accessors.h

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/* Copyright 2026 Stanford University, NVIDIA Corporation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
 
#ifndef __LEGION_ACCESSORS_H__
#define __LEGION_ACCESSORS_H__
 
#include "legion/api/buffers.h"
#include "legion/api/future.h"
#include "legion/api/physical_region.h"
#include "legion/api/transforms.h"
 
namespace Legion {
 
  template<
      PrivilegeMode MODE, typename FT, int N, typename COORD_T = coord_t,
      typename A = Realm::GenericAccessor<FT, N, COORD_T>,
#ifdef LEGION_BOUNDS_CHECKS
      bool CHECK_BOUNDS = true>
#else
      bool CHECK_BOUNDS = false>
#endif
  class FieldAccessor {
  private:
    static_assert(N > 0, "N must be positive");
    static_assert(N <= LEGION_MAX_DIM, "N must be <= LEGION_MAX_DIM");
    static_assert(std::is_integral<COORD_T>::value, "must be integral type");
  public:
    FieldAccessor(void) { }
    FieldAccessor(
        const PhysicalRegion& region, FieldID fid,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // For Realm::AffineAccessor specializations there are additional
    // methods for creating accessors with limited bounding boxes and
    // affine transformations for using alternative coordinates spaces
    // Specify a specific bounds rectangle to use for the accessor
    FieldAccessor(
        const PhysicalRegion& region, FieldID fid,
        const Rect<N, COORD_T> bounds,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify a specific Affine transform to use for interpreting points
    // Not avalable for Realm::MultiAffineAccessor specializations
    template<int M>
    FieldAccessor(
        const PhysicalRegion& region, FieldID fid,
        const AffineTransform<M, N, COORD_T> transform,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify both a transform and a bounds to use
    // Not avalable for Realm::MultiAffineAccessor specializations
    template<int M>
    FieldAccessor(
        const PhysicalRegion& region, FieldID fid,
        const AffineTransform<M, N, COORD_T> transform,
        const Rect<N, COORD_T> bounds,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Create a field accessor for a Future
    // (only with READ-ONLY privileges and AffineAccessors)
    FieldAccessor(
        const Future& future, Memory::Kind kind = Memory::NO_MEMKIND,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Create a field accessor for a Future
    // (only with READ-ONLY privileges and AffineAccessors)
    FieldAccessor(
        const Future& future, const Rect<N, COORD_T> bounds,
        Memory::Kind kind = Memory::NO_MEMKIND,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
  public:
    // Variations of the above four methods but with multiple physical
    // regions specified using input iterators for colocation regions
    // Colocation regions from [start, stop)
    template<typename InputIterator>
    FieldAccessor(
        InputIterator start_region, InputIterator stop_region, FieldID fid,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // For Realm::AffineAccessor specializations there are additional
    // methods for creating accessors with limited bounding boxes and
    // affine transformations for using alternative coordinates spaces
    // Specify a specific bounds rectangle to use for the accessor
    // Colocation regions from [start, stop)
    template<typename InputIterator>
    FieldAccessor(
        InputIterator start_region, InputIterator stop_region, FieldID fid,
        const Rect<N, COORD_T> bounds,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify a specific Affine transform to use for interpreting points
    // Not avalable for Realm::MultiAffineAccessor specializations
    // Colocation regions from [start, stop)
    template<typename InputIterator, int M>
    FieldAccessor(
        InputIterator start_region, InputIterator stop_region, FieldID fid,
        const AffineTransform<M, N, COORD_T> transform,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify both a transform and a bounds to use
    // Not avalable for Realm::MultiAffineAccessor specializations
    // Colocation regions from [start, stop)
    template<typename InputIterator, int M>
    FieldAccessor(
        InputIterator start_region, InputIterator stop_region, FieldID fid,
        const AffineTransform<M, N, COORD_T> transform,
        const Rect<N, COORD_T> bounds,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
  public:
    // Create a FieldAccessor for an UntypedDeferredValue
    // (only with AffineAccessors)
    FieldAccessor(
        const UntypedDeferredValue& value,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Create a FieldAccessor for an UntypedDeferredValue
    // Specify a specific bounds rectangle to use for the accessor
    // (only with AffineAccessors)
    FieldAccessor(
        const UntypedDeferredValue& value, const Rect<N, COORD_T>& bounds,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
  public:
    // Create a FieldAccessor for UntypedDeferredBuffer
    // (only with AffineAccessors)
    FieldAccessor(
        const UntypedDeferredBuffer<COORD_T>& buffer,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Create a FieldAccessor for UntypedDeferredBuffer
    // Specify a specific bounds rectangle to use for the accessor
    // (only with AffineAccessors)
    FieldAccessor(
        const UntypedDeferredBuffer<COORD_T>& buffer,
        const Rect<N, COORD_T>& bounds,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Create a FieldAccessor for UntypedDeferredBuffer
    // Specify a specific Affine transform to use for interpreting points
    // (only with AffineAccessors)
    template<int M>
    FieldAccessor(
        const UntypedDeferredBuffer<COORD_T>& buffer,
        const AffineTransform<M, N, COORD_T>& transform,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Create a FieldAccessor for UntypedDeferredBuffer
    // Specify both a transform and a bounds to use
    // (only with AffineAccessors)
    template<int M>
    FieldAccessor(
        const UntypedDeferredBuffer<COORD_T>& buffer,
        const AffineTransform<M, N, COORD_T>& transform,
        const Rect<N, COORD_T>& bounds,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
  public:
    typedef FT value_type;
    typedef FT& reference;
    typedef const FT& const_reference;
    static const int dim = N;
  };
 
