source: branches/2434_crossvalidation/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory-5.5.0/IAnnotatable.cs @ 18242

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// 
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// 
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// 
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;

namespace ICSharpCode.NRefactory
{
  /// <summary>
  /// Provides an interface to handle annotations in an object.
  /// </summary>
  public interface IAnnotatable
  {
    /// <summary>
    /// Gets all annotations stored on this IAnnotatable.
    /// </summary>
    IEnumerable<object> Annotations {
      get;
    }
    
    /// <summary>
    /// Gets the first annotation of the specified type.
    /// Returns null if no matching annotation exists.
    /// </summary>
    /// <typeparam name='T'>
    /// The type of the annotation.
    /// </typeparam>
    T Annotation<T> () where T: class;
    
    /// <summary>
    /// Gets the first annotation of the specified type.
    /// Returns null if no matching annotation exists.
    /// </summary>
    /// <param name='type'>
    /// The type of the annotation.
    /// </param>
    object Annotation (Type type);
    
    /// <summary>
    /// Adds an annotation to this instance.
    /// </summary>
    /// <param name='annotation'>
    /// The annotation to add.
    /// </param>
    void AddAnnotation (object annotation);
    
    /// <summary>
    /// Removes all annotations of the specified type.
    /// </summary>
    /// <typeparam name='T'>
    /// The type of the annotations to remove.
    /// </typeparam>
    void RemoveAnnotations<T> () where T : class;
    
    /// <summary>
    /// Removes all annotations of the specified type.
    /// </summary>
    /// <param name='type'>
    /// The type of the annotations to remove.
    /// </param>
    void RemoveAnnotations(Type type);
  }
  
  /// <summary>
  /// Base class used to implement the IAnnotatable interface.
  /// This implementation is thread-safe.
  /// </summary>
  [Serializable]
  public abstract class AbstractAnnotatable : IAnnotatable
  {
    // Annotations: points either null (no annotations), to the single annotation,
    // or to an AnnotationList.
    // Once it is pointed at an AnnotationList, it will never change (this allows thread-safety support by locking the list)
    
    object annotations;
    
    /// <summary>
    /// Clones all annotations.
    /// This method is intended to be called by Clone() implementations in derived classes.
    /// <code>
    /// AstNode copy = (AstNode)MemberwiseClone();
    /// copy.CloneAnnotations();
    /// </code>
    /// </summary>
    protected void CloneAnnotations()
    {
      ICloneable cloneable = annotations as ICloneable;
      if (cloneable != null)
        annotations = cloneable.Clone();
    }

    sealed class AnnotationList : List<object>, ICloneable
    {
      // There are two uses for this custom list type:
      // 1) it's private, and thus (unlike List<object>) cannot be confused with real annotations
      // 2) It allows us to simplify the cloning logic by making the list behave the same as a clonable annotation.
      public AnnotationList (int initialCapacity) : base(initialCapacity)
      {
      }
      
      public object Clone ()
      {
        lock (this) {
          AnnotationList copy = new AnnotationList (this.Count);
          for (int i = 0; i < this.Count; i++) {
            object obj = this [i];
            ICloneable c = obj as ICloneable;
            copy.Add (c != null ? c.Clone () : obj);
          }
          return copy;
        }
      }
    }
    
    public virtual void AddAnnotation (object annotation)
    {
      if (annotation == null)
        throw new ArgumentNullException ("annotation");
    retry: // Retry until successful
      object oldAnnotation = Interlocked.CompareExchange (ref this.annotations, annotation, null);
      if (oldAnnotation == null) {
        return; // we successfully added a single annotation
      }
      AnnotationList list = oldAnnotation as AnnotationList;
      if (list == null) {
        // we need to transform the old annotation into a list
        list = new AnnotationList (4);
        list.Add (oldAnnotation);
        list.Add (annotation);
        if (Interlocked.CompareExchange (ref this.annotations, list, oldAnnotation) != oldAnnotation) {
          // the transformation failed (some other thread wrote to this.annotations first)
          goto retry;
        }
      } else {
        // once there's a list, use simple locking
        lock (list) {
          list.Add (annotation);
        }
      }
    }
    
    public virtual void RemoveAnnotations<T> () where T : class
    {
    retry: // Retry until successful
      object oldAnnotations = this.annotations;
      AnnotationList list = oldAnnotations as AnnotationList;
      if (list != null) {
        lock (list)
          list.RemoveAll (obj => obj is T);
      } else if (oldAnnotations is T) {
        if (Interlocked.CompareExchange (ref this.annotations, null, oldAnnotations) != oldAnnotations) {
          // Operation failed (some other thread wrote to this.annotations first)
          goto retry;
        }
      }
    }
    
    public virtual void RemoveAnnotations (Type type)
    {
      if (type == null)
        throw new ArgumentNullException ("type");
    retry: // Retry until successful
      object oldAnnotations = this.annotations;
      AnnotationList list = oldAnnotations as AnnotationList;
      if (list != null) {
        lock (list)
          list.RemoveAll(type.IsInstanceOfType);
      } else if (type.IsInstanceOfType (oldAnnotations)) {
        if (Interlocked.CompareExchange (ref this.annotations, null, oldAnnotations) != oldAnnotations) {
          // Operation failed (some other thread wrote to this.annotations first)
          goto retry;
        }
      }
    }
    
    public T Annotation<T> () where T: class
    {
      object annotations = this.annotations;
      AnnotationList list = annotations as AnnotationList;
      if (list != null) {
        lock (list) {
          foreach (object obj in list) {
            T t = obj as T;
            if (t != null)
              return t;
          }
          return null;
        }
      } else {
        return annotations as T;
      }
    }
    
    public object Annotation (Type type)
    {
      if (type == null)
        throw new ArgumentNullException ("type");
      object annotations = this.annotations;
      AnnotationList list = annotations as AnnotationList;
      if (list != null) {
        lock (list) {
          foreach (object obj in list) {
            if (type.IsInstanceOfType (obj))
              return obj;
          }
        }
      } else {
        if (type.IsInstanceOfType (annotations))
          return annotations;
      }
      return null;
    }
    
    /// <summary>
    /// Gets all annotations stored on this AstNode.
    /// </summary>
    public IEnumerable<object> Annotations {
      get {
        object annotations = this.annotations;
        AnnotationList list = annotations as AnnotationList;
        if (list != null) {
          lock (list) {
            return list.ToArray ();
          }
        } else {
          if (annotations != null)
            return new object[] { annotations };
          else
            return Enumerable.Empty<object> ();
        }
      }
    }
  }
}