source: trunk/sources/HeuristicLab.Persistence/3.3/Default/CompositeSerializers/Number2StringSerializer.cs @ 3199

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

namespace HeuristicLab.Persistence.Default.CompositeSerializers {

  /// <summary>
  /// Serializes a primitive number type using the ToString() method and an
  /// approriate precision and parses back the generated string using
  /// the number type's Parse() method.
  /// 
  /// This serializer has Priorty below zero and is disabled by default
  /// but can be useful in generating custom serializers.
  /// </summary>
  [StorableClass]
  public sealed class Number2StringSerializer : ICompositeSerializer {

    private static readonly List<Type> numberTypes =
      new List<Type> {
        typeof(bool),
        typeof(byte),
        typeof(sbyte),
        typeof(short),
        typeof(ushort),
        typeof(int),
        typeof(uint),
        typeof(long),
        typeof(ulong),
        typeof(float),
        typeof(double),
        typeof(decimal),
      };

    private static readonly Dictionary<Type, MethodInfo> numberParsers;

    static Number2StringSerializer() {
      numberParsers = new Dictionary<Type, MethodInfo>();
      foreach (var type in numberTypes) {
        numberParsers[type] = type
          .GetMethod("Parse", BindingFlags.Static | BindingFlags.Public,
                     null, new[] { typeof(string) }, null);
      }
    }

    /// <summary>
    /// Determines for every type whether the composite serializer is applicable.
    /// </summary>
    /// <param name="type">The type.</param>
    /// <returns>
    ///   <c>true</c> if this instance can serialize the specified type; otherwise, <c>false</c>.
    /// </returns>
    public bool CanSerialize(Type type) {
      return numberParsers.ContainsKey(type);
    }

    /// <summary>
    /// Give a reason if possibly why the given type cannot be serialized by this
    /// ICompositeSerializer.
    /// </summary>
    /// <param name="type">The type.</param>
    /// <returns>
    /// A string justifying why type cannot be serialized.
    /// </returns>
    public string JustifyRejection(Type type) {
      return string.Format("not a number type (one of {0})",
        string.Join(", ", numberTypes.Select(n => n.Name).ToArray()));
    }

    /// <summary>
    /// Formats the specified obj.
    /// </summary>
    /// <param name="obj">The obj.</param>
    /// <returns></returns>
    public string Format(object obj) {
      if (obj.GetType() == typeof(float))
        return ((float)obj).ToString("r", CultureInfo.InvariantCulture);
      if (obj.GetType() == typeof(double))
        return ((double)obj).ToString("r", CultureInfo.InvariantCulture);
      if (obj.GetType() == typeof(decimal))
        return ((decimal)obj).ToString("r", CultureInfo.InvariantCulture);
      return obj.ToString();
    }

    /// <summary>
    /// Parses the specified string value.
    /// </summary>
    /// <param name="stringValue">The string value.</param>
    /// <param name="type">The type.</param>
    /// <returns></returns>
    public object Parse(string stringValue, Type type) {
      try {
        return numberParsers[type]
          .Invoke(null,
              BindingFlags.Static | BindingFlags.PutRefDispProperty,
                    null, new[] { stringValue }, CultureInfo.InvariantCulture);
      } catch (FormatException e) {
        throw new PersistenceException("Invalid element data during number parsing.", e);
      } catch (OverflowException e) {
        throw new PersistenceException("Overflow during number parsing.", e);
      }
    }



    /// <summary>
    /// Defines the Priorty of this composite serializer. Higher number means
    /// higher prioriy. Negative numbers are fallback serializers that are
    /// disabled by default.
    /// All default generic composite serializers have priority 100. Specializations
    /// have priority 200 so they will  be tried first. Priorities are
    /// only considered for default configurations.
    /// </summary>
    /// <value></value>
    public int Priority {
      get { return -100; }
    }

    /// <summary>
    /// Generate MetaInfo necessary for instance creation. (e.g. dimensions
    /// necessary for array creation.
    /// </summary>
    /// <param name="obj">An object.</param>
    /// <returns>An enumerable of <see cref="Tag"/>s.</returns>
    public IEnumerable<Tag> CreateMetaInfo(object obj) {
      yield return new Tag(Format(obj));
    }

    /// <summary>
    /// Decompose an object into <see cref="Tag"/>s, the tag name can be null,
    /// the order in which elements are generated is guaranteed to be
    /// the same as they will be supplied to the Populate method.
    /// </summary>
    /// <param name="obj">An object.</param>
    /// <returns>An enumerable of <see cref="Tag"/>s.</returns>
    public IEnumerable<Tag> Decompose(object obj) {
      // numbers are composed just of meta info
      return new Tag[] { };
    }

    /// <summary>
    /// Create an instance of the object using the provided meta information.
    /// </summary>
    /// <param name="type">A type.</param>
    /// <param name="metaInfo">The meta information.</param>
    /// <returns>A fresh instance of the provided type.</returns>
    public object CreateInstance(Type type, IEnumerable<Tag> metaInfo) {
      var it = metaInfo.GetEnumerator();
      try {
        it.MoveNext();
        return Parse((string)it.Current.Value, type);
      } catch (InvalidOperationException e) {
        throw new PersistenceException(
          String.Format("Insufficient meta information to reconstruct number of type {0}.",
          type.VersionInvariantName()), e);
      } catch (InvalidCastException e) {
        throw new PersistenceException("Invalid meta information element type", e);
      }
    }

    /// <summary>
    /// Fills an object with values from the previously generated <see cref="Tag"/>s
    /// in Decompose. The order in which the values are supplied is
    /// the same as they where generated. <see cref="Tag"/> names might be null.
    /// </summary>
    /// <param name="instance">An empty object instance.</param>
    /// <param name="tags">The tags.</param>
    /// <param name="type">The type.</param>
    public void Populate(object instance, IEnumerable<Tag> tags, Type type) {
      // numbers are composed just of meta info, no need to populate
    }
  }
}