  template<
      typename REDOP, bool EXCLUSIVE, int N, typename COORD_T = coord_t,
      typename A = Realm::GenericAccessor<typename REDOP::RHS, N, COORD_T>,
#ifdef LEGION_BOUNDS_CHECKS
      bool CHECK_BOUNDS = true>
#else
      bool CHECK_BOUNDS = false>
#endif
  class ReductionAccessor {
  private:
    static_assert(N > 0, "N must be positive");
    static_assert(N <= LEGION_MAX_DIM, "N must be <= LEGION_MAX_DIM");
    static_assert(std::is_integral<COORD_T>::value, "must be integral type");
  public:
    ReductionAccessor(void) { }
    ReductionAccessor(
        const PhysicalRegion& region, FieldID fid, ReductionOpID redop,
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // For Realm::AffineAccessor specializations there are additional
    // methods for creating accessors with limited bounding boxes and
    // affine transformations for using alternative coordinates spaces
    // Specify a specific bounds rectangle to use for the accessor
    ReductionAccessor(
        const PhysicalRegion& region, FieldID fid, ReductionOpID redop,
        const Rect<N, COORD_T> bounds, bool silence_warnings = false,
        const char* warning_string = nullptr, size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // Specify a specific Affine transform to use for interpreting points
    // Not available for Realm::MultiAffineAccessor specializations
    template<int M>
    ReductionAccessor(
        const PhysicalRegion& region, FieldID fid, ReductionOpID redop,
        const AffineTransform<M, N, COORD_T> transform,
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // Specify both a transform and a bounds to use
    // Not available for Realm::MultiAffineAccessor specializations
    template<int M>
    ReductionAccessor(
        const PhysicalRegion& region, FieldID fid, ReductionOpID redop,
        const AffineTransform<M, N, COORD_T> transform,
        const Rect<N, COORD_T> bounds, bool silence_warnings = false,
        const char* warning_string = nullptr, size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
  public:
    // Variations of the same four methods above but with multiple
    // physical regions specified using input iterators for colocation regions
    // Colocation regions from [start, stop)
    template<typename InputIterator>
    ReductionAccessor(
        InputIterator start_region, InputIterator stop_region, FieldID fid,
        ReductionOpID redop, bool silence_warnings = false,
        const char* warning_string = nullptr, size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // For Realm::AffineAccessor specializations there are additional
    // methods for creating accessors with limited bounding boxes and
    // affine transformations for using alternative coordinates spaces
    // Specify a specific bounds rectangle to use for the accessor
    // Colocation regions from [start, stop)
    template<typename InputIterator>
    ReductionAccessor(
        InputIterator start_region, InputIterator stop_region, FieldID fid,
        ReductionOpID redop, const Rect<N, COORD_T> bounds,
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // Specify a specific Affine transform to use for interpreting points
    // Not available for Realm::MultiAffineAccessor specializations
    // Colocation regions from [start, stop)
