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//! `StableGraph` keeps indices stable across removals.
//!
//! Depends on `feature = "stable_graph"`.
//!
use std::cmp;
use std::fmt;
use std::iter;
use std::marker::PhantomData;
use std::mem::replace;
use std::mem::size_of;
use std::ops::{Index, IndexMut};
use std::slice;
use fixedbitset::FixedBitSet;
use crate::{Directed, Direction, EdgeType, Graph, Incoming, Outgoing, Undirected};
use crate::iter_format::{DebugMap, IterFormatExt, NoPretty};
use crate::iter_utils::IterUtilsExt;
use super::{index_twice, Edge, Frozen, Node, Pair, DIRECTIONS};
use crate::visit;
use crate::visit::{EdgeIndexable, EdgeRef, IntoEdgeReferences, NodeIndexable};
use crate::IntoWeightedEdge;
// reexport those things that are shared with Graph
#[doc(no_inline)]
pub use crate::graph::{
edge_index, node_index, DefaultIx, EdgeIndex, GraphIndex, IndexType, NodeIndex,
};
use crate::util::enumerate;
#[cfg(feature = "serde-1")]
mod serialization;
/// `StableGraph<N, E, Ty, Ix>` is a graph datastructure using an adjacency
/// list representation.
///
/// The graph **does not invalidate** any unrelated node or edge indices when
/// items are removed.
///
/// `StableGraph` is parameterized over:
///
/// - Associated data `N` for nodes and `E` for edges, also called *weights*.
/// The associated data can be of arbitrary type.
/// - Edge type `Ty` that determines whether the graph edges are directed or undirected.
/// - Index type `Ix`, which determines the maximum size of the graph.
///
/// The graph uses **O(|V| + |E|)** space, and allows fast node and edge insert
/// and efficient graph search.
///
/// It implements **O(e')** edge lookup and edge and node removals, where **e'**
/// is some local measure of edge count.
///
/// - Nodes and edges are each numbered in an interval from *0* to some number
/// *m*, but *not all* indices in the range are valid, since gaps are formed
/// by deletions.
///
/// - You can select graph index integer type after the size of the graph. A smaller
/// size may have better performance.
///
/// - Using indices allows mutation while traversing the graph, see `Dfs`.
///
/// - The `StableGraph` is a regular rust collection and is `Send` and `Sync`
/// (as long as associated data `N` and `E` are).
///
/// - Indices don't allow as much compile time checking as references.
///
/// Depends on crate feature `stable_graph` (default). *Stable Graph is still
/// missing a few methods compared to Graph. You can contribute to help it
/// achieve parity.*
pub struct StableGraph<N, E, Ty = Directed, Ix = DefaultIx> {
g: Graph<Option<N>, Option<E>, Ty, Ix>,
node_count: usize,
edge_count: usize,
// node and edge free lists (both work the same way)
//
// free_node, if not NodeIndex::end(), points to a node index
// that is vacant (after a deletion).
// The free nodes form a doubly linked list using the fields Node.next[0]
// for forward references and Node.next[1] for backwards ones.
// The nodes are stored as EdgeIndex, and the _into_edge()/_into_node()
// methods convert.
// free_edge, if not EdgeIndex::end(), points to a free edge.
// The edges only form a singly linked list using Edge.next[0] to store
// the forward reference.
free_node: NodeIndex<Ix>,
free_edge: EdgeIndex<Ix>,
}
/// A `StableGraph` with directed edges.
///
/// For example, an edge from *1* to *2* is distinct from an edge from *2* to
/// *1*.
pub type StableDiGraph<N, E, Ix = DefaultIx> = StableGraph<N, E, Directed, Ix>;
/// A `StableGraph` with undirected edges.
///
/// For example, an edge between *1* and *2* is equivalent to an edge between
/// *2* and *1*.
pub type StableUnGraph<N, E, Ix = DefaultIx> = StableGraph<N, E, Undirected, Ix>;
impl<N, E, Ty, Ix> fmt::Debug for StableGraph<N, E, Ty, Ix>
where
N: fmt::Debug,
E: fmt::Debug,
Ty: EdgeType,
Ix: IndexType,
{
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let etype = if self.is_directed() {
"Directed"
} else {
"Undirected"
};
let mut fmt_struct = f.debug_struct("StableGraph");
fmt_struct.field("Ty", &etype);
fmt_struct.field("node_count", &self.node_count);
fmt_struct.field("edge_count", &self.edge_count);
if self.g.edges.iter().any(|e| e.weight.is_some()) {
fmt_struct.field(
"edges",
&self
.g
.edges
.iter()
.filter(|e| e.weight.is_some())
.map(|e| NoPretty((e.source().index(), e.target().index())))
.format(", "),
);
}
// skip weights if they are ZST!
if size_of::<N>() != 0 {
fmt_struct.field(
"node weights",
&DebugMap(|| {
self.g
.nodes
.iter()
.map(|n| n.weight.as_ref())
.enumerate()
.filter_map(|(i, wo)| wo.map(move |w| (i, w)))
}),
);
}
if size_of::<E>() != 0 {
fmt_struct.field(
"edge weights",
&DebugMap(|| {
self.g
.edges
.iter()
.map(|n| n.weight.as_ref())
.enumerate()
.filter_map(|(i, wo)| wo.map(move |w| (i, w)))
}),
);
}
fmt_struct.field("free_node", &self.free_node);
fmt_struct.field("free_edge", &self.free_edge);
fmt_struct.finish()
}
}
impl<N, E> StableGraph<N, E, Directed> {
/// Create a new `StableGraph` with directed edges.
///
/// This is a convenience method. See `StableGraph::with_capacity`
/// or `StableGraph::default` for a constructor that is generic in all the
/// type parameters of `StableGraph`.
pub fn new() -> Self {
Self::with_capacity(0, 0)
}
}
impl<N, E, Ty, Ix> StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
/// Create a new `StableGraph` with estimated capacity.
pub fn with_capacity(nodes: usize, edges: usize) -> Self {
StableGraph {
g: Graph::with_capacity(nodes, edges),
node_count: 0,
edge_count: 0,
free_node: NodeIndex::end(),
free_edge: EdgeIndex::end(),
}
}
/// Return the current node and edge capacity of the graph.
pub fn capacity(&self) -> (usize, usize) {
self.g.capacity()
}
/// Reverse the direction of all edges
pub fn reverse(&mut self) {
// swap edge endpoints,
// edge incoming / outgoing lists,
// node incoming / outgoing lists
for edge in &mut self.g.edges {
edge.node.swap(0, 1);
edge.next.swap(0, 1);
}
for node in &mut self.g.nodes {
node.next.swap(0, 1);
}
}
/// Remove all nodes and edges
pub fn clear(&mut self) {
self.node_count = 0;
self.edge_count = 0;
self.free_node = NodeIndex::end();
self.free_edge = EdgeIndex::end();
self.g.clear();
}
/// Remove all edges
pub fn clear_edges(&mut self) {
self.edge_count = 0;
self.free_edge = EdgeIndex::end();
self.g.edges.clear();
// clear edges without touching the free list
for node in &mut self.g.nodes {
if node.weight.is_some() {
node.next = [EdgeIndex::end(), EdgeIndex::end()];
}
}
}
/// Return the number of nodes (vertices) in the graph.
///
/// Computes in **O(1)** time.
pub fn node_count(&self) -> usize {
self.node_count
}
/// Return the number of edges in the graph.
///
/// Computes in **O(1)** time.
pub fn edge_count(&self) -> usize {
self.edge_count
}
/// Whether the graph has directed edges or not.
#[inline]
pub fn is_directed(&self) -> bool {
Ty::is_directed()
}
/// Add a node (also called vertex) with associated data `weight` to the graph.
///
/// Computes in **O(1)** time.
///
/// Return the index of the new node.
