source: branches/2929_PrioritizedGrammarEnumeration/HeuristicLab.Persistence/3.3/Default/CompositeSerializers/NumberEnumerable2StringSerializer.cs

#region License Information
/* HeuristicLab
 * Copyright (C) 2002-2018 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
 *
 * This file is part of HeuristicLab.
 *
 * HeuristicLab is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * HeuristicLab is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with HeuristicLab. If not, see <http://www.gnu.org/licenses/>.
 */
#endregion

using System;
using System.Collections.Generic;
using System.Reflection;
using System.Text;
using HeuristicLab.Persistence.Auxiliary;
using HeuristicLab.Persistence.Core;
using HeuristicLab.Persistence.Default.CompositeSerializers.Storable;
using HeuristicLab.Persistence.Interfaces;

namespace HeuristicLab.Persistence.Default.CompositeSerializers {

  [StorableClass]
  internal sealed class NumberEnumerable2StringSerializer : ICompositeSerializer {

    [StorableConstructor]
    private NumberEnumerable2StringSerializer(bool deserializing) { }
    public NumberEnumerable2StringSerializer() { }

    public int Priority {
      get { return 200; }
    }

    private static readonly Number2StringSerializer numberConverter =
      new Number2StringSerializer();

    private static readonly Dictionary<Type, Type> interfaceCache = new Dictionary<Type, Type>();
    private static readonly object locker = new object();

    public Type GetGenericEnumerableInterface(Type type) {
      lock (locker) {
        if (interfaceCache.ContainsKey(type))
          return interfaceCache[type];
        foreach (Type iface in type.GetInterfaces()) {
          if (iface.IsGenericType &&
            iface.GetGenericTypeDefinition() == typeof(IEnumerable<>) &&
            numberConverter.CanSerialize(iface.GetGenericArguments()[0])) {
            interfaceCache.Add(type, iface);
            return iface;
          }
        }
        interfaceCache.Add(type, null);
      }
      return null;
    }

    public bool ImplementsGenericEnumerable(Type type) {
      return GetGenericEnumerableInterface(type) != null;
    }

    public bool HasAddMethod(Type type) {
      return
        type.GetMethod("Add") != null &&
        type.GetMethod("Add").GetParameters().Length == 1 &&
        type.GetConstructor(
          BindingFlags.Public |
          BindingFlags.NonPublic |
          BindingFlags.Instance,
          null, Type.EmptyTypes, null) != null;
    }

    public bool CanSerialize(Type type) {
      return
        ReflectionTools.HasDefaultConstructor(type) &&
        ImplementsGenericEnumerable(type) &&
        HasAddMethod(type);
    }

    public string JustifyRejection(Type type) {
      if (!ReflectionTools.HasDefaultConstructor(type))
        return "no default constructor";
      if (!ImplementsGenericEnumerable(type))
        return "IEnumerable<> not implemented";
      return "no Add method with one parameter";
    }

    public IEnumerable<Tag> CreateMetaInfo(object o) {
      return new Tag[] { };
    }

    private static object[] emptyArgs = new object[0];
    public IEnumerable<Tag> Decompose(object obj) {
      Type type = obj.GetType();
      Type enumerable = GetGenericEnumerableInterface(type);
      InterfaceMapping iMap = obj.GetType().GetInterfaceMap(enumerable);
      MethodInfo getEnumeratorMethod =
        iMap.TargetMethods[
        Array.IndexOf(
          iMap.InterfaceMethods,
          enumerable.GetMethod("GetEnumerator"))];
      object genericEnumerator = getEnumeratorMethod.Invoke(obj, emptyArgs);
      MethodInfo moveNextMethod = genericEnumerator.GetType().GetMethod("MoveNext");
      PropertyInfo currentProperty = genericEnumerator.GetType().GetProperty("Current");
      StringBuilder sb = new StringBuilder();
      while ((bool)moveNextMethod.Invoke(genericEnumerator, emptyArgs))
        sb.Append(
          numberConverter.Format(
            currentProperty.GetValue(genericEnumerator, null))).Append(';');
      yield return new Tag("compact enumerable", sb.ToString());
    }

    public object CreateInstance(Type type, IEnumerable<Tag> metaInfo) {
      return Activator.CreateInstance(type, true);
    }

    public void Populate(object instance, IEnumerable<Tag> tags, Type type) {
      Type enumerable = GetGenericEnumerableInterface(type);
      Type elementType = enumerable.GetGenericArguments()[0];
      MethodInfo addMethod = type.GetMethod("Add");
      try {
        var tagEnumerator = tags.GetEnumerator();
        tagEnumerator.MoveNext();
        string[] stringValues = ((string)tagEnumerator.Current.Value)
          .Split(new[] { ';' }, StringSplitOptions.RemoveEmptyEntries);
        foreach (var value in stringValues) {
          addMethod.Invoke(instance, new[] { numberConverter.Parse(value, elementType) });
        }
      }
      catch (InvalidOperationException e) {
        throw new PersistenceException("Insufficient element data to reconstruct number enumerable", e);
      }
      catch (InvalidCastException e) {
        throw new PersistenceException("Invalid element data during reconstruction of number enumerable", e);
      }
    }
  }
}