use std::any::type_name;
use crate::{Error, Result};
use hecs::{Entity, Query, QueryItem};
/// Wraps the bulting QueryOne with a Result containing the entity and component instead of option
pub struct QueryOne<'a, Q: Query> {
entity: Entity,
query: hecs::QueryOne<'a, Q>,
}
impl<'a, Q: Query> QueryOne<'a, Q> {
pub(crate) fn new(entity: Entity, query: hecs::QueryOne<'a, Q>) -> Self {
Self { entity, query }
}
/// Get the query result, or return an error if the entity does not satisfy the query
///
/// Must be called at most once.
///
/// Panics if called more than once or if it would construct a borrow that clashes with another
/// pre-existing borrow.
// Note that this uses self's lifetime, not 'a, for soundness.
pub fn get(&'a mut self) -> Result<QueryItem<'a, Q>> {
match self.query.get() {
Some(val) => Ok(val),
None => Err(Error::UnsatisfiedQuery(self.entity, type_name::<Q>())),
}
}
}