///
/// **Panics** if the `StableGraph` is at the maximum number of nodes for
/// its index type.
pub fn add_node(&mut self, weight: N) -> NodeIndex<Ix> {
if self.free_node != NodeIndex::end() {
let node_idx = self.free_node;
self.occupy_vacant_node(node_idx, weight);
node_idx
} else {
self.node_count += 1;
self.g.add_node(Some(weight))
}
}
/// free_node: Which free list to update for the vacancy
fn add_vacant_node(&mut self, free_node: &mut NodeIndex<Ix>) {
let node_idx = self.g.add_node(None);
// link the free list
let node_slot = &mut self.g.nodes[node_idx.index()];
node_slot.next = [free_node._into_edge(), EdgeIndex::end()];
if *free_node != NodeIndex::end() {
self.g.nodes[free_node.index()].next[1] = node_idx._into_edge();
}
*free_node = node_idx;
}
/// Remove `a` from the graph if it exists, and return its weight.
/// If it doesn't exist in the graph, return `None`.
///
/// The node index `a` is invalidated, but none other.
/// Edge indices are invalidated as they would be following the removal of
/// each edge with an endpoint in `a`.
///
/// Computes in **O(e')** time, where **e'** is the number of affected
/// edges, including *n* calls to `.remove_edge()` where *n* is the number
/// of edges with an endpoint in `a`.
pub fn remove_node(&mut self, a: NodeIndex<Ix>) -> Option<N> {
let node_weight = self.g.nodes.get_mut(a.index())?.weight.take()?;
for d in &DIRECTIONS {
let k = d.index();
// Remove all edges from and to this node.
loop {
let next = self.g.nodes[a.index()].next[k];
if next == EdgeIndex::end() {
break;
}
let ret = self.remove_edge(next);
debug_assert!(ret.is_some());
let _ = ret;
}
}
let node_slot = &mut self.g.nodes[a.index()];
//let node_weight = replace(&mut self.g.nodes[a.index()].weight, Entry::Empty(self.free_node));
//self.g.nodes[a.index()].next = [EdgeIndex::end(), EdgeIndex::end()];
node_slot.next = [self.free_node._into_edge(), EdgeIndex::end()];
if self.free_node != NodeIndex::end() {
self.g.nodes[self.free_node.index()].next[1] = a._into_edge();
}
self.free_node = a;
self.node_count -= 1;
Some(node_weight)
}
pub fn contains_node(&self, a: NodeIndex<Ix>) -> bool {
self.get_node(a).is_some()
}
// Return the Node if it is not vacant (non-None weight)
fn get_node(&self, a: NodeIndex<Ix>) -> Option<&Node<Option<N>, Ix>> {
self.g
.nodes
.get(a.index())
.and_then(|node| node.weight.as_ref().map(move |_| node))
}
/// Add an edge from `a` to `b` to the graph, with its associated
/// data `weight`.
///
/// Return the index of the new edge.
///
/// Computes in **O(1)** time.
///
/// **Panics** if any of the nodes don't exist.<br>
/// **Panics** if the `StableGraph` is at the maximum number of edges for
/// its index type.
///
/// **Note:** `StableGraph` allows adding parallel (“duplicate”) edges.
pub fn add_edge(&mut self, a: NodeIndex<Ix>, b: NodeIndex<Ix>, weight: E) -> EdgeIndex<Ix> {
let edge_idx;
let mut new_edge = None::<Edge<_, _>>;
{
let edge: &mut Edge<_, _>;
if self.free_edge != EdgeIndex::end() {
edge_idx = self.free_edge;
edge = &mut self.g.edges[edge_idx.index()];
let _old = replace(&mut edge.weight, Some(weight));
debug_assert!(_old.is_none());
self.free_edge = edge.next[0];
edge.node = [a, b];
} else {
edge_idx = EdgeIndex::new(self.g.edges.len());
assert!(<Ix as IndexType>::max().index() == !0 || EdgeIndex::end() != edge_idx);
new_edge = Some(Edge {
weight: Some(weight),
node: [a, b],
next: [EdgeIndex::end(); 2],
});
edge = new_edge.as_mut().unwrap();
}
let wrong_index = match index_twice(&mut self.g.nodes, a.index(), b.index()) {
Pair::None => Some(cmp::max(a.index(), b.index())),
Pair::One(an) => {
if an.weight.is_none() {
Some(a.index())
} else {
edge.next = an.next;
an.next[0] = edge_idx;
an.next[1] = edge_idx;
None
}
}
Pair::Both(an, bn) => {
// a and b are different indices
if an.weight.is_none() {
Some(a.index())
} else if bn.weight.is_none() {
Some(b.index())
} else {
edge.next = [an.next[0], bn.next[1]];
an.next[0] = edge_idx;
bn.next[1] = edge_idx;
None
}
}
};
if let Some(i) = wrong_index {
panic!(
"StableGraph::add_edge: node index {} is not a node in the graph",
i
);
}
self.edge_count += 1;
}
if let Some(edge) = new_edge {
self.g.edges.push(edge);
}
edge_idx
}
/// free_edge: Which free list to update for the vacancy
fn add_vacant_edge(&mut self, free_edge: &mut EdgeIndex<Ix>) {
let edge_idx = EdgeIndex::new(self.g.edges.len());
debug_assert!(edge_idx != EdgeIndex::end());
let mut edge = Edge {
weight: None,
node: [NodeIndex::end(); 2],
next: [EdgeIndex::end(); 2],
};
edge.next[0] = *free_edge;
*free_edge = edge_idx;
self.g.edges.push(edge);
}
/// Add or update an edge from `a` to `b`.
/// If the edge already exists, its weight is updated.
///
/// Return the index of the affected edge.
///
/// Computes in **O(e')** time, where **e'** is the number of edges
/// connected to `a` (and `b`, if the graph edges are undirected).
///
/// **Panics** if any of the nodes don't exist.
pub fn update_edge(&mut self, a: NodeIndex<Ix>, b: NodeIndex<Ix>, weight: E) -> EdgeIndex<Ix> {
if let Some(ix) = self.find_edge(a, b) {
self[ix] = weight;
return ix;
}
self.add_edge(a, b, weight)
}
/// Remove an edge and return its edge weight, or `None` if it didn't exist.
///
/// Invalidates the edge index `e` but no other.
///
/// Computes in **O(e')** time, where **e'** is the number of edges
/// connected to the same endpoints as `e`.
pub fn remove_edge(&mut self, e: EdgeIndex<Ix>) -> Option<E> {
// every edge is part of two lists,
// outgoing and incoming edges.
// Remove it from both
let (is_edge, edge_node, edge_next) = match self.g.edges.get(e.index()) {
None => return None,
Some(x) => (x.weight.is_some(), x.node, x.next),
};
if !is_edge {
return None;
}
// Remove the edge from its in and out lists by replacing it with
// a link to the next in the list.
self.g.change_edge_links(edge_node, e, edge_next);
// Clear the edge and put it in the free list
let edge = &mut self.g.edges[e.index()];
edge.next = [self.free_edge, EdgeIndex::end()];
edge.node = [NodeIndex::end(), NodeIndex::end()];
self.free_edge = e;
self.edge_count -= 1;
edge.weight.take()
}
/// Access the weight for node `a`.
///
/// Also available with indexing syntax: `&graph[a]`.
pub fn node_weight(&self, a: NodeIndex<Ix>) -> Option<&N> {
match self.g.nodes.get(a.index()) {
Some(no) => no.weight.as_ref(),
None => None,
}
}
/// Access the weight for node `a`, mutably.
///
/// Also available with indexing syntax: `&mut graph[a]`.
pub fn node_weight_mut(&mut self, a: NodeIndex<Ix>) -> Option<&mut N> {
match self.g.nodes.get_mut(a.index()) {
Some(no) => no.weight.as_mut(),
None => None,
}
}
/// Return an iterator yielding immutable access to all node weights.
///
/// The order in which weights are yielded matches the order of their node
/// indices.
pub fn node_weights(&self) -> impl Iterator<Item = &N> {
self.g
.node_weights()
.filter_map(|maybe_node| maybe_node.as_ref())
}
/// Return an iterator yielding mutable access to all node weights.
