First steps towards making single_store context-aware

1. Several changes in the single_store class

- Added a couple of new methods allowing to insert all transforms corresponding to a new
  context in one go
- Added a couple of temporary auxiliary methods (`dump_info()` and `dummy()`)
- Removed the [] operator (expected that the calls to it will be replaced with the calls to `at()`)

2. Some temporary changes in the data_context class

Set the default value for the context to 9999. This is to find the callers who don't
pass the explicit value for the context when calling `single_store::at()`

3. Migrated the clients of `single_store::operator[]()` to `single_store::at()`

4. Also declared `single_store::begin()` and `single_store::end()` methods at `const`

Author: Vakho Tsulaia

core/include/detray/builders/cylinder_portal_generator.hpp

@@ -336,7 +336,7 @@ class cylinder_portal_generator final
         double mean{0.};
 
         for (const auto &sf_desc : surfaces) {
-            const auto &trf = transforms[sf_desc.transform()];
+  	    const auto &trf = transforms.at(sf_desc.transform());
             mean += getter::perp(trf.translation());
         }
 

core/include/detray/core/detail/data_context.hpp

@@ -28,12 +28,17 @@ class data_context {
     DETRAY_HOST_DEVICE
     explicit data_context(dindex value) : m_data{value} {}
 
+    DETRAY_HOST_DEVICE
+    bool operator == (const data_context& other) {
+      return m_data==other.m_data;
+    }
+
     /// @returns the index to find the data for the context - const
     DETRAY_HOST_DEVICE
     dindex get() const { return m_data; }
 
     private:
-    dindex m_data{0};
+    dindex m_data{9999};
 };
 
 }  // namespace detail

core/include/detray/core/detail/single_store.hpp

@@ -109,13 +109,13 @@ class single_store {
 
     /// @returns the collections iterator at the start position.
     DETRAY_HOST_DEVICE
-    constexpr auto begin(const context_type & /*ctx*/ = {}) {
+    constexpr auto begin(const context_type & /*ctx*/ = {}) const {
         return m_container.begin();
     }
 
     /// @returns the collections iterator sentinel.
     DETRAY_HOST_DEVICE
-    constexpr auto end(const context_type & /*ctx*/ = {}) {
+    constexpr auto end(const context_type & /*ctx*/ = {}) const {
         return m_container.end();
     }
 
@@ -132,30 +132,25 @@ class single_store {
         return m_container;
     }
 
-    /// Elementwise access. Needs @c operator[] for storage type - non-const
-    DETRAY_HOST_DEVICE
-    constexpr decltype(auto) operator[](const dindex i) {
-        return m_container[i];
-    }
-
-    /// Elementwise access. Needs @c operator[] for storage type - const
-    DETRAY_HOST_DEVICE
-    constexpr decltype(auto) operator[](const dindex i) const {
-        return m_container[i];
+    /// Temporary dummy method
+    DETRAY_HOST_DEVICE void dummy() const {
+      printf("Dummy\n");
     }
 
     /// @returns context based access to an element (also range checked)
     DETRAY_HOST_DEVICE
     constexpr auto at(const dindex i,
-                      const context_type & /*ctx*/) const noexcept
+                      const context_type & ctx = {}) const noexcept
         -> const T & {
+        if(ctx.get()==9999) dummy(); // Just to check if anybody calling at() without passing the context value
         return m_container.at(i);
     }
 
     /// @returns context based access to an element (also range checked)
     DETRAY_HOST_DEVICE
-    constexpr auto at(const dindex i, const context_type & /*ctx*/) noexcept
+    constexpr auto at(const dindex i, const context_type & ctx = {}) noexcept
         -> T & {
+        if(ctx.get()==9999) dummy(); // Just to check if anybody calling at() without passing the context value
         return m_container.at(i);
     }
 
@@ -276,9 +271,37 @@ class single_store {
         return detray::get_data(m_container);
     }
 
+    DETRAY_HOST void fix_context_size() {
+      m_context_size = static_cast<dindex>(m_container.size());
+      m_n_contexts = 1;
+    }
+
+    template <typename U>
+    DETRAY_HOST auto add_context(container_t<U> &&new_data) noexcept(false)
+        -> void {
+      if(m_n_contexts != 0
+        && new_data.size() == m_context_size) {
+       insert(std::move(new_data));
+       m_n_contexts++;
+      }
+      else {
+       // ToDo: Error?
+      }
+    }
+
+    #include <iostream>
+    DETRAY_HOST void dump_info() const {
+      std::cout << "SINGLE STORE *** \n"
+		<< "Container size " << m_container.size() << "\n"
+		<< "Context size   " << m_context_size << "\n"
+		<< "N Contexts     " << m_n_contexts << std::endl;
+    }
+
     private:
     /// The underlying container implementation
     base_type m_container;
+    dindex m_context_size{0};
+    dindex m_n_contexts{0};
 };
 
 }  // namespace detray

core/include/detray/geometry/tracking_volume.hpp

@@ -87,7 +87,7 @@ class tracking_volume {
     DETRAY_HOST_DEVICE
     constexpr auto transform() const -> const
         typename detector_t::transform3_type & {
-        return m_detector.transform_store()[m_desc.transform()];
+        return m_detector.transform_store().at(m_desc.transform());
     }
 
     /// @returns the center point of the volume.

core/include/detray/navigation/intersection_kernel.hpp

@@ -54,7 +54,7 @@ struct intersection_initialize {
         using mask_t = typename mask_group_t::value_type;
         using algebra_t = typename mask_t::algebra_type;
 
-        const auto &ctf = contextual_transforms[surface.transform()];
+        const auto &ctf = contextual_transforms.at(surface.transform());
 
         // Run over the masks that belong to the surface (only one can be hit)
         for (const auto &mask :
@@ -143,7 +143,7 @@ struct intersection_update {
         using mask_t = typename mask_group_t::value_type;
         using algebra_t = typename mask_t::algebra_type;
 
-        const auto &ctf = contextual_transforms[sfi.sf_desc.transform()];
+        const auto &ctf = contextual_transforms.at(sfi.sf_desc.transform());
 
         // Run over the masks that belong to the surface
         for (const auto &mask :

core/include/detray/utils/grid/grid.hpp

@@ -276,7 +276,7 @@ class grid_impl {
         const track_t &track, const config_t &cfg) const {
 
         // Track position in grid coordinates
-        const auto &trf = det.transform_store()[volume.transform()];
+        const auto &trf = det.transform_store().at(volume.transform());
         const auto loc_pos = project(trf, track.pos(), track.dir());
 
         // Grid lookup

io/include/detray/io/common/geometry_writer.hpp

@@ -129,7 +129,7 @@ class geometry_writer {
         vol_data.index = detail::basic_converter::convert(vol_desc.index());
         vol_data.name = name;
         vol_data.transform =
-            convert<detector_t>(det.transform_store()[vol_desc.transform()]);
+  	    convert<detector_t>(det.transform_store().at(vol_desc.transform()));
         vol_data.type = vol_desc.id();
 
         // Count the surfaces belonging to this volume