Unable to read face data for QUAD: ") +
                          elementStr)
                             .c_str());

                /// Create a QuadGeom to hold the new definition.
                std::array<SegGeom *, QuadGeom::kNedges> edges = {
                    m_meshGraph->GetSegGeom(edge1),
                    m_meshGraph->GetSegGeom(edge2),
                    m_meshGraph->GetSegGeom(edge3),
                    m_meshGraph->GetSegGeom(edge4)};

                if (it == curvedFaces.end())
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<QuadGeom>::AllocateUniquePtr(
                                  indx, edges));
                }
                else
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<QuadGeom>::AllocateUniquePtr(
                                  indx, edges, it->second));
                }
            }
            catch (...)
            {
                NEKERROR(ErrorUtil::efatal,
                         (std::string("Unable to read face data for QUAD: ") +
                          elementStr)
                             .c_str());
            }
        }
        // Keep looking
        element = element->NextSiblingElement();
    }
}

void MeshGraphIOXml::ReadElements()
{
    int meshDimension = m_meshGraph->GetMeshDimension();

    switch (meshDimension)
    {
        case 1:
            v_ReadElements1D();
            break;
        case 2:
            v_ReadElements2D();
            break;
        case 3:
            v_ReadElements3D();
            break;
    }
}

void MeshGraphIOXml::v_ReadElements1D()
{
    auto &curvedEdges  = m_meshGraph->GetCurvedEdges();
    int spaceDimension = m_meshGraph->GetSpaceDimension();

    TiXmlElement *field = nullptr;

    /// Look for elements in ELEMENT block.
    field = m_xmlGeom->FirstChildElement("ELEMENT");

    ASSERTL0(field, "Unable to find ELEMENT tag in file.");

    /// All elements are of the form: "<S ID = n> ... </S>", with
    /// ? being the element type.

    TiXmlElement *segment = field->FirstChildElement("S");
    CurveMap::iterator it;

    while (segment)
    {
        int indx;
        int err = segment->QueryIntAttribute("ID", &indx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read element attribute ID.");

        TiXmlNode *elementChild = segment->FirstChild();
        while (elementChild && elementChild->Type() != TiXmlNode::TINYXML_TEXT)
        {
            elementChild = elementChild->NextSibling();
        }

        ASSERTL0(elementChild, "Unable to read element description body.");
        std::string elementStr = elementChild->ToText()->ValueStr();

        /// Parse out the element components corresponding to type of
        /// element.
        /// Read two vertex numbers
        int vertex1, vertex2;
        std::istringstream elementDataStrm(elementStr.c_str());

        try
        {
            elementDataStrm >> vertex1;
            elementDataStrm >> vertex2;

            ASSERTL0(!elementDataStrm.fail(),
                     (std::string("Unable to read element data for SEGMENT: ") +
                      elementStr)
                         .c_str());

            std::array<PointGeom *, 2> vertices = {
                m_meshGraph->GetPointGeom(vertex1),
                m_meshGraph->GetPointGeom(vertex2)};

            it = curvedEdges.find(indx);

            if (it == curvedEdges.end())
            {
                m_meshGraph->AddGeom(indx,
                                     ObjPoolManager<SegGeom>::AllocateUniquePtr(
                                         indx, spaceDimension, vertices));
            }
            else
            {
                m_meshGraph->AddGeom(
                    indx, ObjPoolManager<SegGeom>::AllocateUniquePtr(
                              indx, spaceDimension, vertices, it->second));
            }
        }
        catch (...)
        {
            NEKERROR(ErrorUtil::efatal,
                     (std::string("Unable to read element data for segment: ") +
                      elementStr)
                         .c_str());
        }
        /// Keep looking for additional segments
        segment = segment->NextSiblingElement("S");
    }
}

void MeshGraphIOXml::v_ReadElements2D()
{
    auto &curvedFaces = m_meshGraph->GetCurvedFaces();

    /// Look for elements in ELEMENT block.
    TiXmlElement *field = m_xmlGeom->FirstChildElement("ELEMENT");

    ASSERTL0(field, "Unable to find ELEMENT tag in file.");

    // Set up curve map for curved elements on an embedded manifold.
    CurveMap::iterator it;

    /// All elements are of the form: "<? ID="#"> ... </?>", with
    /// ? being the element type.

    TiXmlElement *element = field->FirstChildElement();

    while (element)
    {
        std::string elementType(element->ValueStr());

        ASSERTL0(
            elementType == "Q" || elementType == "T",
            (std::string("Unknown 2D element type: ") + elementType).c_str());

        /// Read id attribute.
        int indx;
        int err = element->QueryIntAttribute("ID", &indx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read element attribute ID.");

        it = curvedFaces.find(indx);

        /// Read text element description.
        TiXmlNode *elementChild = element->FirstChild();
        std::string elementStr;
        while (elementChild)
        {
            if (elementChild->Type() == TiXmlNode::TINYXML_TEXT)
            {
                elementStr += elementChild->ToText()->ValueStr();
            }
            elementChild = elementChild->NextSibling();
        }

        ASSERTL0(!elementStr.empty(),
                 "Unable to read element description body.");

        /// Parse out the element components corresponding to type of
        /// element.
        if (elementType == "T")
        {
            // Read three edge numbers
            int edge1, edge2, edge3;
            std::istringstream elementDataStrm(elementStr.c_str());

            try
            {
                elementDataStrm >> edge1;
                elementDataStrm >> edge2;
                elementDataStrm >> edge3;

                ASSERTL0(
                    !elementDataStrm.fail(),
                    (std::string("Unable to read element data for TRIANGLE: ") +
                     elementStr)
                        .c_str());

                /// Create a TriGeom to hold the new definition.
                std::array<SegGeom *, TriGeom::kNedges> edges = {
                    m_meshGraph->GetSegGeom(edge1),
                    m_meshGraph->GetSegGeom(edge2),
                    m_meshGraph->GetSegGeom(edge3)};

                if (it == curvedFaces.end())
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<TriGeom>::AllocateUniquePtr(
                                  indx, edges));
                }
                else
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<TriGeom>::AllocateUniquePtr(
                                  indx, edges, it->second));
                }
            }
            catch (...)
            {
                NEKERROR(
                    ErrorUtil::efatal,
                    (std::string("Unable to read element data for TRIANGLE: ") +
                     elementStr)
                        .c_str());
            }
        }
        else if (elementType == "Q")
        {
            // Read four edge numbers
            int edge1, edge2, edge3, edge4;
            std::istringstream elementDataStrm(elementStr.c_str());

            try
            {
                elementDataStrm >> edge1;
                elementDataStrm >> edge2;
                elementDataStrm >> edge3;
                elementDataStrm >> edge4;

                ASSERTL0(
                    !elementDataStrm.fail(),
                    (std::string("Unable to read element data for QUAD: ") +
                     elementStr)
                        .c_str());

                /// Create a QuadGeom to hold the new definition.
                std::array<SegGeom *, QuadGeom::kNedges> edges = {
                    m_meshGraph->GetSegGeom(edge1),
                    m_meshGraph->GetSegGeom(edge2),
                    m_meshGraph->GetSegGeom(edge3),
                    m_meshGraph->GetSegGeom(edge4)};

                if (it == curvedFaces.end())
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<QuadGeom>::AllocateUniquePtr(
                                  indx, edges));
                }
                else
                {
                    m_meshGraph->AddGeom(
                        indx, ObjPoolManager<QuadGeom>::AllocateUniquePtr(
                                  indx, edges, it->second));
                }
            }
            catch (...)
            {
                NEKERROR(
                    ErrorUtil::efatal,
                    (std::string("Unable to read element data for QUAD: ") +
                     elementStr)
                        .c_str());
            }
        }
        /// Keep looking
        element = element->NextSiblingElement();
    }
}

void MeshGraphIOXml::v_ReadElements3D()
{
    /// Look for elements in ELEMENT block.
    TiXmlElement *field = m_xmlGeom->FirstChildElement("ELEMENT");

    ASSERTL0(field, "Unable to find ELEMENT tag in file.");

    /// All elements are of the form: "<? ID="#"> ... </?>", with
    /// ? being the element type.

