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-rw-r--r--graph/src/adlist.rs2
-rw-r--r--graph/src/adset.rs2
-rw-r--r--graph/src/builder.rs4
-rw-r--r--graph/src/labelled/binary.rs406
-rw-r--r--graph/src/labelled/double.rs9
-rw-r--r--graph/src/lib.rs31
6 files changed, 428 insertions, 26 deletions
diff --git a/graph/src/adlist.rs b/graph/src/adlist.rs
index ba9afb8..ba3077e 100644
--- a/graph/src/adlist.rs
+++ b/graph/src/adlist.rs
@@ -201,7 +201,7 @@ impl Builder for ALGBuilder {
/// implement a customized builder.
fn remove_edge<F>(&mut self, source: usize, target: usize, _predicate: F) -> Result<(), Error>
where
- F: Fn(Self::Label) -> bool,
+ F: FnMut(Self::Label) -> bool,
{
let nodes_len = self.nodes.len();
diff --git a/graph/src/adset.rs b/graph/src/adset.rs
index adf2aaf..a72935a 100644
--- a/graph/src/adset.rs
+++ b/graph/src/adset.rs
@@ -215,7 +215,7 @@ impl Builder for ASGBuilder {
fn remove_edge<F>(&mut self, source: usize, target: usize, _predicate: F) -> Result<(), Error>
where
- F: Fn(Self::Label) -> bool,
+ F: FnMut(Self::Label) -> bool,
{
let nodes_len = self.nodes.len();
diff --git a/graph/src/builder.rs b/graph/src/builder.rs
index 5505e4f..b04e7f6 100644
--- a/graph/src/builder.rs
+++ b/graph/src/builder.rs
@@ -40,7 +40,7 @@ pub trait Builder: Default {
/// target should be removed.
fn remove_edge<F>(&mut self, source: usize, target: usize, predicate: F) -> Result<(), Error>
where
- F: Fn(Self::Label) -> bool;
+ F: FnMut(Self::Label) -> bool;
/// Convert the builder into a graph.
///
@@ -89,5 +89,5 @@ pub trait BuilderMut {
/// target should be removed.
fn remove_edge<F>(&mut self, source: usize, target: usize, predicate: F) -> Result<(), Error>
where
- F: Fn(Self::Label) -> bool;
+ F: FnMut(Self::Label) -> bool;
}
diff --git a/graph/src/labelled/binary.rs b/graph/src/labelled/binary.rs
index 439505d..67d86f9 100644
--- a/graph/src/labelled/binary.rs
+++ b/graph/src/labelled/binary.rs
@@ -2,24 +2,89 @@
//! labels and each node knows about its parents.
use super::*;
-use crate::ParentsGraph;
+use crate::{Parent, ParentsGraph};
-use std::collections::{HashMap as Map, HashSet as Set};
+use std::{
+ collections::{hash_map::Iter as MapIter, HashMap as Map},
+ slice::Iter,
+};
use crate::builder::BuilderMut;
+/// An ad-hoc `IndexSet` for children.
+#[derive(Debug, Clone, Default)]
+struct PLChildren {
+ children: Vec<usize>,
+ indices: Map<usize, usize>,
+}
+
+impl PLChildren {
+ fn iter(&self) -> Iter<'_, usize> {
+ self.children.iter()
+ }
+
+ fn len(&self) -> usize {
+ self.children.len()
+ }
+
+ fn is_empty(&self) -> bool {
+ self.children.is_empty()
+ }
+
+ fn contains(&self, key: &usize) -> bool {
+ self.indices.contains_key(key)
+ }
+
+ // The return value matters not for me.
+ fn insert(&mut self, key: usize) {
+ if let Some(key_index) = self.indices.get(&key) {
+ debug_assert!(*key_index < self.children.len());
+
+ *self.children.get_mut(*key_index).unwrap() = key;
+ } else {
+ let key_index = self.children.len();
+ self.indices.insert(key, key_index);
+ self.children.push(key);
+ }
+ }
+
+ /// Remove an element from children.
