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// This file is part of GAnarchy - decentralized development hub
// Copyright (C) 2021 Soni L.
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.
//! A wrapper for [`DataSource`] that automatically handles
//! [`OverridableKind`].
use std::collections::BTreeSet;
use std::collections::HashSet;
use std::error;
use std::time::Duration;
use impl_trait::impl_trait;
use super::DataSourceBase;
use super::DataSource;
use super::Kind;
use super::OverridableKind;
/// A wrapper for [`DataSource`] that automatically handles
/// [`OverridableKind`].
pub struct EffectiveDataSource<T: DataSourceBase>(T);
/// A wrapper for [`OverridableKind`] that acts like the key for Eq/Hash/Ord.
#[repr(transparent)]
#[derive(Debug)]
pub struct EffectiveKind<T: OverridableKind>(pub T);
impl<T: Kind<Values=BTreeSet<T>> + OverridableKind> Kind for EffectiveKind<T> {
type Values = BTreeSet<Self>;
}
impl_trait! {
impl<T: Kind + OverridableKind> EffectiveKind<T> where Self: Kind {
impl trait OverridableKind {
type Key = T::Key;
fn as_key(&self) -> &Self::Key {
self.0.as_key()
}
}
impl trait PartialEq {
fn eq(&self, other: &Self) -> bool {
self.as_key().eq(other.as_key())
}
fn ne(&self, other: &Self) -> bool {
self.as_key().ne(other.as_key())
}
}
impl trait Eq {
}
impl trait PartialOrd {
fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
Some(self.cmp(other))
}
}
impl trait Ord {
fn cmp(&self, other: &Self) -> std::cmp::Ordering {
self.as_key().cmp(other.as_key())
}
}
impl trait std::hash::Hash {
fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
self.as_key().hash(state);
}
}
}
}
/// Hack to provide appropriate impls for [`EffectiveDataSource`].
pub trait EffectiveDataSourceHelper<K: Kind<Values=V>, V> {
/// Returns the values associated with this kind.
fn get_values_impl(&self) -> K::Values;
}
impl_trait! {
impl<T: DataSourceBase> EffectiveDataSource<T> {
/// Wraps the given [`DataSource`].
pub fn new(source: T) -> Self {
Self(source)
}
/// Unwraps and returns the inner [`DataSource`].
pub fn into_inner(self) -> T {
self.0
}
/// Forwards to the inner [`DataSourceBase`].
impl trait DataSourceBase {
fn update(&mut self) -> (
Duration,
Result<(), Box<dyn error::Error + Send + Sync + 'static>>,
) {
self.0.update()
}
fn exists(&self) -> bool {
self.0.exists()
}
}
/// Filters the inner [`DataSource`] using the appropriate impl.
impl trait<K: Kind> DataSource<K>
where
Self: EffectiveDataSourceHelper<K, K::Values>
{
fn get_values(&self) -> K::Values {
self.get_values_impl()
}
}
/// Filters the inner [`DataSource`] such that only the first instance
/// of a given key is returned.
impl trait<K> EffectiveDataSourceHelper<K, Vec<K>>
where
K: Kind<Values=Vec<K>> + OverridableKind,
T: DataSource<K>
{
fn get_values_impl(&self) -> Vec<K> {
let mut values: Vec<K> = self.0.get_values();
let mut seen = HashSet::<&K::Key>::new();
let mut keep = Vec::with_capacity(values.len());
for value in &values {
keep.push(seen.insert(value.as_key()));
}
drop(seen);
let mut keep = keep.into_iter();
values.retain(|_| keep.next().unwrap());
values
}
}
/// Forwards to the inner [`DataSource`] as there's no filtering we
/// can/need to do here.
impl trait<K> EffectiveDataSourceHelper<
EffectiveKind<K>,
BTreeSet<EffectiveKind<K>>,
>
where
K: Kind<Values=BTreeSet<K>> + OverridableKind,
T: DataSource<EffectiveKind<K>>,
EffectiveKind<K>: Kind<Values=BTreeSet<EffectiveKind<K>>>,
EffectiveKind<K>: OverridableKind,
{
fn get_values_impl(&self) -> BTreeSet<EffectiveKind<K>> {
self.0.get_values()
}
}
/// Forwards to the inner [`DataSource`].
impl trait<K> EffectiveDataSourceHelper<K, Option<K>>
where
K: Kind<Values=Option<K>>,
T: DataSource<K>
{
fn get_values_impl(&self) -> Option<K> {
self.0.get_values()
}
}
}
}
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