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use alloc::collections::BTreeSet; /// `Vertices` returns the set of the vertices which comprise the dag. /// /// # Example /// /// ``` /// use btree_dag::{BTreeDag, AddVertex, Vertices}; /// let mut dag: BTreeDag<String> = BTreeDag::new(); /// /// assert_eq!(dag.vertices().len(), 0); /// ``` pub trait Vertices<T> where T: Ord, { fn vertices(&self) -> BTreeSet<&T>; } /// `AddVertex` adds the vertex x, if it is not there. /// /// # Example /// /// ``` /// use btree_dag::{BTreeDag, AddVertex, Vertices}; /// let mut dag: BTreeDag<String> = BTreeDag::new(); /// dag.add_vertex(String::from("origin")); /// /// assert_eq!(dag.vertices().len(), 1); /// ``` pub trait AddVertex<T> where T: Ord, { fn add_vertex(&mut self, x: T) -> Option<BTreeSet<T>>; } /// `AddEdge` add an edge from the vertex x to the vertex y, if it is not there. /// /// # Example /// /// ``` /// extern crate alloc; /// use alloc::collections::btree_set::BTreeSet; /// use btree_dag::{BTreeDag, AddVertex, AddEdge, GetVertexValue}; /// use btree_dag::error::Error; /// let mut dag: BTreeDag<String> = BTreeDag::new(); /// dag.add_vertex(String::from("origin")); /// dag.add_vertex(String::from("destination")); /// dag.add_edge(String::from("origin"), String::from("destination")); /// /// let x_value: &BTreeSet<String> = dag.get_vertex_value(String::from("origin")).unwrap(); /// assert!(x_value.contains(&String::from("destination"))); /// /// assert!(dag.get_vertex_value(String::from("destination")).unwrap().is_empty()); /// ``` pub trait AddEdge<T> { type Error; fn add_edge(&mut self, x: T, y: T) -> Result<(), Self::Error>; } /// `GetVertexValue` returns the value associated with the vertex x. /// /// # Example /// /// ``` /// extern crate alloc; /// use alloc::collections::btree_set::BTreeSet; /// use btree_dag::{BTreeDag, AddVertex, AddEdge, GetVertexValue}; /// let mut dag: BTreeDag<String> = BTreeDag::new(); /// dag.add_vertex(String::from("origin")); /// dag.add_vertex(String::from("destination")); /// dag.add_edge(String::from("origin"), String::from("destination")); /// /// let vertex_value: &BTreeSet<String> = dag.get_vertex_value(String::from("origin")).unwrap(); /// assert!(vertex_value.contains(&String::from("destination"))); /// ``` pub trait GetVertexValue<T> where T: Ord, { fn get_vertex_value(&self, x: T) -> Option<&BTreeSet<T>>; } /// `RemoveEdge` removes the edge from the vertex x to the vertex y, if it is there. /// /// # Example /// /// ``` /// use btree_dag::{BTreeDag, AddVertex, AddEdge, RemoveEdge, GetVertexValue}; /// let mut dag: BTreeDag<String> = BTreeDag::new(); /// dag.add_vertex(String::from("origin")); /// dag.add_vertex(String::from("destination")); /// dag.add_edge(String::from("origin"), String::from("destination")); /// /// /// dag.remove_edge(String::from("origin"), String::from("destination")); /// /// // Note: deletion of edges cascade i.e. the edge is also deleted from any incident /// // vertices' adjacency lists. /// assert_eq!(dag.get_vertex_value(String::from("origin")).unwrap().len(), 0); /// assert_eq!(dag.get_vertex_value(String::from("destination")).unwrap().len(), 0); /// ``` pub trait RemoveEdge<T> { type Error; fn remove_edge(&mut self, x: T, y: T) -> Result<(), Self::Error>; } /// `RemoveVertex` removes the vertex x, if it is there. /// /// # Example /// /// ``` /// extern crate alloc; /// use alloc::collections::btree_set::BTreeSet; /// use btree_dag::{BTreeDag, AddVertex, AddEdge, RemoveVertex, GetVertexValue, Vertices}; /// let mut dag: BTreeDag<String> = BTreeDag::new(); /// dag.add_vertex(String::from("origin")); /// dag.add_vertex(String::from("destination")); /// dag.add_edge(String::from("origin"), String::from("destination")); /// /// /// dag.remove_vertex(String::from("destination")); /// assert_eq!(dag.vertices().len(), 1); /// /// // Note: removing a vertex will also cascade delete any incident edges. /// assert_eq!(dag.get_vertex_value(String::from("origin")).unwrap().len(), 0); /// ``` pub trait RemoveVertex<T> where T: Ord, { type Error; fn remove_vertex(&mut self, x: T) -> Result<(), Self::Error>; } /// `Adjacent` tests whether there is an edge from the vertex x to the vertex y. /// An error is thrown if either x, or y do not exist. By definition of adjacent there /// must exist an edge e, with value (x, y) in order for vertices x, and y to be /// considered adjacent. /// /// # Example /// /// ``` /// use btree_dag::{BTreeDag, AddVertex, AddEdge, Adjacent}; /// use btree_dag::error::Error; /// let mut dag: BTreeDag<String> = BTreeDag::new(); /// dag.add_vertex(String::from("origin")); /// dag.add_vertex(String::from("destination")); /// dag.add_edge(String::from("origin"), String::from("destination")); /// /// assert!(dag.adjacent(String::from("origin"), String::from("destination")).unwrap()); /// // Note: the dag is directed, and the definition of adjacent /// // can be phrased, if there exists a relationship from x to y. Therefore /// // A and B adjacent implies B and A cannot be adjacent. /// let err: Error = dag.add_edge(String::from("destination"), String::from("origin")).unwrap_err(); /// assert_eq!(err, Error::EdgeExistsError) /// ``` pub trait Adjacent<T> { type Error; fn adjacent(&self, x: T, y: T) -> Result<bool, Self::Error>; } /// `Connections` lists all vertices y such that there is an edge from the vertex x to /// the vertex y. An error is thrown if x does not exist. /// /// # Example /// /// ``` /// use btree_dag::{BTreeDag, AddVertex, AddEdge, Connections}; /// let mut dag: BTreeDag<String> = BTreeDag::new(); /// dag.add_vertex(String::from("origin")); /// dag.add_vertex(String::from("destination")); /// dag.add_edge(String::from("origin"), String::from("destination")); /// /// assert!(dag.connections(String::from("origin")).unwrap().contains(&String::from("destination"))); /// ``` pub trait Connections<T> { fn connections(&self, x: T) -> Option<&BTreeSet<T>>; }