vector.h

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2024, Paul Elder <paul.elder@ideasonboard.com>
 *
 * Vector and related operations
 */
#pragma once

#include <algorithm>
#include <array>
#include <cmath>
#include <functional>
#include <numeric>
#include <optional>
#include <ostream>

#include <libcamera/base/log.h>
#include <libcamera/base/span.h>

#include "libcamera/internal/matrix.h"
#include "libcamera/internal/yaml_parser.h"

namespace libcamera {

LOG_DECLARE_CATEGORY(Vector)

#ifndef __DOXYGEN__
template<typename T, unsigned int Rows,
     std::enable_if_t<std::is_arithmetic_v<T>> * = nullptr>
#else
template<typename T, unsigned int Rows>
#endif /* __DOXYGEN__ */
class Vector
{
public:
    constexpr Vector() = default;

    constexpr explicit Vector(T scalar)
    {
        data_.fill(scalar);
    }

    constexpr Vector(const std::array<T, Rows> &data)
    {
        for (unsigned int i = 0; i < Rows; i++)
            data_[i] = data[i];
    }

    const T &operator[](size_t i) const
    {
        ASSERT(i < data_.size());
        return data_[i];
    }

    T &operator[](size_t i)
    {
        ASSERT(i < data_.size());
        return data_[i];
    }

    constexpr Vector<T, Rows> operator-() const
    {
        Vector<T, Rows> ret;
        for (unsigned int i = 0; i < Rows; i++)
            ret[i] = -data_[i];
        return ret;
    }

    constexpr Vector operator+(const Vector &other) const
    {
        return apply(*this, other, std::plus<>{});
    }

    constexpr Vector operator+(T scalar) const
    {
        return apply(*this, scalar, std::plus<>{});
    }

    constexpr Vector operator-(const Vector &other) const
    {
        return apply(*this, other, std::minus<>{});
    }

    constexpr Vector operator-(T scalar) const
    {
        return apply(*this, scalar, std::minus<>{});
    }

    constexpr Vector operator*(const Vector &other) const
    {
        return apply(*this, other, std::multiplies<>{});
    }

    constexpr Vector operator*(T scalar) const
    {
        return apply(*this, scalar, std::multiplies<>{});
    }

    constexpr Vector operator/(const Vector &other) const
    {
        return apply(*this, other, std::divides<>{});
    }

    constexpr Vector operator/(T scalar) const
    {
        return apply(*this, scalar, std::divides<>{});
    }

    Vector &operator+=(const Vector &other)
    {
        return apply(other, [](T a, T b) { return a + b; });
    }

    Vector &operator+=(T scalar)
    {
        return apply(scalar, [](T a, T b) { return a + b; });
    }

    Vector &operator-=(const Vector &other)
    {
        return apply(other, [](T a, T b) { return a - b; });
    }

    Vector &operator-=(T scalar)
    {
        return apply(scalar, [](T a, T b) { return a - b; });
    }

    Vector &operator*=(const Vector &other)
    {
        return apply(other, [](T a, T b) { return a * b; });
    }

    Vector &operator*=(T scalar)
    {
        return apply(scalar, [](T a, T b) { return a * b; });
    }

    Vector &operator/=(const Vector &other)
    {
        return apply(other, [](T a, T b) { return a / b; });
    }

    Vector &operator/=(T scalar)
    {
        return apply(scalar, [](T a, T b) { return a / b; });
    }

    constexpr Vector min(const Vector &other) const
    {
        return apply(*this, other, [](T a, T b) { return std::min(a, b); });
    }

    constexpr Vector min(T scalar) const
    {
        return apply(*this, scalar, [](T a, T b) { return std::min(a, b); });
    }

    constexpr Vector max(const Vector &other) const
    {
        return apply(*this, other, [](T a, T b) { return std::max(a, b); });
    }

    constexpr Vector max(T scalar) const
    {
        return apply(*this, scalar, [](T a, T b) -> T { return std::max(a, b); });
    }

    constexpr T dot(const Vector<T, Rows> &other) const
    {
        T ret = 0;
        for (unsigned int i = 0; i < Rows; i++)
            ret += data_[i] * other[i];
        return ret;
    }

#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 1>>
#endif /* __DOXYGEN__ */
    constexpr const T &x() const { return data_[0]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 2>>
#endif /* __DOXYGEN__ */
    constexpr const T &y() const { return data_[1]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 3>>
#endif /* __DOXYGEN__ */
    constexpr const T &z() const { return data_[2]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 1>>
#endif /* __DOXYGEN__ */
    constexpr T &x() { return data_[0]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 2>>
#endif /* __DOXYGEN__ */
    constexpr T &y() { return data_[1]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 3>>
#endif /* __DOXYGEN__ */
    constexpr T &z() { return data_[2]; }

