SparseVector.h

//
// Created by henri on 24.10.24.
//
 
#ifndef IDOL_SPARSEVECTOR_H
#define IDOL_SPARSEVECTOR_H
 
#include <vector>
#include "idol/general/utils/exceptions/Exception.h"
#include "idol/general/numericals.h"
#include <idol/mixed-integer/modeling/variables/Var.h>
#include <idol/general/utils/Map.h>
 
namespace idol {
    class Var;
    class Ctr;
 
    namespace impl {
 
        template<class T>
        struct hash_object {
            auto operator()(const T& t_obj) const { return std::hash<unsigned int>()(t_obj.id()); }
        };
 
        template<class T>
        struct equal_to_object {
            auto operator()(const T& t_a, const T& t_b) const { return t_a.id() == t_b.id(); }
        };
 
        template<class T>
        struct less_object {
            auto operator()(const T& t_a, const T& t_b) const { return t_a.id() < t_b.id(); }
        };
 
    }
}
 
template<> struct std::hash<idol::Var> : public idol::impl::hash_object<idol::Var> {};
template<> struct std::equal_to<idol::Var> : public idol::impl::equal_to_object<idol::Var> {};
template<> struct std::less<idol::Var> : public idol::impl::less_object<idol::Var> {};
 
template<> struct std::hash<idol::Ctr> : public idol::impl::hash_object<idol::Ctr> {};
template<> struct std::equal_to<idol::Ctr> : public idol::impl::equal_to_object<idol::Ctr> {};
template<> struct std::less<idol::Ctr> : public idol::impl::less_object<idol::Ctr> {};
 
namespace idol {
    template<class, class>
    class SparseVector;
}
 
#ifdef IDOL_USE_TSL
#include <tsl/sparse_map.h>
#include <tsl/ordered_map.h>
#define IDOL_REF_VALUE(t_iterator) t_iterator.value()
#else
#ifdef IDOL_USE_ROBINHOOD
#include <robin_hood.h>
#define IDOL_REF_VALUE(t_iterator) t_iterator->second
#else
#include <map>
#define IDOL_REF_VALUE(t_iterator) t_iterator->second
#endif
#endif
 
template<class IndexT, class ValueT>
class idol::SparseVector {
private:
#ifdef IDOL_USE_TSL
    using map_t = std::conditional_t<
            sizeof(ValueT) < 32,
            tsl::sparse_map<IndexT, ValueT>,
            tsl::ordered_map<IndexT, ValueT>
    >;
#else
    #ifdef IDOL_USE_ROBINHOOD
    using map_t = robin_hood::unordered_map<IndexT, ValueT>;
#else
    using map_t = std::unordered_map<IndexT, ValueT>;
#endif
#endif
    map_t m_map;
 
    static ValueT s_zero_value;
public:
    SparseVector() = default;
 
    SparseVector(const IndexT& t_index, const ValueT& t_value) : m_map({ { t_index, t_value} }) {
        if (::idol::is_zero(t_value, Tolerance::Sparsity)) {
            m_map.clear();
        }
    }
 
    SparseVector(const SparseVector&) = default;
    SparseVector(SparseVector&&) = default;
 
    SparseVector& operator=(const SparseVector&) = default;
    SparseVector& operator=(SparseVector&&) noexcept = default;
 
    virtual SparseVector& operator+=(const SparseVector& t_vector);
    virtual SparseVector& operator-=(const SparseVector& t_vector);
    virtual SparseVector& operator*=(std::conditional_t<std::is_arithmetic_v<ValueT>, ValueT, double> t_scalar);
    virtual SparseVector& operator/=(std::conditional_t<std::is_arithmetic_v<ValueT>, ValueT, double> t_scalar);
    SparseVector operator-() const;
 
    [[nodiscard]] unsigned int size() const { return m_map.size(); }
 
    [[nodiscard]] bool empty() const { return m_map.empty(); }
 
    [[nodiscard]] bool has_index(const IndexT& t_index) const { return m_map.find(t_index) != m_map.end(); }
 
