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use super::engine_error;
use crate::specification::engines::AbstractEngine;
use crate::specification::entities::CleartextEntity;
engine_error! {
CleartextDiscardingRetrievalError for CleartextDiscardingRetrievalEngine @
}
/// A trait for engines retrieving (discarding) arbitrary values from cleartexts .
///
/// # Semantics
///
/// This [discarding](super#operation-semantics) operation fills the `value` arbitrary value with
/// the retrieval of the `input` cleartext. By arbitrary here, we mean that `Value` can be any type
/// that suits the backend implementor (an integer, a struct wrapping integers, a struct wrapping
/// foreign data or any other thing).
///
/// # Formal Definition
pub trait CleartextDiscardingRetrievalEngine<Cleartext, Value>: AbstractEngine
where
Cleartext: CleartextEntity,
{
/// Retrieves an arbitrary value from a cleartext.
fn discard_retrieve_cleartext(
&mut self,
value: &mut Value,
input: &Cleartext,
) -> Result<(), CleartextDiscardingRetrievalError<Self::EngineError>>;
/// Unsafely retrieves an arbitrary value from a cleartext.
///
/// # Safety
/// For the _general_ safety concerns regarding this operation, refer to the different variants
/// of [`CleartextDiscardingRetrievalError`]. For safety concerns _specific_ to an engine, refer
/// to the implementer safety section.
unsafe fn discard_retrieve_cleartext_unchecked(&mut self, value: &mut Value, input: &Cleartext);
}