ex13_49_String.cpp

#include "ex13_49_String.h"
#include <algorithm>

std::pair<char*, char*> 
String::alloc_n_copy(const char *b, const char *e)
{
	auto str = alloc.allocate(e-b);
	return{ str, std::uninitialized_copy(b, e, str)};
}

void String::range_initializer(const char *first, const char *last)
{
	auto newstr = alloc_n_copy(first, last);
	elements = newstr.first;
	end = newstr.second;
}

String::String(const char *s)
{
	char *sl = const_cast<char*>(s);
	while (*sl)
		++sl;
	range_initializer(s, ++sl);
}

String::String(const String& rhs)
{
	range_initializer(rhs.elements, rhs.end);
}

void String::free()
{
	if (elements) {
		std::for_each(elements, end, [this](char &c){ alloc.destroy(&c); });
		alloc.deallocate(elements, end - elements);
	}	
}

String::~String()
{
	free();
}

String& String::operator = (const String &rhs)
{
	auto newstr = alloc_n_copy(rhs.elements, rhs.end);
	free();
	elements = newstr.first;
	end = newstr.second;
	return *this;
}

String::String(String &&s) NOEXCEPT : elements(s.elements), end(s.end)
{
	s.elements = s.end = nullptr;
}

String& String::operator = (String &&rhs) NOEXCEPT
{
	if (this != &rhs) {
		free();
		elements = rhs.elements;
		end = rhs.end;
		rhs.elements = rhs.end = nullptr;
	}
	return *this;
}