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14.26a.h
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14.26a.h
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/*
* Exercise 14.26: Define subscript operators for your StrVec, String, StrBlob,
* and StrBlobPtr classes.
*
* By Faisal Saadatmand
*/
#ifndef STR_VEC_H
#define STR_VEC_H
#include <initializer_list>
#include <iostream>
#include <memory>
#include <string>
#include <utility>
class StrVec {
friend bool operator==(const StrVec &, const StrVec &);
friend bool operator!=(const StrVec &, const StrVec &);
friend bool operator<(const StrVec &, const StrVec &);
public:
StrVec() : elements(nullptr), first_free(nullptr), cap(nullptr) { }
StrVec(std::initializer_list<std::string>);
StrVec(const StrVec &);
StrVec(StrVec &&) noexcept; // move constructor
StrVec& operator=(const StrVec &);
StrVec& operator=(StrVec &&) noexcept; // move assignment operator
~StrVec() { free(); }
void push_back(const std::string &);
size_t size() const { return first_free - elements; }
size_t capacity() const { return cap - elements; }
std::string *begin() const { return elements; }
std::string *end() const { return first_free; }
void reserve(const size_t &);
void resize(const size_t &, const std::string &s = "");
StrVec& operator=(std::initializer_list<std::string>);
std::string& operator[](std::size_t n) { return elements[n]; }
const std::string& operator[](std::size_t n) const
{ return elements[n]; }
private:
static std::allocator<std::string> alloc;
void chk_n_alloc() { if (size() == capacity()) reallocate(); }
std::pair<std::string *, std::string *>
alloc_n_copy(const std::string *, const std::string *);
void free();
void reallocate(size_t n = 0);
std::string *elements;
std::string *first_free;
std::string *cap;
};
// static member
std::allocator<std::string> StrVec::alloc;
// constructor
StrVec::StrVec(std::initializer_list<std::string> il) : StrVec()
{
reallocate(il.size());
for (auto p = il.begin(); p != il.end(); ++p)
alloc.construct(first_free++, *p);
}
// copy-control functions
StrVec::StrVec(const StrVec &s)
{
auto newdata = alloc_n_copy(s.begin(), s.end());
elements = newdata.first;
first_free = cap = newdata.second;
std::cout << "StrVec(const StrVec &)\n";
}
StrVec::StrVec(StrVec &&s) noexcept : elements(s.elements),
first_free(s.first_free), cap(s.cap)
{
s.elements = s.first_free = cap = nullptr;
std::cout << "StrVec(StrVec &&)\n";
}
StrVec&
StrVec::operator=(const StrVec &rhs)
{
auto data = alloc_n_copy(rhs.begin(), rhs.end());
free();
elements = data.first;
first_free = cap = data.second;
std::cout << "StrVec& operator=(const StrVec &)\n";
return *this;
}
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;
}
std::cout << "StrVec& operator=(StrVec &&)\n";
return *this;
}
// member functions
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, uninitialized_copy(b, e, data)};
}
void
StrVec::free()
{
if (elements) {
for (auto p = first_free; p != elements;)
alloc.destroy(--p);
alloc.deallocate(elements, cap - elements);
}
}
void
StrVec::reallocate(size_t n) // n is optional
{
auto newcapacity = (n) ? n : (size()) ? 2 * size() : 1;
auto newdata = alloc.allocate(newcapacity);
auto dest = newdata; // points to the next free pos in the new array
auto elem = elements; // points to next element in the old array
for (size_t i = 0; i != size(); ++i)
alloc.construct(dest++, std::move(*elem++));
free();
elements = newdata;
first_free = dest;
cap = elements + newcapacity;
}
void
StrVec::reserve(const size_t &n)
{
if (n > capacity()) // requested size is bigger than capacity
reallocate(n); // use optional argument
}
void
StrVec::resize(const size_t &n, const std::string &s)
{
if (n > capacity())
reallocate(n);
auto newsize = first_free + (n - size()); // points to the new first_free
while (first_free != newsize)
if (first_free < newsize)
alloc.construct(first_free++, s);
else
alloc.destroy(--first_free);
}
StrVec&
StrVec::operator=(std::initializer_list<std::string> il)
{
for (const auto &str : il)
push_back(str);
return *this;
}
// non-member functions
bool operator==(const StrVec &lhs, const StrVec &rhs)
{
bool result = false;
if (lhs.size() == rhs.size()) {
result = true;
auto rhsP = rhs.elements;
for (const auto &elem : lhs)
if (elem != *rhsP++) {
result = false;
break;
}
}
return result;
}
bool operator!=(const StrVec &lhs, const StrVec &rhs)
{
return !(lhs == rhs);
}
// using dictionary ordering
bool operator<(const StrVec &lhs, const StrVec &rhs)
{
if (lhs.size() == rhs.size()) {
auto rhsP = rhs.begin();
for (const auto &str : lhs) {
if (str != *rhsP)
return str < *rhsP;
++rhsP;
}
}
return lhs.size() < rhs.size();
}
#endif