graphrecords-query 0.5.0

High-performance graph-based data records
Documentation 
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use crate::{
    BareValueDomain, IndexDomain, QueryResult, ReturnValueDomain, Unit, ValueDomain, element::Arity,
};
use std::marker::PhantomData;

pub trait ElementShape: 'static {
    type Element<'a>: 'a;

    type ValueDomain: ValueDomain;
}

pub trait ReturnShape: ElementShape {
    type ReturnElement<'a>: 'a;

    fn into_return_element(element: Self::Element<'_>) -> Self::ReturnElement<'_>;
}

pub struct Indexed<K: IndexDomain, V: ValueDomain>(PhantomData<(K, V)>);
pub struct Bare<V: BareValueDomain>(PhantomData<V>);

impl<K: IndexDomain, V: ValueDomain> ElementShape for Indexed<K, V> {
    type Element<'a> = (K::Index<'a>, QueryResult<V::Value<'a>>);
    type ValueDomain = V;
}
impl<V: BareValueDomain> ElementShape for Bare<V> {
    type Element<'a> = QueryResult<V::Value<'a>>;
    type ValueDomain = V;
}

impl<K: IndexDomain, V: ReturnValueDomain> ReturnShape for Indexed<K, V> {
    type ReturnElement<'a> = (K::Index<'a>, QueryResult<V::Value<'a>>);

    fn into_return_element(element: Self::Element<'_>) -> Self::ReturnElement<'_> {
        element
    }
}

impl<K: IndexDomain> ReturnShape for Indexed<K, Unit> {
    type ReturnElement<'a> = QueryResult<K::Owned>;

    fn into_return_element(element: Self::Element<'_>) -> Self::ReturnElement<'_> {
        let (index, value) = element;

        value.map(|()| K::to_owned(&index))
    }
}

impl<V: BareValueDomain + ReturnValueDomain> ReturnShape for Bare<V> {
    type ReturnElement<'a> = QueryResult<V::Value<'a>>;

    fn into_return_element(element: Self::Element<'_>) -> Self::ReturnElement<'_> {
        element
    }
}

pub type Return<'a, S, C> = <C as Arity>::Container<'a, <S as ElementShape>::Element<'a>>;