    template<typename InputIterator, int M>
    ReductionAccessor(
        InputIterator start_region, InputIterator stop_region, FieldID fid,
        ReductionOpID redop, const AffineTransform<M, N, COORD_T> transform,
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // Specify both a transform and a bounds to use
    // Not available for Realm::MultiAffineAccessor specializations
    // Colocation regions from [start, stop)
    template<typename InputIterator, int M>
    ReductionAccessor(
        InputIterator start_region, InputIterator stop_region, FieldID fid,
        ReductionOpID redop, const AffineTransform<M, N, COORD_T> transform,
        const Rect<N, COORD_T> bounds, bool silence_warnings = false,
        const char* warning_string = nullptr, size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
  public:
    // Create a ReductionAccessor for an UntypedDeferredValue
    // (only with AffineAccessors)
    ReductionAccessor(
        const UntypedDeferredValue& value, bool silence_warnings = false,
        const char* warning_string = nullptr, size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // Create a ReductionAccessor for an UntypedDeferredValue
    // Specify a specific bounds rectangle to use for the accessor
    // (only with AffineAccessors)
    ReductionAccessor(
        const UntypedDeferredValue& value, const Rect<N, COORD_T>& bounds,
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
  public:
    // Create a ReductionAccessor for an UntypedDeferredBuffer
    // (only with AffineAccessors)
    ReductionAccessor(
        const UntypedDeferredBuffer<COORD_T>& buffer,
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // Create a ReductionAccessor for an UntypedDeferredBuffer
    // Specify a specific bounds rectangle to use for the accessor
    // (only with AffineAccessors)
    ReductionAccessor(
        const UntypedDeferredBuffer<COORD_T>& buffer,
        const Rect<N, COORD_T>& bounds, bool silence_warnings = false,
        const char* warning_string = nullptr, size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // Create a ReductionAccessor for an UntypedDeferredBuffer
    // Specify a specific Affine transform to use for interpreting points
    // (only with AffineAccessors)
    template<int M>
    ReductionAccessor(
        const UntypedDeferredBuffer<COORD_T>& buffer,
        const AffineTransform<M, N, COORD_T>& transform,
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
    // Create a ReductionAccessor for an UntypedDeferredBuffer
    // Specify both a transform and a bounds to use
    // (only with AffineAccessors)
    template<int M>
    ReductionAccessor(
        const UntypedDeferredBuffer<COORD_T>& buffer,
        const AffineTransform<M, N, COORD_T>& transform,
        const Rect<N, COORD_T>& bounds, bool silence_warnings = false,
        const char* warning_string = nullptr, size_t subfield_offset = 0,
        size_t actual_field_size = sizeof(typename REDOP::RHS),
#ifdef LEGION_DEBUG
        bool check_field_size = true
#else
        bool check_field_size = false
#endif
    )
    { }
  public:
    typedef typename REDOP::RHS value_type;
    typedef typename REDOP::RHS& reference;
    typedef const typename REDOP::RHS& const_reference;
    static const int dim = N;
  };
 