///
/// The order in which weights are yielded matches the order of their node
/// indices.
pub fn node_weights_mut(&mut self) -> impl Iterator<Item = &mut N> {
self.g
.node_weights_mut()
.filter_map(|maybe_node| maybe_node.as_mut())
}
/// Return an iterator over the node indices of the graph
pub fn node_indices(&self) -> NodeIndices<N, Ix> {
NodeIndices {
iter: enumerate(self.raw_nodes()),
}
}
/// Access the weight for edge `e`.
///
/// Also available with indexing syntax: `&graph[e]`.
pub fn edge_weight(&self, e: EdgeIndex<Ix>) -> Option<&E> {
match self.g.edges.get(e.index()) {
Some(ed) => ed.weight.as_ref(),
None => None,
}
}
/// Access the weight for edge `e`, mutably
///
/// Also available with indexing syntax: `&mut graph[e]`.
pub fn edge_weight_mut(&mut self, e: EdgeIndex<Ix>) -> Option<&mut E> {
match self.g.edges.get_mut(e.index()) {
Some(ed) => ed.weight.as_mut(),
None => None,
}
}
/// Return an iterator yielding immutable access to all edge weights.
///
/// The order in which weights are yielded matches the order of their edge
/// indices.
pub fn edge_weights(&self) -> impl Iterator<Item = &E> {
self.g
.edge_weights()
.filter_map(|maybe_edge| maybe_edge.as_ref())
}
/// Return an iterator yielding mutable access to all edge weights.
///
/// The order in which weights are yielded matches the order of their edge
/// indices.
pub fn edge_weights_mut(&mut self) -> impl Iterator<Item = &mut E> {
self.g
.edge_weights_mut()
.filter_map(|maybe_edge| maybe_edge.as_mut())
}
/// Access the source and target nodes for `e`.
pub fn edge_endpoints(&self, e: EdgeIndex<Ix>) -> Option<(NodeIndex<Ix>, NodeIndex<Ix>)> {
match self.g.edges.get(e.index()) {
Some(ed) if ed.weight.is_some() => Some((ed.source(), ed.target())),
_otherwise => None,
}
}
/// Return an iterator over the edge indices of the graph
pub fn edge_indices(&self) -> EdgeIndices<E, Ix> {
EdgeIndices {
iter: enumerate(self.raw_edges()),
}
}
/// Return an iterator over all the edges connecting `a` and `b`.
///
/// - `Directed`: Outgoing edges from `a`.
/// - `Undirected`: All edges connected to `a`.
///
/// Iterator element type is `EdgeReference<E, Ix>`.
pub fn edges_connecting(
&self,
a: NodeIndex<Ix>,
b: NodeIndex<Ix>,
) -> EdgesConnecting<E, Ty, Ix> {
EdgesConnecting {
target_node: b,
edges: self.edges_directed(a, Direction::Outgoing),
ty: PhantomData,
}
}
/// Lookup if there is an edge from `a` to `b`.
///
/// Computes in **O(e')** time, where **e'** is the number of edges
/// connected to `a` (and `b`, if the graph edges are undirected).
pub fn contains_edge(&self, a: NodeIndex<Ix>, b: NodeIndex<Ix>) -> bool {
self.find_edge(a, b).is_some()
}
/// Lookup an edge from `a` to `b`.
///
/// Computes in **O(e')** time, where **e'** is the number of edges
/// connected to `a` (and `b`, if the graph edges are undirected).
pub fn find_edge(&self, a: NodeIndex<Ix>, b: NodeIndex<Ix>) -> Option<EdgeIndex<Ix>> {
if !self.is_directed() {
self.find_edge_undirected(a, b).map(|(ix, _)| ix)
} else {
match self.get_node(a) {
None => None,
Some(node) => self.g.find_edge_directed_from_node(node, b),
}
}
}
/// Lookup an edge between `a` and `b`, in either direction.
///
/// If the graph is undirected, then this is equivalent to `.find_edge()`.
///
/// Return the edge index and its directionality, with `Outgoing` meaning
/// from `a` to `b` and `Incoming` the reverse,
/// or `None` if the edge does not exist.
pub fn find_edge_undirected(
&self,
a: NodeIndex<Ix>,
b: NodeIndex<Ix>,
) -> Option<(EdgeIndex<Ix>, Direction)> {
match self.get_node(a) {
None => None,
Some(node) => self.g.find_edge_undirected_from_node(node, b),
}
}
/// Return an iterator of all nodes with an edge starting from `a`.
///
/// - `Directed`: Outgoing edges from `a`.
/// - `Undirected`: All edges connected to `a`.
///
/// Produces an empty iterator if the node doesn't exist.<br>
/// Iterator element type is `NodeIndex<Ix>`.
///
/// Use [`.neighbors(a).detach()`][1] to get a neighbor walker that does
/// not borrow from the graph.
///
/// [1]: struct.Neighbors.html#method.detach
pub fn neighbors(&self, a: NodeIndex<Ix>) -> Neighbors<E, Ix> {
self.neighbors_directed(a, Outgoing)
}
/// Return an iterator of all neighbors that have an edge between them and `a`,
/// in the specified direction.
/// If the graph's edges are undirected, this is equivalent to *.neighbors(a)*.
///
/// - `Directed`, `Outgoing`: All edges from `a`.
/// - `Directed`, `Incoming`: All edges to `a`.
/// - `Undirected`: All edges connected to `a`.
///
/// Produces an empty iterator if the node doesn't exist.<br>
/// Iterator element type is `NodeIndex<Ix>`.
///
/// Use [`.neighbors_directed(a, dir).detach()`][1] to get a neighbor walker that does
/// not borrow from the graph.
///
/// [1]: struct.Neighbors.html#method.detach
pub fn neighbors_directed(&self, a: NodeIndex<Ix>, dir: Direction) -> Neighbors<E, Ix> {
let mut iter = self.neighbors_undirected(a);
if self.is_directed() {
let k = dir.index();
iter.next[1 - k] = EdgeIndex::end();
iter.skip_start = NodeIndex::end();
}
iter
}
/// Return an iterator of all neighbors that have an edge between them and `a`,
/// in either direction.
/// If the graph's edges are undirected, this is equivalent to *.neighbors(a)*.
///
/// - `Directed` and `Undirected`: All edges connected to `a`.
///
/// Produces an empty iterator if the node doesn't exist.<br>
/// Iterator element type is `NodeIndex<Ix>`.
///
/// Use [`.neighbors_undirected(a).detach()`][1] to get a neighbor walker that does
/// not borrow from the graph.
///
/// [1]: struct.Neighbors.html#method.detach
pub fn neighbors_undirected(&self, a: NodeIndex<Ix>) -> Neighbors<E, Ix> {
Neighbors {
skip_start: a,
edges: &self.g.edges,
next: match self.get_node(a) {
None => [EdgeIndex::end(), EdgeIndex::end()],
Some(n) => n.next,
},
}
}
/// Return an iterator of all edges of `a`.
///
/// - `Directed`: Outgoing edges from `a`.
/// - `Undirected`: All edges connected to `a`.
///
/// Produces an empty iterator if the node doesn't exist.<br>
/// Iterator element type is `EdgeReference<E, Ix>`.
pub fn edges(&self, a: NodeIndex<Ix>) -> Edges<E, Ty, Ix> {
self.edges_directed(a, Outgoing)
}
/// Return an iterator of all edges of `a`, in the specified direction.
///
/// - `Directed`, `Outgoing`: All edges from `a`.
/// - `Directed`, `Incoming`: All edges to `a`.
/// - `Undirected`, `Outgoing`: All edges connected to `a`, with `a` being the source of each
/// edge.
/// - `Undirected`, `Incoming`: All edges connected to `a`, with `a` being the target of each
/// edge.
