fera-graph 0.2.0

// 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/.

use prelude::*;
use props::HashMapProp;

use std::cmp::Ordering;
use std::collections::{hash_map, hash_set, HashMap, HashSet};
use std::hash::{Hash, Hasher};
use std::iter::Cloned;
use std::marker::PhantomData;

pub type AdjSetGraph<V> = AdjSet<V, Undirected>;
pub type AdjSetDigraph<V> = AdjSet<V, Directed>;

type HashMapAdj<K, V> = HashMap<K, V>;
type HashSetAdj<K> = HashSet<K>;

pub struct AdjSet<V: AdjSetVertex, K: AdjSetEdgeKind<V>> {
    adj: HashMapAdj<V, HashSetAdj<V>>,
    num_edges: usize,
    _marker: PhantomData<K>,
}

impl<V, K> Default for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    fn default() -> Self {
        Self::new()
    }
}

pub trait AdjSetEdgeKind<V: AdjSetVertex>: UniformEdgeKind {
    type Edge: AdjSetEdge<V>;
}

pub trait AdjSetVertex: 'static + GraphItem + PartialOrd {}

impl<V: 'static + GraphItem + PartialOrd> AdjSetVertex for V {}

pub trait AdjSetEdge<V>: 'static + GraphItem
where
    V: AdjSetVertex,
{
    fn new(u: V, v: V) -> Self;

    fn source(&self) -> V;

    fn target(&self) -> V;
}

// Undirected

#[derive(Copy, Clone, Eq, Debug)]
pub struct UndirectedEdge<V>(V, V);

impl<V: PartialEq> PartialEq for UndirectedEdge<V> {
    fn eq(&self, other: &Self) -> bool {
        self.0 == other.0 && self.1 == other.1 || self.1 == other.0 && self.0 == other.1
    }
}

impl<V: PartialEq> PartialEq<(V, V)> for UndirectedEdge<V> {
    fn eq(&self, other: &(V, V)) -> bool {
        self.0 == other.0 && self.1 == other.1 || self.1 == other.0 && self.0 == other.1
    }
}

impl<V: Ord> PartialOrd for UndirectedEdge<V> {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        let r = if self.0 <= self.1 {
            if other.0 <= other.1 {
                self.0.cmp(&other.0).then_with(|| self.1.cmp(&other.1))
            } else {
                self.0.cmp(&other.1).then_with(|| self.1.cmp(&other.0))
            }
        } else if other.0 <= other.1 {
            self.1.cmp(&other.0).then_with(|| self.0.cmp(&other.1))
        } else {
            self.1.cmp(&other.1).then_with(|| self.0.cmp(&other.0))
        };
        Some(r)
    }
}

impl<V: Ord> Ord for UndirectedEdge<V> {
    fn cmp(&self, other: &Self) -> Ordering {
        self.partial_cmp(other).unwrap()
    }
}

impl<V: PartialOrd + Hash> Hash for UndirectedEdge<V> {
    fn hash<H: Hasher>(&self, state: &mut H) {
        if self.0 < self.1 {
            self.0.hash(state);
            self.1.hash(state);
        } else {
            self.1.hash(state);
            self.0.hash(state);
        }
    }
}

impl<V> AdjSetEdge<V> for UndirectedEdge<V>
where
    V: AdjSetVertex + PartialOrd,
{
    fn new(u: V, v: V) -> Self {
        UndirectedEdge(u, v)
    }

    fn source(&self) -> V {
        self.0
    }

    fn target(&self) -> V {
        self.1
    }
}

impl<V> AdjSetEdgeKind<V> for Undirected
where
    V: AdjSetVertex + PartialOrd,
{
    type Edge = UndirectedEdge<V>;
}

