1 files changed, 139 insertions, 0 deletions
diff --git a/a6/stack_new.cc b/a6/stack_new.cc
new file mode 100644
index 0000000..49f234f
--- /dev/null
+++ b/a6/stack_new.cc
@@ -0,0 +1,139 @@
+#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';
+
+}