source: trunk/sources/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory-5.5.0/TypeSystem/Implementation/BaseTypeCollector.cs @ 11807

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// 
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// 
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// 
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using System;
using System.Collections.Generic;

namespace ICSharpCode.NRefactory.TypeSystem.Implementation
{
  /// <summary>
  /// Helper class for the GetAllBaseTypes() implementation.
  /// </summary>
  sealed class BaseTypeCollector : List<IType>
  {
    readonly Stack<IType> activeTypes = new Stack<IType>();
    
    /// <summary>
    /// If this option is enabled, the list will not contain interfaces when retrieving the base types
    /// of a class.
    /// </summary>
    internal bool SkipImplementedInterfaces;
    
    public void CollectBaseTypes(IType type)
    {
      IType def = type.GetDefinition() ?? type;
      
      // Maintain a stack of currently active type definitions, and avoid having one definition
      // multiple times on that stack.
      // This is necessary to ensure the output is finite in the presence of cyclic inheritance:
      // class C<X> : C<C<X>> {} would not be caught by the 'no duplicate output' check, yet would
      // produce infinite output.
      if (activeTypes.Contains(def))
        return;
      activeTypes.Push(def);
      // Note that we also need to push non-type definitions, e.g. for protecting against
      // cyclic inheritance in type parameters (where T : S where S : T).
      // The output check doesn't help there because we call Add(type) only at the end.
      // We can't simply call this.Add(type); at the start because that would return in an incorrect order.
      
      // Avoid outputting a type more than once - necessary for "diamond" multiple inheritance
      // (e.g. C implements I1 and I2, and both interfaces derive from Object)
      if (!this.Contains(type)) {
        foreach (IType baseType in type.DirectBaseTypes) {
          if (SkipImplementedInterfaces && def != null && def.Kind != TypeKind.Interface && def.Kind != TypeKind.TypeParameter) {
            if (baseType.Kind == TypeKind.Interface) {
              // skip the interface
              continue;
            }
          }
          CollectBaseTypes(baseType);
        }
        // Add(type) at the end - we want a type to be output only after all its base types were added.
        this.Add(type);
        // Note that this is not the same as putting the this.Add() call in front and then reversing the list.
        // For the diamond inheritance, Add() at the start produces "C, I1, Object, I2",
        // while Add() at the end produces "Object, I1, I2, C".
      }
      activeTypes.Pop();
    }
  }
}