Class ref_small_vector

include/pybind11/detail/argument_vector.h:362–414

/// destructor, and avoids the need for reinterpret_cast when passing to vectorcall.
template <std::size_t InlineSize>
class ref_small_vector {
public:
    ref_small_vector() = default;

    ~ref_small_vector() {
        for (std::size_t i = 0; i < m_ptrs.size(); ++i) {
            Py_XDECREF(m_ptrs[i]);
        }
    }

    // Disable copy (prevent accidental double-decref)
    ref_small_vector(const ref_small_vector &) = delete;
    ref_small_vector &operator=(const ref_small_vector &) = delete;

    // Move is allowed
    ref_small_vector(ref_small_vector &&other) noexcept : m_ptrs(std::move(other.m_ptrs)) {
        // other.m_ptrs is now empty, so its destructor won't decref anything
    }

    ref_small_vector &operator=(ref_small_vector &&other) noexcept {
        if (this != &other) {
            // Decref our current contents
            for (std::size_t i = 0; i < m_ptrs.size(); ++i) {
                Py_XDECREF(m_ptrs[i]);
            }
            m_ptrs = std::move(other.m_ptrs);
        }
        return *this;
    }

    /// Add a pointer, taking ownership (no incref, will decref on destruction)
    void push_back_steal(PyObject *p) { m_ptrs.push_back(p); }

    /// Add a pointer, borrowing (increfs now, will decref on destruction)
    void push_back_borrow(PyObject *p) {
        Py_XINCREF(p);
        m_ptrs.push_back(p);
    }

    /// Add a null pointer (for PY_VECTORCALL_ARGUMENTS_OFFSET slot)
    void push_back_null() { m_ptrs.push_back(nullptr); }

    void reserve(std::size_t sz) { m_ptrs.reserve(sz); }

    std::size_t size() const { return m_ptrs.size(); }

    PyObject *operator[](std::size_t idx) const { return m_ptrs[idx]; }

    PyObject *const *data() const { return m_ptrs.data(); }

private:
    small_vector<PyObject *, InlineSize> m_ptrs;
};

PYBIND11_NAMESPACE_END(detail)
PYBIND11_NAMESPACE_END(PYBIND11_NAMESPACE)