#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 1>>
#endif /* __DOXYGEN__ */
    constexpr const T &r() const { return data_[0]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 2>>
#endif /* __DOXYGEN__ */
    constexpr const T &g() const { return data_[1]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 3>>
#endif /* __DOXYGEN__ */
    constexpr const T &b() const { return data_[2]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 1>>
#endif /* __DOXYGEN__ */
    constexpr T &r() { return data_[0]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 2>>
#endif /* __DOXYGEN__ */
    constexpr T &g() { return data_[1]; }
#ifndef __DOXYGEN__
    template<bool Dependent = false, typename = std::enable_if_t<Dependent || Rows >= 3>>
#endif /* __DOXYGEN__ */
    constexpr T &b() { return data_[2]; }

    constexpr double length2() const
    {
        double ret = 0;
        for (unsigned int i = 0; i < Rows; i++)
            ret += data_[i] * data_[i];
        return ret;
    }

    constexpr double length() const
    {
        return std::sqrt(length2());
    }

    template<typename R = T>
    constexpr R sum() const
    {
        return std::accumulate(data_.begin(), data_.end(), R{});
    }

private:
    template<class BinaryOp>
    static constexpr Vector apply(const Vector &lhs, const Vector &rhs, BinaryOp op)
    {
        Vector result;
        std::transform(lhs.data_.begin(), lhs.data_.end(),
                   rhs.data_.begin(), result.data_.begin(),
                   op);

        return result;
    }

    template<class BinaryOp>
    static constexpr Vector apply(const Vector &lhs, T rhs, BinaryOp op)
    {
        Vector result;
        std::transform(lhs.data_.begin(), lhs.data_.end(),
                   result.data_.begin(),
                   [&op, rhs](T v) { return op(v, rhs); });

        return result;
    }

    template<class BinaryOp>
    Vector &apply(const Vector &other, BinaryOp op)
    {
        auto itOther = other.data_.begin();
        std::for_each(data_.begin(), data_.end(),
                  [&op, &itOther](T &v) { v = op(v, *itOther++); });

        return *this;
    }

    template<class BinaryOp>
    Vector &apply(T scalar, BinaryOp op)
    {
        std::for_each(data_.begin(), data_.end(),
                  [&op, scalar](T &v) { v = op(v, scalar); });

        return *this;
    }

    std::array<T, Rows> data_;
};

template<typename T>
using RGB = Vector<T, 3>;

template<typename T, unsigned int Rows, unsigned int Cols>
Vector<T, Rows> operator*(const Matrix<T, Rows, Cols> &m, const Vector<T, Cols> &v)
{
    Vector<T, Rows> result;

    for (unsigned int i = 0; i < Rows; i++) {
        T sum = 0;
        for (unsigned int j = 0; j < Cols; j++)
            sum += m[i][j] * v[j];
        result[i] = sum;
    }

    return result;
}

template<typename T, unsigned int Rows>
bool operator==(const Vector<T, Rows> &lhs, const Vector<T, Rows> &rhs)
{
    for (unsigned int i = 0; i < Rows; i++) {
        if (lhs[i] != rhs[i])
            return false;
    }

    return true;
}

template<typename T, unsigned int Rows>
bool operator!=(const Vector<T, Rows> &lhs, const Vector<T, Rows> &rhs)
{
    return !(lhs == rhs);
}

#ifndef __DOXYGEN__
bool vectorValidateYaml(const YamlObject &obj, unsigned int size);
#endif /* __DOXYGEN__ */

#ifndef __DOXYGEN__
template<typename T, unsigned int Rows>
std::ostream &operator<<(std::ostream &out, const Vector<T, Rows> &v)
{
    out << "Vector { ";
    for (unsigned int i = 0; i < Rows; i++) {
        out << v[i];
        out << ((i + 1 < Rows) ? ", " : " ");
    }
    out << " }";

    return out;
}

template<typename T, unsigned int Rows>
struct YamlObject::Getter<Vector<T, Rows>> {
    std::optional<Vector<T, Rows>> get(const YamlObject &obj) const
    {
        if (!vectorValidateYaml(obj, Rows))
            return std::nullopt;

        Vector<T, Rows> vector;

        unsigned int i = 0;
        for (const YamlObject &entry : obj.asList()) {
            const auto value = entry.get<T>();
            if (!value)
                return std::nullopt;
            vector[i++] = *value;
        }

        return vector;
    }
};
#endif /* __DOXYGEN__ */

} /* namespace libcamera */