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;
}