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iod::aos_view
#include <iostream>
#include <iod/aos_view.hh>
#include "symbols.hh"
#include <cassert>
// aos_view allows to view several arrays as a unique array of structures.
// Any class with a size() method and operator[](int i) is supported.
// The view only hold references to the arrays so no deep array copy is involved.
int main()
{
using namespace iod;
using namespace s;
// Basic usage.
{
std::vector<int> A = {1,2,3,4};
std::vector<char> B = {'a', 'b', 'c', 'd'};
// Map array A to struct member a and array B to member b.
auto v = iod::aos_view(_a = A, _b = B);
assert(v[2].a == 3);
assert(v[2].b == 'c');
// For range loop
for (auto x : v)
std::cout << x.a << " " << x.b << std::endl;
for (size_t i = 0; i < v.size(); i++)
std::cout << v[i].a << " " << v[i].b << std::endl;
// Views are writable.
v[2].a = 42; // Write to A[2]
v[2].b = 'z'; // Write to B[2]
assert(A[2] == 42);
assert(B[2] == 'z');
}
// Test if it does not copy arrays.
{
struct Arr1
{
Arr1() {};
Arr1(const Arr1& e) = delete;
Arr1& operator=(const Arr1& e) = delete;
decltype(auto) operator[](int i) { return 42; }
int size() { return 1; }
};
Arr1 A;
Arr1 B;
auto v = iod::aos_view(s::_a = A);
assert(v[0].a == 42);
}
// const vectors lead to read only views.
{
const std::vector<int> A = {1,2,3,4};
const std::vector<char> B = {'a', 'b', 'c', 'd'};
auto v = iod::aos_view(s::_a = A, s::_b = B);
assert(v[2].a == 3);
assert(v[2].b == 'c');
// cannot assign to non-static data member 'a' with const-qualified type 'value_type
// ' (aka 'const int &')
// v[2].a = 42;
}
// Mix computed vectors and in-memory vectors.
{
std::vector<int> A = {1,2,3,4};
auto v = aos_view(_a = A,
_b = [] (int i) { return i * 2; });
for (auto x : v)
std::cout << x.a << " " << x.b << std::endl;
v[3].a = 12;
assert(v[3].a == 12);
// error: expression is not assignable.
// v[3].b = 12;
}
// Attach code.
{
std::vector<int> A = {1,2,3,4};
auto v = aos_view(_a = A,
_b = [&] (int i, std::string s) {
std::cout << A[i] << s << std::endl ; });
for (auto x : v)
x.b(" test");
}
// inplace sort. Not implemented.
// {
// std::vector<int> A = {4,3,1,2};
// std::vector<char> B = {'a', 'b', 'c', 'd'};
// auto v = aos_view(_a = A , _b = B);
// // Sort wrt a member of the SOA.
// sort(v, _a);
// // Sort wrt a function.
// sort(v, [] (auto x, auto y) { return x.a < y.a; });
// for (auto x : v)
// std::cout << x.a << " " << x.b << std::endl;
// }
}
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