Flecs: include/flecs/addons/meta.h File Reference
Description: A fast entity component system (ECS) for C & C++

| Flecs v4.0 A fast entity component system (ECS) for C & C++

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meta.h File Reference

Meta addon. More...

`#include "meta_c.h"`
Include dependency graph for meta.h:

Go to the source code of this file.

## Classes
struct | EcsType
| Component that is automatically added to every type with the right kind. More...
struct | EcsPrimitive
| Component added to primitive types. More...
struct | EcsMember
| Component added to member entities. More...
struct | ecs_member_value_range_t
| Type expressing a range for a member value. More...
struct | EcsMemberRanges
| Component added to member entities to express valid value ranges. More...
struct | ecs_member_t
| Element type of members vector in EcsStruct. More...
struct | EcsStruct
| Component added to struct type entities. More...
struct | ecs_enum_constant_t
| Type that describes an enum constant. More...
struct | EcsEnum
| Component added to enum type entities. More...
struct | ecs_bitmask_constant_t
| Type that describes an bitmask constant. More...
struct | EcsBitmask
| Component added to bitmask type entities. More...
struct | EcsConstants
| Component with datastructures for looking up enum/bitmask constants. More...
struct | EcsArray
| Component added to array type entities. More...
struct | EcsVector
| Component added to vector type entities. More...
struct | ecs_serializer_t
| Serializer interface. More...
struct | EcsOpaque
| Opaque type reflection data. More...
struct | ecs_unit_translation_t
| Helper type to describe translation between two units. More...
struct | EcsUnit
| Component that stores unit data. More...
struct | EcsUnitPrefix
| Component that stores unit prefix data. More...
struct | ecs_meta_op_t
| Meta type serializer instruction data. More...
struct | EcsTypeSerializer
| Component that stores the type serializer. More...
struct | ecs_meta_scope_t
| Type with information about currently serialized scope. More...
struct | ecs_meta_cursor_t
| Type that enables iterating/populating a value using reflection data. More...
struct | ecs_primitive_desc_t
| Used with ecs_primitive_init(). More...
struct | ecs_enum_desc_t
| Used with ecs_enum_init(). More...
struct | ecs_bitmask_desc_t
| Used with ecs_bitmask_init(). More...
struct | ecs_array_desc_t
| Used with ecs_array_init(). More...
struct | ecs_vector_desc_t
| Used with ecs_vector_init(). More...
struct | ecs_struct_desc_t
| Used with ecs_struct_init(). More...
struct | ecs_opaque_desc_t
| Used with ecs_opaque_init(). More...
struct | ecs_unit_desc_t
| Used with ecs_unit_init(). More...
struct | ecs_unit_prefix_desc_t
| Used with ecs_unit_prefix_init(). More...

## Macros
#define | FLECS_META_H
#define | ECS_MEMBER_DESC_CACHE_SIZE (32)
| Max number of constants/members that can be specified in desc structs.
#define | ECS_META_MAX_SCOPE_DEPTH (32)
| Maximum level of type nesting.
#define | ecs_primitive(world, ...)
| Create a primitive type.
#define | ecs_enum(world, ...)
| Create an enum type.
#define | ecs_bitmask(world, ...)
| Create a bitmask type.
#define | ecs_array(world, ...)
| Create an array type.
#define | ecs_vector(world, ...)
| Create a vector type.
#define | ecs_opaque(world, ...)
| Create an opaque type.
#define | ecs_struct(world, ...)
| Create a struct type.
#define | ecs_unit(world, ...)
| Create a unit.
#define | ecs_unit_prefix(world, ...)
| Create a unit prefix.
#define | ecs_quantity(world, ...)
| Create a unit quantity.

