Created by:
admin
*published*
## Description:

### Class relationships

### On the literate code map additions

Language:
Javascript

Commit:
master

Tags:
featured-js

In computer science, a graph is an abstract data type that is meant to implement the undirected graph and directed graph concepts from mathematics, specifically the field of graph theory

A graph data structure consists of a finite (and possibly mutable) set of vertices or nodes or points, together with a set of unordered pairs of these vertices for an undirected graph or a set of ordered pairs for a directed graph. These pairs are known as edges, arcs, or lines for an undirected graph and as arrows, directed edges, directed arcs, or directed lines for a directed graph. The vertices may be part of the graph structure, or may be external entities represented by integer indices or references.

Text and source code from https://github.com/trekhleb/javascript-algorithms/tree/master/src/data-structures/graph

There were no relationships to reverse engineer so I added them manually with

`Graph "*" *--> GraphVertex : vertices`

`Graph "*" *--> GraphEdge : edges`

`GraphVertex "*" *--> GraphEdge : edges`

markup.

I've added a couple of literate code map "method" compartments containing code fragments and a little bit of commentary.

The PlantUML markup is

`class Graph {`

` `

` method("constructor", "isDirected = false")`

` The constructor looks like this:`

` ````

` this.vertices = {};`

` this.edges = {};`

` this.isDirected = isDirected;`

` ````

` This class doesn't actually create instances`

` of any other class - any such wiring is done`

` by callers of this classes e.g. via addEdge etc. xref("1", "source")`

` method("addEdge", "edge")`

` xref("1")`

` `

` This method doesn't just add edges to <b>this.edges</b>`

` `

` ````

` // Check if edge has been already added.`

` if (this.edges[edge.getKey()]) {`

` throw new Error('Edge has already been added before');`

` } else {`

` this.edges[edge.getKey()] = edge;`

` }`

` ````

` it also adds information to <b>this.vertices</b> `

` ````

` // Try to find and end start vertices.`

` let startVertex = this.getVertexByKey(edge.startVertex.getKey());`

` let endVertex = this.getVertexByKey(edge.endVertex.getKey());`

` // Insert start vertex if it wasn't inserted.`

` if (!startVertex) {`

` this.addVertex(edge.startVertex);`

` startVertex = this.getVertexByKey(edge.startVertex.getKey());`

` }`

` ````

`}`

Additional analysis could easily be done to add even more information to this diagram. This is just a beginning.

List of repository modules/files being visualised in the above diagram:

`src/data-structures/graph/Graph.js`

`src/data-structures/graph/GraphEdge.js`

`src/data-structures/graph/GraphVertex.js`