Template Class HierarchicalGeometryContainer

Class Documentation

template<typename value_t>
class Acts::HierarchicalGeometryContainer

Store homogeneous elements anchored in the geometry hierarchy.

The core functionality is to find an equivalent element for a given identifier via 

auto it = container.find(GeometryID(...));
if (it != container.end()) {
    ...
}
Template Parameters

  • value_t: stored element type

Trailing zero components of stored geometry identifiers are used as broadcast values to refer to higher-level objects within the geometry, e.g. a geometry identifier with vanishing approach and sensitive index refers to the full layer. All stored geometry identifiers must set at least the highest hierarchy level.

The container also supports range-based iteration over all stored elements 

for (const auto& element : container) {
    ...
}

and index-based access to stored elements and associated geometry identifiers 

GeometryID id3 = container.idAt(3);
const auto& element4 = container.valueAt(4);

Adding elements is potentially expensive as the internal lookup structure must be updated. In addition, modifying an element in-place can potentially change its identifier which would also break the lookup. Thus, the container can not be modified after construction to prevent misuse.

Note

No guarantees are given for the element order when using range-based or index-based access. Any apparent ordering must be considered an implementation detail and might change.

Public Types

using Iterator = typename std::vector<value_t>::const_iterator
using Size = typename std::vector<value_t>::size_type
using Value = value_t

Public Functions

template<typename id_getter_t = detail::DefaultGeometryIdGetter>
HierarchicalGeometryContainer(std::vector<Value> &&elements, id_getter_t getId = id_getter_t())

Construct the container from the given elements.

Parameters

  • elements: input elements (must be unique with respect to identifier)

  • getId: functor to retrieve the id of an element

Template Parameters

  • id_getter_t: Functor type to retrieve the id of an element

HierarchicalGeometryContainer() = default
HierarchicalGeometryContainer(const HierarchicalGeometryContainer&) = default
HierarchicalGeometryContainer(HierarchicalGeometryContainer&&) = default
~HierarchicalGeometryContainer() = default
Iterator begin() const

Return an iterator pointing to the beginning of the stored elements.

bool empty() const

Check if any elements are stored.

Iterator end() const

Return an iterator pointing to the end of the stored elements.

Iterator find(GeometryID id) const

Find the most specific element for a given geometry identifier.

This can be either the element matching exactly to the given geometry id, if it exists, or the element from the next available higher level within the geometry hierachy.

Parameters

  • id: geometry identifier for which information is requested

Return Value

  • iterator: to an existing element

  • <tt>.end()</tt>: iterator if no matching element exists

GeometryID idAt(Size index) const

Access the geometry identifier for the i-th element with bounds check.

Exceptions

  • std::out_of_range: for invalid indices

HierarchicalGeometryContainer &operator=(const HierarchicalGeometryContainer&) = default
HierarchicalGeometryContainer &operator=(HierarchicalGeometryContainer&&) = default
Size size() const

Return the number of stored elements.

const Value &valueAt(Size index) const

Access the i-th element in the container with bounds check.

Exceptions

  • std::out_of_range: for invalid indices