File Coverage

src/panda/optional.h

Criterion	Covered	Total	%
statement	9	9	100.0
branch	5	6	83.3
condition			n/a
subroutine			n/a
pod			n/a
total	14	15	93.3

#pragma once

#if __cpp_lib_optional >= 201603L
#  include
namespace panda {
  template
  using optional = std::optional;
}
#else

namespace panda {

template  struct optional {
    ~optional() { reset(); }

    optional() : nullable_val(nullptr) {}

    optional(const T& val) : nullable_val(new (storage) T(val)) {}

    optional(const optional& oth) : nullable_val(oth ? new (storage) T(*oth) : nullptr) {}

    optional& operator=(optional const& oth) {
        if (&oth != this) {
            reset();
            if (oth)
                nullable_val = new (storage) T(*oth);
        }
        return *this;
    }

    optional& operator=(const T& val) {
        reset();
        nullable_val = new (storage) T(val);
        return *this;
    }

    void reset() {
        if (nullable_val)
            nullable_val->~T();
        nullable_val = nullptr;
    }

    T&       operator*() { return *nullable_val; }
    const T& operator*() const { return *nullable_val; }
    T*       operator->() { return nullable_val; }
    const T* operator->() const { return nullable_val; }

    T value_or(const T& default_val) const { return nullable_val ? *nullable_val : default_val; }

    T value() const { return *nullable_val; }

    explicit operator bool() const { return nullable_val != nullptr; }

private:
    T* nullable_val;
    alignas(alignof(T)) char storage[sizeof(T)];
};

template  struct optional_tools {
    using type = optional;
    static type default_value () { return type{}; }
};

template <> struct optional_tools {
    using type = void;
    static void default_value () {}
};

template  inline constexpr bool operator== (const optional& lhs, const optional& rhs) {
    return (lhs && rhs) ? (*lhs == *rhs) : (lhs || rhs ? false : true);
}
template  inline constexpr bool operator!= (const optional& lhs, const optional& rhs) { return !operator==(lhs, rhs); }

template
inline constexpr bool operator< (const optional& lhs, const optional& rhs) {
    return (lhs && rhs) ? (*lhs < *rhs) : (rhs ? true : false);
}

template
constexpr bool operator<= (const optional& lhs, const optional& rhs) {
    return (lhs && rhs) ? (*lhs < *rhs) : (lhs ? false : true);
}

template
constexpr bool operator> (const optional& lhs, const optional& rhs) {
    return (lhs && rhs) ? (*lhs < *rhs) : (lhs ? true : false);
}

template
constexpr bool operator>= (const optional& lhs, const optional& rhs) {
    return (lhs && rhs) ? (*lhs < *rhs) : (rhs ? false : true);
}

template  constexpr bool operator== (const optional& opt, const U& value) { return opt && *opt == value; }
template  constexpr bool operator== (const T& value, const optional& opt) { return opt && value == *opt; }
template  constexpr bool operator!= (const optional& opt, const U& value) { return !operator==(opt, value); }
template  constexpr bool operator!= (const T& value, const optional& opt) { return !operator==(value, opt); }
template  constexpr bool operator<  (const optional& opt, const U& value) { return opt ? *opt < value : true; }
template  constexpr bool operator<  (const T& value, const optional& opt) { return opt && value < *opt; }
template  constexpr bool operator<= (const optional& opt, const U& value) { return opt ? *opt <= value : true; }
template  constexpr bool operator<= (const T& value, const optional& opt) { return opt && value <= *opt; }
template  constexpr bool operator>  (const optional& opt, const U& value) { return opt && *opt > value; }
template  constexpr bool operator>  (const T& value, const optional& opt) { return opt ? value > *opt : true; }
template  constexpr bool operator>= (const optional& opt, const U& value) { return opt && *opt >= value; }
template  constexpr bool operator>= (const T& value, const optional& opt) { return opt ? value >= *opt : true; }

}

#endif