iter.hpp

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#pragma once

 
namespace flecs
{

 
namespace _ {


template <typename T>
struct range_iterator
{
    explicit range_iterator(T value)
        : value_(value){}
 
    bool operator!=(range_iterator const& other) const
    {
        return value_ != other.value_;
    }
 
    T const& operator*() const
    {
        return value_;
    }
 
    range_iterator& operator++()
    {
        ++value_;
        return *this;
    }
 
private:
    T value_;
};
 
} // namespace _
 
} // namespace flecs
 
namespace flecs
{


struct iter {
private:
    using row_iterator = _::range_iterator<size_t>;
 
public:
    iter(ecs_iter_t *it) : iter_(it) { }

    row_iterator begin() const {
        return row_iterator(0);
    }

    row_iterator end() const {
        return row_iterator(static_cast<size_t>(iter_->count));
    }

    flecs::entity system() const;

    flecs::entity event() const;

    flecs::id event_id() const;

    flecs::world world() const;

    const flecs::iter_t* c_ptr() const {
        return iter_;
    }

    size_t count() const {
        ecs_check(iter_->flags & EcsIterIsValid, ECS_INVALID_PARAMETER,
            "operation invalid before calling next()");
        return static_cast<size_t>(iter_->count);
    error:
        return 0;
    }

    ecs_ftime_t delta_time() const {
        return iter_->delta_time;
    }

    ecs_ftime_t delta_system_time() const {
        return iter_->delta_system_time;
    }

    flecs::type type() const;

    flecs::table table() const;

    flecs::table other_table() const;

    flecs::table_range range() const;

    void* ctx() {
        return iter_->ctx;
    }

    template <typename T>
    T* ctx() {
        return static_cast<T*>(iter_->ctx);
    }

    void* param() {
        return iter_->param;
    }

    template <typename T>
    T* param() {
        /* TODO: type check */
        return static_cast<T*>(iter_->param);
    }

    flecs::entity entity(size_t row) const;

    bool is_self(int8_t index) const {
        return ecs_field_is_self(iter_, index);
    }

    bool is_set(int8_t index) const {
        return ecs_field_is_set(iter_, index);
    }

    bool is_readonly(int8_t index) const {
        return ecs_field_is_readonly(iter_, index);
    }

    int32_t field_count() const {
        return iter_->field_count;
    }

    size_t size(int8_t index) const {
        return ecs_field_size(iter_, index);
    }

    flecs::entity src(int8_t index) const;

    flecs::id id(int8_t index) const;

    flecs::id pair(int8_t index) const;

    int32_t column_index(int8_t index) const {
        return ecs_field_column(iter_, index);
    }

    int8_t term_index() const {
        return iter_->term_index;
    }

    flecs::string str() const {
        char *s = ecs_iter_str(iter_);
        return flecs::string(s);
    }

    template <typename T, typename A = actual_type_t<T>, if_t<is_const_v<T>> = 0>
    flecs::field<A> field(int8_t index) const;

    template <typename T, typename A = actual_type_t<T>, if_not_t<is_const_v<T>> = 0>
    flecs::field<A> field(int8_t index) const;

    flecs::untyped_field field(int8_t index) const {
        ecs_assert(!(iter_->flags & EcsIterCppEach) || 
               ecs_field_src(iter_, index) != 0, ECS_INVALID_OPERATION,
            "cannot .field from .each, use .field_at(%d, row) instead", index);
        return get_unchecked_field(index);
    }

    void* field_at(int8_t index, size_t row) const {
        if (iter_->row_fields & (1llu << index)) {
            return get_unchecked_field_at(index, row)[0];
        } else {
            return get_unchecked_field(index)[row];
        }
    }

    template <typename T, typename A = actual_type_t<T>, if_t< is_const_v<T> > = 0>
    const A& field_at(int8_t index, size_t row) const {
        if (iter_->row_fields & (1llu << index)) {
            return get_field_at<A>(index, row)[0];
        } else {
            return get_field<A>(index)[row];
        }
    }

