Graph.cs

Go to the documentation of this file.

#region License
/*This file is part of Satsuma Graph Library
Copyright © 2013 Balázs Szalkai

This software is provided 'as-is', without any express or implied
warranty. In no event will the authors be held liable for any damages
arising from the use of this software.

Permission is granted to anyone to use this software for any purpose,
including commercial applications, and to alter it and redistribute it
freely, subject to the following restrictions:

   1. The origin of this software must not be misrepresented; you must not
   claim that you wrote the original software. If you use this software
   in a product, an acknowledgment in the product documentation would be
   appreciated but is not required.

   2. Altered source versions must be plainly marked as such, and must not be
   misrepresented as being the original software.

   3. This notice may not be removed or altered from any source
   distribution.*/
#endregion

using System;
using System.Collections.Generic;

namespace Satsuma
{
    public struct Node : IEquatable<Node>
    {
        public long Id { get; private set; }

        public Node(long id) 
            : this()
        {
            Id = id;
        }

        public static Node Invalid
        {
            get { return new Node(0); }
        }

        public bool Equals(Node other)
        {
            return Id == other.Id;
        }

        public override bool Equals(object obj)
        {
            if (obj is Node) return Equals((Node)obj);
            return false;
        }

        public override int GetHashCode()
        {
             return Id.GetHashCode();
        }

        public override string ToString()
        {
            return "#" + Id;
        }

        public static bool operator ==(Node a, Node b)
        {
            return a.Equals(b);
        }

        public static bool operator !=(Node a, Node b)
        {
            return !(a == b);
        }
    }

    public struct Arc : IEquatable<Arc>
    {
        public long Id { get; private set; }

        public Arc(long id)
            : this()
        {
            Id = id;
        }

        public static Arc Invalid
        {
            get { return new Arc(0); }
        }

        public bool Equals(Arc other)
        {
            return Id == other.Id;
        }

        public override bool Equals(object obj)
        {
            if (obj is Arc) return Equals((Arc)obj);
            return false;
        }

        public override int GetHashCode()
        {
            return Id.GetHashCode();
        }

        public override string ToString()
        {
            return "|" + Id;
        }

        public static bool operator ==(Arc a, Arc b)
        {
            return a.Equals(b);
        }

        public static bool operator !=(Arc a, Arc b)
        {
            return !(a == b);
        }
    }

    public enum Directedness
    {
        Directed,
        Undirected
    }

    public interface IBuildableGraph : IClearable
    {
        Node AddNode();
        Arc AddArc(Node u, Node v, Directedness directedness);
    }

    public interface IDestroyableGraph : IClearable
    {
        bool DeleteNode(Node node);
        bool DeleteArc(Arc arc);
    }

    public interface IArcLookup
    {
        Node U(Arc arc);
        Node V(Arc arc);
        bool IsEdge(Arc arc);
    }

    public static class ArcLookupExtensions
    {
        public static string ArcToString(this IArcLookup graph, Arc arc)
        {
            if (arc == Arc.Invalid) return "Arc.Invalid";
            return graph.U(arc) + (graph.IsEdge(arc) ? "<-->" : "--->") + graph.V(arc);
        }

        public static Node Other(this IArcLookup graph, Arc arc, Node node)
        {
            Node u = graph.U(arc);
            if (u != node) return u;
            return graph.V(arc);
        }

        public static Node[] Nodes(this IArcLookup graph, Arc arc, bool allowDuplicates = true)
        {
            var u = graph.U(arc);
            var v = graph.V(arc);
            if (!allowDuplicates && u == v) return new Node[] { u };
            return new Node[] { u, v };
        }
    }

    public enum ArcFilter
    {
        All,
        Edge,
        Forward,
        Backward
    }

    public interface IGraph : IArcLookup
    {
        IEnumerable<Node> Nodes();
        IEnumerable<Arc> Arcs(ArcFilter filter = ArcFilter.All);
        IEnumerable<Arc> Arcs(Node u, ArcFilter filter = ArcFilter.All);
        IEnumerable<Arc> Arcs(Node u, Node v, ArcFilter filter = ArcFilter.All);

        int NodeCount();
        int ArcCount(ArcFilter filter = ArcFilter.All);
        int ArcCount(Node u, ArcFilter filter = ArcFilter.All);
        int ArcCount(Node u, Node v, ArcFilter filter = ArcFilter.All);

        bool HasNode(Node node);
        bool HasArc(Arc arc);
    }

    public sealed class CustomGraph : Supergraph
    {
        public CustomGraph()
            : base(null) { }
    }
}