    TiXmlElement *element = field->FirstChildElement();

    while (element)
    {
        std::string elementType(element->ValueStr());

        // A - tet, P - pyramid, R - prism, H - hex
        ASSERTL0(
            elementType == "A" || elementType == "P" || elementType == "R" ||
                elementType == "H",
            (std::string("Unknown 3D element type: ") + elementType).c_str());

        /// Read id attribute.
        int indx;
        int err = element->QueryIntAttribute("ID", &indx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read element attribute ID.");

        /// Read text element description.
        TiXmlNode *elementChild = element->FirstChild();
        std::string elementStr;
        while (elementChild)
        {
            if (elementChild->Type() == TiXmlNode::TINYXML_TEXT)
            {
                elementStr += elementChild->ToText()->ValueStr();
            }
            elementChild = elementChild->NextSibling();
        }

        ASSERTL0(!elementStr.empty(),
                 "Unable to read element description body.");

        std::istringstream elementDataStrm(elementStr.c_str());

        /// Parse out the element components corresponding to type of
        /// element.

        // Tetrahedral
        if (elementType == "A")
        {
            try
            {
                /// Create arrays for the tri and quad faces.
                constexpr int kNfaces  = TetGeom::kNfaces;
                constexpr int kNtfaces = TetGeom::kNtfaces;
                constexpr int kNqfaces = TetGeom::kNqfaces;
                std::array<TriGeom *, kNtfaces> tfaces;
                int Ntfaces = 0;
                int Nqfaces = 0;

                /// Fill the arrays and make sure there aren't too many
                /// faces.
                std::stringstream errorstring;
                errorstring << "Element " << indx << " must have " << kNtfaces
                            << " triangle face(s), and " << kNqfaces
                            << " quadrilateral face(s).";
                for (int i = 0; i < kNfaces; i++)
                {
                    int faceID;
                    elementDataStrm >> faceID;
                    Geometry2D *face = m_meshGraph->GetGeometry2D(faceID);
                    if (face == nullptr ||
                        (face->GetShapeType() != LibUtilities::eTriangle &&
                         face->GetShapeType() != LibUtilities::eQuadrilateral))
                    {
                        std::stringstream errorstring;
                        errorstring << "Element " << indx
                                    << " has invalid face: " << faceID;
                        ASSERTL0(false, errorstring.str().c_str());
                    }
                    else if (face->GetShapeType() == LibUtilities::eTriangle)
                    {
                        ASSERTL0(Ntfaces < kNtfaces, errorstring.str().c_str());
                        tfaces[Ntfaces++] = static_cast<TriGeom *>(face);
                    }
                    else if (face->GetShapeType() ==
                             LibUtilities::eQuadrilateral)
                    {
                        ASSERTL0(Nqfaces < kNqfaces, errorstring.str().c_str());
                    }
                }

                /// Make sure all of the face indicies could be read, and
                /// that there weren't too few.
                ASSERTL0(!elementDataStrm.fail(),
                         (std::string(
                              "Unable to read element data for TETRAHEDRON: ") +
                          elementStr)
                             .c_str());
                ASSERTL0(Ntfaces == kNtfaces, errorstring.str().c_str());
                ASSERTL0(Nqfaces == kNqfaces, errorstring.str().c_str());

                auto tetGeom =
                    ObjPoolManager<TetGeom>::AllocateUniquePtr(indx, tfaces);
                m_meshGraph->PopulateFaceToElMap(tetGeom.get(), kNfaces);
                m_meshGraph->AddGeom(indx, std::move(tetGeom));
            }
            catch (...)
            {
                NEKERROR(ErrorUtil::efatal,
                         (std::string(
                              "Unable to read element data for TETRAHEDRON: ") +
                          elementStr)
                             .c_str());
            }
        }
        // Pyramid
        else if (elementType == "P")
        {
            try
            {
                /// Create arrays for the tri and quad faces.
                constexpr int kNfaces  = PyrGeom::kNfaces;
                constexpr int kNtfaces = PyrGeom::kNtfaces;
                constexpr int kNqfaces = PyrGeom::kNqfaces;
                std::array<Geometry2D *, kNfaces> faces;
                int Nfaces  = 0;
                int Ntfaces = 0;
                int Nqfaces = 0;

                /// Fill the arrays and make sure there aren't too many
                /// faces.
                std::stringstream errorstring;
                errorstring << "Element " << indx << " must have " << kNtfaces
                            << " triangle face(s), and " << kNqfaces
                            << " quadrilateral face(s).";
                for (int i = 0; i < kNfaces; i++)
                {
                    int faceID;
                    elementDataStrm >> faceID;
                    Geometry2D *face = m_meshGraph->GetGeometry2D(faceID);
                    if (face == nullptr ||
                        (face->GetShapeType() != LibUtilities::eTriangle &&
                         face->GetShapeType() != LibUtilities::eQuadrilateral))
                    {
                        std::stringstream errorstring;
                        errorstring << "Element " << indx
                                    << " has invalid face: " << faceID;
                        ASSERTL0(false, errorstring.str().c_str());
                    }
                    else if (face->GetShapeType() == LibUtilities::eTriangle)
                    {
                        ASSERTL0(Ntfaces < kNtfaces, errorstring.str().c_str());
                        faces[Nfaces++] = static_cast<TriGeom *>(face);
                        Ntfaces++;
                    }
                    else if (face->GetShapeType() ==
                             LibUtilities::eQuadrilateral)
                    {
                        ASSERTL0(Nqfaces < kNqfaces, errorstring.str().c_str());
                        faces[Nfaces++] = static_cast<QuadGeom *>(face);
                        Nqfaces++;
                    }
                }

                /// Make sure all of the face indicies could be read, and
                /// that there weren't too few.
                ASSERTL0(
                    !elementDataStrm.fail(),
                    (std::string("Unable to read element data for PYRAMID: ") +
                     elementStr)
                        .c_str());
                ASSERTL0(Ntfaces == kNtfaces, errorstring.str().c_str());
                ASSERTL0(Nqfaces == kNqfaces, errorstring.str().c_str());

                auto pyrGeom =
                    ObjPoolManager<PyrGeom>::AllocateUniquePtr(indx, faces);
                m_meshGraph->PopulateFaceToElMap(pyrGeom.get(), kNfaces);
                m_meshGraph->AddGeom(indx, std::move(pyrGeom));
            }
            catch (...)
            {
                NEKERROR(
                    ErrorUtil::efatal,
                    (std::string("Unable to read element data for PYRAMID: ") +
                     elementStr)
                        .c_str());
            }
        }
        // Prism
        else if (elementType == "R")
        {
            try
            {
                /// Create arrays for the tri and quad faces.
                constexpr int kNfaces  = PrismGeom::kNfaces;
                constexpr int kNtfaces = PrismGeom::kNtfaces;
                constexpr int kNqfaces = PrismGeom::kNqfaces;
                std::array<Geometry2D *, kNfaces> faces;
                int Ntfaces = 0;
                int Nqfaces = 0;
                int Nfaces  = 0;

                /// Fill the arrays and make sure there aren't too many
                /// faces.
                std::stringstream errorstring;
                errorstring << "Element " << indx << " must have " << kNtfaces
                            << " triangle face(s), and " << kNqfaces
                            << " quadrilateral face(s).";

                for (int i = 0; i < kNfaces; i++)
                {
                    int faceID;
                    elementDataStrm >> faceID;
                    Geometry2D *face = m_meshGraph->GetGeometry2D(faceID);
                    if (face == nullptr ||
                        (face->GetShapeType() != LibUtilities::eTriangle &&
                         face->GetShapeType() != LibUtilities::eQuadrilateral))
                    {
                        std::stringstream errorstring;
                        errorstring << "Element " << indx
                                    << " has invalid face: " << faceID;
                        ASSERTL0(false, errorstring.str().c_str());
                    }
                    else if (face->GetShapeType() == LibUtilities::eTriangle)
                    {
                        ASSERTL0(Ntfaces < kNtfaces, errorstring.str().c_str());
                        faces[Nfaces++] = static_cast<TriGeom *>(face);
                        Ntfaces++;
                    }
                    else if (face->GetShapeType() ==
                             LibUtilities::eQuadrilateral)
                    {
                        ASSERTL0(Nqfaces < kNqfaces, errorstring.str().c_str());
                        faces[Nfaces++] = static_cast<QuadGeom *>(face);
                        Nqfaces++;
                    }
                }