## Typedefs
typedef bool | ecs_bool_t
| Primitive type definitions.
typedef char | ecs_char_t
| Builtin char type.
typedef unsigned char | ecs_byte_t
| Builtin ecs_byte type.
typedef uint8_t | ecs_u8_t
| Builtin u8 type.
typedef uint16_t | ecs_u16_t
| Builtin u16 type.
typedef uint32_t | ecs_u32_t
| Builtin u32 type.
typedef uint64_t | ecs_u64_t
| Builtin u64 type.
typedef uintptr_t | ecs_uptr_t
| Builtin uptr type.
typedef int8_t | ecs_i8_t
| Builtin i8 type.
typedef int16_t | ecs_i16_t
| Builtin i16 type.
typedef int32_t | ecs_i32_t
| Builtin i32 type.
typedef int64_t | ecs_i64_t
| Builtin i64 type.
typedef intptr_t | ecs_iptr_t
| Builtin iptr type.
typedef float | ecs_f32_t
| Builtin f32 type.
typedef double | ecs_f64_t
| Builtin f64 type.
typedef char * | ecs_string_t
| Builtin string type.
typedef enum ecs_type_kind_t | ecs_type_kind_t
| Type kinds supported by meta addon.
typedef struct EcsType | EcsType
| Component that is automatically added to every type with the right kind.
typedef enum ecs_primitive_kind_t | ecs_primitive_kind_t
| Primitive type kinds supported by meta addon.
typedef struct EcsPrimitive | EcsPrimitive
| Component added to primitive types.
typedef struct EcsMember | EcsMember
| Component added to member entities.
typedef struct ecs_member_value_range_t | ecs_member_value_range_t
| Type expressing a range for a member value.
typedef struct EcsMemberRanges | EcsMemberRanges
| Component added to member entities to express valid value ranges.
typedef struct ecs_member_t | ecs_member_t
| Element type of members vector in EcsStruct.
typedef struct EcsStruct | EcsStruct
| Component added to struct type entities.
typedef struct ecs_enum_constant_t | ecs_enum_constant_t
| Type that describes an enum constant.
typedef struct EcsEnum | EcsEnum
| Component added to enum type entities.
typedef struct ecs_bitmask_constant_t | ecs_bitmask_constant_t
| Type that describes an bitmask constant.
typedef struct EcsBitmask | EcsBitmask
| Component added to bitmask type entities.
typedef struct EcsConstants | EcsConstants
| Component with datastructures for looking up enum/bitmask constants.
typedef struct EcsArray | EcsArray
| Component added to array type entities.
typedef struct EcsVector | EcsVector
| Component added to vector type entities.
typedef struct ecs_serializer_t | ecs_serializer_t
| Serializer interface.
typedef int(* | ecs_meta_serialize_t) (const ecs_serializer_t *ser, const void *src)
| Callback invoked serializing an opaque type.
typedef int(* | ecs_meta_serialize_member_t) (const ecs_serializer_t *ser, const void *src, const char *name)
| Callback invoked to serialize an opaque struct member.
typedef int(* | ecs_meta_serialize_element_t) (const ecs_serializer_t *ser, const void *src, size_t elem)
| Callback invoked to serialize an opaque vector/array element.
typedef struct EcsOpaque | EcsOpaque
| Opaque type reflection data.
typedef struct ecs_unit_translation_t | ecs_unit_translation_t
| Helper type to describe translation between two units.
typedef struct EcsUnit | EcsUnit
| Component that stores unit data.
typedef struct EcsUnitPrefix | EcsUnitPrefix
| Component that stores unit prefix data.
typedef enum ecs_meta_op_kind_t | ecs_meta_op_kind_t
| Serializer instruction opcodes.
typedef struct ecs_meta_op_t | ecs_meta_op_t
| Meta type serializer instruction data.
typedef struct EcsTypeSerializer | EcsTypeSerializer
| Component that stores the type serializer.
typedef struct ecs_meta_scope_t | ecs_meta_scope_t
| Type with information about currently serialized scope.
typedef struct ecs_meta_cursor_t | ecs_meta_cursor_t
| Type that enables iterating/populating a value using reflection data.
typedef struct ecs_primitive_desc_t | ecs_primitive_desc_t
| Used with ecs_primitive_init().
typedef struct ecs_enum_desc_t | ecs_enum_desc_t
| Used with ecs_enum_init().
typedef struct ecs_bitmask_desc_t | ecs_bitmask_desc_t
| Used with ecs_bitmask_init().
typedef struct ecs_array_desc_t | ecs_array_desc_t
| Used with ecs_array_init().
typedef struct ecs_vector_desc_t | ecs_vector_desc_t
| Used with ecs_vector_init().
typedef struct ecs_struct_desc_t | ecs_struct_desc_t
| Used with ecs_struct_init().
typedef struct ecs_opaque_desc_t | ecs_opaque_desc_t
| Used with ecs_opaque_init().
typedef struct ecs_unit_desc_t | ecs_unit_desc_t
| Used with ecs_unit_init().
typedef struct ecs_unit_prefix_desc_t | ecs_unit_prefix_desc_t
| Used with ecs_unit_prefix_init().

