Span

A span represents a non-owning, cheap-to-copy view of a contiguous block of data. It allows the user to safely pass around and iterate through these objects without risk of going out of bounds of their desired view (careless use of operator[] notwithstanding), or paying a performance cost to duplicate data. A span object can have static extent (in which case the size of the viewed range is known at compile time) or a dynamic extent. This is determined by the second template parameter, which defaults to dynamic extent.

dp::span matches the interface of the modern std::span, except that it supports dp::array construction rather than std::array. While it may be possible to construct a span from a range stored non-contiguously, the behaviour of such a span will be undefined.

Features

begin cbegin	Returns an iterator to the beginning
end cend	Returns an iterator to the end
rbegin crbegin	Returns a reverse iterator to the beginning
rend crend	Returns a reverse iterator to the end
front	Accesses the first element
back	Accesses the last element
operator[]	Provides indexed access
data	Returns a pointer to the viewed storage
size	Returns the number of elements in the view
size_bytes	Returns the total size of the viewed elements, in bytes
empty	Checks if the view is empty.
first	Obtains a subspan consisting of the first N elements of the sequence
last	Obtains a subspan consisting of the last N elements of the sequence
subspan	Obtains a subspan
as_bytes as_writeable_bytes	Converts a span to a view of its underlying bytes

Sample code

#include <vector>

#include "cpp98/span.h"

void printSpan(dp::span<int> sp){
    typedef dp::span<int>::const_iterator Iter;
    for(Iter it = sp.begin(); it != sp.end(); ++it){
        Print(*it + ' ');
    }
    Print('\n');
}

int main() {
    int c_arr[10] = { 1,2,3,4,5,6,7,8,9,10 };
    printSpan(c_arr);  //Prints 1 2 3 4 5 6 7 8 9 10

    std::vector<int> vec;
    for (int i = 0; i < 5; ++i) vec.push_back(i);
    printSpan(vec);  //Prints 1 2 3 4 5

    dp::span<int> span = dp::span<int>(vec).subspan(2,3); //Note, no copies made

    printSpan(span); //Prints 2 3 4
}