// Directed

pub type DirectedEdge<V> = (V, V);

impl<V> AdjSetEdge<V> for DirectedEdge<V>
where
    V: AdjSetVertex,
{
    fn new(u: V, v: V) -> Self {
        (u, v)
    }

    fn source(&self) -> V {
        self.0
    }

    fn target(&self) -> V {
        self.1
    }
}

impl<V> AdjSetEdgeKind<V> for Directed
where
    V: AdjSetVertex,
{
    type Edge = DirectedEdge<V>;
}

// Graph traits implementation

impl<'a, V, K> VertexTypes<'a, AdjSet<V, K>> for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    type VertexIter = Cloned<hash_map::Keys<'a, V, HashSetAdj<V>>>;
    type OutNeighborIter = Cloned<hash_set::Iter<'a, V>>;
}

impl<V, K> WithVertex for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    type Vertex = V;
    type OptionVertex = Option<V>;
}

impl<'a, V, K> EdgeTypes<'a, AdjSet<V, K>> for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    type EdgeIter = Edges<'a, V, K>;
    type OutEdgeIter = OutEdges<'a, V, K>;
}

impl<V, K> WithEdge for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    type Kind = K;
    type Edge = K::Edge;
    type OptionEdge = Option<K::Edge>;

    fn source(&self, e: Edge<Self>) -> Vertex<Self> {
        e.source()
    }

    fn target(&self, e: Edge<Self>) -> Vertex<Self> {
        e.target()
    }

    fn orientation(&self, _e: Edge<Self>) -> Orientation {
        K::orientation()
    }

    fn get_reverse(&self, e: Edge<Self>) -> Option<Edge<Self>> {
        Some(K::Edge::new(e.target(), e.source()))
    }
}

impl<V, K> VertexList for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    fn vertices(&self) -> VertexIter<Self> {
        self.adj.keys().cloned()
    }

    fn num_vertices(&self) -> usize {
        self.adj.len()
    }
}

impl<V, K> EdgeList for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    fn edges(&self) -> EdgeIter<Self> {
        Edges {
            iter: self.adj.iter(),
            inner: None,
            _marker: PhantomData,
        }
    }

    fn num_edges(&self) -> usize {
        self.num_edges
    }

    fn get_edge_by_ends(&self, u: Vertex<Self>, v: Vertex<Self>) -> Option<Edge<Self>> {
        self.adj
            .get(&u)
            .and_then(|adj| adj.get(&v))
            .and_then(|_| Some(K::Edge::new(u, v)))
    }
}

impl<V, K> Adjacency for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    fn out_neighbors(&self, v: Vertex<Self>) -> OutNeighborIter<Self> {
        self.out_neighbors_(v).iter().cloned()
    }

    fn out_degree(&self, v: Vertex<Self>) -> usize {
        self.out_neighbors_(v).len()
    }
}

impl<V, K> Incidence for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    fn out_edges(&self, v: Vertex<Self>) -> OutEdgeIter<Self> {
        OutEdges {
            source: v,
            adj: self.out_neighbors_(v).iter(),
            _marker: PhantomData,
        }
    }
}

impl<V, K> AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    pub fn new() -> Self {
        AdjSet {
            adj: Default::default(),
            num_edges: 0,
            _marker: PhantomData,
        }
    }

    pub fn add_vertex(&mut self, v: V) {
        self.adj.entry(v).or_insert_with(Default::default);
    }

    pub fn add_edge(&mut self, u: V, v: V) -> K::Edge {
        if self.get_edge_by_ends(u, v).is_some() {
            panic!("Multiedge not supported");
        }

        // insert u and (u, v)
        self.adj.entry(u).or_insert_with(Default::default).insert(v);

        // insert v
        let entry = self.adj.entry(v).or_insert_with(Default::default);

        if K::is_undirected() {
            // insert (v, u)
            entry.insert(u);
        }

        self.num_edges += 1;

        K::Edge::new(u, v)
    }

    fn out_neighbors_(&self, v: Vertex<Self>) -> &HashSetAdj<V> {
        self.adj
            .get(&v)
            .unwrap_or_else(|| panic!("{:?} is not a valid vertex", v))
    }
}

