indexset.h

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#pragma once
 
#include "mim/util/vector.h"
 
namespace mim {
 
template<class Indexer, class Key>
class IndexSet {
public:
    class reference {
    private:
        reference(uint64_t& word, uint64_t pos)
            : word_(word)
            , pos_(pos) {}
 
    public:
        reference operator=(bool b) noexcept {
            if (b)
                word_ |= uint64_t(1) << pos_;
            else
                word_ &= ~(uint64_t(1) << pos_);
            return *this;
        }
        operator bool() const { return word_ & (uint64_t(1) << pos_); }
 
    private:
        uint64_t word() const { return word_; }
 
        uint64_t& word_;
        uint64_t pos_;
 
        friend class IndexSet;
    };
 
    // TODO write iterators
    // TODO add size
 
    IndexSet(const Indexer& indexer)
        : indexer_(indexer)
        , bits_((capacity() + 63u) / 64u) {}
    IndexSet(const IndexSet& other)
        : indexer_(other.indexer())
        , bits_(other.bits_) {}
    IndexSet(IndexSet&& other) noexcept
        : indexer_(std::move(other.indexer_))
        , bits_(std::move(other.bits_)) {}
    IndexSet& operator=(IndexSet other) noexcept { return swap(*this, other), *this; }
 
    const Indexer& indexer() const { return indexer_; }
    size_t capacity() const { return indexer().size(); }
    size_t next(size_t pos = 0) {
        for (size_t i = pos, e = capacity(); i != e; ++i)
            if (bits_[i]) return i;
        return pos;
    }
    reference operator[](Key key) {
        auto i = indexer().index(key);
        assert(i != size_t(-1));
        return reference(bits_[i / 64u], i % 64u);
    }
    bool operator[](Key key) const { return (*const_cast<IndexSet<Indexer, Key>*>(this))[key]; }
 
    /// Depending on @p flag this method either inserts (true) or removes (false) @p key and returns true if successful.
    template<bool flag>
    bool set(Key key) {
        auto ref = (*this)[key];
        auto old = ref.word();
        ref      = flag;
        return old != ref.word();
    }
    bool insert(Key key) { return set<true>(key); } ///< Inserts \p key and returns true if successful.
    bool erase(Key key) { return set<false>(key); } ///< Erase \p key and returns true if successful.
    bool contains(Key key) const { return (*this)[key]; }
    void clear() { std::ranges::fill(bits_, 0u); }
 
    template<class Op>
    IndexSet& transform(const IndexSet& other, Op op) {
        assert(this->size() == other.size());
        for (size_t i = 0, e = capacity(); i != e; ++i)
            this->bits_[i] = op(this->bits_[i], other.bits_[i]);
        return *this;
    }
    IndexSet& operator&=(const IndexSet& other) { return transform(other, std::bit_and<uint64_t>()); }
    IndexSet& operator|=(const IndexSet& other) { return transform(other, std::bit_or<uint64_t>()); }
    IndexSet& operator^=(const IndexSet& other) { return transform(other, std::bit_xor<uint64_t>()); }
    friend void swap(IndexSet& set1, IndexSet& set2) noexcept {
        using std::swap;
        assert(&set1.indexer() == &set2.indexer());
        swap(set1.bits_, set2.bits_);
    }
 
private:
    const Indexer& indexer_;
    Vector<uint64_t> bits_;
};
 
/// @name IndexSet visit
///@{
template<class Indexer, class Key>
bool visit(IndexSet<Indexer, Key>& set, const Key& key) {
    return !set.insert(key);
}
 
template<class Indexer, class Key>
void visit_first(IndexSet<Indexer, Key>& set, const Key& key) {
    assert(!set.contains(key));
    visit(set, key);
}
///@}
 
} // namespace mim