ex13_49_StrVec.cpp

#include "ex13_49_StrVec.h"
#include <algorithm> // for_each

void StrVec::push_back(const std::string& s)
{
    chk_n_alloc();
    alloc.construct(first_free++, s);
}

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

void StrVec::free()
{
    if (elements) {
        for_each(elements, first_free,
                 [this](std::string& rhs) { alloc.destroy(&rhs); });
        alloc.deallocate(elements, cap - elements);
    }
}

void StrVec::range_initialize(const std::string* first, const std::string* last)
{
    auto newdata = alloc_n_copy(first, last);
    elements = newdata.first;
    first_free = cap = newdata.second;
}

StrVec::StrVec(const StrVec& rhs)
{
    range_initialize(rhs.begin(), rhs.end());
}

StrVec::StrVec(std::initializer_list<std::string> il)
{
    range_initialize(il.begin(), il.end());
}

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

StrVec& StrVec::operator=(const StrVec& rhs)
{
    auto data = alloc_n_copy(rhs.begin(), rhs.end());
    free();
    elements = data.first;
    first_free = cap = data.second;
    return *this;
}

void StrVec::alloc_n_move(size_t new_cap)
{
    auto newdata = alloc.allocate(new_cap);
    auto dest = newdata;
    auto elem = elements;
    for (size_t i = 0; i != size(); ++i)
        alloc.construct(dest++, std::move(*elem++));
    free();
    elements = newdata;
    first_free = dest;
    cap = elements + new_cap;
}

void StrVec::reallocate()
{
    auto newcapacity = size() ? 2 * size() : 1;
    alloc_n_move(newcapacity);
}

void StrVec::reserve(size_t new_cap)
{
    if (new_cap <= capacity()) return;
    alloc_n_move(new_cap);
}

void StrVec::resize(size_t count)
{
    resize(count, std::string());
}

void StrVec::resize(size_t count, const std::string& s)
{
    if (count > size()) {
        if (count > capacity()) reserve(count * 2);
        for (size_t i = size(); i != count; ++i)
            alloc.construct(first_free++, s);
    }
    else if (count < size()) {
        while (first_free != elements + count) alloc.destroy(--first_free);
    }
}

StrVec::StrVec(StrVec&& s) NOEXCEPT : elements(s.elements),
                                      first_free(s.first_free),
                                      cap(s.cap)
{
    // leave s in a state in which it is safe to run the destructor.
    s.elements = s.first_free = s.cap = nullptr;
}

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