                /// Make sure all of the face indices could be read, and
                /// that there weren't too few.
                ASSERTL0(
                    !elementDataStrm.fail(),
                    (std::string("Unable to read element data for PRISM: ") +
                     elementStr)
                        .c_str());
                ASSERTL0(Ntfaces == kNtfaces, errorstring.str().c_str());
                ASSERTL0(Nqfaces == kNqfaces, errorstring.str().c_str());

                auto prismGeom =
                    ObjPoolManager<PrismGeom>::AllocateUniquePtr(indx, faces);
                m_meshGraph->PopulateFaceToElMap(prismGeom.get(), kNfaces);
                m_meshGraph->AddGeom(indx, std::move(prismGeom));
            }
            catch (...)
            {
                NEKERROR(
                    ErrorUtil::efatal,
                    (std::string("Unable to read element data for PRISM: ") +
                     elementStr)
                        .c_str());
            }
        }
        // Hexahedral
        else if (elementType == "H")
        {
            try
            {
                /// Create arrays for the tri and quad faces.
                constexpr int kNfaces  = HexGeom::kNfaces;
                constexpr int kNtfaces = HexGeom::kNtfaces;
                constexpr int kNqfaces = HexGeom::kNqfaces;
                // TriGeomUniquePtr tfaces[kNtfaces];
                std::array<QuadGeom *, kNqfaces> qfaces;
                int Ntfaces = 0;
                int Nqfaces = 0;

                /// Fill the arrays and make sure there aren't too many
                /// faces.
                std::stringstream errorstring;
                errorstring << "Element " << indx << " must have " << kNtfaces
                            << " triangle face(s), and " << kNqfaces
                            << " quadrilateral face(s).";
                for (int i = 0; i < kNfaces; i++)
                {
                    int faceID;
                    elementDataStrm >> faceID;
                    Geometry2D *face = m_meshGraph->GetGeometry2D(faceID);
                    if (face == nullptr ||
                        (face->GetShapeType() != LibUtilities::eTriangle &&
                         face->GetShapeType() != LibUtilities::eQuadrilateral))
                    {
                        std::stringstream errorstring;
                        errorstring << "Element " << indx
                                    << " has invalid face: " << faceID;
                        ASSERTL0(false, errorstring.str().c_str());
                    }
                    else if (face->GetShapeType() == LibUtilities::eTriangle)
                    {
                        ASSERTL0(Ntfaces < kNtfaces, errorstring.str().c_str());
                    }
                    else if (face->GetShapeType() ==
                             LibUtilities::eQuadrilateral)
                    {
                        ASSERTL0(Nqfaces < kNqfaces, errorstring.str().c_str());
                        qfaces[Nqfaces++] = static_cast<QuadGeom *>(face);
                    }
                }

                /// Make sure all of the face indicies could be read, and
                /// that there weren't too few.
                ASSERTL0(!elementDataStrm.fail(),
                         (std::string(
                              "Unable to read element data for HEXAHEDRAL: ") +
                          elementStr)
                             .c_str());
                ASSERTL0(Ntfaces == kNtfaces, errorstring.str().c_str());
                ASSERTL0(Nqfaces == kNqfaces, errorstring.str().c_str());

                auto hexGeom =
                    ObjPoolManager<HexGeom>::AllocateUniquePtr(indx, qfaces);
                m_meshGraph->PopulateFaceToElMap(hexGeom.get(), kNfaces);
                m_meshGraph->AddGeom(indx, std::move(hexGeom));
            }
            catch (...)
            {
                NEKERROR(ErrorUtil::efatal,
                         (std::string(
                              "Unable to read element data for HEXAHEDRAL: ") +
                          elementStr)
                             .c_str());
            }
        }
        /// Keep looking
        element = element->NextSiblingElement();
    }
}

void MeshGraphIOXml::ReadComposites()
{
    auto &meshComposites   = m_meshGraph->GetComposites();
    auto &compositesLabels = m_meshGraph->GetCompositesLabels();

    TiXmlElement *field = nullptr;

    /// Look for elements in ELEMENT block.
    field = m_xmlGeom->FirstChildElement("COMPOSITE");

    ASSERTL0(field, "Unable to find COMPOSITE tag in file.");

    TiXmlElement *node = field->FirstChildElement("C");

    // Sequential counter for the composite numbers.
    int nextCompositeNumber = -1;

    while (node)
    {
        /// All elements are of the form: "<? ID="#"> ... </?>", with
        /// ? being the element type.

        nextCompositeNumber++;

        int indx;
        int err = node->QueryIntAttribute("ID", &indx);
        ASSERTL0(err == TIXML_SUCCESS, "Unable to read attribute ID.");
        // ASSERTL0(indx == nextCompositeNumber, "Composite IDs must begin with
        // zero and be sequential.");

        TiXmlNode *compositeChild = node->FirstChild();
        // This is primarily to skip comments that may be present.
        // Comments appear as nodes just like elements.
        // We are specifically looking for text in the body
        // of the definition.
        while (compositeChild &&
               compositeChild->Type() != TiXmlNode::TINYXML_TEXT)
        {
            compositeChild = compositeChild->NextSibling();
        }

        ASSERTL0(compositeChild, "Unable to read composite definition body.");
        std::string compositeStr = compositeChild->ToText()->ValueStr();

        /// Parse out the element components corresponding to type of element.

        std::istringstream compositeDataStrm(compositeStr.c_str());

        try
        {
            bool first = true;
            std::string prevCompositeElementStr;

            while (!compositeDataStrm.fail())
            {
                std::string compositeElementStr;
                compositeDataStrm >> compositeElementStr;

                if (!compositeDataStrm.fail())
                {
                    if (first)
                    {
                        first = false;
                        meshComposites[indx] =
                            MemoryManager<Composite>::AllocateSharedPtr();
                    }

                    if (compositeElementStr.length() > 0)
                    {
                        ResolveGeomRef(prevCompositeElementStr,
                                       compositeElementStr,
                                       meshComposites[indx]);
                    }
                    prevCompositeElementStr = compositeElementStr;
                }
            }
        }
        catch (...)
        {
            NEKERROR(
                ErrorUtil::efatal,
                (std::string("Unable to read COMPOSITE data for composite: ") +
                 compositeStr)
                    .c_str());
        }

        // Read optional name as string and save to compositeLabels if exists
        std::string name;
        err = node->QueryStringAttribute("NAME", &name);
        if (err == TIXML_SUCCESS)
        {
            compositesLabels[indx] = name;
        }

        /// Keep looking for additional composite definitions.
        node = node->NextSiblingElement("C");
    }

    ASSERTL0(nextCompositeNumber >= 0,
             "At least one composite must be specified.");
}

void MeshGraphIOXml::ResolveGeomRef(const std::string &prevToken,
                                    const std::string &token,
                                    CompositeSharedPtr &composite)
{
    int meshDimension = m_meshGraph->GetMeshDimension();

    switch (meshDimension)
    {
        case 1:
            ResolveGeomRef1D(prevToken, token, composite);
            break;
        case 2:
            ResolveGeomRef2D(prevToken, token, composite);
            break;
        case 3:
            ResolveGeomRef3D(prevToken, token, composite);
            break;
    }
}

void MeshGraphIOXml::ResolveGeomRef1D(const std::string &prevToken,
                                      const std::string &token,
                                      CompositeSharedPtr &composite)
{
    try
    {
        std::istringstream tokenStream(token);
        std::istringstream prevTokenStream(prevToken);

        char type;
        char prevType;

        tokenStream >> type;

        std::string::size_type indxBeg = token.find_first_of('[') + 1;
        std::string::size_type indxEnd = token.find_last_of(']') - 1;

        ASSERTL0(
            indxBeg <= indxEnd,
            (std::string("Error reading index definition:") + token).c_str());

        std::string indxStr = token.substr(indxBeg, indxEnd - indxBeg + 1);

        typedef std::vector<unsigned int> SeqVectorType;
        SeqVectorType seqVector;

        if (!ParseUtils::GenerateSeqVector(indxStr.c_str(), seqVector))
        {
            NEKERROR(ErrorUtil::efatal,
                     (std::string("Ill-formed sequence definition: ") + indxStr)
                         .c_str());
        }

        prevTokenStream >> prevType;

