source: branches/3026_IntegrationIntoSymSpace/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory-5.5.0/PatternMatching/Choice.cs

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// to whom the Software is furnished to do so, subject to the following conditions:
// 
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// substantial portions of the Software.
// 
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// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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using System;
using System.Collections;
using System.Collections.Generic;

namespace ICSharpCode.NRefactory.PatternMatching
{
  /// <summary>
  /// Matches one of several alternatives.
  /// </summary>
  public class Choice : Pattern, IEnumerable<INode>
  {
    readonly List<INode> alternatives = new List<INode>();
    
    public void Add(string name, INode alternative)
    {
      if (alternative == null)
        throw new ArgumentNullException("alternative");
      alternatives.Add(new NamedNode(name, alternative));
    }
    
    public void Add(INode alternative)
    {
      if (alternative == null)
        throw new ArgumentNullException("alternative");
      alternatives.Add(alternative);
    }
    
    public override bool DoMatch(INode other, Match match)
    {
      var checkPoint = match.CheckPoint();
      foreach (INode alt in alternatives) {
        if (alt.DoMatch(other, match))
          return true;
        else
          match.RestoreCheckPoint(checkPoint);
      }
      return false;
    }
    
    IEnumerator<INode> IEnumerable<INode>.GetEnumerator()
    {
      return alternatives.GetEnumerator();
    }
    
    IEnumerator IEnumerable.GetEnumerator()
    {
      return alternatives.GetEnumerator();
    }
  }
}