///
/// Produces an empty iterator if the node `a` doesn't exist.<br>
/// Iterator element type is `EdgeReference<E, Ix>`.
pub fn edges_directed(&self, a: NodeIndex<Ix>, dir: Direction) -> Edges<E, Ty, Ix> {
Edges {
skip_start: a,
edges: &self.g.edges,
direction: dir,
next: match self.get_node(a) {
None => [EdgeIndex::end(), EdgeIndex::end()],
Some(n) => n.next,
},
ty: PhantomData,
}
}
/// Return an iterator over either the nodes without edges to them
/// (`Incoming`) or from them (`Outgoing`).
///
/// An *internal* node has both incoming and outgoing edges.
/// The nodes in `.externals(Incoming)` are the source nodes and
/// `.externals(Outgoing)` are the sinks of the graph.
///
/// For a graph with undirected edges, both the sinks and the sources are
/// just the nodes without edges.
///
/// The whole iteration computes in **O(|V|)** time.
pub fn externals(&self, dir: Direction) -> Externals<N, Ty, Ix> {
Externals {
iter: self.raw_nodes().iter().enumerate(),
dir,
ty: PhantomData,
}
}
/// Index the `StableGraph` by two indices, any combination of
/// node or edge indices is fine.
///
/// **Panics** if the indices are equal or if they are out of bounds.
pub fn index_twice_mut<T, U>(
&mut self,
i: T,
j: U,
) -> (
&mut <Self as Index<T>>::Output,
&mut <Self as Index<U>>::Output,
)
where
Self: IndexMut<T> + IndexMut<U>,
T: GraphIndex,
U: GraphIndex,
{
assert!(T::is_node_index() != U::is_node_index() || i.index() != j.index());
// Allow two mutable indexes here -- they are nonoverlapping
unsafe {
let self_mut = self as *mut _;
(
<Self as IndexMut<T>>::index_mut(&mut *self_mut, i),
<Self as IndexMut<U>>::index_mut(&mut *self_mut, j),
)
}
}
/// Keep all nodes that return `true` from the `visit` closure,
/// remove the others.
///
/// `visit` is provided a proxy reference to the graph, so that
/// the graph can be walked and associated data modified.
///
/// The order nodes are visited is not specified.
///
/// The node indices of the removed nodes are invalidated, but none other.
/// Edge indices are invalidated as they would be following the removal of
/// each edge with an endpoint in a removed node.
///
/// Computes in **O(n + e')** time, where **n** is the number of node indices and
/// **e'** is the number of affected edges, including *n* calls to `.remove_edge()`
/// where *n* is the number of edges with an endpoint in a removed node.
pub fn retain_nodes<F>(&mut self, mut visit: F)
where
F: FnMut(Frozen<Self>, NodeIndex<Ix>) -> bool,
{
for i in 0..self.node_bound() {
let ix = node_index(i);
if self.contains_node(ix) && !visit(Frozen(self), ix) {
self.remove_node(ix);
}
}
self.check_free_lists();
}
/// Keep all edges that return `true` from the `visit` closure,
/// remove the others.
///
/// `visit` is provided a proxy reference to the graph, so that
/// the graph can be walked and associated data modified.
///
/// The order edges are visited is not specified.
///
/// The edge indices of the removed edes are invalidated, but none other.
///
/// Computes in **O(e'')** time, **e'** is the number of affected edges,
/// including the calls to `.remove_edge()` for each removed edge.
pub fn retain_edges<F>(&mut self, mut visit: F)
where
F: FnMut(Frozen<Self>, EdgeIndex<Ix>) -> bool,
{
for i in 0..self.edge_bound() {
let ix = edge_index(i);
if self.edge_weight(ix).is_some() && !visit(Frozen(self), ix) {
self.remove_edge(ix);
}
}
self.check_free_lists();
}
/// Create a new `StableGraph` from an iterable of edges.
///
/// Node weights `N` are set to default values.
/// Edge weights `E` may either be specified in the list,
/// or they are filled with default values.
///
/// Nodes are inserted automatically to match the edges.
///
/// ```
/// use petgraph::stable_graph::StableGraph;
///
/// let gr = StableGraph::<(), i32>::from_edges(&[
/// (0, 1), (0, 2), (0, 3),
/// (1, 2), (1, 3),
/// (2, 3),
/// ]);
/// ```
pub fn from_edges<I>(iterable: I) -> Self
where
I: IntoIterator,
I::Item: IntoWeightedEdge<E>,
<I::Item as IntoWeightedEdge<E>>::NodeId: Into<NodeIndex<Ix>>,
N: Default,
{
let mut g = Self::with_capacity(0, 0);
g.extend_with_edges(iterable);
g
}
/// Create a new `StableGraph` by mapping node and
/// edge weights to new values.
///
/// The resulting graph has the same structure and the same
/// graph indices as `self`.
pub fn map<'a, F, G, N2, E2>(
&'a self,
mut node_map: F,
mut edge_map: G,
) -> StableGraph<N2, E2, Ty, Ix>
where
F: FnMut(NodeIndex<Ix>, &'a N) -> N2,
G: FnMut(EdgeIndex<Ix>, &'a E) -> E2,
{
let g = self.g.map(
move |i, w| w.as_ref().map(|w| node_map(i, w)),
move |i, w| w.as_ref().map(|w| edge_map(i, w)),
);
StableGraph {
g,
node_count: self.node_count,
edge_count: self.edge_count,
free_node: self.free_node,
free_edge: self.free_edge,
}
}
/// Create a new `StableGraph` by mapping nodes and edges.
/// A node or edge may be mapped to `None` to exclude it from
/// the resulting graph.
///
/// Nodes are mapped first with the `node_map` closure, then
/// `edge_map` is called for the edges that have not had any endpoint
/// removed.
///
/// The resulting graph has the structure of a subgraph of the original graph.
/// Nodes and edges that are not removed maintain their old node or edge
/// indices.
pub fn filter_map<'a, F, G, N2, E2>(
&'a self,
mut node_map: F,
mut edge_map: G,
) -> StableGraph<N2, E2, Ty, Ix>
where
F: FnMut(NodeIndex<Ix>, &'a N) -> Option<N2>,
G: FnMut(EdgeIndex<Ix>, &'a E) -> Option<E2>,
{
let node_bound = self.node_bound();
let edge_bound = self.edge_bound();
let mut result_g = StableGraph::with_capacity(node_bound, edge_bound);
// use separate free lists so that
// add_node / add_edge below do not reuse the tombstones
let mut free_node = NodeIndex::end();
let mut free_edge = EdgeIndex::end();
// the stable graph keeps the node map itself
for (i, node) in enumerate(self.raw_nodes()) {
if i >= node_bound {
break;
}
if let Some(node_weight) = node.weight.as_ref() {
if let Some(new_weight) = node_map(NodeIndex::new(i), node_weight) {
result_g.add_node(new_weight);
continue;
}
}
result_g.add_vacant_node(&mut free_node);
}
for (i, edge) in enumerate(self.raw_edges()) {
if i >= edge_bound {
break;
}
let source = edge.source();
let target = edge.target();
if let Some(edge_weight) = edge.weight.as_ref() {
if result_g.contains_node(source) && result_g.contains_node(target) {
if let Some(new_weight) = edge_map(EdgeIndex::new(i), edge_weight) {
result_g.add_edge(source, target, new_weight);
continue;
}
}
}
result_g.add_vacant_edge(&mut free_edge);
}
result_g.free_node = free_node;
result_g.free_edge = free_edge;
result_g.check_free_lists();
result_g
}
/// Extend the graph from an iterable of edges.
///
/// Node weights `N` are set to default values.
/// Edge weights `E` may either be specified in the list,
/// or they are filled with default values.
