flecs-zig-ble/src/iter.zig

const c = @import("./c.zig");

const Entity = @import("./entity.zig").Entity;
const Id = @import("./id.zig").Id;
const World = @import("./world.zig").World;

pub fn Iter(comptime ctx: anytype) type {
    return struct {
        world: *World(ctx),
        raw: *c.ecs_iter_t,
        owned: bool,

        const Self = @This();

        pub fn fromRawPtr(world: *World(ctx), ptr: *c.ecs_iter_t) Self {
            return .{ .world = world, .raw = ptr, .owned = false };
        }

        pub fn fromRawValue(world: *World(ctx), value: c.ecs_iter_t) !Self {
            var raw = try world.allocator.create(c.ecs_iter_t);
            raw.* = value;
            return .{ .world = world, .raw = raw, .owned = true };
        }

        pub fn deinit(self: Self) void {
            if (self.isValid()) c.ecs_iter_fini(self.raw);
            if (self.owned) self.world.allocator.destroy(self.raw);
        }

        pub fn isValid(self: Self) bool {
            return (self.raw.flags & c.EcsIterIsValid) != 0;
        }

        pub fn getCount(self: Self) usize {
            return @intCast(self.raw.count);
        }

        pub fn getDeltaTime(self: Self) f32 {
            return self.raw.delta_time;
        }

        pub fn field(self: Self, comptime T: type, index: usize) []T {
            var raw_ptr = c.ecs_field_w_size(self.raw, @sizeOf(T), @intCast(index));
            var typed_ptr: [*]T = @alignCast(@ptrCast(raw_ptr));
            return typed_ptr[0..self.getCount()];
        }

        pub fn fieldId(self: Self, index: usize) Id(ctx) {
            const raw = c.ecs_field_id(self.raw, @intCast(index));
            return Id(ctx).fromRaw(self.world, raw);
        }

        pub fn fieldSource(self: Self, index: usize) Entity(ctx) {
            const raw = c.ecs_field_src(self.raw, @intCast(index));
            return Entity(ctx).fromRaw(self.world, raw);
        }
    };
}