rules.h File Reference

Rule query engine addon. More...

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Macros
#define	ecs_rule(world, ...)    ecs_rule_init(world, &(ecs_filter_desc_t) __VA_ARGS__ )
	Convenience macro for rule creation.

Functions
FLECS_API ecs_rule_t *	ecs_rule_init (ecs_world_t *world, const ecs_filter_desc_t *desc)
	Create a rule.
FLECS_API void	ecs_rule_fini (ecs_rule_t *rule)
	Delete a rule.
FLECS_API const ecs_filter_t *	ecs_rule_get_filter (const ecs_rule_t *rule)
	Obtain filter from rule.
FLECS_API int32_t	ecs_rule_var_count (const ecs_rule_t *rule)
	Return number of variables in rule.
FLECS_API int32_t	ecs_rule_find_var (const ecs_rule_t *rule, const char *name)
	Find variable index.
FLECS_API const char *	ecs_rule_var_name (const ecs_rule_t *rule, int32_t var_id)
	Get variable name.
FLECS_API bool	ecs_rule_var_is_entity (const ecs_rule_t *rule, int32_t var_id)
	Test if variable is an entity.
FLECS_API ecs_iter_t	ecs_rule_iter (const ecs_world_t *world, const ecs_rule_t *rule)
	Iterate a rule.
FLECS_API bool	ecs_rule_next (ecs_iter_t *it)
	Progress rule iterator.
FLECS_API bool	ecs_rule_next_instanced (ecs_iter_t *it)
	Progress instanced iterator.
FLECS_API char *	ecs_rule_str (const ecs_rule_t *rule)
	Convert rule to a string.
FLECS_API char *	ecs_rule_str_w_profile (const ecs_rule_t *rule, const ecs_iter_t *it)
	Convert rule to string with profile.
FLECS_API const char *	ecs_rule_parse_vars (ecs_rule_t *rule, ecs_iter_t *it, const char *expr)
	Populate variables from key-value string.

Detailed Description

Rule query engine addon.

Rules are advanced queries that in addition to the capabilities of regular queries and filters have the following features:

• query for all components of an entity (vs. all entities for a component)
• query for all relationship pairs of an entity
• support for query variables that are resolved at evaluation time
• automatic traversal of transitive relationships

Definition in file rules.h.