        // All composites must be of the same dimension.
        bool validSequence =
            (prevToken.empty() || // No previous, then current is just fine.
             (type == 'V' && prevType == 'V') ||
             (type == 'S' && prevType == 'S'));

        ASSERTL0(validSequence,
                 std::string("Invalid combination of composite items: ") +
                     type + " and " + prevType + ".");

        switch (type)
        {
            case 'V': // Vertex
                for (SeqVectorType::iterator iter = seqVector.begin();
                     iter != seqVector.end(); ++iter)
                {
                    composite->m_geomVec.push_back(
                        m_meshGraph->GetPointGeom(*iter));
                }
                break;

            case 'S': // Segment
                for (SeqVectorType::iterator iter = seqVector.begin();
                     iter != seqVector.end(); ++iter)
                {
                    composite->m_geomVec.push_back(
                        m_meshGraph->GetSegGeom(*iter));
                }
                break;

            default:
                NEKERROR(ErrorUtil::efatal,
                         "Unrecognized composite token: " + token);
        }
    }
    catch (...)
    {
        NEKERROR(ErrorUtil::efatal,
                 "Problem processing composite token: " + token);
    }

    return;
}

void MeshGraphIOXml::ResolveGeomRef2D(const std::string &prevToken,
                                      const std::string &token,
                                      CompositeSharedPtr &composite)
{
    try
    {
        std::istringstream tokenStream(token);
        std::istringstream prevTokenStream(prevToken);

        char type;
        char prevType;

        tokenStream >> type;

        std::string::size_type indxBeg = token.find_first_of('[') + 1;
        std::string::size_type indxEnd = token.find_last_of(']') - 1;

        ASSERTL0(
            indxBeg <= indxEnd,
            (std::string("Error reading index definition:") + token).c_str());

        std::string indxStr = token.substr(indxBeg, indxEnd - indxBeg + 1);
        std::vector<unsigned int> seqVector;
        std::vector<unsigned int>::iterator seqIter;

        bool err = ParseUtils::GenerateSeqVector(indxStr.c_str(), seqVector);

        ASSERTL0(err,
                 (std::string("Error reading composite elements: ") + indxStr)
                     .c_str());

        prevTokenStream >> prevType;

        // All composites must be of the same dimension.
        bool validSequence =
            (prevToken.empty() || // No previous, then current is just fine.
             (type == 'V' && prevType == 'V') ||
             (type == 'E' && prevType == 'E') ||
             ((type == 'T' || type == 'Q') &&
              (prevType == 'T' || prevType == 'Q')));

        ASSERTL0(validSequence,
                 std::string("Invalid combination of composite items: ") +
                     type + " and " + prevType + ".");

        switch (type)
        {
            case 'E': // Edge
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    composite->m_geomVec.push_back(
                        m_meshGraph->GetSegGeom(*seqIter));
                }
                break;
            }

            case 'T': // Triangle
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    auto tri = m_meshGraph->GetTriGeom(*seqIter);
                    if (m_meshGraph->CheckRange(*tri))
                    {
                        composite->m_geomVec.push_back(tri);
                    }
                }
                break;
            }

            case 'Q': // Quad
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    auto quad = m_meshGraph->GetQuadGeom(*seqIter);
                    if (m_meshGraph->CheckRange(*quad))
                    {
                        composite->m_geomVec.push_back(quad);
                    }
                }
                break;
            }

            case 'V': // Vertex
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    composite->m_geomVec.push_back(
                        m_meshGraph->GetPointGeom(*seqIter));
                }
                break;
            }

            default:
                NEKERROR(ErrorUtil::efatal,
                         "Unrecognized composite token: " + token);
        }
    }
    catch (...)
    {
        NEKERROR(ErrorUtil::efatal,
                 "Problem processing composite token: " + token);
    }

    return;
}

void MeshGraphIOXml::ResolveGeomRef3D(const std::string &prevToken,
                                      const std::string &token,
                                      CompositeSharedPtr &composite)
{
    try
    {
        std::istringstream tokenStream(token);
        std::istringstream prevTokenStream(prevToken);

        char type;
        char prevType;

        tokenStream >> type;

        std::string::size_type indxBeg = token.find_first_of('[') + 1;
        std::string::size_type indxEnd = token.find_last_of(']') - 1;

        ASSERTL0(indxBeg <= indxEnd,
                 "Error reading index definition: " + token);

        std::string indxStr = token.substr(indxBeg, indxEnd - indxBeg + 1);

        std::vector<unsigned int> seqVector;
        std::vector<unsigned int>::iterator seqIter;

        bool err = ParseUtils::GenerateSeqVector(indxStr.c_str(), seqVector);

        ASSERTL0(err, "Error reading composite elements: " + indxStr);

        prevTokenStream >> prevType;

        // All composites must be of the same dimension.  This map makes things
        // clean to compare.
        std::map<char, int> typeMap;
        typeMap['V'] = 1; // Vertex
        typeMap['E'] = 1; // Edge
        typeMap['T'] = 2; // Triangle
        typeMap['Q'] = 2; // Quad
        typeMap['A'] = 3; // Tet
        typeMap['P'] = 3; // Pyramid
        typeMap['R'] = 3; // Prism
        typeMap['H'] = 3; // Hex

        // Make sure only geoms of the same dimension are combined.
        bool validSequence =
            (prevToken.empty() || (typeMap[type] == typeMap[prevType]));

        ASSERTL0(validSequence,
                 std::string("Invalid combination of composite items: ") +
                     type + " and " + prevType + ".");

        switch (type)
        {
            case 'V': // Vertex
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    composite->m_geomVec.push_back(
                        m_meshGraph->GetPointGeom(*seqIter));
                }
                break;
            }

            case 'E': // Edge
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    composite->m_geomVec.push_back(
                        m_meshGraph->GetSegGeom(*seqIter));
                }
                break;
            }

            case 'F': // Face
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    Geometry2D *face = m_meshGraph->GetGeometry2D(*seqIter);
                    if (face == nullptr)
                    {
                        NEKERROR(ErrorUtil::ewarning,
                                 "Unknown face index: " +
                                     std::to_string(*seqIter));
                    }
                    else
                    {
                        if (m_meshGraph->CheckRange(*face))
                        {
                            composite->m_geomVec.push_back(face);
                        }
                    }
                }
                break;
            }

            case 'T': // Triangle
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    auto geom = m_meshGraph->GetTriGeom(*seqIter);

                    if (m_meshGraph->CheckRange(*geom))
                    {
                        composite->m_geomVec.push_back(geom);
                    }
                }
                break;
            }

            case 'Q': // Quad
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    auto geom = m_meshGraph->GetQuadGeom(*seqIter);

                    if (m_meshGraph->CheckRange(*geom))
                    {
                        composite->m_geomVec.push_back(geom);
                    }
                }
                break;
            }

            // Tetrahedron
            case 'A':
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    auto geom = m_meshGraph->GetTetGeom(*seqIter);

                    if (m_meshGraph->CheckRange(*geom))
                    {
                        composite->m_geomVec.push_back(geom);
                    }
                }
                break;
            }

            // Pyramid
            case 'P':
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    auto geom = m_meshGraph->GetPyrGeom(*seqIter);

                    if (m_meshGraph->CheckRange(*geom))
                    {
                        composite->m_geomVec.push_back(geom);
                    }
                }
                break;
            }

            // Prism
            case 'R':
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    auto geom = m_meshGraph->GetPrismGeom(*seqIter);

                    if (m_meshGraph->CheckRange(*geom))
                    {
                        composite->m_geomVec.push_back(geom);
                    }
                }
                break;
            }