## Enumerations
enum | ecs_type_kind_t { EcsPrimitiveType , EcsBitmaskType , EcsEnumType , EcsStructType , EcsArrayType , EcsVectorType , EcsOpaqueType , EcsTypeKindLast = EcsOpaqueType }
| Type kinds supported by meta addon. More...
enum | ecs_primitive_kind_t { EcsBool = 1 , EcsChar , EcsByte , EcsU8 , EcsU16 , EcsU32 , EcsU64 , EcsI8 , EcsI16 , EcsI32 , EcsI64 , EcsF32 , EcsF64 , EcsUPtr , EcsIPtr , EcsString , EcsEntity , EcsId , EcsPrimitiveKindLast = EcsId }
| Primitive type kinds supported by meta addon. More...
enum | ecs_meta_op_kind_t { EcsOpPushStruct , EcsOpPushArray , EcsOpPushVector , EcsOpPop , EcsOpOpaqueStruct , EcsOpOpaqueArray , EcsOpOpaqueVector , EcsOpForward , EcsOpScope , EcsOpOpaqueValue , EcsOpEnum , EcsOpBitmask , EcsOpPrimitive , EcsOpBool , EcsOpChar , EcsOpByte , EcsOpU8 , EcsOpU16 , EcsOpU32 , EcsOpU64 , EcsOpI8 , EcsOpI16 , EcsOpI32 , EcsOpI64 , EcsOpF32 , EcsOpF64 , EcsOpUPtr , EcsOpIPtr , EcsOpString , EcsOpEntity , EcsOpId , EcsMetaTypeOpKindLast = EcsOpId }
| Serializer instruction opcodes. More...

