Data structures

We are going to implement the vertex and edge entities using an approach with structs, generics, and protocols. We are going to start building the basic blocks (vertex, edge), and then we will create further data structures on top of them (adjacency list, graph), and so on.

Vertex

We are going to add a new struct to represent the vertex entity. Create a new playground file in Xcode and name it B05101_7_AdjacencyList. In the Sources folder, add a new Swift file and name it Vertex.swift. Add the following code to this file:

public struct Vertex<T:Equatable>:Equatable {
    public var data:T
    public let index:Int
}

We have defined the Vertex struct and we have indicated that it uses some generic type, T. We also defined that the generic T must be Equatable. Conforming to the Equatable protocol helps us to make comparisons later.

What do we need to store enough information to represent a vertex? You can see that we defined two properties: some data of generic...