+ ///
+ /// We must preserve the order of elements, so we have to shift
+ /// every element that follows it, which leads to a slow
+ /// performance. So try to avoid removing edges, if possible.
+ fn remove(&mut self, key: usize) {
+ let key_index = if let Some(key_index_result) = self.indices.get(&key) {
+ *key_index_result
+ } else {
+ // If the key is not contained in children, we have
+ // nothing to do.
+ return;
+ };
+
+ let children_len = self.children.len();
+
+ debug_assert!(key_index < children_len);
+
+ for i in (key_index + 1)..children_len {
+ let key = self.children.get(i).unwrap();
+ *self.indices.get_mut(key).unwrap() -= 1;
+ }
+
+ self.children.remove(key_index);
+ }
+}
+
/// A node has some children, some parents, and a label.
#[derive(Debug, Clone)]
struct PLNode<T: GraphLabel> {
- children: Set<usize>,
- // REVIEW: If performance for removing edges is a bottleneck, use
- // a hash set here.
- parents: Vec<usize>,
+ children: PLChildren,
+ parents: Map<usize, usize>,
label: T,
}
impl<T: GraphLabel> PLNode<T> {
- fn new(children: Set<usize>, parents: Vec<usize>, label: T) -> Self {
+ fn new(children: PLChildren, parents: Map<usize, usize>, label: T) -> Self {
Self {
children,
parents,
@@ -62,7 +127,7 @@ impl<T: GraphLabel> Default for PLGraph<T> {
}
impl<T: GraphLabel> Graph for PLGraph<T> {
- type Iter<'a> = std::iter::Copied<std::collections::hash_set::Iter<'a, usize>>
+ type Iter<'a> = std::iter::Copied<Iter<'a, usize>>
where
Self: 'a;
@@ -103,6 +168,7 @@ impl<T: GraphLabel> Graph for PLGraph<T> {
}
}
+ #[inline]
fn has_edge(&self, source: usize, target: usize) -> Result<bool, Error> {
if let Some(node) = self.nodes.get(source) {
if !self.has_node(target) {
@@ -116,7 +182,7 @@ impl<T: GraphLabel> Graph for PLGraph<T> {
}
fn replace_by_builder(&mut self, _builder: impl Builder<Result = Self>) {
- unimplemented!("for later")
+ todo!()
}
fn print_viz(&self, _filename: &str) -> Result<(), std::io::Error> {
@@ -124,14 +190,53 @@ impl<T: GraphLabel> Graph for PLGraph<T> {
}
}
+/// An iterator of parents.
+///
+/// This is to avoid a boxed allocation.
+#[derive(Debug, Clone)]
+pub struct ParentIter<'a> {
+ /// MapIter yields (&usize, &usize), so we need to dereference
+ /// that.
+ parents: MapIter<'a, usize, usize>,
+}
+
+impl<'a> ParentIter<'a> {
+ fn new(parents: MapIter<'a, usize, usize>) -> Self {
+ Self { parents }
+ }
+}
+
+impl<'a> Iterator for ParentIter<'a> {
+ type Item = Parent;
+
+ #[inline]
+ fn next(&mut self) -> Option<Self::Item> {
+ self.parents
+ .next()
+ .map(|(key, value)| Parent::new(*key, *value))
+ }
+
+ #[inline]
+ fn size_hint(&self) -> (usize, Option<usize>) {
+ self.parents.size_hint()
+ }
+}
+
+impl<'a> ExactSizeIterator for ParentIter<'a> {
+ #[inline]
+ fn len(&self) -> usize {
+ self.parents.len()
+ }
+}
+
impl<T: GraphLabel> ParentsGraph for PLGraph<T> {
- type Iter<'a> = std::iter::Copied<std::slice::Iter<'a, usize>>
+ type Iter<'a> = ParentIter<'a>
where Self: 'a;
#[inline]
fn parents_of(&self, node_id: usize) -> Result<<Self as ParentsGraph>::Iter<'_>, Error> {
if let Some(node) = self.nodes.get(node_id) {
- Ok(node.parents.iter().copied())
+ Ok(ParentIter::new(node.parents.iter()))
} else {
Err(Error::IndexOutOfBounds(node_id, self.nodes.len()))
}
@@ -203,10 +308,12 @@ impl<'a, T: GraphLabel> BuilderMut for PLGBuilderMut<'a, T> {
where
Self::Label: 'b;
+ #[inline]
fn from_graph_mut(graph: &mut Self::Graph) -> Self::ResultBuilder<'_> {
PLGBuilderMut { graph }
}
+ #[inline]
fn add_vertex(&mut self, label: Self::Label) -> usize {
if let Some(old) = self.graph.label_index_map.get(&label) {
*old
@@ -222,11 +329,16 @@ impl<'a, T: GraphLabel> BuilderMut for PLGBuilderMut<'a, T> {
}
}
+ #[inline]
fn add_edge(&mut self, source: usize, target: usize, _label: Self::Label) -> Result<(), Error> {
if self.graph.has_edge(source, target)? {
- return Err(Error::DuplicatedEdge(source, target));
+ return Ok(());
}
+ // The validity of source and target is guaranteed now.
