graph.h

#pragma once
#include <iostream>

using namespace std;

/**
 * Used to capture an edge with a weight 
 */
struct weightedEdge
{
    string subject;
    string object;
    int weight;
};

/** 
 * Used (when we already have the subject nodes)
 * to capture an object node and the associated
 * weight
 */
struct weightedNode
{
    string object;
    int weight;
};

// Creating our generic Id type
template <typename Id = int>
struct _weightedEdge
{
    Id subject;
    Id object;
    int weight;
};

template <typename Id = int>
struct _weightedNode
{
    Id object;
    int weight;
};

/**
 * The abstract data strucuture with which we 
 */
template <class NodeKind = string>
class Graph
{
public:
    virtual ~Graph();
    virtual int nodeCount();
    virtual int edgeCount();
    virtual void addEdge(NodeKind subject, NodeKind object, int weight);
    virtual vector<_weightedEdge<NodeKind>> weightedEdges(NodeKind subject);
    virtual _weightedEdge<NodeKind> lightestEdge(NodeKind subject);
};

// Algorithms such as djikstras are more efficient
// to implement on the *id* rather than doing conversions
// between the id rather than the more abstract graph
// so we create this struct with internals that we
// can use to create djikstras algoritm
template <typename Id = int>
struct GraphWithIdInternals
{
    int nodeCount();
    int edgeCount();
    Id toId(string subject);
    string fromId(Id id);
    vector<_weightedEdge<Id>> weightedEdges(Id subject);
    _weightedEdge<Id> lightestEdge(Id suject);
    void addEdge(string subject, string object, int weight);
};