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Merge pull request #78 from kernhanda/kernhanda/heterogenous-assignment-not_null

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Add various copy assignment operators to not_null and maybe_null_*.
This commit is contained in:
Neil MacIntosh
2015-09-28 07:05:43 -07:00
parent 6554e83c79 7d8e609faf
commit 3571792058
3 changed files with 138 additions and 40 deletions
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include/gsl.h
+91 -38
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@@ -111,21 +111,27 @@ class not_null
static_assert(std::is_assignable<T&, std::nullptr_t>::value, "T cannot be assigned nullptr.");
public:
not_null(T t) : ptr_(t) { ensure_invariant(); }
// deleting these two prevents compilation when initialized with a nullptr or literal 0
not_null(std::nullptr_t) = delete;
not_null(int) = delete;
not_null& operator=(const T& t) { ptr_ = t; ensure_invariant(); return *this; }
not_null(const not_null &other) = default;
not_null& operator=(const not_null &other) = default;
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
not_null(const not_null<U> &other) : ptr_(other.get())
not_null(const not_null<U> &other)
{
*this = other;
}
not_null<T>& operator=(const T& t) { ptr_ = t; ensure_invariant(); return *this; }
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
not_null& operator=(const not_null<U> &other)
{
ptr_ = other.get();
return *this;
}
// prevents compilation when someone attempts to assign a nullptr
not_null(std::nullptr_t) = delete;
not_null(int) = delete;
not_null<T>& operator=(std::nullptr_t) = delete;
not_null<T>& operator=(int) = delete;
@@ -166,26 +172,18 @@ private:
//
// Describes an optional pointer - provides symmetry with not_null
//
template<class T>
class maybe_null_ret;
template<class T>
class maybe_null_dbg
{
static_assert(std::is_assignable<T&, std::nullptr_t>::value, "T cannot be assigned nullptr.");
public:
maybe_null_dbg() : ptr_(nullptr), tested_(false) {}
maybe_null_dbg(std::nullptr_t) : ptr_(nullptr), tested_(false) {}
maybe_null_dbg(const T& p) : ptr_(p), tested_(false) {}
maybe_null_dbg(const maybe_null_dbg& rhs) : ptr_(rhs.ptr_), tested_(false) {}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_dbg(const not_null<U> &other) : ptr_(other.get()), tested_(false)
{
}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_dbg(const maybe_null_dbg<U> &other) : ptr_(other.get()), tested_(false)
{
}
maybe_null_dbg& operator=(const T& p)
{
if (ptr_ != p)
@@ -196,6 +194,8 @@ public:
return *this;
}
maybe_null_dbg(const maybe_null_dbg& rhs) : ptr_(rhs.ptr_), tested_(false) {}
maybe_null_dbg& operator=(const maybe_null_dbg& rhs)
{
if (this != &rhs)
@@ -206,6 +206,43 @@ public:
return *this;
}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_dbg(const not_null<U> &other) : ptr_(other.get()), tested_(false) {}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_dbg& operator=(const not_null<U> &other)
{
ptr_ = other.get();
tested_ = false;
return *this;
}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_dbg(const maybe_null_dbg<U> &other) : ptr_(other.get()), tested_(false) {}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_dbg& operator=(const maybe_null_dbg<U> &other)
{
ptr_ = other.get();
tested_ = false;
return *this;
}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_dbg(const maybe_null_ret<U> &other) : ptr_(other.get()), tested_(false) {}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_dbg& operator=(const maybe_null_ret<U> &other)
{
ptr_ = other.get();
tested_ = false;
return *this;
}
bool present() const { tested_ = true; return ptr_ != nullptr; }
bool operator==(const T& rhs) const { tested_ = true; return ptr_ == rhs; }
@@ -225,8 +262,6 @@ public:
T operator->() const { return get(); }
private:
const size_t ptee_size_ = sizeof(*ptr_); // T must be a pointer type
// unwanted operators...pointers only point to single objects!
// TODO ensure all arithmetic ops on this type are unavailable
maybe_null_dbg<T>& operator++() = delete;
@@ -249,27 +284,46 @@ class maybe_null_ret
public:
maybe_null_ret() : ptr_(nullptr) {}
maybe_null_ret(std::nullptr_t) : ptr_(nullptr) {}
maybe_null_ret(const T& p) : ptr_(p) {}
maybe_null_ret& operator=(const T& p) { ptr_ = p; return *this; }
maybe_null_ret(const maybe_null_ret& rhs) = default;
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret(const not_null<U> &other) : ptr_(other.get())
{
}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret(const maybe_null_ret<U> &other) : ptr_(other.get())
{
}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret(const maybe_null_dbg<U> &other) : ptr_(other.get())
{
}
maybe_null_ret& operator=(const T& p) { if (ptr_ != p) { ptr_ = p; } return *this; }
maybe_null_ret& operator=(const maybe_null_ret& rhs) = default;
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret(const not_null<U> &other) : ptr_(other.get()) {}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret& operator=(const not_null<U> &other)
{
ptr_ = other.get();
return *this;
}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret(const maybe_null_ret<U> &other) : ptr_(other.get()) {}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret& operator=(const maybe_null_ret<U> &other)
{
ptr_ = other.get();
return *this;
}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret(const maybe_null_dbg<U> &other) : ptr_(other.get()) {}
template <typename U, typename Dummy = std::enable_if_t<std::is_convertible<U, T>::value>>
maybe_null_ret& operator=(const maybe_null_dbg<U> &other)
{
ptr_ = other.get();
return *this;
}
bool present() const { return ptr_ != nullptr; }
T get() const { return ptr_; }
@@ -289,7 +343,6 @@ private:
maybe_null_ret<T>& operator-(size_t) = delete;
maybe_null_ret<T>& operator-=(size_t) = delete;
const size_t ptee_size_ = sizeof(*ptr_); // T must be a pointer type
T ptr_;
};