## Functions
FLECS_API const ecs_entity_t | ecs_id (EcsType)
| Id for component added to all types with reflection data.
FLECS_API const ecs_entity_t | ecs_id (EcsTypeSerializer)
| Id for component that stores a type specific serializer.
FLECS_API const ecs_entity_t | ecs_id (EcsPrimitive)
| Id for component that stores reflection data for a primitive type.
FLECS_API const ecs_entity_t | ecs_id (EcsEnum)
| Id for component that stores reflection data for an enum type.
FLECS_API const ecs_entity_t | ecs_id (EcsBitmask)
| Id for component that stores reflection data for a bitmask type.
FLECS_API const ecs_entity_t | ecs_id (EcsConstants)
| Id for component that stores reflection data for a constants.
FLECS_API const ecs_entity_t | ecs_id (EcsMember)
| Id for component that stores reflection data for struct members.
FLECS_API const ecs_entity_t | ecs_id (EcsMemberRanges)
| Id for component that stores min/max ranges for member values.
FLECS_API const ecs_entity_t | ecs_id (EcsStruct)
| Id for component that stores reflection data for a struct type.
FLECS_API const ecs_entity_t | ecs_id (EcsArray)
| Id for component that stores reflection data for an array type.
FLECS_API const ecs_entity_t | ecs_id (EcsVector)
| Id for component that stores reflection data for a vector type.
FLECS_API const ecs_entity_t | ecs_id (EcsOpaque)
| Id for component that stores reflection data for an opaque type.
FLECS_API const ecs_entity_t | ecs_id (EcsUnit)
| Id for component that stores unit data.
FLECS_API const ecs_entity_t | ecs_id (EcsUnitPrefix)
| Id for component that stores unit prefix data.
FLECS_API const ecs_entity_t | ecs_id (ecs_bool_t)
| Builtin boolean type.
FLECS_API const ecs_entity_t | ecs_id (ecs_char_t)
| Builtin char type.
FLECS_API const ecs_entity_t | ecs_id (ecs_byte_t)
| Builtin byte type.
FLECS_API const ecs_entity_t | ecs_id (ecs_u8_t)
| Builtin 8 bit unsigned int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_u16_t)
| Builtin 16 bit unsigned int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_u32_t)
| Builtin 32 bit unsigned int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_u64_t)
| Builtin 64 bit unsigned int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_uptr_t)
| Builtin pointer sized unsigned int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_i8_t)
| Builtin 8 bit signed int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_i16_t)
| Builtin 16 bit signed int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_i32_t)
| Builtin 32 bit signed int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_i64_t)
| Builtin 64 bit signed int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_iptr_t)
| Builtin pointer sized signed int type.
FLECS_API const ecs_entity_t | ecs_id (ecs_f32_t)
| Builtin 32 bit floating point type.
FLECS_API const ecs_entity_t | ecs_id (ecs_f64_t)
| Builtin 64 bit floating point type.
FLECS_API const ecs_entity_t | ecs_id (ecs_string_t)
| Builtin string type.
FLECS_API char * | ecs_meta_serializer_to_str (ecs_world_t *world, ecs_entity_t type)
| Convert serializer to string.
FLECS_API ecs_meta_cursor_t | ecs_meta_cursor (const ecs_world_t *world, ecs_entity_t type, void *ptr)
| Create meta cursor.
FLECS_API void * | ecs_meta_get_ptr (ecs_meta_cursor_t *cursor)
| Get pointer to current field.
FLECS_API int | ecs_meta_next (ecs_meta_cursor_t *cursor)
| Move cursor to next field.
FLECS_API int | ecs_meta_elem (ecs_meta_cursor_t *cursor, int32_t elem)
| Move cursor to a field.
FLECS_API int | ecs_meta_member (ecs_meta_cursor_t *cursor, const char *name)
| Move cursor to member.
FLECS_API int | ecs_meta_try_member (ecs_meta_cursor_t *cursor, const char *name)
| Same as ecs_meta_member() but doesn't throw an error.
FLECS_API int | ecs_meta_dotmember (ecs_meta_cursor_t *cursor, const char *name)
| Move cursor to member.
FLECS_API int | ecs_meta_try_dotmember (ecs_meta_cursor_t *cursor, const char *name)
| Same as ecs_meta_dotmember() but doesn't throw an error.
FLECS_API int | ecs_meta_push (ecs_meta_cursor_t *cursor)
| Push a scope (required/only valid for structs & collections).
FLECS_API int | ecs_meta_pop (ecs_meta_cursor_t *cursor)
| Pop a struct or collection scope (must follow a push).
FLECS_API bool | ecs_meta_is_collection (const ecs_meta_cursor_t *cursor)
| Is the current scope a collection?
FLECS_API ecs_entity_t | ecs_meta_get_type (const ecs_meta_cursor_t *cursor)
| Get type of current field.
FLECS_API ecs_entity_t | ecs_meta_get_unit (const ecs_meta_cursor_t *cursor)
| Get unit of current field.
FLECS_API const char * | ecs_meta_get_member (const ecs_meta_cursor_t *cursor)
| Get member name of current field.
FLECS_API ecs_entity_t | ecs_meta_get_member_id (const ecs_meta_cursor_t *cursor)
| Get member entity of current field.
FLECS_API int | ecs_meta_set_bool (ecs_meta_cursor_t *cursor, bool value)
| Set field with boolean value.
FLECS_API int | ecs_meta_set_char (ecs_meta_cursor_t *cursor, char value)
| Set field with char value.
FLECS_API int | ecs_meta_set_int (ecs_meta_cursor_t *cursor, int64_t value)
| Set field with int value.
FLECS_API int | ecs_meta_set_uint (ecs_meta_cursor_t *cursor, uint64_t value)
| Set field with uint value.
FLECS_API int | ecs_meta_set_float (ecs_meta_cursor_t *cursor, double value)
| Set field with float value.
FLECS_API int | ecs_meta_set_string (ecs_meta_cursor_t *cursor, const char *value)
| Set field with string value.
FLECS_API int | ecs_meta_set_string_literal (ecs_meta_cursor_t *cursor, const char *value)
| Set field with string literal value (has enclosing "").
FLECS_API int | ecs_meta_set_entity (ecs_meta_cursor_t *cursor, ecs_entity_t value)
| Set field with entity value.
FLECS_API int | ecs_meta_set_id (ecs_meta_cursor_t *cursor, ecs_id_t value)
| Set field with (component) id value.
FLECS_API int | ecs_meta_set_null (ecs_meta_cursor_t *cursor)
| Set field with null value.
FLECS_API int | ecs_meta_set_value (ecs_meta_cursor_t *cursor, const ecs_value_t *value)
| Set field with dynamic value.
FLECS_API bool | ecs_meta_get_bool (const ecs_meta_cursor_t *cursor)
| Get field value as boolean.
FLECS_API char | ecs_meta_get_char (const ecs_meta_cursor_t *cursor)
| Get field value as char.
FLECS_API int64_t | ecs_meta_get_int (const ecs_meta_cursor_t *cursor)
| Get field value as signed integer.
FLECS_API uint64_t | ecs_meta_get_uint (const ecs_meta_cursor_t *cursor)
| Get field value as unsigned integer.
FLECS_API double | ecs_meta_get_float (const ecs_meta_cursor_t *cursor)
| Get field value as float.
FLECS_API const char * | ecs_meta_get_string (const ecs_meta_cursor_t *cursor)
| Get field value as string.
FLECS_API ecs_entity_t | ecs_meta_get_entity (const ecs_meta_cursor_t *cursor)
| Get field value as entity.
FLECS_API ecs_id_t | ecs_meta_get_id (const ecs_meta_cursor_t *cursor)
| Get field value as (component) id.
FLECS_API double | ecs_meta_ptr_to_float (ecs_primitive_kind_t type_kind, const void *ptr)
| Convert pointer of primitive kind to float.
FLECS_API ecs_size_t | ecs_meta_op_get_elem_count (const ecs_meta_op_t *op, const void *ptr)
| Get element count for array/vector operations.
FLECS_API ecs_entity_t | ecs_primitive_init (ecs_world_t *world, const ecs_primitive_desc_t *desc)
| Create a new primitive type.
FLECS_API ecs_entity_t | ecs_enum_init (ecs_world_t *world, const ecs_enum_desc_t *desc)
| Create a new enum type.
FLECS_API ecs_entity_t | ecs_bitmask_init (ecs_world_t *world, const ecs_bitmask_desc_t *desc)
| Create a new bitmask type.
FLECS_API ecs_entity_t | ecs_array_init (ecs_world_t *world, const ecs_array_desc_t *desc)
| Create a new array type.
FLECS_API ecs_entity_t | ecs_vector_init (ecs_world_t *world, const ecs_vector_desc_t *desc)
| Create a new vector type.
FLECS_API ecs_entity_t | ecs_struct_init (ecs_world_t *world, const ecs_struct_desc_t *desc)
| Create a new struct type.
FLECS_API ecs_entity_t | ecs_opaque_init (ecs_world_t *world, const ecs_opaque_desc_t *desc)
| Create a new opaque type.
FLECS_API ecs_entity_t | ecs_unit_init (ecs_world_t *world, const ecs_unit_desc_t *desc)
| Create a new unit.
FLECS_API ecs_entity_t | ecs_unit_prefix_init (ecs_world_t *world, const ecs_unit_prefix_desc_t *desc)
| Create a new unit prefix.
FLECS_API ecs_entity_t | ecs_quantity_init (ecs_world_t *world, const ecs_entity_desc_t *desc)
| Create a new quantity.
FLECS_API void | FlecsMetaImport (ecs_world_t *world)
| Meta module import function.