+
+ let parent_child_index = self.graph.degree(source).unwrap();
+
self.graph
.nodes
.get_mut(source)
@@ -239,35 +351,295 @@ impl<'a, T: GraphLabel> BuilderMut for PLGBuilderMut<'a, T> {
.get_mut(target)
.unwrap()
.parents
- .push(source);
+ .insert(source, parent_child_index);
Ok(())
}
+ /// Remove an edge from the source to the target.
+ ///
+ /// Since some graphs are labelled, the users are allowed to pass
+ /// a predicate to determine if an edge from the source to the
+ /// target should be removed.
+ ///
+ /// # Performance
+ ///
+ /// Removal is slow since we need to keep the order of the elements.
fn remove_edge<F>(&mut self, source: usize, target: usize, _predicate: F) -> Result<(), Error>
where
- F: Fn(Self::Label) -> bool,
+ F: FnMut(Self::Label) -> bool,
{
if !self.graph.has_edge(source, target)? {
return Ok(());
}
+ // Both source and target are valid indices now.
+
+ let child_index = *self
+ .graph
+ .nodes
+ .get(target)
+ .unwrap()
+ .parents
+ .get(&source)
+ .unwrap();
+
+ let source_degree = self.graph.degree(source).unwrap();
+
+ // Decrement the relevant children's parents index.
+ for i in (child_index + 1)..source_degree {
+ let child = *self
+ .graph
+ .nodes
+ .get(source)
+ .unwrap()
+ .children
+ .children
+ .get(i)
+ .unwrap();
+
+ *self
+ .graph
+ .nodes
+ .get_mut(child)
+ .unwrap()
+ .parents
+ .get_mut(&source)
+ .unwrap() -= 1;
+ }
+
self.graph
.nodes
.get_mut(source)
.unwrap()
.children
- .remove(&target);
+ .remove(target);
self.graph
.nodes
.get_mut(target)
.unwrap()
.parents
- .retain(|parent| *parent != source);
+ .remove(&source);
+
+ Ok(())
+ }
+}
+
+#[cfg(test)]
+mod binary_test {
+ use super::*;
+ use std::collections::HashSet as Set;
+
+ macro_rules! set {
+ ($type:tt) => { Set::<$type>::default() };
+ ($($num:expr),*) => {
+ {
+ let mut set: Set<_> = Set::default();
+ $(set.insert($num);)*
+ set
+ }
+ };
+ }
+
+ #[test]
+ fn test_graph_apis() -> Result<(), Error> {
+ let mut graph: PLGraph<usize> = Default::default();
+
+ // testing empty graph
+ assert!(graph.is_empty());
+
+ let mut builder = PLGBuilderMut::from_graph_mut(&mut graph);
+
+ // testing adding an empty node
+ assert_eq!(builder.add_vertex(0), 0);
+
+ // testing nodes_len
+ assert_eq!(graph.nodes_len(), 1);