///
/// Nodes are inserted automatically to match the edges.
pub fn extend_with_edges<I>(&mut self, iterable: I)
where
I: IntoIterator,
I::Item: IntoWeightedEdge<E>,
<I::Item as IntoWeightedEdge<E>>::NodeId: Into<NodeIndex<Ix>>,
N: Default,
{
let iter = iterable.into_iter();
for elt in iter {
let (source, target, weight) = elt.into_weighted_edge();
let (source, target) = (source.into(), target.into());
self.ensure_node_exists(source);
self.ensure_node_exists(target);
self.add_edge(source, target, weight);
}
}
//
// internal methods
//
fn raw_nodes(&self) -> &[Node<Option<N>, Ix>] {
self.g.raw_nodes()
}
fn raw_edges(&self) -> &[Edge<Option<E>, Ix>] {
self.g.raw_edges()
}
/// Create a new node using a vacant position,
/// updating the free nodes doubly linked list.
fn occupy_vacant_node(&mut self, node_idx: NodeIndex<Ix>, weight: N) {
let node_slot = &mut self.g.nodes[node_idx.index()];
let _old = replace(&mut node_slot.weight, Some(weight));
debug_assert!(_old.is_none());
let previous_node = node_slot.next[1];
let next_node = node_slot.next[0];
node_slot.next = [EdgeIndex::end(), EdgeIndex::end()];
if previous_node != EdgeIndex::end() {
self.g.nodes[previous_node.index()].next[0] = next_node;
}
if next_node != EdgeIndex::end() {
self.g.nodes[next_node.index()].next[1] = previous_node;
}
if self.free_node == node_idx {
self.free_node = next_node._into_node();
}
self.node_count += 1;
}
/// Create the node if it does not exist,
/// adding vacant nodes for padding if needed.
fn ensure_node_exists(&mut self, node_ix: NodeIndex<Ix>)
where
N: Default,
{
if let Some(Some(_)) = self.g.node_weight(node_ix) {
return;
}
while node_ix.index() >= self.g.node_count() {
let mut free_node = self.free_node;
self.add_vacant_node(&mut free_node);
self.free_node = free_node;
}
self.occupy_vacant_node(node_ix, N::default());
}
#[cfg(feature = "serde-1")]
/// Fix up node and edge links after deserialization
fn link_edges(&mut self) -> Result<(), NodeIndex<Ix>> {
// set up free node list
self.node_count = 0;
self.edge_count = 0;
let mut free_node = NodeIndex::end();
for node_index in 0..self.g.node_count() {
let node = &mut self.g.nodes[node_index];
if node.weight.is_some() {
self.node_count += 1;
} else {
// free node
node.next = [free_node._into_edge(), EdgeIndex::end()];
if free_node != NodeIndex::end() {
self.g.nodes[free_node.index()].next[1] = EdgeIndex::new(node_index);
}
free_node = NodeIndex::new(node_index);
}
}
self.free_node = free_node;
let mut free_edge = EdgeIndex::end();
for (edge_index, edge) in enumerate(&mut self.g.edges) {
if edge.weight.is_none() {
// free edge
edge.next = [free_edge, EdgeIndex::end()];
free_edge = EdgeIndex::new(edge_index);
continue;
}
let a = edge.source();
let b = edge.target();
let edge_idx = EdgeIndex::new(edge_index);
match index_twice(&mut self.g.nodes, a.index(), b.index()) {
Pair::None => return Err(if a > b { a } else { b }),
Pair::One(an) => {
edge.next = an.next;
an.next[0] = edge_idx;
an.next[1] = edge_idx;
}
Pair::Both(an, bn) => {
// a and b are different indices
edge.next = [an.next[0], bn.next[1]];
an.next[0] = edge_idx;
bn.next[1] = edge_idx;
}
}
self.edge_count += 1;
}
self.free_edge = free_edge;
Ok(())
}
#[cfg(not(debug_assertions))]
fn check_free_lists(&self) {}
#[cfg(debug_assertions)]
// internal method to debug check the free lists (linked lists)
// For the nodes, also check the backpointers of the doubly linked list.
fn check_free_lists(&self) {
let mut free_node = self.free_node;
let mut prev_free_node = NodeIndex::end();
let mut free_node_len = 0;
while free_node != NodeIndex::end() {
if let Some(n) = self.g.nodes.get(free_node.index()) {
if n.weight.is_none() {
debug_assert_eq!(n.next[1]._into_node(), prev_free_node);
prev_free_node = free_node;
free_node = n.next[0]._into_node();
free_node_len += 1;
continue;
}
debug_assert!(
false,
"Corrupt free list: pointing to existing {:?}",
free_node.index()
);
}
debug_assert!(false, "Corrupt free list: missing {:?}", free_node.index());
}
debug_assert_eq!(self.node_count(), self.raw_nodes().len() - free_node_len);
let mut free_edge_len = 0;
let mut free_edge = self.free_edge;
while free_edge != EdgeIndex::end() {
if let Some(n) = self.g.edges.get(free_edge.index()) {
if n.weight.is_none() {
free_edge = n.next[0];
free_edge_len += 1;
continue;
}
debug_assert!(
false,
"Corrupt free list: pointing to existing {:?}",
free_node.index()
);
}
debug_assert!(false, "Corrupt free list: missing {:?}", free_edge.index());
}
debug_assert_eq!(self.edge_count(), self.raw_edges().len() - free_edge_len);
}
}
/// The resulting cloned graph has the same graph indices as `self`.
impl<N, E, Ty, Ix: IndexType> Clone for StableGraph<N, E, Ty, Ix>
where
N: Clone,
E: Clone,
{
fn clone(&self) -> Self {
StableGraph {
g: self.g.clone(),
node_count: self.node_count,
edge_count: self.edge_count,
free_node: self.free_node,
free_edge: self.free_edge,
}
}
fn clone_from(&mut self, rhs: &Self) {
self.g.clone_from(&rhs.g);
self.node_count = rhs.node_count;
self.edge_count = rhs.edge_count;
self.free_node = rhs.free_node;
self.free_edge = rhs.free_edge;
}
}
/// Index the `StableGraph` by `NodeIndex` to access node weights.
///
/// **Panics** if the node doesn't exist.
impl<N, E, Ty, Ix> Index<NodeIndex<Ix>> for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type Output = N;
fn index(&self, index: NodeIndex<Ix>) -> &N {
self.node_weight(index).unwrap()
}
}
/// Index the `StableGraph` by `NodeIndex` to access node weights.
///
/// **Panics** if the node doesn't exist.
impl<N, E, Ty, Ix> IndexMut<NodeIndex<Ix>> for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
fn index_mut(&mut self, index: NodeIndex<Ix>) -> &mut N {
self.node_weight_mut(index).unwrap()
}
}
/// Index the `StableGraph` by `EdgeIndex` to access edge weights.
///
/// **Panics** if the edge doesn't exist.
impl<N, E, Ty, Ix> Index<EdgeIndex<Ix>> for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type Output = E;
fn index(&self, index: EdgeIndex<Ix>) -> &E {
self.edge_weight(index).unwrap()
}
}
/// Index the `StableGraph` by `EdgeIndex` to access edge weights.
///
/// **Panics** if the edge doesn't exist.
impl<N, E, Ty, Ix> IndexMut<EdgeIndex<Ix>> for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
fn index_mut(&mut self, index: EdgeIndex<Ix>) -> &mut E {
self.edge_weight_mut(index).unwrap()
}
}
/// Create a new empty `StableGraph`.
impl<N, E, Ty, Ix> Default for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
fn default() -> Self {
Self::with_capacity(0, 0)
}
}
/// Convert a `Graph` into a `StableGraph`
///
/// Computes in **O(|V| + |E|)** time.
///
/// The resulting graph has the same node and edge indices as
/// the original graph.
impl<N, E, Ty, Ix> From<Graph<N, E, Ty, Ix>> for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
fn from(g: Graph<N, E, Ty, Ix>) -> Self {
let nodes = g.nodes.into_iter().map(|e| Node {
weight: Some(e.weight),
next: e.next,
});
let edges = g.edges.into_iter().map(|e| Edge {
weight: Some(e.weight),
node: e.node,
next: e.next,
});
StableGraph {
node_count: nodes.len(),
edge_count: edges.len(),
g: Graph {
edges: edges.collect(),
nodes: nodes.collect(),
ty: g.ty,
},
free_node: NodeIndex::end(),
free_edge: EdgeIndex::end(),
}
}
}
/// Convert a `StableGraph` into a `Graph`
///
/// Computes in **O(|V| + |E|)** time.