            // Hex
            case 'H':
            {
                for (seqIter = seqVector.begin(); seqIter != seqVector.end();
                     ++seqIter)
                {
                    auto geom = m_meshGraph->GetHexGeom(*seqIter);

                    if (m_meshGraph->CheckRange(*geom))
                    {
                        composite->m_geomVec.push_back(geom);
                    }
                }
                break;
            }

            default:
                NEKERROR(ErrorUtil::efatal,
                         "Unrecognized composite token: " + token);
        }
    }
    catch (...)
    {
        NEKERROR(ErrorUtil::efatal,
                 "Problem processing composite token: " + token);
    }

    return;
}

void WriteVert(PointGeom *vert, TiXmlElement *vertTag)
{
    std::stringstream s;
    s << std::scientific << std::setprecision(8) << (*vert)(0) << " "
      << (*vert)(1) << " " << (*vert)(2);
    TiXmlElement *v = new TiXmlElement("V");
    v->SetAttribute("ID", vert->GetGlobalID());
    v->LinkEndChild(new TiXmlText(s.str()));
    vertTag->LinkEndChild(v);
}

void MeshGraphIOXml::v_WriteVertices(TiXmlElement *geomTag,
                                     std::vector<int> keysToWrite)
{
    TiXmlElement *vertTag = new TiXmlElement("VERTEX");

    if (keysToWrite.empty())
    {
        for (auto [id, vert] : m_meshGraph->GetGeomMap<PointGeom>())
        {
            WriteVert(vert, vertTag);
        }
    }
    else
    {
        for (int id : keysToWrite)
        {
            WriteVert(m_meshGraph->GetPointGeom(id), vertTag);
        }
    }

    geomTag->LinkEndChild(vertTag);
}

void WriteEdge(SegGeom *seg, TiXmlElement *edgeTag, std::string &tag,
               int edgeID)
{
    std::stringstream s;
    s << seg->GetVid(0) << " " << seg->GetVid(1);
    TiXmlElement *e = new TiXmlElement(tag);
    e->SetAttribute("ID", edgeID);
    e->LinkEndChild(new TiXmlText(s.str()));
    edgeTag->LinkEndChild(e);
}

void MeshGraphIOXml::v_WriteEdges(TiXmlElement *geomTag,
                                  std::vector<int> keysToWrite)
{
    int meshDimension = m_meshGraph->GetMeshDimension();

    TiXmlElement *edgeTag =
        new TiXmlElement(meshDimension == 1 ? "ELEMENT" : "EDGE");
    std::string tag = meshDimension == 1 ? "S" : "E";

    if (keysToWrite.empty())
    {
        for (auto [id, seg] : m_meshGraph->GetGeomMap<SegGeom>())
        {
            WriteEdge(seg, edgeTag, tag, id);
        }
    }
    else
    {
        for (int id : keysToWrite)
        {
            WriteEdge(m_meshGraph->GetSegGeom(id), edgeTag, tag, id);
        }
    }

    geomTag->LinkEndChild(edgeTag);
}

void WriteTri(TriGeom *tri, TiXmlElement *faceTag, std::string &tag, int triID)
{
    std::stringstream s;
    s << tri->GetEid(0) << " " << tri->GetEid(1) << " " << tri->GetEid(2);
    TiXmlElement *t = new TiXmlElement(tag);
    t->SetAttribute("ID", triID);
    t->LinkEndChild(new TiXmlText(s.str()));
    faceTag->LinkEndChild(t);
}
void MeshGraphIOXml::v_WriteTris(TiXmlElement *faceTag,
                                 std::vector<int> keysToWrite)
{
    std::string tag = "T";

    if (keysToWrite.empty())
    {
        for (auto [id, tri] : m_meshGraph->GetGeomMap<TriGeom>())
        {
            WriteTri(tri, faceTag, tag, id);
        }
    }
    else
    {
        for (int id : keysToWrite)
        {
            WriteTri(m_meshGraph->GetTriGeom(id), faceTag, tag, id);
        }
    }
}

void WriteQuad(QuadGeom *quad, TiXmlElement *faceTag, std::string &tag,
               int quadID)
{
    std::stringstream s;
    s << quad->GetEid(0) << " " << quad->GetEid(1) << " " << quad->GetEid(2)
      << " " << quad->GetEid(3);
    TiXmlElement *q = new TiXmlElement(tag);
    q->SetAttribute("ID", quadID);
    q->LinkEndChild(new TiXmlText(s.str()));
    faceTag->LinkEndChild(q);
}
void MeshGraphIOXml::v_WriteQuads(TiXmlElement *faceTag,
                                  std::vector<int> keysToWrite)
{
    std::string tag = "Q";

    if (keysToWrite.empty())
    {
        for (auto [id, quad] : m_meshGraph->GetGeomMap<QuadGeom>())
        {
            WriteQuad(quad, faceTag, tag, id);
        }
    }
    else
    {
        for (int id : keysToWrite)
        {
            WriteQuad(m_meshGraph->GetQuadGeom(id), faceTag, tag, id);
        }
    }
}

void WriteHex(HexGeom *hex, TiXmlElement *elmtTag, std::string &tag, int hexID)
{
    std::stringstream s;
    s << hex->GetFid(0) << " " << hex->GetFid(1) << " " << hex->GetFid(2) << " "
      << hex->GetFid(3) << " " << hex->GetFid(4) << " " << hex->GetFid(5)
      << " ";
    TiXmlElement *h = new TiXmlElement(tag);
    h->SetAttribute("ID", hexID);
    h->LinkEndChild(new TiXmlText(s.str()));
    elmtTag->LinkEndChild(h);
}
void MeshGraphIOXml::v_WriteHexs(TiXmlElement *elmtTag,
                                 std::vector<int> keysToWrite)
{
    std::string tag = "H";

    if (keysToWrite.empty())
    {
        for (auto [id, hex] : m_meshGraph->GetGeomMap<HexGeom>())
        {
            WriteHex(hex, elmtTag, tag, id);
        }
    }
    else
    {
        for (int id : keysToWrite)
        {
            WriteHex(m_meshGraph->GetHexGeom(id), elmtTag, tag, id);
        }
    }
}

void WritePrism(PrismGeom *pri, TiXmlElement *elmtTag, std::string &tag,
                int priID)
{
    std::stringstream s;
    s << pri->GetFid(0) << " " << pri->GetFid(1) << " " << pri->GetFid(2) << " "
      << pri->GetFid(3) << " " << pri->GetFid(4) << " ";
    TiXmlElement *p = new TiXmlElement(tag);
    p->SetAttribute("ID", priID);
    p->LinkEndChild(new TiXmlText(s.str()));
    elmtTag->LinkEndChild(p);
}
void MeshGraphIOXml::v_WritePrisms(TiXmlElement *elmtTag,
                                   std::vector<int> keysToWrite)
{
    std::string tag = "R";

    if (keysToWrite.empty())
    {
        for (auto [id, prism] : m_meshGraph->GetGeomMap<PrismGeom>())
        {
            WritePrism(prism, elmtTag, tag, id);
        }
    }
    else
    {
        for (int id : keysToWrite)
        {
            WritePrism(m_meshGraph->GetPrismGeom(id), elmtTag, tag, id);
        }
    }
}

void WritePyr(PyrGeom *pyr, TiXmlElement *elmtTag, std::string &tag, int pyrID)
{
    std::stringstream s;
    s << pyr->GetFid(0) << " " << pyr->GetFid(1) << " " << pyr->GetFid(2) << " "
      << pyr->GetFid(3) << " " << pyr->GetFid(4) << " ";
    TiXmlElement *p = new TiXmlElement(tag);
    p->SetAttribute("ID", pyrID);
    p->LinkEndChild(new TiXmlText(s.str()));
    elmtTag->LinkEndChild(p);
}
void MeshGraphIOXml::v_WritePyrs(TiXmlElement *elmtTag,
                                 std::vector<int> keysToWrite)
{
    std::string tag = "P";

    if (keysToWrite.empty())
    {
        for (auto [id, pyr] : m_meshGraph->GetGeomMap<PyrGeom>())
        {
            WritePyr(pyr, elmtTag, tag, id);
        }
    }
    else
    {
        for (int id : keysToWrite)
        {
            WritePyr(m_meshGraph->GetPyrGeom(id), elmtTag, tag, id);
        }
    }
}

