Method AddVertex

pgraph/pgraph.go:231–253

AddVertex uses variadic input to add all listed vertices to the graph.

(xv ...Vertex)

// AddVertex uses variadic input to add all listed vertices to the graph.
func (obj *Graph) AddVertex(xv ...Vertex) {
	if obj.adjacency == nil { // initialize on first use
		obj.adjacency = make(map[Vertex]map[Vertex]Edge)
	}
	if obj.revadjmap == nil { // initialize on first use
		obj.revadjmap = make(map[Vertex]map[Vertex]Edge)
	}
	for _, v := range xv {
		if v == nil {
			panic("nil vertex")
		}
		// The inner maps start as nil and get allocated by AddEdge on
		// first use. Nil maps are safe to range over, read, len() and
		// delete() from, so only the writes in AddEdge need to care.
		// This halves the allocations for graphs full of vertices.
		if _, exists := obj.adjacency[v]; !exists {
			obj.adjacency[v] = nil
		}
		if _, exists := obj.revadjmap[v]; !exists {
			obj.revadjmap[v] = nil
		}
	}
}

// DeleteVertex uses variadic input to delete all listed vertices from the
// graph.