  template<
      typename FT, int N, typename COORD_T = coord_t,
      typename A = Realm::GenericAccessor<FT, N, COORD_T>,
#ifdef LEGION_BOUNDS_CHECKS
      bool CHECK_BOUNDS = true>
#else
      bool CHECK_BOUNDS = false>
#endif
  class PaddingAccessor {
  public:
    PaddingAccessor(void) { }
    PaddingAccessor(
        const PhysicalRegion& region, FieldID fid,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
  };
 
#ifdef LEGION_MULTI_REGION_ACCESSOR
  // Multi-Region Accessors are a provisional feature now and are likely
  // to be deprecated and removed in the near future. Instead of multi-region
  // accessors you should be able to use the new colocation constructors
  // on the traditional Field Accessors.
  template<
      typename FT, int N, typename COORD_T = coord_t,
      typename A = Realm::GenericAccessor<FT, N, COORD_T>,
#ifdef LEGION_BOUNDS_CHECKS
      bool CHECK_BOUNDS = true,
#else
      bool CHECK_BOUNDS = false,
#endif
#ifdef LEGION_PRIVILEGE_CHECKS
      bool CHECK_PRIVILEGES = true,
#else
      bool CHECK_PRIVILEGES = false,
#endif
      // Only used if bounds/privilege checks enabled
      // Can safely over-approximate, but may cost space
      // Especially GPU parameter space
      int MAX_REGIONS = 4>
  class MultiRegionAccessor {
  private:
    static_assert(N > 0, "N must be positive");
    static_assert(N <= LEGION_MAX_DIM, "N must be <= LEGION_MAX_DIM");
    static_assert(std::is_integral<COORD_T>::value, "must be integral type");
  public:
    MultiRegionAccessor(void) { }
  public:  // iterator based construction of the multi-region accessors
    template<typename InputIterator>
    MultiRegionAccessor(
        InputIterator start, InputIterator stop,
        // The actual field size in case it is different from
        // the one being used in FT and we still want to check
        FieldID fid, size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify a specific bounds rectangle to use for the accessor
    template<typename InputIterator>
    MultiRegionAccessor(
        InputIterator start, InputIterator stop, const Rect<N, COORD_T> bounds,
        FieldID fid,
        // The actual field size in case it is different from
        // the one being used in FT and we still want to check
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify a specific Affine transform to use for interpreting points
    template<int M, typename InputIterator>
    MultiRegionAccessor(
        InputIterator start, InputIterator stop,
        const AffineTransform<M, N, COORD_T> transform,
        // The actual field size in case it is different from
        // the one being used in FT and we still want to check
        FieldID fid, size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify both a transform and a bounds to use
    template<int M, typename InputIterator>
    MultiRegionAccessor(
        InputIterator start, InputIterator stop,
        const AffineTransform<M, N, COORD_T> transform,
        const Rect<N, COORD_T> bounds, FieldID fid,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
  public:  // explicit data structure versions of the implicit iterators above
    MultiRegionAccessor(
        const std::vector<PhysicalRegion>& regions,
        // The actual field size in case it is different from
        // the one being used in FT and we still want to check
        FieldID fid, size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify a specific bounds rectangle to use for the accessor
    MultiRegionAccessor(
        const std::vector<PhysicalRegion>& regions,
        const Rect<N, COORD_T> bounds, FieldID fid,
        // The actual field size in case it is different from
        // the one being used in FT and we still want to check
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify a specific Affine transform to use for interpreting points
    template<int M>
    MultiRegionAccessor(
        const std::vector<PhysicalRegion>& regions,
        const AffineTransform<M, N, COORD_T> transform,
        // The actual field size in case it is different from
        // the one being used in FT and we still want to check
        FieldID fid, size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
    // Specify both a transform and a bounds to use
    template<int M>
    MultiRegionAccessor(
        const std::vector<PhysicalRegion>& regions,
        const AffineTransform<M, N, COORD_T> transform,
        const Rect<N, COORD_T> bounds, FieldID fid,
        // The actual field size in case it is different from the
        // one being used in FT and we still want to check it
        size_t actual_field_size = sizeof(FT),
#ifdef LEGION_DEBUG
        bool check_field_size = true,
#else
        bool check_field_size = false,
#endif
        bool silence_warnings = false, const char* warning_string = nullptr,
        size_t subfield_offset = 0)
    { }
  public:
    typedef FT value_type;
    typedef FT& reference;
    typedef const FT& const_reference;
    static const int dim = N;
  };
#endif  // LEGION_MULTI_REGION_ACCESSOR
 
}  // namespace Legion
 
#include "accessors.inl"
 
#endif  // __LEGION_ACCESSORS_H__