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#include <iostream>
#include <string>
#include <functional>
#include <stdexcept>
#include "generator.h"
// Universal allocator
namespace memory
{
void* ptr{};
std::size_t n{};
}
void* operator new(std::size_t n)// throw(std::bad_alloc)
{
std::cout << "new (" << n << " bytes from "
<< memory::ptr << " which is size " << memory::n << ")\n";
if(memory::ptr == nullptr) throw std::bad_alloc();
if(n > memory::n) throw std::bad_alloc();
auto ptr = memory::ptr;
memory::ptr = nullptr; // use only once
memory::n = 0;
return ptr;
}
void operator delete(void*) throw()
{
std::cout << "delete\n";
// Do nothing. actual memory is allocated on the stack
}
void operator delete(void*, std::size_t) throw()
{
std::cout << "delete[]\n";
// Do nothing. actual memory is allocated on the stack
}
template<std::size_t S, typename T = char>
class StackNew
{
public:
StackNew()
{
std::cout << "StackNew ptr=" << (void*)buf
<< " of size " << S * sizeof(T) << '\n';
memory::ptr = buf;
memory::n = S * sizeof(T);
}
private:
T buf[S];
};
template<typename T>
Generator<T> iota(T start)
{
while(true)
{
co_yield start++;
}
}
int main()
{
std::cout << " ** std::string:\n";
{
StackNew<100> buffer;
std::string str{"hello allocating string world"};
try
{
str.reserve(50); // no stack buffer supplied so throws std::bad_alloc
}
catch(std::bad_alloc &e)
{
std::cout << "Stack buffer missing!\n";
}
}
std::cout << '\n';
std::cout << " ** std::vector:\n";
{
StackNew<10, int> buffer;
std::vector<int> vec{1,2,3,4,5,6,7,8,9,10};
StackNew<20, int> buffer2;
try
{
vec.resize(21); // throws std::bad_alloc
}
catch(std::bad_alloc &e)
{
std::cout << "Stack buffer was too small!\n";
}
}
std::cout << '\n';
std::cout << " ** std::function:\n";
{
std::function<int()> f;
{
StackNew<32> buffer;
char foo[32]{};
f = [foo]()
{
int i = 0;
for(auto v : foo)
{
i += v;
}
return i;
};
}
[[maybe_unused]]auto x = f();
}
std::cout << '\n';
std::cout << " ** co-routines:\n";
{
StackNew<100> buffer;
auto gen = iota(0);
while(true)
{
auto i = gen();
if(i > 10) break;
std::cout << i << " ";
}
std::cout << '\n';
}
std::cout << '\n';
}
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