exists.hpp

 
#ifndef UFO_CONTAINER_TREE_PREDICATE_EXISTS_HPP
#define UFO_CONTAINER_TREE_PREDICATE_EXISTS_HPP
 
// UFO
#include <ufo/container/tree/predicate/filter.hpp>
 
namespace ufo::pred
{
 
template <bool Negated = false>
struct Exists {
};
 
template <bool Negated>
[[nodiscard]] constexpr Exists<!Negated> operator!(Exists<Negated> const&) noexcept
{
    return Exists<!Negated>{};
}
 
static constexpr inline Exists<false> const exists;
 
template <bool Negated>
struct Filter<Exists<Negated>> {
    using Pred = Exists<Negated>;
 
    template <class Tree>
    static constexpr void init(Pred&, Tree const&) noexcept
    {
    }
 
    template <class Value>
    [[nodiscard]] static constexpr bool returnableValue(Pred const&, Value const&) noexcept
    {
        return true;
    }
 
    template <class Tree>
    [[nodiscard]] static constexpr bool returnable(Pred const&, Tree const& t,
                                                   typename Tree::Node const& n) noexcept
    {
        if constexpr (Negated) {
            return !t.exists(n);
        } else {
            return t.exists(n);
        }
    }
 
    template <class Tree>
    [[nodiscard]] static constexpr bool traversable(Pred const&, Tree const& t,
                                                    typename Tree::Node const& n) noexcept
    {
        if constexpr (Negated) {
            return true;
        } else {
            return t.isParent(n.index);
        }
    }
 
    template <class Tree>
    [[nodiscard]] static constexpr bool returnableRay(Pred const& p, Tree const& t,
                                                      typename Tree::Node const& n,
                                                      typename Tree::Ray const&) noexcept
    {
        return returnable(p, t, n);
    }
 
    template <class Tree>
    [[nodiscard]] static constexpr bool traversableRay(Pred const& p, Tree const& t,
                                                       typename Tree::Node const& n,
                                                       typename Tree::Ray const&) noexcept
    {
        return traversable(p, t, n);
    }
};
}  // namespace ufo::pred
 
#endif  // UFO_CONTAINER_TREE_PREDICATE_EXISTS_HPP