WorkspaceCreation.h

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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2016 ISIS Rutherford Appleton Laboratory UKRI,
//   NScD Oak Ridge National Laboratory, European Spallation Source,
//   Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#pragma once
 
#include "MantidDataObjects/DllConfig.h"
#include "MantidHistogramData/Histogram.h"
 
#include <memory>
#include <type_traits>
 
namespace Mantid {
namespace Indexing {
class IndexInfo;
}
namespace Geometry {
class Instrument;
}
namespace API {
class MatrixWorkspace;
class HistoWorkspace;
} // namespace API
namespace DataObjects {
class EventWorkspace;
class Workspace2D;
 
namespace detail {
MANTID_DATAOBJECTS_DLL HistogramData::Histogram stripData(HistogramData::Histogram histogram);
 
template <class T> std::unique_ptr<T> createHelper() { return std::make_unique<T>(); }
 
template <class T> std::unique_ptr<T> createConcreteHelper() { return std::make_unique<T>(); }
 
template <> MANTID_DATAOBJECTS_DLL std::unique_ptr<API::HistoWorkspace> createHelper();
 
// Dummy specialization, should never be called, must exist for compilation.
template <> MANTID_DATAOBJECTS_DLL std::unique_ptr<EventWorkspace> createHelper();
// Dummy specialization, should never be called, must exist for compilation.
template <> MANTID_DATAOBJECTS_DLL std::unique_ptr<API::MatrixWorkspace> createHelper();
 
// Dummy specialization, should never be called, must exist for compilation.
template <> MANTID_DATAOBJECTS_DLL std::unique_ptr<API::MatrixWorkspace> createConcreteHelper();
// Dummy specialization, should never be called, must exist for compilation.
template <> MANTID_DATAOBJECTS_DLL std::unique_ptr<API::HistoWorkspace> createConcreteHelper();
 
template <class HistArg> void fixDistributionFlag(API::MatrixWorkspace &, const HistArg &) {}
 
template <>
MANTID_DATAOBJECTS_DLL void fixDistributionFlag(API::MatrixWorkspace &workspace,
                                                const HistogramData::Histogram &histArg);
 
template <class T> struct IsIndexInfo { using type = std::false_type; };
template <> struct IsIndexInfo<Indexing::IndexInfo> { using type = std::true_type; };
template <class UseIndexInfo>
void initializeFromParent(const API::MatrixWorkspace &parent, API::MatrixWorkspace &workspace);
} // namespace detail
 
template <class T, class P, class IndexArg, class HistArg,
          class = typename std::enable_if<std::is_base_of<API::MatrixWorkspace, P>::value>::type>
std::unique_ptr<T> create(const P &parent, const IndexArg &indexArg, const HistArg &histArg) {
  // Figure out (dynamic) target type:
  // - Type is same as parent if T is base of parent
  // - If T is not base of parent, conversion may occur. Currently only
  //   supported for EventWorkspace
  std::unique_ptr<T> ws;
  if (std::is_base_of<API::HistoWorkspace, T>::value && parent.id() == "EventWorkspace") {
    // Drop events, create Workspace2D or T whichever is more derived.
    ws = detail::createHelper<T>();
  } else {
    try {
      // If parent is more derived than T: create type(parent)
      ws = dynamic_cast<const T &>(parent).cloneEmpty();
    } catch (std::bad_cast &) {
      // If T is more derived than parent: create T
      ws = detail::createConcreteHelper<T>();
    }
  }
 
  // The instrument is also copied by initializeFromParent, but if indexArg is
  // IndexInfo and contains non-empty spectrum definitions the initialize call
  // will fail due to invalid indices in the spectrum definitions. Therefore, we
  // copy the instrument first. This should be cleaned up once we figure out the
  // future of WorkspaceFactory.
  ws->setInstrument(parent.getInstrument());
  ws->initialize(indexArg, HistogramData::Histogram(histArg));
  detail::initializeFromParent<typename detail::IsIndexInfo<IndexArg>::type>(parent, *ws);
  // initializeFromParent sets the distribution flag to the same value as
  // parent. In case histArg is an actual Histogram that is not the correct
  // behavior so we have to set it back to the value given by histArg.
  detail::fixDistributionFlag(*ws, histArg);
  return ws;
}
 
template <class T, class IndexArg, class HistArg,
          typename std::enable_if<!std::is_base_of<API::MatrixWorkspace, IndexArg>::value>::type * = nullptr>
std::unique_ptr<T> create(const IndexArg &indexArg, const HistArg &histArg) {
  auto ws = std::make_unique<T>();
  ws->initialize(indexArg, HistogramData::Histogram(histArg));
  return ws;
}
 
template <class T, class IndexArg, class HistArg,
          typename std::enable_if<!std::is_base_of<API::MatrixWorkspace, IndexArg>::value>::type * = nullptr>
std::unique_ptr<T> create(const std::shared_ptr<const Geometry::Instrument> &instrument, const IndexArg &indexArg,
                          const HistArg &histArg) {
  auto ws = std::make_unique<T>();
  ws->setInstrument(std::move(instrument));
  ws->initialize(indexArg, HistogramData::Histogram(histArg));
  return ws;
}
 
template <class T, class P, typename std::enable_if<std::is_base_of<API::MatrixWorkspace, P>::value>::type * = nullptr>
std::unique_ptr<T> create(const P &parent) {
  const auto numHistograms = parent.getNumberHistograms();
  auto ws = create<T>(parent, numHistograms, detail::stripData(parent.histogram(0)));
  for (size_t i = 0; i < numHistograms; ++i) {
    ws->setSharedX(i, parent.sharedX(i));
  }
  return ws;
}
 
// Templating with HistArg clashes with the IndexArg template above. Could be
// fixed with many enable_if cases, but for now we simply provide 3 variants
// (Histogram, BinEdges, Points) by hand.
template <class T, class P, typename std::enable_if<std::is_base_of<API::MatrixWorkspace, P>::value>::type * = nullptr>
std::unique_ptr<T> create(const P &parent, const HistogramData::Histogram &histogram) {
  return create<T>(parent, parent.getNumberHistograms(), histogram);
}
 
template <class T, class P, typename std::enable_if<std::is_base_of<API::MatrixWorkspace, P>::value>::type * = nullptr>
std::unique_ptr<T> create(const P &parent, const HistogramData::BinEdges &binEdges) {
  return create<T>(parent, parent.getNumberHistograms(), binEdges);
}
 
template <class T, class P, typename std::enable_if<std::is_base_of<API::MatrixWorkspace, P>::value>::type * = nullptr>
std::unique_ptr<T> create(const P &parent, const HistogramData::Points &points) {
  return create<T>(parent, parent.getNumberHistograms(), points);
}
 
} // namespace DataObjects
} // namespace Mantid