## Variables
FLECS_API const ecs_entity_t | EcsQuantity
| Tag added to unit quantities.

## Detailed Description

Meta addon.

The meta addon enables reflecting on component data. Types are stored as entities, with components that store the reflection data. A type has at least two components:

- EcsComponent: core component, contains size & alignment
- EcsType: component that indicates what kind of type the entity is

Additionally the type may have an additional component that contains the reflection data for the type. For example, structs have these components:

- EcsComponent
- EcsType
- EcsStruct

Structs can be populated by adding child entities with the EcsMember component. Adding a child with a Member component to an entity will automatically add the EcsStruct component to the parent.

Enums/bitmasks can be populated by adding child entities with the Constant tag. By default constants are automatically assigned values when they are added to the enum/bitmask. The parent entity must have the EcsEnum or EcsBitmask component before adding the constants.

To create enum constants with a manual value, set (Constant, i32) to the desired value. To create bitmask constants with a manual value, set (Constant, u32) to the desired value. Constants with manual values should not conflict with other constants.

The _init APIs are convenience wrappers around creating the entities and components for the types.

When a type is created it automatically receives the EcsComponent and EcsType components. The former means that the resulting type can be used as a regular component:

// Create Position type
ecs_entity_t pos = ecs_struct_init(world, &(ecs_struct_desc_t){
.entity.name = "Position",
.members = {
{"x", ecs_id(ecs_f32_t)},
{"y", ecs_id(ecs_f32_t)}
}
});
// Create entity with Position component
ecs_entity_t e = ecs_new_w_id(world, pos);
ecs_id
FLECS_API const ecs_entity_t ecs_id(EcsDocDescription)
Component id for EcsDocDescription.
ecs_f32_t
float ecs_f32_t
Builtin f32 type.
Definition meta.h:108
ecs_struct_init
FLECS_API ecs_entity_t ecs_struct_init(ecs_world_t *world, const ecs_struct_desc_t *desc)
Create a new struct type.
ecs_entity_t
ecs_id_t ecs_entity_t
An entity identifier.
Definition flecs.h:361
ecs_new_w_id
ecs_entity_t ecs_new_w_id(ecs_world_t *world, ecs_id_t component)
Create new entity with (component) id.
ecs_struct_desc_t
Used with ecs_struct_init().
Definition meta.h:1114

Type entities do not have to be named.

Definition in file meta.h.