7.3 KiB
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Header: array_view.h
Since: All versions
Similar to: gsl::array_view
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This class implements a view in to a range of a C array, etl::array, std::array, etl::vector and std::vector.
It will support construction from any class that supports data() and size() member functions as well as plain C arrays.
If ETL_ARRAY_VIEW_IS_MUTABLE is defined, then the contents of the view are mutable.
The view is non-mutable by default, which is the opposite to the behaviour in 17.5.0 or earlier.
etl::array_view<typename T>
Template deduction guides
C++17 and above
template <typename TArray>
etl::array_view(TArray& a)
-> etl::array_view<typename TArray::value_type>;
template <typename TIterator>
etl::array_view(const TIterator begin_, const TIterator end_)
-> etl::array_view<etl::remove_pointer_t<TIterator>>;
template <typename TIterator, typename TSize>
etl::array_view(const TIterator begin_, const TSize size_)
-> etl::array_view<etl::remove_pointer_t<TIterator>>;
Examples
etl::array data{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
etl::array_view view1{ data };
etl::array_view view2{ data.begin(), data.end() };
etl::array_view view3{ data.begin(), data.size() };
etl::array_view view4{ view1 };
Member types
value_type
size_type
difference_type
reference
const_reference
pointer
const_pointer
iterator
const_iterator
reverse_iterator
const_reverse_iterator
Constructors
ETL_CONSTEXPR array_view()
Description
Default constructor.
template <typename TArray>
ETL_CONSTEXPR explicit array_view(TArray& a)
Description
Construct from array or vector like class.
template <typename TIterator>
ETL_CONSTEXPR array_view(TIterator begin_, TIterator end_)
Description
Construct from an iterator or pointer range.
template <typename TIterator, typename TSize>
ETL_CONSTEXPR array_view(TIterator begin_, TSize size_)
Description
Construct from a start and size
template<const size_t ARRAY_SIZE>
ETL_CONSTEXPR explicit array_view(T(&begin_)[ARRAY_SIZE])
Description
Construct from a compile time sized C array.
ETL_CONSTEXPR array_view(const array_view& other)
Description
Copy constructor.
Modifiers
template <typename TIterator>
void assign(TIterator begin_, TIterator end_)
Description
Assigns begin and end of the supplied range.
Does not copy the elements in the range.
template <typename TIterator, typename TSize>
void assign(TIterator begin_, TSize size_)
Description
Assign from a start iterator and length.
Does not copy the elements in the range.
void remove_prefix(size_type n)
Description
Shrinks the view from the front.
A value of n larger than the array will result in undefined behaviour.
void remove_suffix(size_type n)
Description
Shrinks the view from the back.
A value of n larger than the array will result in undefined behaviour.
void fill(value_type value)
Introduced: 20.24.0
Description Fill the underlying array with value.
Element access
Mutable access is only possible by defining the macro ETL_ARRAY_VIEW_IS_MUTABLE.
In this case, reference, pointer, iterator and reverse_iterator are defined as their const counterparts.
reference at(size_t i)
const_reference at(size_t i) const
Description
Gets a reference or const reference to the indexed element.
Emits an etl::array_view_uninitialised if the view is not initialised.
Emits an etl::array_view_bounds if the index is not in range.
If asserts or exceptions are not enabled then undefined behaviour occurs.
Parameters
i The index.
Returns
A reference or const reference to the indexed element
reference operator[](size_t i)
const_reference operator[](size_t i) const
Description
Gets a reference or const reference to the indexed element.
Returns
A reference or const reference to the indexed element.
Undefined behaviour if the array_view is empty.
reference front()
const_reference front() const
Description
Gets a reference or const reference to the first element.
Returns
A reference or const reference to the first element.
Undefined behaviour if the array_view is empty.
reference back()
const_reference back() const
Description
Gets a reference or const reference to the last element.
Returns
A reference or const reference to the last element.
Undefined behaviour if the array_view is empty.
pointer data()
const_pointer data() const
Description
Gets a pointer or const pointer to the first element.
Returns
A pointer or const pointer to the first element.
Equal to end() if the array_view is empty.
Iterators
iterator begin()
const_iterator begin() const
const_iterator cbegin() const
Description
Returns an iterator to the beginning of the array view.
iterator end()
const_iterator end() const
const_iterator cend() const
Description
Returns an iterator to the end of the array view.
iterator rbegin()
const_iterator rbegin() const
const_iterator crbegin() const
Description
Gets a reverse iterator to the beginning of the array view.
iterator rend()
const_iterator rend() const
const_iterator crend() const
Description
Gets a reverse iterator to the end of the array view.
Capacity
bool empty() const
Description
Returns true if the size of the array view is zero, otherwise false.
size_t size() const
Description
Returns the size of the view.
C++size_t max_size() const
Description
Returns the maximum possible size of the view.
Non-member functions
Lexicographically comparisons
operator ==
Returns
Returns true if the contents of the array views are equal, otherwise false.
operator !=
Returns
true if the contents of the array views are not equal, otherwise false.
operator <
Returns
true if the contents of the lhs are lexicographically less than the
contents of the rhs, otherwise false.
operator <=
Returns
true if the contents of the lhs are lexicographically less than or equal to the
contents of the rhs, otherwise false.
operator >
Returns
true if the contents of the lhs are lexicographically greater than the
contents of the rhs, otherwise false.
operator >=
Returns
true if the contents of the lhs are lexicographically greater than or equal to the
contents of the rhs, otherwise false.
Hash
There are specialisations of etl::hash for array_view.
Example
etl::array<int, 10> data = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
typedef etl::array_view<int> View;
View view(data.begin() + 2, data.end() - 2);
void Print(const View& view)
{
for (size_t i = 0; i < view.size(); ++i)
{
std::cout << view[i] << " ";
}
}
Print(view); // Prints "3 4 5 6 7 8"
size_t hashvalue = etl::hash<View>()(view);