#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;
}