Add remove functions for node and edge (#189)

Author: bwetherfield

Sources/DataStructures/Graph/Protocols/GraphProtocol.swift

@@ -25,9 +25,9 @@ public protocol GraphProtocol {
     var edges: Set<Edge> { get }
 
     // MARK: - Instance Methods
-
-    /// Removes the edge from the given `source` to the given `destination`.
-    mutating func removeEdge(from source: Node, to destination: Node)
+    
+    /// Removes `edge` from graph.
+    mutating func remove(_ edge: Edge)
 }
 
 extension GraphProtocol {
@@ -37,6 +37,19 @@ extension GraphProtocol {
     public mutating func insert(_ node: Node) {
         nodes.insert(node)
     }
+    
+    /// Removes the edge from the given `source` to the given `destination`.
+    @inlinable
+    public mutating func removeEdge(from source: Node, to destination: Node) {
+        remove(Edge(source, destination))
+    }
+    
+    /// Removes the given `node` and removes all edges that contain it.
+    @inlinable
+    public mutating func remove(_ node: Node) {
+        nodes.remove(node)
+        edges.filter { $0.contains(node) }.forEach { remove($0) }
+    }
 
     /// - Returns: `true` if the `GraphProtocol`-conforming type value contains the given `node`.
     /// Otherwise, `false`.

Sources/DataStructures/Graph/Protocols/UnweightedGraphProtocol.swift

@@ -43,11 +43,11 @@ extension UnweightedGraphProtocol {
         insert(destination)
         edges.insert(Edge(source,destination))
     }
-
-    /// Removes the edge between the given `source` and `destination` nodes.
+    
+    /// Removes `edge` from graph.
     @inlinable
-    public mutating func removeEdge(from source: Node, to destination: Node) {
-        edges.remove(Edge(source,destination))
+    public mutating func remove(_ edge: Edge) {
+        edges.remove(edge)
     }
 }
 

Sources/DataStructures/Graph/Protocols/WeightedGraphProtocol.swift

@@ -69,14 +69,9 @@ extension WeightedGraphProtocol {
         weights[Edge(source,destination)] = weight
     }
 
-    /// Removes the edge between the given `source` and `destination` nodes.
+    /// Remove `edge` from graph.
     @inlinable
-    public mutating func removeEdge(from source: Node, to destination: Node) {
-        removeEdge(Edge(source, destination))
-    }
-
-    @inlinable
-    public mutating func removeEdge(_ edge: Edge) {
+    public mutating func remove(_ edge: Edge) {
         weights[edge] = nil
     }