copy_constructors.h

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#pragma once
#include <memory>
#include <unordered_map>
#include <vector>
// This file defines many macros for controlling copy constructors and move constructors on classes.
 
// NOLINTBEGIN(bugprone-macro-parentheses): Although this is a good check in general, here, we
// cannot add parantheses around the arguments, for it would be invalid syntax.
#define DELETE_COPY_CONSTRUCT(Object) Object(const Object& other) = delete
#define DELETE_COPY_ASSN(Object) Object& operator=(const Object& other) = delete
 
#define DELETE_MOVE_CONSTRUCT(Object) Object(Object&& other) = delete
#define DELETE_MOVE_ASSN(Object) Object& operator=(Object&& other) = delete
 
#define DELETE_BOTH_COPY(Object) \
 DELETE_COPY_CONSTRUCT(Object); \
 DELETE_COPY_ASSN(Object)
 
#define DELETE_BOTH_MOVE(Object) \
 DELETE_MOVE_CONSTRUCT(Object); \
 DELETE_MOVE_ASSN(Object)
 
#define DEFAULT_MOVE_CONSTRUCT(Object) Object(Object&& other) = default
#define DEFAULT_MOVE_ASSN(Object) Object& operator=(Object&& other) = default
 
#define DEFAULT_BOTH_MOVE(Object) \
 DEFAULT_MOVE_CONSTRUCT(Object); \
 DEFAULT_MOVE_ASSN(Object)
 
#define EXPLICIT_COPY_METHOD(Object) \
 Object copy() const { \
 return *this; \
 }
 
// EXPLICIT_COPY_DEFAULT_MOVE should be the default choice. It expects a PRIVATE copy constructor to
// be defined, which will be used by an explicit `copy()` method. For instance:
//
// private:
// MyClass(const MyClass& other) : field(other.field.copy()) {}
//
// public:
// EXPLICIT_COPY_DEFAULT_MOVE(MyClass);
//
// Now:
//
// MyClass o1;
// MyClass o2 = o1; // Compile error, copy assignment deleted.
// MyClass o2 = o1.copy(); // OK.
// MyClass o2(o1); // Compile error, copy constructor is private.
#define EXPLICIT_COPY_DEFAULT_MOVE(Object) \
 DELETE_COPY_ASSN(Object); \
 DEFAULT_BOTH_MOVE(Object); \
 EXPLICIT_COPY_METHOD(Object)
 
// NO_COPY should be used for objects that for whatever reason, should never be copied, but can be
// moved.
#define DELETE_COPY_DEFAULT_MOVE(Object) \
 DELETE_BOTH_COPY(Object); \
 DEFAULT_BOTH_MOVE(Object)
 
// NO_MOVE_OR_COPY exists solely for explicitness, when an object cannot be moved nor copied. Any
// object containing a lock cannot be moved or copied.
#define DELETE_COPY_AND_MOVE(Object) \
 DELETE_BOTH_COPY(Object); \
 DELETE_BOTH_MOVE(Object)
// NOLINTEND(bugprone-macro-parentheses):
 
template<typename T>
static std::vector<T> copyVector(const std::vector<T>& objects) {
 std::vector<T> result;
 result.reserve(objects.size());
 for (auto& object : objects) {
 result.push_back(object.copy());
 }
 return result;
}
 
template<typename T>
static std::vector<std::shared_ptr<T>> copyVector(const std::vector<std::shared_ptr<T>>& objects) {
 std::vector<std::shared_ptr<T>> result;
 result.reserve(objects.size());
 for (auto& object : objects) {
 T& ob = *object;
 result.push_back(ob.copy());
 }
 return result;
}
 
template<typename T>
static std::vector<std::unique_ptr<T>> copyVector(const std::vector<std::unique_ptr<T>>& objects) {
 std::vector<std::unique_ptr<T>> result;
 result.reserve(objects.size());
 for (auto& object : objects) {
 T& ob = *object;
 result.push_back(ob.copy());
 }
 return result;
}
 
// TODO: remove
template<typename T>
static std::vector<std::unique_ptr<T>> cloneVector(const std::vector<std::unique_ptr<T>>& objects) {
 std::vector<std::unique_ptr<T>> result;
 result.reserve(objects.size());
 for (auto& object : objects) {
 T& ob = *object;
 result.push_back(ob.clone());
 }
 return result;
}
 
template<typename K, typename V>
static std::unordered_map<K, V> copyMap(const std::unordered_map<K, V>& objects) {
 std::unordered_map<K, V> result;
 for (auto& [k, v] : objects) {
 result.insert({k, v.copy()});
 }
 return result;
}