optional exception check, primarily adding noexcept to signatures

-- also reordered the assignments in set/clear to ensure "has_value_" doesn't change if the assignment operator of T throws
This commit is contained in:
Crzyrndm 2018-07-10 17:22:54 +12:00
parent ad69e7bf11
commit 34e8f274de

View File

@ -40,14 +40,17 @@ public:
/// <summary>
/// Default contructor. is_set() will be false initially.
/// </summary>
optional() : has_value_(false), value_(T())
optional() noexcept(std::is_nothrow_default_constructible<T>{})
: has_value_(false), value_(T())
{
}
/// <summary>
/// Constructs this optional with a value.
/// noexcept if T copy ctor is noexcept
/// </summary>
optional(const T &value) : has_value_(true), value_(value)
optional(const T &value) noexcept(std::is_nothrow_copy_constructible<T>{})
: has_value_(true), value_(value)
{
}
@ -55,7 +58,7 @@ public:
/// Returns true if this object currently has a value set. This should
/// be called before accessing the value with optional::get().
/// </summary>
bool is_set() const
bool is_set() const noexcept
{
return has_value_;
}
@ -63,10 +66,10 @@ public:
/// <summary>
/// Sets the value to value.
/// </summary>
void set(const T &value)
void set(const T &value) noexcept(std::is_nothrow_assignable<T, T>{})
{
has_value_ = true;
value_ = value;
has_value_ = true;
}
/// <summary>
@ -101,20 +104,18 @@ public:
/// Resets the internal value using its default constructor. After this is
/// called, is_set() will return false until a new value is provided.
/// </summary>
void clear()
void clear() noexcept(std::is_nothrow_assignable<T, T>{} && std::is_nothrow_default_constructible<T>{})
{
has_value_ = false;
value_ = T();
has_value_ = false;
}
/// <summary>
/// Assignment operator. Equivalent to setting the value using optional::set.
/// </summary>
optional &operator=(const T &rhs)
optional &operator=(const T &rhs) noexcept(noexcept(set(std::declval<T &>())))
{
has_value_ = true;
value_ = rhs;
set(rhs);
return *this;
}
@ -123,9 +124,10 @@ public:
/// or both have a value and those values are equal according to
/// their equality operator.
/// </summary>
bool operator==(const optional<T> &other) const
bool operator==(const optional<T> &other) const noexcept
{
if (has_value_ != other.has_value_) {
if (has_value_ != other.has_value_)
{
return false;
}
if (!has_value_)
@ -140,7 +142,7 @@ public:
/// or both have a value and those values are equal according to
/// their equality operator.
/// </summary>
bool operator!=(const optional<T> &other) const
bool operator!=(const optional<T> &other) const noexcept
{
return !operator==(other);
}