+
+ let mut builder = PLGBuilderMut::from_graph_mut(&mut graph);
+
+ // testing more vertices and edges
+
+ builder.add_vertex(1);
+ builder.add_vertex(2);
+ builder.add_vertex(3);
+ builder.add_vertex(4);
+ builder.add_vertex(5);
+
+ builder.add_edge(1, 0, 0)?;
+ builder.add_edge(2, 0, 0)?;
+ builder.add_edge(2, 1, 0)?;
+ builder.add_edge(3, 0, 0)?;
+ builder.add_edge(3, 2, 0)?;
+ builder.add_edge(4, 1, 0)?;
+ builder.add_edge(4, 2, 0)?;
+ builder.add_edge(5, 2, 0)?;
+ builder.add_edge(5, 3, 0)?;
+ builder.add_edge(5, 1, 0)?;
+
+ // testing adding a duplicatedly labelled node
+ assert_eq!(builder.add_vertex(0), 0);
+
+ let graph = graph;
+
+ // ensuring the correct length
+ assert_eq!(graph.nodes_len(), 6);
+
+ // testing children_of
+ assert_eq!(graph.children_of(5)?.collect::<Set<_>>(), set!(1, 3, 2));
+
+ // testing parents_of
+
+ assert_eq!(
+ graph.parents_of(0)?.collect::<Set<_>>(),
+ set!(Parent::new(1, 0), Parent::new(2, 0), Parent::new(3, 0))
+ );
+
+ assert_eq!(
+ graph.parents_of(1)?.collect::<Set<_>>(),
+ set!(Parent::new(2, 1), Parent::new(4, 0), Parent::new(5, 2))
+ );
+
+ assert_eq!(graph.parents_of(5)?.len(), 0);
+
+ // testing degree
+ assert_eq!(graph.degree(4)?, 2);
+
+ // testing is_empty_node
+ assert!(graph.is_empty_node(0)?);
+ assert!(!graph.is_empty_node(1)?);
+
+ // testing has_edge
+ assert!(graph.has_edge(3, 2)?);
+ assert!(!graph.has_edge(3, 1)?);
+ assert!(matches!(
+ graph.has_edge(3, 6),
+ Err(Error::IndexOutOfBounds(6, 6))
+ ));
Ok(())
}
}
-// TODO: tests
+#[cfg(test)]
+mod test_plgraph_builder {
+ use super::*;
+
+ #[test]
+ fn test_builder() -> Result<(), Box<dyn std::error::Error>> {
+ let mut graph = PLGraph::<usize>::default();
+ let mut builder = PLGBuilderMut::from_graph_mut(&mut graph);
+
+ // Add five nodes
+ builder.add_vertex(0);
+ builder.add_vertex(1);
+ builder.add_vertex(2);
+ builder.add_vertex(3);
+ builder.add_vertex(4);
+
+ // println!("five empty nodes: {builder:?}");
+
+ // Link each node to its successor and link the last node with
+ // the first one to form a cycle.
+ for i in 0..5 {
+ builder.add_edge(i, if i < 4 { i + 1 } else { 0 }, 0)?;
+ }
+
+ // println!("a cycle of five nodes: {builder:?}");
+
+ // Remove the link from the last node to the first node.