///
/// This translates the stable graph into a graph with node and edge indices in
/// a compact interval without holes (like `Graph`s always are).
///
/// Only if the stable graph had no vacancies after deletions (if node bound was
/// equal to node count, and the same for edges), would the resulting graph have
/// the same node and edge indices as the input.
impl<N, E, Ty, Ix> From<StableGraph<N, E, Ty, Ix>> for Graph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
fn from(graph: StableGraph<N, E, Ty, Ix>) -> Self {
let mut result_g = Graph::with_capacity(graph.node_count(), graph.edge_count());
// mapping from old node index to new node index
let mut node_index_map = vec![NodeIndex::end(); graph.node_bound()];
for (i, node) in enumerate(graph.g.nodes) {
if let Some(nw) = node.weight {
node_index_map[i] = result_g.add_node(nw);
}
}
for edge in graph.g.edges {
let source_index = edge.source().index();
let target_index = edge.target().index();
if let Some(ew) = edge.weight {
let source = node_index_map[source_index];
let target = node_index_map[target_index];
debug_assert!(source != NodeIndex::end());
debug_assert!(target != NodeIndex::end());
result_g.add_edge(source, target, ew);
}
}
result_g
}
}
/// Iterator over all nodes of a graph.
#[derive(Debug, Clone)]
pub struct NodeReferences<'a, N: 'a, Ix: IndexType = DefaultIx> {
iter: iter::Enumerate<slice::Iter<'a, Node<Option<N>, Ix>>>,
}
impl<'a, N, Ix> Iterator for NodeReferences<'a, N, Ix>
where
Ix: IndexType,
{
type Item = (NodeIndex<Ix>, &'a N);
fn next(&mut self) -> Option<Self::Item> {
self.iter
.ex_find_map(|(i, node)| node.weight.as_ref().map(move |w| (node_index(i), w)))
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, hi) = self.iter.size_hint();
(0, hi)
}
}
impl<'a, N, Ix> DoubleEndedIterator for NodeReferences<'a, N, Ix>
where
Ix: IndexType,
{
fn next_back(&mut self) -> Option<Self::Item> {
self.iter
.ex_rfind_map(|(i, node)| node.weight.as_ref().map(move |w| (node_index(i), w)))
}
}
/// Reference to a `StableGraph` edge.
#[derive(Debug)]
pub struct EdgeReference<'a, E: 'a, Ix = DefaultIx> {
index: EdgeIndex<Ix>,
node: [NodeIndex<Ix>; 2],
weight: &'a E,
}
impl<'a, E, Ix: IndexType> Clone for EdgeReference<'a, E, Ix> {
fn clone(&self) -> Self {
*self
}
}
impl<'a, E, Ix: IndexType> Copy for EdgeReference<'a, E, Ix> {}
impl<'a, E, Ix: IndexType> PartialEq for EdgeReference<'a, E, Ix>
where
E: PartialEq,
{
fn eq(&self, rhs: &Self) -> bool {
self.index == rhs.index && self.weight == rhs.weight
}
}
impl<'a, Ix, E> EdgeReference<'a, E, Ix>
where
Ix: IndexType,
{
/// Access the edge’s weight.
///
/// **NOTE** that this method offers a longer lifetime
/// than the trait (unfortunately they don't match yet).
pub fn weight(&self) -> &'a E {
self.weight
}
}
/// Iterator over the edges of from or to a node
#[derive(Debug, Clone)]
pub struct Edges<'a, E: 'a, Ty, Ix: 'a = DefaultIx>
where
Ty: EdgeType,
Ix: IndexType,
{
/// starting node to skip over
skip_start: NodeIndex<Ix>,
edges: &'a [Edge<Option<E>, Ix>],
/// Next edge to visit.
next: [EdgeIndex<Ix>; 2],
/// For directed graphs: the direction to iterate in
/// For undirected graphs: the direction of edges
direction: Direction,
ty: PhantomData<Ty>,
}
impl<'a, E, Ty, Ix> Iterator for Edges<'a, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type Item = EdgeReference<'a, E, Ix>;
fn next(&mut self) -> Option<Self::Item> {
// type direction | iterate over reverse
// |
// Directed Outgoing | outgoing no
// Directed Incoming | incoming no
// Undirected Outgoing | both incoming
// Undirected Incoming | both outgoing
// For iterate_over, "both" is represented as None.
// For reverse, "no" is represented as None.
let (iterate_over, reverse) = if Ty::is_directed() {
(Some(self.direction), None)
} else {
(None, Some(self.direction.opposite()))
};
if iterate_over.unwrap_or(Outgoing) == Outgoing {
let i = self.next[0].index();
if let Some(Edge {
node,
weight: Some(weight),
next,
}) = self.edges.get(i)
{
self.next[0] = next[0];
return Some(EdgeReference {
index: edge_index(i),
node: if reverse == Some(Outgoing) {
swap_pair(*node)
} else {
*node
},
weight,
});
}
}
if iterate_over.unwrap_or(Incoming) == Incoming {
while let Some(Edge { node, weight, next }) = self.edges.get(self.next[1].index()) {
debug_assert!(weight.is_some());
let edge_index = self.next[1];
self.next[1] = next[1];
// In any of the "both" situations, self-loops would be iterated over twice.
// Skip them here.
if iterate_over.is_none() && node[0] == self.skip_start {
continue;
}
return Some(EdgeReference {
index: edge_index,
node: if reverse == Some(Incoming) {
swap_pair(*node)
} else {
*node
},
weight: weight.as_ref().unwrap(),
});
}
}
None
}
}
/// Iterator over the multiple directed edges connecting a source node to a target node
#[derive(Debug, Clone)]
pub struct EdgesConnecting<'a, E: 'a, Ty, Ix: 'a = DefaultIx>
where
Ty: EdgeType,
Ix: IndexType,
{
target_node: NodeIndex<Ix>,
edges: Edges<'a, E, Ty, Ix>,
ty: PhantomData<Ty>,
}
impl<'a, E, Ty, Ix> Iterator for EdgesConnecting<'a, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type Item = EdgeReference<'a, E, Ix>;
fn next(&mut self) -> Option<EdgeReference<'a, E, Ix>> {
let target_node = self.target_node;
self.edges
.by_ref()
.find(|&edge| edge.node[1] == target_node)
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, upper) = self.edges.size_hint();
(0, upper)
}
}
fn swap_pair<T>(mut x: [T; 2]) -> [T; 2] {
x.swap(0, 1);
x
}
/// Iterator over all edges of a graph.
#[derive(Debug, Clone)]
pub struct EdgeReferences<'a, E: 'a, Ix: 'a = DefaultIx> {
iter: iter::Enumerate<slice::Iter<'a, Edge<Option<E>, Ix>>>,
}
impl<'a, E, Ix> Iterator for EdgeReferences<'a, E, Ix>
where
Ix: IndexType,
{
type Item = EdgeReference<'a, E, Ix>;
fn next(&mut self) -> Option<Self::Item> {
self.iter.ex_find_map(|(i, edge)| {
edge.weight.as_ref().map(move |weight| EdgeReference {
index: edge_index(i),
node: edge.node,
weight,
})
})
}
}
impl<'a, E, Ix> DoubleEndedIterator for EdgeReferences<'a, E, Ix>
where
Ix: IndexType,
{
fn next_back(&mut self) -> Option<Self::Item> {
self.iter.ex_rfind_map(|(i, edge)| {
edge.weight.as_ref().map(move |weight| EdgeReference {
index: edge_index(i),
node: edge.node,
weight,
})
})
}
}
/// An iterator over either the nodes without edges to them or from them.
