willow-data-model 0.7.0

The core datatypes of Willow, an eventually consistent data store with improved distributed deletion.
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use crate::paths::*;

/// A keylike value is one that can be used to uniquely identify an [Entry](https://willowprotocol.org/specs/data-model/index.html#Entry) within a [namespace](https://willowprotocol.org/specs/data-model/index.html#namespace)-specific [store](https://willowprotocol.org/specs/data-model/index.html#store).
///
/// A [subspace_id](https://willowprotocol.org/specs/data-model/index.html#entry_subspace_id) and a [path](https://willowprotocol.org/specs/data-model/index.html#entry_path) together uniquely identify an entry in a namespace, because between any two non-equal entries with of equal [subspace_id](https://willowprotocol.org/specs/data-model/index.html#entry_subspace_id), [path](https://willowprotocol.org/specs/data-model/index.html#entry_path), and [namespace_id](https://willowprotocol.org/specs/data-model/index.html#entry_namespace_id), one would overwrite the other.
pub trait Keylike<const MCL: usize, const MCC: usize, const MPL: usize, S> {
    /// Returns the [subspace_id](https://willowprotocol.org/specs/data-model/index.html#entry_subspace_id) of `self`.
    fn wdm_subspace_id(&self) -> &S;

    /// Returns the [path](https://willowprotocol.org/specs/data-model/index.html#entry_path) of `self`.
    fn wdm_path(&self) -> &Path<MCL, MCC, MPL>;
}

impl<const MCL: usize, const MCC: usize, const MPL: usize, S> Keylike<MCL, MCC, MPL, S>
    for (S, Path<MCL, MCC, MPL>)
{
    fn wdm_subspace_id(&self) -> &S {
        &self.0
    }

    fn wdm_path(&self) -> &Path<MCL, MCC, MPL> {
        &self.1
    }
}

/// Methods for working with [`Keylikes`](Keylike).
///
/// This trait is automatically implemented by all types implementing [`Keylike`].
pub trait KeylikeExt<const MCL: usize, const MCC: usize, const MPL: usize, S>:
    Keylike<MCL, MCC, MPL, S>
{
    /// Returns whether `self` and `other` describe equal keys, i.e., whether their [subspace ids](Keylike::wdm_subspace_id) and [paths](Keylike::wdm_path) are both equal.
    ///
    /// # Examples
    ///
    /// ```
    /// use willow_data_model::prelude::*;
    ///
    /// assert!(("alfie", Path::<4, 4, 4>::new()).wdm_key_eq(&("alfie", Path::<4, 4, 4>::new())));
    /// assert!(!("alfie", Path::<4, 4, 4>::new()).wdm_key_eq(&("betty", Path::<4, 4, 4>::new())));
    /// ```
    fn wdm_key_eq<OtherKey>(&self, other: &OtherKey) -> bool
    where
        OtherKey: Keylike<MCL, MCC, MPL, S>,
        S: PartialEq,
    {
        self.wdm_subspace_id() == other.wdm_subspace_id() && self.wdm_path() == other.wdm_path()
    }

    /// Returns whether `self` and `other` describe non-equal keys, i.e., whether their [subspace ids](Keylike::wdm_subspace_id) and [paths](Keylike::wdm_path) are not both equal.
    ///
    /// # Examples
    ///
    /// ```
    /// use willow_data_model::prelude::*;
    ///
    /// assert!(!("alfie", Path::<4, 4, 4>::new()).wdm_key_ne(&("alfie", Path::<4, 4, 4>::new())));
    /// assert!(("alfie", Path::<4, 4, 4>::new()).wdm_key_ne(&("betty", Path::<4, 4, 4>::new())));
    /// ```
    fn wdm_key_ne<OtherKey>(&self, other: &OtherKey) -> bool
    where
        OtherKey: Keylike<MCL, MCC, MPL, S>,
        S: PartialEq,
    {
        self.wdm_subspace_id() != other.wdm_subspace_id() || self.wdm_path() != other.wdm_path()
    }
}

impl<const MCL: usize, const MCC: usize, const MPL: usize, S, T> KeylikeExt<MCL, MCC, MPL, S> for T where
    T: Keylike<MCL, MCC, MPL, S> + ?Sized
{
}