// Props

impl<V, K, T> WithVertexProp<T> for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
    T: Clone,
{
    type VertexProp = HashMapProp<V, T>;
}

impl<V, K, T> WithEdgeProp<T> for AdjSet<V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
    T: Clone,
{
    type EdgeProp = HashMapProp<K::Edge, T>;
}

// Iterators

pub struct Edges<'a, V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    iter: hash_map::Iter<'a, V, HashSetAdj<V>>,
    inner: Option<(V, hash_set::Iter<'a, V>)>,
    _marker: PhantomData<K>,
}

impl<'a, V, K> Iterator for Edges<'a, V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    type Item = K::Edge;

    fn next(&mut self) -> Option<Self::Item> {
        loop {
            if let Some((source, ref mut inner)) = self.inner {
                if let Some(target) = inner.next() {
                    if K::is_undirected() && source > *target {
                        continue;
                    }
                    return Some(K::Edge::new(source, *target));
                }
            }

            if let Some((source, inner)) = self.iter.next() {
                self.inner = Some((*source, inner.iter()));
            } else {
                return None;
            }
        }
    }

    // TODO: implements size_hint and ExactSizeIterator
}

pub struct OutEdges<'a, V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    source: V,
    adj: hash_set::Iter<'a, V>,
    _marker: PhantomData<K>,
}

impl<'a, V, K> Iterator for OutEdges<'a, V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    type Item = K::Edge;

    fn next(&mut self) -> Option<Self::Item> {
        let source = self.source;
        self.adj.next().map(|target| K::Edge::new(source, *target))
    }

    fn size_hint(&self) -> (usize, Option<usize>) {
        self.adj.size_hint()
    }
}

impl<'a, V, K> ExactSizeIterator for OutEdges<'a, V, K>
where
    V: AdjSetVertex,
    K: AdjSetEdgeKind<V>,
{
    fn len(&self) -> usize {
        self.adj.len()
    }
}

#[cfg(test)]
mod tests {
    pub use super::*;
    pub use fera_fun::vec;
    pub use prelude::*;
    pub use tests::GraphTests;

    pub fn sorted<T: Clone + Ord>(xs: &[T]) -> Vec<T> {
        let mut v = xs.to_vec();
        v.sort();
        v
    }

    mod undirected {
        use super::*;
        struct Test;

        impl GraphTests for Test {
            type G = AdjSetGraph<u32>;

            fn new() -> (Self::G, Vec<Vertex<Self::G>>, Vec<Edge<Self::G>>) {
                let e = UndirectedEdge::new;
                let mut g = AdjSet::new();
                g.add_edge(1, 2);
                g.add_edge(3, 4);
                g.add_edge(4, 1);
                g.add_edge(7, 4);
                let v = vec(g.vertices());
                let ee = vec(g.edges());
                assert_eq!(sorted(&v), vec![1, 2, 3, 4, 7]);
                assert_eq!(sorted(&ee), vec![e(1, 2), e(1, 4), e(3, 4), e(4, 7)]);
                (g, v, ee)
            }
        }

        graph_tests!{Test}
    }

    mod directed {
        use super::*;
        struct Test;

        impl GraphTests for Test {
            type G = AdjSetDigraph<u32>;

            fn new() -> (Self::G, Vec<Vertex<Self::G>>, Vec<Edge<Self::G>>) {
                let mut g = AdjSet::new();
                g.add_edge(1, 2);
                g.add_edge(3, 4);
                g.add_edge(4, 1);
                g.add_edge(7, 4);
                let v = vec(g.vertices());
                let ee = vec(g.edges());
                assert_eq!(sorted(&v), vec![1, 2, 3, 4, 7]);
                assert_eq!(sorted(&ee), vec![(1, 2), (3, 4), (4, 1), (7, 4)]);
                (g, v, ee)
            }
        }

        graph_tests!{Test}
    }
}