+ builder.remove_edge(4, 0, |_| true)?;
+
+ // println!("a line of five nodes: {builder:?}");
+
+ // build a graph
+
+ let graph = graph;
+
+ println!("final graph: {graph:?}");
+
+ Ok(())
+ }
+
+ #[test]
+ fn test_errors() -> Result<(), Box<dyn std::error::Error>> {
+ let mut graph = PLGraph::<usize>::default();
+ let mut builder = PLGBuilderMut::from_graph_mut(&mut graph);
+
+ // Add five nodes
+ builder.add_vertex(0);
+ builder.add_vertex(1);
+ builder.add_vertex(2);
+ builder.add_vertex(3);
+ builder.add_vertex(4);
+
+ // println!("five empty nodes: {builder:?}");
+
+ // Errors in add_edge
+
+ // println!();
+ // println!("Testing errors in add_edge:");
+ // println!();
+
+ assert!(matches!(
+ builder.add_edge(0, 5, 0),
+ Err(Error::IndexOutOfBounds(5, 5))
+ ));
+
+ // println!("Right error for an index out of bounds as the target");
+
+ assert!(matches!(
+ builder.add_edge(10, 5, 0),
+ Err(Error::IndexOutOfBounds(10, 5))
+ ));
+
+ // println!("Right error for an index out of bounds as the source");
+
+ assert!(matches!(
+ builder.add_edge(10, 50, 0),
+ Err(Error::IndexOutOfBounds(10, 5))
+ ));
+
+ // println!("Right error for both indices out of bounds");
+
+ // Errors in remove_edge
+
+ // println!();
+ // println!("Testing errors in remove_edge:");
+ // println!();
+
+ assert!(matches!(
+ builder.remove_edge(0, 5, |_| true),
+ Err(Error::IndexOutOfBounds(5, 5))
+ ));
+
+ // println!("Right error for an index out of bounds as the target");
+
+ assert!(matches!(
+ builder.remove_edge(10, 5, |_| true),
+ Err(Error::IndexOutOfBounds(10, 5))
+ ));
+
+ // println!("Right error for an index out of bounds as the source");
+
+ assert!(matches!(
+ builder.remove_edge(10, 50, |_| true),
+ Err(Error::IndexOutOfBounds(10, 5))
+ ));
+
+ // println!("Right error for both indices out of bounds");
+
+ assert!(builder.remove_edge(0, 1, |_| true).is_ok());
+
+ // println!("No errors for removing a non-existing edge");
+
+ // println!();
+
+ let graph = graph;
+
+ println!("final graph: {graph:?}");
+
+ Ok(())
+ }
+}
diff --git a/graph/src/labelled/double.rs b/graph/src/labelled/double.rs
index 53b5dc8..4ab8a38 100644
--- a/graph/src/labelled/double.rs
+++ b/graph/src/labelled/double.rs
@@ -554,9 +554,14 @@ impl<T: GraphLabel> Builder for DLGBuilder<T> {
Ok(())
}
- fn remove_edge<F>(&mut self, source: usize, target: usize, predicate: F) -> Result<(), Error>
+ fn remove_edge<F>(
+ &mut self,
+ source: usize,
+ target: usize,
+ mut predicate: F,
+ ) -> Result<(), Error>
where
- F: Fn(Self::Label) -> bool,
+ F: FnMut(Self::Label) -> bool,
{
let nodes_len = self.nodes.len();
diff --git a/graph/src/lib.rs b/graph/src/lib.rs
index 26159c6..6813df3 100644
--- a/graph/src/lib.rs
+++ b/graph/src/lib.rs
@@ -214,12 +214,37 @@ impl<T: Hash + Eq + PartialEq + Clone + Copy + Ord + PartialOrd + Display + Debu
{
}
+/// We need both the node index of a parent and the edge index of the
+/// child that points to this parent.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+pub struct Parent(usize, usize);
+
+impl Parent {
+ /// Return the index of the parent node.
+ #[inline]
+ pub fn node(&self) -> usize {
+ self.0
+ }
+
+ /// Return the index of the edge that points to the child.
+ #[inline]
+ pub fn edge(&self) -> usize {
+ self.1
+ }
+
+ /// Construct a parent strucure.
+ #[inline]
+ pub fn new(node: usize, edge: usize) -> Self {
+ Self(node, edge)
+ }
+}
+
/// A parents-knowing graph can return an iterator of parents for any
/// node.
pub trait ParentsGraph: Graph {
/// The type of an iterator that goes through the parents of a
/// node.
- type Iter<'a>: Iterator<Item = usize> + 'a
+ type Iter<'a>: Iterator<Item = Parent> + 'a
where
Self: 'a;
@@ -340,14 +365,14 @@ mod test_cycle_detection {
let graph = builder.build_ref();
- assert_eq!(graph.contains_cycles()?, true);
+ assert!(!graph.contains_cycles()?);
// Remove the link from the last node to the first node.
builder.remove_edge(4, 0, |_| true)?;
let graph = builder.build();
- assert_eq!(graph.contains_cycles()?, false);
+ assert!(!graph.contains_cycles()?);
Ok(())
}