    [[nodiscard]] const ValueT& get(const IndexT& t_index1) const;
 
    void set(const IndexT& t_index, const ValueT& t_value);
 
    [[nodiscard]] virtual bool is_zero(double t_tolerance) const;
 
    void remove(const IndexT& t_index) { m_map.erase(t_index); }
 
    void clear() { m_map.clear(); }
 
    void reserve(unsigned int t_capacity) {
#ifdef IDOL_USE_TSL
        m_map.reserve(t_capacity);
#endif
    }
 
    using iterator = typename map_t::iterator;
    using const_iterator = typename map_t::const_iterator;
 
    [[nodiscard]] iterator begin() { return m_map.begin(); }
 
    [[nodiscard]] iterator end() { return m_map.end(); }
 
    [[nodiscard]] const_iterator begin() const { return m_map.cbegin(); }
 
    [[nodiscard]] const_iterator end() const { return m_map.cend(); }
 
    [[nodiscard]] const_iterator cbegin() const { return m_map.cbegin(); }
 
    [[nodiscard]] const_iterator cend() const { return m_map.cend(); }
 
    SparseVector& merge_without_conflict(const SparseVector& t_vec);
};
 
template<class IndexT, class ValueT> ValueT idol::SparseVector<IndexT, ValueT>::s_zero_value {};
 
template<class IndexT, class ValueT>
idol::SparseVector<IndexT, ValueT>
idol::SparseVector<IndexT, ValueT>::operator-() const {
    SparseVector result;
 
    for (const auto& [var, val] : m_map) {
        result.m_map.emplace(var, -val);
    }
 
    return result;
}
 
template<class IndexT, class ValueT>
idol::SparseVector<IndexT, ValueT> &
idol::SparseVector<IndexT, ValueT>::operator/=(std::conditional_t<std::is_arithmetic_v<ValueT>, ValueT, double> t_scalar) {
 
    std::vector<IndexT> to_be_removed;
    to_be_removed.reserve(m_map.size());
 
    for (auto it = m_map.begin(), end = m_map.end() ; it != end ; ++it) {
        IDOL_REF_VALUE(it) /= t_scalar;
        if (::idol::is_zero(it->second, Tolerance::Sparsity)) {
            to_be_removed.emplace_back(it->first);
        }
    }
 
    for (const auto& index : to_be_removed) {
        m_map.erase(index);
    }
 
    return *this;
}
 
template<class IndexT, class ValueT>
idol::SparseVector<IndexT, ValueT> &
idol::SparseVector<IndexT, ValueT>::operator-=(const SparseVector &t_vector) {
 
    if (this == &t_vector) {
        m_map.clear();
        return *this;
    }
 
    for (const auto& [var, val] : t_vector.m_map) {
        ValueT minus_val{};
        minus_val -= val;
        auto [it, inserted] = m_map.emplace(var, minus_val);
        if (!inserted) {
            IDOL_REF_VALUE(it) += std::move(minus_val);
            if (::idol::is_zero(it->second, Tolerance::Sparsity)) {
                m_map.erase(it);
            }
        }
    }
 
    return *this;
}
 
template<class IndexT, class ValueT>
idol::SparseVector<IndexT, ValueT> &
idol::SparseVector<IndexT, ValueT>::operator*=(std::conditional_t<std::is_arithmetic_v<ValueT>, ValueT, double> t_scalar) {
 
    std::vector<IndexT> to_be_removed;
    to_be_removed.reserve(m_map.size());
 
    for (auto it = m_map.begin(), end = m_map.end() ; it != end ; ++it) {
        IDOL_REF_VALUE(it) *= t_scalar;
        if (::idol::is_zero(it->second, Tolerance::Sparsity)) {
            to_be_removed.emplace_back(it->first);
        }
    }
 