#[derive(Debug, Clone)]
pub struct Externals<'a, N: 'a, Ty, Ix: IndexType = DefaultIx> {
iter: iter::Enumerate<slice::Iter<'a, Node<Option<N>, Ix>>>,
dir: Direction,
ty: PhantomData<Ty>,
}
impl<'a, N: 'a, Ty, Ix> Iterator for Externals<'a, N, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type Item = NodeIndex<Ix>;
fn next(&mut self) -> Option<NodeIndex<Ix>> {
let k = self.dir.index();
loop {
match self.iter.next() {
None => return None,
Some((index, node)) => {
if node.weight.is_some()
&& node.next[k] == EdgeIndex::end()
&& (Ty::is_directed() || node.next[1 - k] == EdgeIndex::end())
{
return Some(NodeIndex::new(index));
} else {
continue;
}
}
}
}
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, upper) = self.iter.size_hint();
(0, upper)
}
}
/// Iterator over the neighbors of a node.
///
/// Iterator element type is `NodeIndex`.
#[derive(Debug, Clone)]
pub struct Neighbors<'a, E: 'a, Ix: 'a = DefaultIx> {
/// starting node to skip over
skip_start: NodeIndex<Ix>,
edges: &'a [Edge<Option<E>, Ix>],
next: [EdgeIndex<Ix>; 2],
}
impl<'a, E, Ix> Neighbors<'a, E, Ix>
where
Ix: IndexType,
{
/// Return a “walker” object that can be used to step through the
/// neighbors and edges from the origin node.
///
/// Note: The walker does not borrow from the graph, this is to allow mixing
/// edge walking with mutating the graph's weights.
pub fn detach(&self) -> WalkNeighbors<Ix> {
WalkNeighbors {
inner: super::WalkNeighbors {
skip_start: self.skip_start,
next: self.next,
},
}
}
}
impl<'a, E, Ix> Iterator for Neighbors<'a, E, Ix>
where
Ix: IndexType,
{
type Item = NodeIndex<Ix>;
fn next(&mut self) -> Option<NodeIndex<Ix>> {
// First any outgoing edges
match self.edges.get(self.next[0].index()) {
None => {}
Some(edge) => {
debug_assert!(edge.weight.is_some());
self.next[0] = edge.next[0];
return Some(edge.node[1]);
}
}
// Then incoming edges
// For an "undirected" iterator (traverse both incoming
// and outgoing edge lists), make sure we don't double
// count selfloops by skipping them in the incoming list.
while let Some(edge) = self.edges.get(self.next[1].index()) {
debug_assert!(edge.weight.is_some());
self.next[1] = edge.next[1];
if edge.node[0] != self.skip_start {
return Some(edge.node[0]);
}
}
None
}
}
/// A “walker” object that can be used to step through the edge list of a node.
///
/// See [*.detach()*](struct.Neighbors.html#method.detach) for more information.
///
/// The walker does not borrow from the graph, so it lets you step through
/// neighbors or incident edges while also mutating graph weights, as
/// in the following example:
///
/// ```
/// use petgraph::visit::Dfs;
/// use petgraph::Incoming;
/// use petgraph::stable_graph::StableGraph;
///
/// let mut gr = StableGraph::new();
/// let a = gr.add_node(0.);
/// let b = gr.add_node(0.);
/// let c = gr.add_node(0.);
/// gr.add_edge(a, b, 3.);
/// gr.add_edge(b, c, 2.);
/// gr.add_edge(c, b, 1.);
///
/// // step through the graph and sum incoming edges into the node weight
/// let mut dfs = Dfs::new(&gr, a);
/// while let Some(node) = dfs.next(&gr) {
/// // use a detached neighbors walker
/// let mut edges = gr.neighbors_directed(node, Incoming).detach();
/// while let Some(edge) = edges.next_edge(&gr) {
/// gr[node] += gr[edge];
/// }
/// }
///
/// // check the result
/// assert_eq!(gr[a], 0.);
/// assert_eq!(gr[b], 4.);
/// assert_eq!(gr[c], 2.);
/// ```
pub struct WalkNeighbors<Ix> {
inner: super::WalkNeighbors<Ix>,
}
impl<Ix: IndexType> Clone for WalkNeighbors<Ix> {
clone_fields!(WalkNeighbors, inner);
}
impl<Ix: IndexType> WalkNeighbors<Ix> {
/// Step to the next edge and its endpoint node in the walk for graph `g`.
///
/// The next node indices are always the others than the starting point
/// where the `WalkNeighbors` value was created.
/// For an `Outgoing` walk, the target nodes,
/// for an `Incoming` walk, the source nodes of the edge.
pub fn next<N, E, Ty: EdgeType>(
&mut self,
g: &StableGraph<N, E, Ty, Ix>,
) -> Option<(EdgeIndex<Ix>, NodeIndex<Ix>)> {
self.inner.next(&g.g)
}
pub fn next_node<N, E, Ty: EdgeType>(
&mut self,
g: &StableGraph<N, E, Ty, Ix>,
) -> Option<NodeIndex<Ix>> {
self.next(g).map(|t| t.1)
}
pub fn next_edge<N, E, Ty: EdgeType>(
&mut self,
g: &StableGraph<N, E, Ty, Ix>,
) -> Option<EdgeIndex<Ix>> {
self.next(g).map(|t| t.0)
}
}
/// Iterator over the node indices of a graph.
#[derive(Debug, Clone)]
pub struct NodeIndices<'a, N: 'a, Ix: 'a = DefaultIx> {
iter: iter::Enumerate<slice::Iter<'a, Node<Option<N>, Ix>>>,
}
impl<'a, N, Ix: IndexType> Iterator for NodeIndices<'a, N, Ix> {
type Item = NodeIndex<Ix>;
fn next(&mut self) -> Option<Self::Item> {
self.iter.ex_find_map(|(i, node)| {
if node.weight.is_some() {
Some(node_index(i))
} else {
None
}
})
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, upper) = self.iter.size_hint();
(0, upper)
}
}
impl<'a, N, Ix: IndexType> DoubleEndedIterator for NodeIndices<'a, N, Ix> {
fn next_back(&mut self) -> Option<Self::Item> {
self.iter.ex_rfind_map(|(i, node)| {
if node.weight.is_some() {
Some(node_index(i))
} else {
None
}
})
}
}
/// Iterator over the edge indices of a graph.