    template <typename T, typename A = actual_type_t<T>, if_not_t< is_const_v<T> > = 0>
    A& field_at(int8_t index, size_t row) const {
        ecs_assert(!ecs_field_is_readonly(iter_, index),
            ECS_ACCESS_VIOLATION, NULL);
        if (iter_->row_fields & (1llu << index)) {
            return get_field_at<A>(index, row)[0];
        } else {
            return get_field<A>(index)[row];
        }
    }

    flecs::field<const flecs::entity_t> entities() const {
        return flecs::field<const flecs::entity_t>(
            iter_->entities, static_cast<size_t>(iter_->count), false);
    }

    bool changed() {
        return ecs_iter_changed(iter_);
    }

    void skip() {
        ecs_iter_skip(iter_);
    }

    uint64_t group_id() const {
        return ecs_iter_get_group(iter_);
    }

    flecs::entity get_var(int var_id) const;

    flecs::entity get_var(const char *name) const;

    bool next() {
        if (iter_->flags & EcsIterIsValid && iter_->table) {
            ECS_TABLE_UNLOCK(iter_->world, iter_->table);
        }
        bool result = iter_->next(iter_);
        iter_->flags |= EcsIterIsValid;
        if (result && iter_->table) {
            ECS_TABLE_LOCK(iter_->world, iter_->table);
        }
        return result;
    }

    void each() {
        iter_->callback(iter_);
    }

    template <typename Func>
    void targets(int8_t index, const Func& func);

    void fini() {
        if (iter_->flags & EcsIterIsValid && iter_->table) {
            ECS_TABLE_UNLOCK(iter_->world, iter_->table);
        }
        ecs_iter_fini(iter_);
    }
 
private:
    /* Get field, check if correct type is used. */
    template <typename T, typename A = actual_type_t<T>>
    flecs::field<T> get_field(int8_t index) const {
 
#ifndef FLECS_NDEBUG
        ecs_entity_t term_id = ecs_field_id(iter_, index);
        ecs_assert(ECS_HAS_ID_FLAG(term_id, PAIR) ||
            term_id == _::type<T>::id(iter_->world),
            ECS_COLUMN_TYPE_MISMATCH, NULL);
#endif
 
        size_t count;
        bool is_shared = !ecs_field_is_self(iter_, index);
 
        /* If a shared field is retrieved with field(), there will only be a
         * single value. Ensure that the application does not accidentally read
         * out of bounds. */
        if (is_shared) {
            count = 1;
        } else {
            /* If field is owned, there will be as many values as there are
             * entities. */
            count = static_cast<size_t>(iter_->count);
        }
 
        return flecs::field<A>(
            static_cast<T*>(ecs_field_w_size(iter_, sizeof(A), index)),
            count, is_shared);
    }
 
    /* Get field, check if correct type is used. */
    template <typename T, typename A = actual_type_t<T>>
    flecs::field<T> get_field_at(int8_t index, int32_t row) const {
 
#ifndef FLECS_NDEBUG
        ecs_entity_t term_id = ecs_field_id(iter_, index);
        ecs_assert(ECS_HAS_ID_FLAG(term_id, PAIR) ||
            term_id == _::type<T>::id(iter_->world),
            ECS_COLUMN_TYPE_MISMATCH, NULL);
#endif
 
        return flecs::field<A>(
            static_cast<T*>(ecs_field_at_w_size(iter_, sizeof(A), index, row)),
                1, false);
    }
 
    flecs::untyped_field get_unchecked_field(int8_t index) const {
        size_t count;
        size_t size = ecs_field_size(iter_, index);
        bool is_shared = !ecs_field_is_self(iter_, index);
 
        /* If a shared field is retrieved with field(), there will only be a
         * single value. Ensure that the application does not accidentally read
         * out of bounds. */
        if (is_shared) {
            count = 1;
        } else {
            /* If field is owned, there will be as many values as there are
             * entities. */
            count = static_cast<size_t>(iter_->count);
        }
 
        return flecs::untyped_field(
            ecs_field_w_size(iter_, size, index), size, count, is_shared);
    }
 
    flecs::untyped_field get_unchecked_field_at(int8_t index, size_t row) const {
        size_t size = ecs_field_size(iter_, index);
        return flecs::untyped_field(
            ecs_field_at_w_size(iter_, size, index, static_cast<int32_t>(row)), 
                size, 1, false);
    }
 
    flecs::iter_t *iter_;
};
 
} // namespace flecs