    for (const auto& index : to_be_removed) {
        m_map.erase(index);
    }
 
    return *this;
}
 
template<class IndexT, class ValueT>
bool idol::SparseVector<IndexT, ValueT>::is_zero(double t_tolerance) const {
    for (const auto& [var, val] : m_map) {
        if (!::idol::is_zero(val, t_tolerance)) {
            return false;
        }
    }
    return true;
}
 
template<class IndexT, class ValueT>
idol::SparseVector<IndexT, ValueT>&
idol::SparseVector<IndexT, ValueT>::operator+=(const SparseVector &t_vector) {
 
    if (this == &t_vector) {
        return operator*=(2.);
    }
 
    for (const auto& [var, val] : t_vector.m_map) {
        auto [it, inserted] = m_map.emplace(var, val);
        if (!inserted) {
            IDOL_REF_VALUE(it) += val;
            if (::idol::is_zero(it->second, Tolerance::Sparsity)) {
                m_map.erase(it);
            }
        }
    }
 
    return *this;
}
 
template<class IndexT, class ValueT>
idol::SparseVector<IndexT, ValueT> &
idol::SparseVector<IndexT, ValueT>::merge_without_conflict(const SparseVector &t_vec) {
 
    for (const auto& [var, val] : t_vec.m_map) {
        auto [it, inserted] = m_map.emplace(var, val);
        if (!inserted) {
            throw Exception("Found conflict when explicitly merging without conflict.");
        }
    }
 
    return *this;
}
 
template<class IndexT, class ValueT>
const ValueT& idol::SparseVector<IndexT, ValueT>::get(const IndexT &t_index1) const {
 
    const auto it = m_map.find(t_index1);
 
    if (it == m_map.end()) {
        return s_zero_value;
    }
 
    return it->second;
}
 
template<class IndexT, class ValueT>
void idol::SparseVector<IndexT, ValueT>::set(const IndexT &t_index, const ValueT &t_value) {
 
    if (::idol::is_zero(t_value, Tolerance::Sparsity)) {
        remove(t_index);
        return;
    }
 
    auto [it, inserted] = m_map.emplace(t_index, t_value);
 
    if (!inserted) {
        IDOL_REF_VALUE(it) = t_value;
    }
 
}
 
namespace idol {
 
    template<class IndexT, class ValueT>
    static  std::ostream & operator<<(std::ostream &t_stream, const idol::SparseVector<IndexT, ValueT> &t_vector) {
 
        for (const auto& [index, value] : t_vector) {
            t_stream << index << ": " << value << '\n';
        }
 
        return t_stream;
    }
 
    template<class IndexT, class ValueT>
    SparseVector<IndexT, ValueT> operator+(SparseVector<IndexT, ValueT>&& t_x, const SparseVector<IndexT, ValueT>& t_y) {
        return std::move(t_x) += t_y;
    }
 
    template<class IndexT, class ValueT>
    SparseVector<IndexT, ValueT> operator+(const SparseVector<IndexT, ValueT>& t_x, SparseVector<IndexT, ValueT>&& t_y) {
        return std::move(t_y) += t_x;
    }
 
    template<class IndexT, class ValueT>
    SparseVector<IndexT, ValueT> operator+(const SparseVector<IndexT, ValueT>& t_x, const SparseVector<IndexT, ValueT>& t_y) {
        return SparseVector(t_x) += t_y;
    }
 
    template<class IndexT, class ValueT>
    SparseVector<IndexT, ValueT> operator-(SparseVector<IndexT, ValueT> t_x, const SparseVector<IndexT, ValueT>& t_y) {
        return std::move(t_x) -= t_y;
    }
 
    template<class IndexT, class ValueT>
    SparseVector<IndexT, ValueT> operator+(SparseVector<IndexT, ValueT> t_x, double t_factor) {
        return std::move(t_x) *= t_factor;
    }
 
    template<class IndexT, class ValueT>
    SparseVector<IndexT, ValueT> operator+(double t_factor, SparseVector<IndexT, ValueT> t_x) {
        return std::move(t_x) *= t_factor;
    }
 
}
 
#endif //IDOL_SPARSEVECTOR_H