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// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//
// Copyright (c) DUSK NETWORK. All rights reserved.

use core::borrow::Borrow;
use core::ops::Deref;

use canonical::Canon;

use crate::{AnnoIter, Compound, LinkAnnotation};

mod cardinality;
mod max_key;
mod unit;

// re-exports
pub use cardinality::{Cardinality, Nth};
pub use max_key::{GetMaxKey, Keyed, MaxKey};

/// The trait defining an annotation type over a leaf
pub trait Annotation<Leaf>: Default + Canon + Combine<Self> {
    /// Creates an annotation from the leaf type
    fn from_leaf(leaf: &Leaf) -> Self;
}

/// Trait for defining how to combine Annotations
pub trait Combine<A> {
    /// Combines multiple annotations
    fn combine<C>(iter: AnnoIter<C, A>) -> Self
    where
        C: Compound<A>,
        A: Annotation<C::Leaf> + Borrow<Self>;
}

#[derive(Debug)]
/// Custom pointer type, like a lightweight `std::borrow::Cow` since it
/// is not available in `core`
pub enum WrappedAnnotation<'a, C, A> {
    /// The annotation is owned
    Owned(A),
    /// The annotation is a reference
    Link(LinkAnnotation<'a, C, A>),
}

impl<'a, C, A> Deref for WrappedAnnotation<'a, C, A> {
    type Target = A;

    fn deref(&self) -> &Self::Target {
        match self {
            WrappedAnnotation::Owned(ref a) => a,
            WrappedAnnotation::Link(a) => a,
        }
    }
}