Struct column

Synopsis

#include <include/flecs/addons/cpp/iter.hpp>

template <typename T>
struct column

Description

Wrapper class around a column.

Template Parameters

T - component type of the column.

Methods

	column overload	Create column from component array.
	column overload	Create column from iterator.
	operator*	Return first element of component array
	operator->	Return first element of component array
	operator[]	Return element in component array

Source

Lines 39-99 in include/flecs/addons/cpp/iter.hpp.

template <typename T>
struct column {
    static_assert(std::is_empty<T>::value == false, 
        "invalid type for column, cannot iterate empty type");

    /** Create column from component array.
     *
     * @param array Pointer to the component array.
     * @param count Number of elements in component array.
     * @param is_shared Is the component shared or not.
     */
    column(T* array, size_t count, bool is_shared = false)
        : m_array(array)
        , m_count(count) 
        , m_is_shared(is_shared) {}

    /** Create column from iterator.
     *
     * @param iter Iterator object.
     * @param column Index of the signature of the query being iterated over.
     */
    column(iter &iter, int column);

    /** Return element in component array.
     * This operator may only be used if the column is not shared.
     * 
     * @param index Index of element.
     * @return Reference to element.
     */
    T& operator[](size_t index) const {
        ecs_assert(index < m_count, ECS_COLUMN_INDEX_OUT_OF_RANGE, NULL);
        ecs_assert(!index || !m_is_shared, ECS_INVALID_PARAMETER, NULL);
        ecs_assert(m_array != nullptr, ECS_COLUMN_INDEX_OUT_OF_RANGE, NULL);
        return m_array[index];
    }

    /** Return first element of component array.
     * This operator is typically used when the column is shared.
     *
     * @return Reference to the first element.
     */
    T& operator*() const {
      ecs_assert(m_array != nullptr, ECS_COLUMN_INDEX_OUT_OF_RANGE, NULL);
      return *m_array;
    }

    /** Return first element of component array.
     * This operator is typically used when the column is shared.
     * 
     * @return Pointer to the first element.
     */
    T* operator->() const {
        ecs_assert(m_array != nullptr, ECS_COLUMN_INDEX_OUT_OF_RANGE, NULL);
        return m_array;
    }

protected:
    T* m_array;
    size_t m_count;
    bool m_is_shared;
};