Factory.cs

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Threading.Tasks;
using System.Xml;
using Waher.Runtime.Inventory;
 
namespace TAG.Simulator
{
    public static class Factory
    {
        private static readonly Dictionary<string, ISimulationNode> nodeTypes = new Dictionary<string, ISimulationNode>();
        private static readonly Dictionary<string, KeyValuePair<string, Assembly>> schemas = new Dictionary<string, KeyValuePair<string, Assembly>>();
        private static bool initialized = false;
 
        public static void Initialize()
        {
            if (!initialized)
            {
                object[] Arguments = new object[] { null, null };
 
                foreach (Type T in Types.GetTypesImplementingInterface(typeof(ISimulationNode)))
                {
                    TypeInfo TI = T.GetTypeInfo();
                    if (TI.IsAbstract)
                        continue;
 
                    ISimulationNode Node = (ISimulationNode)Activator.CreateInstance(T, Arguments);
                    string Key = Node.Namespace + "#" + Node.LocalName;
 
                    if (nodeTypes.ContainsKey(Key))
                        throw new Exception("A class handling " + Key + " has already been registered.");
                    else
                        nodeTypes[Key] = Node;
 
                    string s = Node.Namespace;
                    if (!schemas.ContainsKey(s))
                        schemas[s] = new KeyValuePair<string, Assembly>(Node.SchemaResource, TI.Assembly);
                }
 
                initialized = true;
            }
        }
 
        public static bool TryGetSchemaResource(string Namespace, out KeyValuePair<string, Assembly> Result)
        {
            return schemas.TryGetValue(Namespace, out Result);
        }
 
        public static async Task<ISimulationNode> Create(XmlElement Definition, ISimulationNode Parent, Model Model)
        {
            string Key;
 
            if (!initialized)
                throw new NotSupportedException("Factory not initialized.");
 
            Key = Definition.NamespaceURI + "#" + Definition.LocalName;
            if (!nodeTypes.TryGetValue(Key, out ISimulationNode Result))
                throw new Exception("Unable to instantiate objects of type " + Definition.NamespaceURI + "#" + Definition.LocalName);
 
            Result = Result.Create(Parent, Model);
            await Result.FromXml(Definition);
 
            return Result;
        }
    }
}