Views

Synopsis:

template <typename ValueType, int Rank, typename TraversalOrder=void> class array_view;
template <typename ValueType,           typename TraversalOrder=void> class matrix_view;
template <typename ValueType>                                         class vector_view;

template <typename ValueType, int Rank, typename TraversalOrder=void> class array_const_view;
template <typename ValueType,           typename TraversalOrder=void> class matrix_const_view;
template <typename ValueType>                                         class vector_const_view;

  • The view types of X (= array, matrix, vector) are called X_view, and X_const_view, with the same template parameters as the regular type.

  • A view is give access to a restricted portion of the array, matrix or vector, i.e. a partial view of the data. The view can also be complete (i.e. show all the container).

  • The views model the MutableCuboidArray, MutableMatrix, MutableVector, like the corresponding regular type.

  • The const views are similar to view, except that theirs contents cannot be modified. They model the ImmutableCuboidArray, ImmutableMatrix, ImmutableVector, like the corresponding const regular type.

  • Views have view semantics, i.e. their behave like a documentation/manual/triqs to the data, they are not regular type. In particular, they never make copy of the data. See Regular type vs view type for a detailed discussion of the difference between a regular type and its corresponding view.

  • Views are largely interoperable: it is easy and quick to take a matrix_view of an array, or vice versa. Cf constructors belows.

  • Const views can be constructed from a view, but the reverse is not true (Cf constructors).

  • Memory Management

    Views offers a strong guarantee of the existence of the data, like a std::shared_ptr. Cf View memory management for details.

Template parameters

Template parameter Accepted type Access in the class Meaning
ValueType any regular type (typically a scalar). value_type The type of the element of the array
Rank int rank The rank of the array
TraversalOrder ull_t   Traversal Order for all loops

NB: Rank is only present for array, since matrix have rank 2 and vector rank 1.

Member types

Member type Definitions
value_type ValueType
view_type The corresponding view type
const_view_type The corresponding const view type
regular_type The corresponding regular type

Member constexpr

Member Type Definitions
rank int Rank of the container (Rank for array), 2 for matrix, 1 for vector

Member functions

Member function Meaning
(constructor)  
(destructor)  
operator () element of access/views/lazy expressions
operator = assigns values to the container
operator +=,-=,*=,/= compound assignment operators
begin/cbegin returns iterator to the beginning
end/cend returns iterator to the end
rebind rebind the view
bool is_empty() const Is the array empty ?

Note

views cannot be resized.

Non-member functions

Member function Meaning
swap Swap of 2 containers
deep_swap Deep swap of the data of 2 containers ???
operator<< Writing to stream