Add reserve_vertices and reserve_edges to GraphTopologyAddition

src/traits.rs

@@ -174,7 +174,6 @@ pub trait GraphTopology {
     fn incidence_cursor(&self, v: Self::Vertex) -> Self::IncidenceCursor;
 }
 
-// TODO: Add functions to reserve memory for vertices and edges.
 /// A trait that adds construction operations to an undirected graph topology.
 ///
 /// This trait provides methods for addition of vertices and edges, and capacity management in an
@@ -186,6 +185,20 @@ pub trait GraphTopologyAddition: GraphTopology {
     /// Returns the total number of edges the graph can hold without reallocating.
     fn edge_capacity(&self) -> usize;
 
+    /// Reserves capacity for at least `additional` more vertices. Does nothing if capacity is
+    /// already sufficient.
+    ///
+    /// Use this before adding multiple vertices to avoid incremental growth on each call to
+    /// [`add_vertex`].
+    fn reserve_vertices(&mut self, additional: usize);
+
+    /// Reserves capacity for at least `additional` more edges. Does nothing if capacity is already
+    /// sufficient.
+    ///
+    /// Use this before adding multiple edges to avoid incremental growth on each call to
+    /// [`add_edge`].
+    fn reserve_edges(&mut self, additional: usize);
+
     /// Adds a new isolated vertex and returns its handle.
     fn add_vertex(&mut self) -> Self::Vertex;