#[derive(Debug, Clone)]
pub struct EdgeIndices<'a, E: 'a, Ix: 'a = DefaultIx> {
iter: iter::Enumerate<slice::Iter<'a, Edge<Option<E>, Ix>>>,
}
impl<'a, E, Ix: IndexType> Iterator for EdgeIndices<'a, E, Ix> {
type Item = EdgeIndex<Ix>;
fn next(&mut self) -> Option<Self::Item> {
self.iter.ex_find_map(|(i, node)| {
if node.weight.is_some() {
Some(edge_index(i))
} else {
None
}
})
}
fn size_hint(&self) -> (usize, Option<usize>) {
let (_, upper) = self.iter.size_hint();
(0, upper)
}
}
impl<'a, E, Ix: IndexType> DoubleEndedIterator for EdgeIndices<'a, E, Ix> {
fn next_back(&mut self) -> Option<Self::Item> {
self.iter.ex_rfind_map(|(i, node)| {
if node.weight.is_some() {
Some(edge_index(i))
} else {
None
}
})
}
}
impl<N, E, Ty, Ix> visit::GraphBase for StableGraph<N, E, Ty, Ix>
where
Ix: IndexType,
{
type NodeId = NodeIndex<Ix>;
type EdgeId = EdgeIndex<Ix>;
}
impl<N, E, Ty, Ix> visit::Visitable for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type Map = FixedBitSet;
fn visit_map(&self) -> FixedBitSet {
FixedBitSet::with_capacity(self.node_bound())
}
fn reset_map(&self, map: &mut Self::Map) {
map.clear();
map.grow(self.node_bound());
}
}
impl<N, E, Ty, Ix> visit::Data for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type NodeWeight = N;
type EdgeWeight = E;
}
impl<N, E, Ty, Ix> visit::GraphProp for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type EdgeType = Ty;
}
impl<'a, N, E: 'a, Ty, Ix> visit::IntoNodeIdentifiers for &'a StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type NodeIdentifiers = NodeIndices<'a, N, Ix>;
fn node_identifiers(self) -> Self::NodeIdentifiers {
StableGraph::node_indices(self)
}
}
impl<N, E, Ty, Ix> visit::NodeCount for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
fn node_count(&self) -> usize {
self.node_count()
}
}
impl<'a, N, E, Ty, Ix> visit::IntoNodeReferences for &'a StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type NodeRef = (NodeIndex<Ix>, &'a N);
type NodeReferences = NodeReferences<'a, N, Ix>;
fn node_references(self) -> Self::NodeReferences {
NodeReferences {
iter: enumerate(self.raw_nodes()),
}
}
}
impl<N, E, Ty, Ix> visit::NodeIndexable for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
/// Return an upper bound of the node indices in the graph
fn node_bound(&self) -> usize {
self.node_indices().next_back().map_or(0, |i| i.index() + 1)
}
fn to_index(&self, ix: NodeIndex<Ix>) -> usize {
ix.index()
}
fn from_index(&self, ix: usize) -> Self::NodeId {
NodeIndex::new(ix)
}
}
impl<'a, N, E: 'a, Ty, Ix> visit::IntoNeighbors for &'a StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type Neighbors = Neighbors<'a, E, Ix>;
fn neighbors(self, n: Self::NodeId) -> Self::Neighbors {
(*self).neighbors(n)
}
}
impl<'a, N, E: 'a, Ty, Ix> visit::IntoNeighborsDirected for &'a StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type NeighborsDirected = Neighbors<'a, E, Ix>;
fn neighbors_directed(self, n: NodeIndex<Ix>, d: Direction) -> Self::NeighborsDirected {
StableGraph::neighbors_directed(self, n, d)
}
}
impl<'a, N, E, Ty, Ix> visit::IntoEdges for &'a StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type Edges = Edges<'a, E, Ty, Ix>;
fn edges(self, a: Self::NodeId) -> Self::Edges {
self.edges(a)
}
}
impl<'a, Ix, E> visit::EdgeRef for EdgeReference<'a, E, Ix>
where
Ix: IndexType,
{
type NodeId = NodeIndex<Ix>;
type EdgeId = EdgeIndex<Ix>;
type Weight = E;
fn source(&self) -> Self::NodeId {
self.node[0]
}
fn target(&self) -> Self::NodeId {
self.node[1]
}
fn weight(&self) -> &E {
self.weight
}
fn id(&self) -> Self::EdgeId {
self.index
}
}
impl<N, E, Ty, Ix> visit::EdgeIndexable for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
fn edge_bound(&self) -> usize {
self.edge_references()
.next_back()
.map_or(0, |edge| edge.id().index() + 1)
}
fn to_index(&self, ix: EdgeIndex<Ix>) -> usize {
ix.index()
}
fn from_index(&self, ix: usize) -> Self::EdgeId {
EdgeIndex::new(ix)
}
}
impl<'a, N, E, Ty, Ix> visit::IntoEdgesDirected for &'a StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type EdgesDirected = Edges<'a, E, Ty, Ix>;
fn edges_directed(self, a: Self::NodeId, dir: Direction) -> Self::EdgesDirected {
self.edges_directed(a, dir)
}
}
impl<'a, N: 'a, E: 'a, Ty, Ix> visit::IntoEdgeReferences for &'a StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
type EdgeRef = EdgeReference<'a, E, Ix>;
type EdgeReferences = EdgeReferences<'a, E, Ix>;
/// Create an iterator over all edges in the graph, in indexed order.
///
/// Iterator element type is `EdgeReference<E, Ix>`.
fn edge_references(self) -> Self::EdgeReferences {
EdgeReferences {
iter: self.g.edges.iter().enumerate(),
}
}
}
impl<N, E, Ty, Ix> visit::EdgeCount for StableGraph<N, E, Ty, Ix>
where
Ty: EdgeType,
Ix: IndexType,
{
#[inline]
fn edge_count(&self) -> usize {
self.edge_count()
}
}
#[test]
fn stable_graph() {
let mut gr = StableGraph::<_, _>::with_capacity(0, 0);
let a = gr.add_node(0);
let b = gr.add_node(1);
let c = gr.add_node(2);
let _ed = gr.add_edge(a, b, 1);
println!("{:?}", gr);
gr.remove_node(b);
println!("{:?}", gr);
let d = gr.add_node(3);
println!("{:?}", gr);
gr.check_free_lists();
gr.remove_node(a);
gr.check_free_lists();
gr.remove_node(c);
gr.check_free_lists();
println!("{:?}", gr);
gr.add_edge(d, d, 2);
println!("{:?}", gr);
let e = gr.add_node(4);
gr.add_edge(d, e, 3);
println!("{:?}", gr);
for neigh in gr.neighbors(d) {
println!("edge {:?} -> {:?}", d, neigh);
}
gr.check_free_lists();
}
#[test]
fn dfs() {
use crate::visit::Dfs;
let mut gr = StableGraph::<_, _>::with_capacity(0, 0);
let a = gr.add_node("a");
let b = gr.add_node("b");
let c = gr.add_node("c");
let d = gr.add_node("d");
gr.add_edge(a, b, 1);
gr.add_edge(a, c, 2);
gr.add_edge(b, c, 3);
gr.add_edge(b, d, 4);
gr.add_edge(c, d, 5);
gr.add_edge(d, b, 6);
gr.add_edge(c, b, 7);
println!("{:?}", gr);
let mut dfs = Dfs::new(&gr, a);
while let Some(next) = dfs.next(&gr) {
println!("dfs visit => {:?}, weight={:?}", next, &gr[next]);
}
}
#[test]
fn test_retain_nodes() {
let mut gr = StableGraph::<_, _>::with_capacity(6, 6);
let a = gr.add_node("a");
let f = gr.add_node("f");
let b = gr.add_node("b");
let c = gr.add_node("c");
let d = gr.add_node("d");
let e = gr.add_node("e");
gr.add_edge(a, b, 1);
gr.add_edge(a, c, 2);
gr.add_edge(b, c, 3);
gr.add_edge(b, d, 4);
gr.add_edge(c, d, 5);
gr.add_edge(d, b, 6);
gr.add_edge(c, b, 7);
gr.add_edge(d, e, 8);
gr.remove_node(f);
assert_eq!(gr.node_count(), 5);
assert_eq!(gr.edge_count(), 8);
gr.retain_nodes(|frozen_gr, ix| frozen_gr[ix] >= "c");
assert_eq!(gr.node_count(), 3);
assert_eq!(gr.edge_count(), 2);
gr.check_free_lists();
}
#[test]
fn extend_with_edges() {
let mut gr = StableGraph::<_, _>::default();
let a = gr.add_node("a");
let b = gr.add_node("b");
let c = gr.add_node("c");
let _d = gr.add_node("d");
gr.remove_node(a);
gr.remove_node(b);
gr.remove_node(c);
gr.extend_with_edges(vec![(0, 1, ())]);
assert_eq!(gr.node_count(), 3);
assert_eq!(gr.edge_count(), 1);
gr.check_free_lists();
gr.extend_with_edges(vec![(5, 1, ())]);
assert_eq!(gr.node_count(), 4);
assert_eq!(gr.edge_count(), 2);
gr.check_free_lists();
}
#[test]
fn test_reverse() {
let mut gr = StableGraph::<_, _>::default();
let a = gr.add_node("a");
let b = gr.add_node("b");
gr.add_edge(a, b, 0);
let mut reversed_gr = gr.clone();
reversed_gr.reverse();
for i in gr.node_indices() {
itertools::assert_equal(gr.edges_directed(i, Incoming), reversed_gr.edges(i));
}
}