GlobalID

GlobalID.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using UnityEngine;
using Object = UnityEngine.Object;

// This is a System.Guid, except it can be serialized by Unity,
// so it can be used to permanently store the ID of an entity.

[Serializable, StructLayout(LayoutKind.Explicit)]
public struct GlobalID : IEquatable<GlobalID> {
    [FieldOffset(0), NonSerialized]  public Guid guid;
    [FieldOffset(0), SerializeField] public long guidPart1;
    [FieldOffset(8), SerializeField] public long guidPart2;
    
    public static GlobalID GenerateNewID() {
        return new GlobalID {
            guid = Guid.NewGuid()
        };
    }

    public bool IsSet() {
        return guidPart1 != 0 || guidPart2 != 0;
    }

    public override string ToString() {
        return guid.ToString();
    }
    
    public static bool TryParse(string guidString, out GlobalID result) {
        if (Guid.TryParse(guidString, out Guid guid)) {
            result = new GlobalID {
                guid = guid
            };
            return true;
        } else {
            result = default;
            return false;
        }
    }
    
    public bool Equals(GlobalID other) {
        return guid.Equals(other.guid);
    }
    
    public override bool Equals(object other) {
        if (other is GlobalID otherID) {
            return guid.Equals(otherID.guid);
        }
        return false;
    }
    
    public static bool operator ==(GlobalID lhs, GlobalID rhs) {
        return lhs.guid == rhs.guid;
    }
    
    public static bool operator !=(GlobalID lhs, GlobalID rhs) {
        return lhs.guid != rhs.guid;
    }
    
    public static bool operator >(GlobalID lhs, GlobalID rhs) {
        if (lhs.guidPart1 == rhs.guidPart1) {
            return lhs.guidPart2 > rhs.guidPart2;
        }
        return lhs.guidPart1 > rhs.guidPart1;
    }
    public static bool operator <(GlobalID lhs, GlobalID rhs) {
        if (lhs.guidPart1 == rhs.guidPart1) {
            return lhs.guidPart2 < rhs.guidPart2;
        }
        return lhs.guidPart1 < rhs.guidPart1;
    }
    

    public override int GetHashCode() {
        return guidPart1.GetHashCode() * 31 + guidPart2.GetHashCode();
    }
}