diff options
| -rw-r--r-- | butl/optional | 35 |
1 files changed, 34 insertions, 1 deletions
diff --git a/butl/optional b/butl/optional index 0877f52..f6cc15e 100644 --- a/butl/optional +++ b/butl/optional @@ -5,7 +5,8 @@ #ifndef BUTL_OPTIONAL #define BUTL_OPTIONAL -#include <utility> // move() +#include <utility> // move() +#include <functional> // hash namespace butl { @@ -38,6 +39,7 @@ namespace butl T& operator* () {return value_;} const T& operator* () const {return value_;} + bool has_value () const {return !null_;} explicit operator bool () const {return !null_;} private: @@ -58,6 +60,37 @@ namespace butl { return !(x == y); } + + template <typename T> + inline auto + operator< (const optional<T>& x, const optional<T>& y) -> decltype (*x < *y) + { + bool px (x), py (y); + return px < py || (px && py && *x < *y); + } + + template <typename T> + inline auto + operator> (const optional<T>& x, const optional<T>& y) -> decltype (*x > *y) + { + return y < x; + } +} + +namespace std +{ + template <typename T> + struct hash<butl::optional<T>>: hash<T> + { + using argument_type = butl::optional<T>; + + size_t + operator() (const butl::optional<T>& o) const + noexcept (noexcept (hash<T> {} (*o))) + { + return o ? hash<T>::operator() (*o) : static_cast<size_t> (-3333); + } + }; } #endif // BUTL_OPTIONAL |