void WriteTet(TetGeom *tet, TiXmlElement *elmtTag, std::string &tag, int tetID)
{
    std::stringstream s;
    s << tet->GetFid(0) << " " << tet->GetFid(1) << " " << tet->GetFid(2) << " "
      << tet->GetFid(3) << " ";
    TiXmlElement *t = new TiXmlElement(tag);
    t->SetAttribute("ID", tetID);
    t->LinkEndChild(new TiXmlText(s.str()));
    elmtTag->LinkEndChild(t);
}
void MeshGraphIOXml::v_WriteTets(TiXmlElement *elmtTag,
                                 std::vector<int> keysToWrite)
{
    std::string tag = "A";

    if (keysToWrite.empty())
    {
        for (auto [id, tet] : m_meshGraph->GetGeomMap<TetGeom>())
        {
            WriteTet(tet, elmtTag, tag, id);
        }
    }
    else
    {
        for (int id : keysToWrite)
        {
            WriteTet(m_meshGraph->GetTetGeom(id), elmtTag, tag, id);
        }
    }
}

void MeshGraphIOXml::v_WriteCurves(TiXmlElement *geomTag, CurveMap &edges,
                                   CurveMap &faces)
{
    TiXmlElement *curveTag = new TiXmlElement("CURVED");
    CurveMap::iterator curveIt;
    int curveId = 0;

    for (curveIt = edges.begin(); curveIt != edges.end(); ++curveIt)
    {
        CurveSharedPtr curve = curveIt->second;
        TiXmlElement *c      = new TiXmlElement("E");
        std::stringstream s;
        s.precision(8);

        for (int j = 0; j < curve->m_points.size(); ++j)
        {
            PointGeom *p = curve->m_points[j];
            s << std::scientific << (*p)(0) << " " << (*p)(1) << " " << (*p)(2)
              << "   ";
        }

        c->SetAttribute("ID", curveId++);
        c->SetAttribute("EDGEID", curve->m_curveID);
        c->SetAttribute("NUMPOINTS", curve->m_points.size());
        c->SetAttribute("TYPE", LibUtilities::kPointsTypeStr[curve->m_ptype]);
        c->LinkEndChild(new TiXmlText(s.str()));
        curveTag->LinkEndChild(c);
    }

    for (curveIt = faces.begin(); curveIt != faces.end(); ++curveIt)
    {
        CurveSharedPtr curve = curveIt->second;
        TiXmlElement *c      = new TiXmlElement("F");
        std::stringstream s;
        s.precision(8);

        for (int j = 0; j < curve->m_points.size(); ++j)
        {
            PointGeom *p = curve->m_points[j];
            s << std::scientific << (*p)(0) << " " << (*p)(1) << " " << (*p)(2)
              << "   ";
        }

        c->SetAttribute("ID", curveId++);
        c->SetAttribute("FACEID", curve->m_curveID);
        c->SetAttribute("NUMPOINTS", curve->m_points.size());
        c->SetAttribute("TYPE", LibUtilities::kPointsTypeStr[curve->m_ptype]);
        c->LinkEndChild(new TiXmlText(s.str()));
        curveTag->LinkEndChild(c);
    }

    geomTag->LinkEndChild(curveTag);
}

void MeshGraphIOXml::WriteComposites(TiXmlElement *geomTag, CompositeMap &comps,
                                     std::map<int, std::string> &compLabels)
{
    auto &compositesLabels = m_meshGraph->GetCompositesLabels();
    TiXmlElement *compTag  = new TiXmlElement("COMPOSITE");

    for (auto &cIt : comps)
    {
        if (cIt.second->m_geomVec.size() == 0)
        {
            continue;
        }

        TiXmlElement *c = new TiXmlElement("C");
        c->SetAttribute("ID", cIt.first);
        if (!compositesLabels[cIt.first].empty())
        {
            c->SetAttribute("NAME", compLabels[cIt.first]);
        }
        c->LinkEndChild(new TiXmlText(GetCompositeString(cIt.second)));
        compTag->LinkEndChild(c);
    }

    geomTag->LinkEndChild(compTag);
}

void MeshGraphIOXml::WriteDomain(TiXmlElement *geomTag,
                                 std::map<int, CompositeMap> &domainMap)
{
    TiXmlElement *domTag = new TiXmlElement("DOMAIN");

    std::vector<unsigned int> idxList;
    for (auto &domain : domainMap)
    {
        TiXmlElement *c = new TiXmlElement("D");
        idxList.clear();
        std::stringstream s;
        s << " "
          << "C"
          << "[";

        for (const auto &elem : domain.second)
        {
            idxList.push_back(elem.first);
        }

        s << ParseUtils::GenerateSeqString(idxList) << "] ";
        c->SetAttribute("ID", domain.first);
        c->LinkEndChild(new TiXmlText(s.str()));
        domTag->LinkEndChild(c);
    }

    geomTag->LinkEndChild(domTag);
}

void MeshGraphIOXml::WriteDefaultExpansion(TiXmlElement *root)
{
    int meshDimension    = m_meshGraph->GetMeshDimension();
    auto &meshComposites = m_meshGraph->GetComposites();

    TiXmlElement *expTag = new TiXmlElement("EXPANSIONS");

    for (auto it = meshComposites.begin(); it != meshComposites.end(); it++)
    {
        if (it->second->m_geomVec[0]->GetShapeDim() == meshDimension)
        {
            TiXmlElement *exp = new TiXmlElement("E");
            exp->SetAttribute("COMPOSITE",
                              "C[" + std::to_string(it->first) + "]");
            exp->SetAttribute("NUMMODES", 4);
            exp->SetAttribute("TYPE", "MODIFIED");
            exp->SetAttribute("FIELDS", "u");

            expTag->LinkEndChild(exp);
        }
    }
    root->LinkEndChild(expTag);
}

/**
 * @brief Write out an XML file containing the GEOMETRY block
 * representing this MeshGraph instance inside a NEKTAR tag.
 */
void MeshGraphIOXml::v_WriteGeometry(
    const std::string &outfilename, bool defaultExp,
    const LibUtilities::FieldMetaDataMap &metadata)
{
    int meshDimension  = m_meshGraph->GetMeshDimension();
    int spaceDimension = m_meshGraph->GetSpaceDimension();

    // Create empty TinyXML document.
    TiXmlDocument doc;
    TiXmlDeclaration *decl = new TiXmlDeclaration("1.0", "utf-8", "");
    doc.LinkEndChild(decl);

    TiXmlElement *root = new TiXmlElement("NEKTAR");
    doc.LinkEndChild(root);
    TiXmlElement *geomTag = new TiXmlElement("GEOMETRY");
    root->LinkEndChild(geomTag);

    // Add provenance information using FieldIO library.
    LibUtilities::FieldIO::AddInfoTag(LibUtilities::XmlTagWriterSharedPtr(
                                          new LibUtilities::XmlTagWriter(root)),
                                      metadata);

    // Update attributes with dimensions.
    geomTag->SetAttribute("DIM", meshDimension);
    geomTag->SetAttribute("SPACE", spaceDimension);

    if (m_session != nullptr && !m_session->GetComm()->IsSerial())
    {
        geomTag->SetAttribute("PARTITION", m_session->GetComm()->GetRank());
    }

    // Clear existing elements.
    geomTag->Clear();

    // Write out informatio
    v_WriteVertices(geomTag);
    v_WriteEdges(geomTag);
    if (meshDimension > 1)
    {
        TiXmlElement *faceTag =
            new TiXmlElement(meshDimension == 2 ? "ELEMENT" : "FACE");

        v_WriteTris(faceTag);
        v_WriteQuads(faceTag);
        geomTag->LinkEndChild(faceTag);
    }
    if (meshDimension > 2)
    {
        TiXmlElement *elmtTag = new TiXmlElement("ELEMENT");

        v_WriteHexs(elmtTag);
        v_WritePyrs(elmtTag);
        v_WritePrisms(elmtTag);
        v_WriteTets(elmtTag);

        geomTag->LinkEndChild(elmtTag);
    }
    v_WriteCurves(geomTag, m_meshGraph->GetCurvedEdges(),
                  m_meshGraph->GetCurvedFaces());
    WriteComposites(geomTag, m_meshGraph->GetComposites(),
                    m_meshGraph->GetCompositesLabels());
    WriteDomain(geomTag, m_meshGraph->GetDomain());

    if (defaultExp)
    {
        WriteDefaultExpansion(root);
    }

    auto &movement = m_meshGraph->GetMovement();
    if (movement)
    {
        movement->WriteMovement(root);
    }

