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Constuctor chaining, better/more efficient moving

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Imbus 2025-01-11 17:13:50 +01:00
parent 5c20408a04
commit 1a0b3697f2
2 changed files with 22 additions and 11 deletions
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29
vector/vec.cc
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@ -2,14 +2,16 @@
#include <cstddef>
#include <cstring>
#include <iostream>
#include <iterator>
Vec::Vec() : cap(INITIAL_LEN), w_idx(0), arr(nullptr) {
std::cout << "Allocating vector" << std::endl;
arr = new T[INITIAL_LEN];
Vec::Vec() : Vec(INITIAL_LEN) {}
Vec::Vec(std::size_t size) : cap(size), w_idx(0), arr(new T[size]) {
std::cout << "Allocating vector of size " << size << std::endl;
}
Vec::Vec(std::initializer_list<T> il) : Vec() {
for (auto &a : il) push_back(a);
Vec::Vec(std::initializer_list<T> il) : Vec(il.size()) {
for (auto &elem : il) push_back(std::move(elem));
}
Vec::~Vec() {
@ -26,12 +28,18 @@ T &Vec::operator[](std::size_t idx) const noexcept {
exit(1);
}
void Vec::push_back(const T &value) noexcept {
void Vec::push_back(const T &value) {
arr[w_idx++] = value;
if (w_idx == cap) {
if (w_idx == cap)
resize(cap * 2);
}
void Vec::push_back(T &&value) {
arr[w_idx++] = std::move(value);
if (w_idx == cap)
resize(cap * 2);
}
}
std::size_t Vec::size() const { return w_idx; }
@ -39,9 +47,10 @@ std::size_t Vec::size() const { return w_idx; }
std::size_t Vec::capacity() const noexcept { return cap; }
void Vec::resize(std::size_t newsize) {
std::cout << "Reallocating" << std::endl;
std::cout << "Reallocating: " << cap << " to " << newsize << std::endl;
T *newarr = new T[newsize];
std::memcpy(newarr, arr, w_idx);
std::move(arr, arr + w_idx, newarr);
delete[] arr;
arr = newarr;
cap = newsize;

4
vector/vec.h
View file

@ -13,6 +13,7 @@ class Vec {
public:
Vec();
explicit Vec(std::size_t);
Vec(std::initializer_list<T>);
Vec(const Vec &other); // Copy
Vec(Vec &&other) noexcept; // Move
@ -25,7 +26,8 @@ class Vec {
std::size_t size() const;
std::size_t capacity() const noexcept;
void push_back(const T &value) noexcept;
void push_back(const T &value); // May except
void push_back(T &&value);
void pop_back() noexcept;
void clear() noexcept;