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_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(int32_t index) const {
        return ecs_field_is_self(iter_, index);
    }
 
    bool is_set(int32_t index) const {
        return ecs_field_is_set(iter_, index);
    }
 
    bool is_readonly(int32_t index) const {
        return ecs_field_is_readonly(iter_, index);
    }
 
    int32_t field_count() const {
        return iter_->field_count;
    }
 
    size_t size(int32_t index) const {
        return ecs_field_size(iter_, index);
    }
 
    flecs::entity src(int32_t index) const;
 
    flecs::id id(int32_t index) const;
 
    flecs::id pair(int32_t index) const;
 
    int32_t column_index(int32_t index) const {
        return ecs_field_column(iter_, index);
    }
 
    int32_t term_index() const {
        return iter_->term_index + 1; // in iter_t, the term index is zero-based, so add 1.
    }
 
    flecs::string str() const {
        char *s = ecs_iter_str(iter_);
        return flecs::string(s);
    }
 
    template <typename T, typename A = actual_type_t<T>,
        typename std::enable_if<std::is_const<T>::value, void>::type* = nullptr>
    flecs::field<A> field(int32_t index) const;
 
    template <typename T, typename A = actual_type_t<T>,
        typename std::enable_if<
            std::is_const<T>::value == false, void>::type* = nullptr>
    flecs::field<A> field(int32_t index) const;
 
    flecs::untyped_field field(int32_t index) const {
        ecs_assert(!(iter_->flags & EcsIterCppEach), ECS_INVALID_OPERATION,
            "cannot .field from .each, use .field_at(%d, row) instead", index);
        return get_unchecked_field(index);
    }
 
    void* field_at(int32_t index, size_t row) const {
        return get_unchecked_field(index)[row];
    }
 
    template <typename T, typename A = actual_type_t<T>,
        typename std::enable_if<std::is_const<T>::value, void>::type* = nullptr>
    const A& field_at(int32_t index, size_t row) const {
        return get_field<A>(index)[row];
    }
 
    template <typename T, typename A = actual_type_t<T>,
        typename std::enable_if<
            std::is_const<T>::value == false, void>::type* = nullptr>
    A& field_at(int32_t index, size_t row) const {
        ecs_assert(!ecs_field_is_readonly(iter_, index),
            ECS_ACCESS_VIOLATION, NULL);
        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_);
    }
 
    /* Return group id for current table (grouped queries only) */
    uint64_t group_id() const {
        return iter_->group_id;
    }
 
    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_);
    }
 
    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(int32_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 column is retrieved with 'column', 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 column 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);
    }
 
    flecs::untyped_field get_unchecked_field(int32_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 column is retrieved with 'column', 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 column 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_, 0, index), size, count, is_shared);
    }
 
    flecs::iter_t *iter_;
};
 
} // namespace flecs