    // Save file.
    doc.SaveFile(outfilename);
}

void MeshGraphIOXml::WriteXMLGeometry(
    std::string outname, std::vector<std::set<unsigned int>> elements,
    std::vector<unsigned int> partitions)
{
    // so in theory this function is used by the mesh partitioner
    // giving instructions on how to write out a paritioned mesh.
    // the theory goes that the elements stored in the meshgraph are the
    // "whole" mesh so based on the information from the elmements list
    // we can filter the mesh entities and write some individual files
    // hopefully

    // this is xml so we are going to write a directory with lots of
    // xml files
    std::string dirname = outname + "_xml";
    fs::path pdirname(dirname);

    if (!fs::is_directory(dirname))
    {
        fs::create_directory(dirname);
    }

    ASSERTL0(elements.size() == partitions.size(),
             "error in partitioned information");

    for (int i = 0; i < partitions.size(); i++)
    {
        TiXmlDocument doc;
        TiXmlDeclaration *decl = new TiXmlDeclaration("1.0", "utf-8", "");
        doc.LinkEndChild(decl);

        TiXmlElement *root = doc.FirstChildElement("NEKTAR");
        TiXmlElement *geomTag;

        // Try to find existing NEKTAR tag.
        if (!root)
        {
            root = new TiXmlElement("NEKTAR");
            doc.LinkEndChild(root);

            geomTag = new TiXmlElement("GEOMETRY");
            root->LinkEndChild(geomTag);
        }
        else
        {
            // Try to find existing GEOMETRY tag.
            geomTag = root->FirstChildElement("GEOMETRY");

            if (!geomTag)
            {
                geomTag = new TiXmlElement("GEOMETRY");
                root->LinkEndChild(geomTag);
            }
        }

        int meshDimension  = m_meshGraph->GetMeshDimension();
        int spaceDimension = m_meshGraph->GetSpaceDimension();

        geomTag->SetAttribute("DIM", meshDimension);
        geomTag->SetAttribute("SPACE", spaceDimension);
        geomTag->SetAttribute("PARTITION", partitions[i]);

        // Add Mesh //
        // Get the elements
        auto &vertSet        = m_meshGraph->GetGeomMap<PointGeom>();
        auto &segGeoms       = m_meshGraph->GetGeomMap<SegGeom>();
        auto &triGeoms       = m_meshGraph->GetGeomMap<TriGeom>();
        auto &quadGeoms      = m_meshGraph->GetGeomMap<QuadGeom>();
        auto &tetGeoms       = m_meshGraph->GetGeomMap<TetGeom>();
        auto &pyrGeoms       = m_meshGraph->GetGeomMap<PyrGeom>();
        auto &prismGeoms     = m_meshGraph->GetGeomMap<PrismGeom>();
        auto &hexGeoms       = m_meshGraph->GetGeomMap<HexGeom>();
        auto &curvedEdges    = m_meshGraph->GetCurvedEdges();
        auto &curvedFaces    = m_meshGraph->GetCurvedFaces();
        auto &meshComposites = m_meshGraph->GetComposites();
        auto &globalDomain   = m_meshGraph->GetDomain();

        std::vector<int> localHexKeys;
        std::vector<int> localPyrKeys;
        std::vector<int> localPrismKeys;
        std::vector<int> localTetKeys;
        std::vector<int> localTriKeys;
        std::vector<int> localQuadKeys;
        std::vector<int> localEdgeKeys;
        std::vector<int> localVertKeys;
        CurveMap localCurveEdge;
        CurveMap localCurveFace;

        std::vector<std::set<unsigned int>> entityIds(4);
        entityIds[meshDimension] = elements[i];

        switch (meshDimension)
        {
            case 3:
            {
                for (auto &j : entityIds[3])
                {
                    Geometry *g = nullptr;

                    if (auto it{hexGeoms.find(j)}; it != hexGeoms.end())
                    {
                        g = (*it).second;
                        localHexKeys.push_back(j);
                    }
                    else if (auto it{pyrGeoms.find(j)}; it != pyrGeoms.end())
                    {
                        g = (*it).second;
                        localPyrKeys.push_back(j);
                    }
                    else if (auto it{prismGeoms.find(j)};
                             it != prismGeoms.end())
                    {
                        g = (*it).second;
                        localPrismKeys.push_back(j);
                    }
                    else if (auto it{tetGeoms.find(j)}; it != tetGeoms.end())
                    {
                        g = (*it).second;
                        localTetKeys.push_back(j);
                    }
                    else
                    {
                        ASSERTL0(false, "element in partition not found");
                    }

                    for (int k = 0; k < g->GetNumFaces(); k++)
                    {
                        entityIds[2].insert(g->GetFid(k));
                    }
                    for (int k = 0; k < g->GetNumEdges(); k++)
                    {
                        entityIds[1].insert(g->GetEid(k));
                    }
                    for (int k = 0; k < g->GetNumVerts(); k++)
                    {
                        entityIds[0].insert(g->GetVid(k));
                    }
                }
            }
            break;
            case 2:
            {
                for (auto &j : entityIds[2])
                {
                    Geometry *g = nullptr;
                    if (auto it{triGeoms.find(j)}; it != triGeoms.end())
                    {
                        g = (*it).second;
                        localTriKeys.push_back(j);
                    }
                    else if (auto it{quadGeoms.find(j)}; it != quadGeoms.end())
                    {
                        g = (*it).second;
                        localQuadKeys.push_back(j);
                    }
                    else
                    {
                        ASSERTL0(false, "element in partition not found");
                    }

                    for (int k = 0; k < g->GetNumEdges(); k++)
                    {
                        entityIds[1].insert(g->GetEid(k));
                    }
                    for (int k = 0; k < g->GetNumVerts(); k++)
                    {
                        entityIds[0].insert(g->GetVid(k));
                    }
                }
            }
            break;
            case 1:
            {
                for (auto &j : entityIds[1])
                {
                    Geometry *g = nullptr;
                    if (auto it{segGeoms.find(j)}; it != segGeoms.end())
                    {
                        g = (*it).second;
                        localEdgeKeys.push_back(j);
                    }
                    else
                    {
                        ASSERTL0(false, "element in partition not found");
                    }

                    for (int k = 0; k < g->GetNumVerts(); k++)
                    {
                        entityIds[0].insert(g->GetVid(k));
                    }
                }
            }
        }

        if (meshDimension > 2)
        {
            for (auto &j : entityIds[2])
            {
                if (triGeoms.find(j) != triGeoms.end())
                {
                    localTriKeys.push_back(j);
                }
                else if (quadGeoms.find(j) != quadGeoms.end())
                {
                    localQuadKeys.push_back(j);
                }
                else
                {
                    ASSERTL0(false, "face not found");
                }
            }
        }

        if (meshDimension > 1)
        {
            for (auto &j : entityIds[1])
            {
                if (segGeoms.find(j) != segGeoms.end())
                {
                    localEdgeKeys.push_back(j);
                }
                else
                {
                    ASSERTL0(false, "edge not found");
                }
            }
        }

        for (auto &j : entityIds[0])
        {
            if (vertSet.find(j) != vertSet.end())
            {
                localVertKeys.push_back(j);
            }
            else
            {
                ASSERTL0(false, "vert not found");
            }
        }

        if (!localVertKeys.empty())
        {
            v_WriteVertices(geomTag, localVertKeys);
        }

        if (!localEdgeKeys.empty())
        {
            v_WriteEdges(geomTag, localEdgeKeys);
        }

        if (meshDimension > 1)
        {
            TiXmlElement *faceTag =
                new TiXmlElement(meshDimension == 2 ? "ELEMENT" : "FACE");

            if (!localTriKeys.empty())
            {
                v_WriteTris(faceTag, localTriKeys);
            }

            if (!localQuadKeys.empty())
            {
                v_WriteQuads(faceTag, localQuadKeys);
            }

            geomTag->LinkEndChild(faceTag);
        }
        if (meshDimension > 2)
        {
            TiXmlElement *elmtTag = new TiXmlElement("ELEMENT");

            if (!localHexKeys.empty())
            {
                v_WriteHexs(elmtTag, localHexKeys);
            }
            if (!localPyrKeys.empty())
            {
                v_WritePyrs(elmtTag, localPyrKeys);
            }
            if (!localPrismKeys.empty())
            {
                v_WritePrisms(elmtTag, localPrismKeys);
            }
            if (!localTetKeys.empty())
            {
                v_WriteTets(elmtTag, localTetKeys);
            }

            geomTag->LinkEndChild(elmtTag);
        }

        for (auto &j : localTriKeys)
        {
            if (curvedFaces.count(j))
            {
                localCurveFace[j] = curvedFaces[j];
            }
        }
        for (auto &j : localQuadKeys)
        {
            if (curvedFaces.count(j))
            {
                localCurveFace[j] = curvedFaces[j];
            }
        }
        for (auto &j : localEdgeKeys)
        {
            if (curvedEdges.count(j))
            {
                localCurveEdge[j] = curvedEdges[j];
            }
        }

        v_WriteCurves(geomTag, localCurveEdge, localCurveFace);

        CompositeMap localComp;
        std::map<int, std::string> localCompLabels;

        for (auto &j : meshComposites)
        {
            CompositeSharedPtr comp = CompositeSharedPtr(new Composite);
            int dim                 = j.second->m_geomVec[0]->GetShapeDim();

            for (int k = 0; k < j.second->m_geomVec.size(); k++)
            {
                if (entityIds[dim].count(j.second->m_geomVec[k]->GetGlobalID()))
                {
                    comp->m_geomVec.push_back(j.second->m_geomVec[k]);
                }
            }

            if (comp->m_geomVec.size())
            {
                localComp[j.first]    = comp;
                auto compositesLabels = m_meshGraph->GetCompositesLabels();
                if (!compositesLabels[j.first].empty())
                {
                    localCompLabels[j.first] = compositesLabels[j.first];
                }
            }
        }

        WriteComposites(geomTag, localComp, localCompLabels);

        std::map<int, CompositeMap> domain;
        for (auto &j : localComp)
        {
            for (auto &dom : globalDomain)
            {
                for (auto &dIt : dom.second)
                {
                    if (j.first == dIt.first)
                    {
                        domain[dom.first][j.first] = j.second;
                        break;
                    }
                }
            }
        }

        WriteDomain(geomTag, domain);

        if (m_session->DefinesElement("NEKTAR/CONDITIONS"))
        {
            std::set<int> vBndRegionIdList;
            TiXmlElement *vConditions =
                new TiXmlElement(*m_session->GetElement("Nektar/Conditions"));
            TiXmlElement *vBndRegions =
                vConditions->FirstChildElement("BOUNDARYREGIONS");
            // Use fine-level for mesh partition (Parallel-in-Time)
            LibUtilities::SessionReader::GetXMLElementTimeLevel(vBndRegions, 0);
            TiXmlElement *vBndConditions =
                vConditions->FirstChildElement("BOUNDARYCONDITIONS");
            // Use fine-level for mesh partition (Parallel-in-Time)
            LibUtilities::SessionReader::GetXMLElementTimeLevel(vBndConditions,
                                                                0);
            TiXmlElement *vItem;

            if (vBndRegions)
            {
                // Check for parallel-in-time
                bool multiLevel =
                    vConditions->FirstChildElement("BOUNDARYREGIONS")
                        ->FirstChildElement("TIMELEVEL") != nullptr;

                TiXmlElement *vNewBndRegions =
                    multiLevel ? new TiXmlElement("TIMELEVEL")
                               : new TiXmlElement("BOUNDARYREGIONS");
                vItem                  = vBndRegions->FirstChildElement();
                auto graph_bndRegOrder = m_meshGraph->GetBndRegionOrdering();
                while (vItem)
                {
                    std::string vSeqStr =
                        vItem->FirstChild()->ToText()->Value();
                    std::string::size_type indxBeg =
                        vSeqStr.find_first_of('[') + 1;
                    std::string::size_type indxEnd =
                        vSeqStr.find_last_of(']') - 1;
                    vSeqStr = vSeqStr.substr(indxBeg, indxEnd - indxBeg + 1);
                    std::vector<unsigned int> vSeq;
                    ParseUtils::GenerateSeqVector(vSeqStr.c_str(), vSeq);

                    std::vector<unsigned int> idxList;

                    for (unsigned int i = 0; i < vSeq.size(); ++i)
                    {
                        if (localComp.find(vSeq[i]) != localComp.end())
                        {
                            idxList.push_back(vSeq[i]);
                        }
                    }
                    int p = atoi(vItem->Attribute("ID"));

                    std::string vListStr =
                        ParseUtils::GenerateSeqString(idxList);

                    if (vListStr.length() == 0)
                    {
                        TiXmlElement *tmp = vItem;
                        vItem             = vItem->NextSiblingElement();
                        vBndRegions->RemoveChild(tmp);
                    }
                    else
                    {
                        vListStr                  = "C[" + vListStr + "]";
                        TiXmlText *vList          = new TiXmlText(vListStr);
                        TiXmlElement *vNewElement = new TiXmlElement("B");
                        vNewElement->SetAttribute("ID", p);
                        vNewElement->LinkEndChild(vList);
                        vNewBndRegions->LinkEndChild(vNewElement);
                        vBndRegionIdList.insert(p);
                        vItem = vItem->NextSiblingElement();
                    }

                    // store original bnd region order
                    m_bndRegOrder[p]     = vSeq;
                    graph_bndRegOrder[p] = vSeq;
                }
                if (multiLevel)
                {
                    // Use fine-level for mesh partition (Parallel-in-Time)
                    size_t timeLevel = 0;
                    while (vBndRegions)
                    {
                        vNewBndRegions->SetAttribute("VALUE", timeLevel);
                        vConditions->FirstChildElement("BOUNDARYREGIONS")
                            ->ReplaceChild(vBndRegions, *vNewBndRegions);
                        vBndRegions = vBndRegions->NextSiblingElement();
                        timeLevel++;
                    }
                }
                else
                {
                    vConditions->ReplaceChild(vBndRegions, *vNewBndRegions);
                }
            }

            if (vBndConditions)
            {
                vItem = vBndConditions->FirstChildElement();
                while (vItem)
                {
                    std::set<int>::iterator x;
                    if ((x = vBndRegionIdList.find(atoi(vItem->Attribute(
                             "REF")))) != vBndRegionIdList.end())
                    {
                        vItem->SetAttribute("REF", *x);
                        vItem = vItem->NextSiblingElement();
                    }
                    else
                    {
                        TiXmlElement *tmp = vItem;
                        vItem             = vItem->NextSiblingElement();
                        vBndConditions->RemoveChild(tmp);
                    }
                }
            }
            root->LinkEndChild(vConditions);
        }

        // Distribute other sections of the XML to each process as is.
        TiXmlElement *vSrc =
            m_session->GetElement("Nektar")->FirstChildElement();
        while (vSrc)
        {
            std::string vName = boost::to_upper_copy(vSrc->ValueStr());
            if (vName != "GEOMETRY" && vName != "CONDITIONS")
            {
                root->LinkEndChild(new TiXmlElement(*vSrc));
            }
            vSrc = vSrc->NextSiblingElement();
        }

        // Save Mesh

        boost::format pad("P%1$07d.xml");
        pad % partitions[i];
        fs::path pFilename(pad.str());

        fs::path fullpath = pdirname / pFilename;
        doc.SaveFile(LibUtilities::PortablePath(fullpath));
    }
}

CompositeOrdering MeshGraphIOXml::CreateCompositeOrdering()
{
    auto &meshComposites = m_meshGraph->GetComposites();
    auto &domain         = m_meshGraph->GetDomain();

    CompositeOrdering ret;

    for (auto &c : meshComposites)
    {
        bool fillComp = true;
        for (auto &d : domain[0])
        {
            if (c.second == d.second)
            {
                fillComp = false;
            }
        }
        if (fillComp)
        {
            std::vector<unsigned int> ids;
            for (auto &elmt : c.second->m_geomVec)
            {
                ids.push_back(elmt->GetGlobalID());
            }
            ret[c.first] = ids;
        }
    }

    return ret;
}

} // namespace Nektar::SpatialDomains
