source: branches/RemoveBackwardsCompatibility/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory-5.5.0/PatternMatching/Pattern.cs @ 14861

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// 
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// 
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// substantial portions of the Software.
// 
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using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;

namespace ICSharpCode.NRefactory.PatternMatching
{
  /// <summary>
  /// Base class for all patterns.
  /// </summary>
  public abstract class Pattern : INode
  {
    /// <summary>
    /// Gets the string that matches any string.
    /// </summary>
    public static readonly string AnyString = "$any$";
    
    public static bool MatchString(string pattern, string text)
    {
      return pattern == AnyString || pattern == text;
    }
    
    internal struct PossibleMatch
    {
      public readonly INode NextOther; // next node after the last matched node
      public readonly int Checkpoint; // checkpoint
      
      public PossibleMatch(INode nextOther, int checkpoint)
      {
        this.NextOther = nextOther;
        this.Checkpoint = checkpoint;
      }
    }
    
    bool INode.IsNull {
      get { return false; }
    }
    
    Role INode.Role {
      get { return null; }
    }
    
    INode INode.NextSibling {
      get { return null; }
    }
    
    INode INode.FirstChild {
      get { return null; }
    }
    
    public abstract bool DoMatch(INode other, Match match);
    
    public virtual bool DoMatchCollection(Role role, INode pos, Match match, BacktrackingInfo backtrackingInfo)
    {
      return DoMatch (pos, match);
    }
    
    public static bool DoMatchCollection(Role role, INode firstPatternChild, INode firstOtherChild, Match match)
    {
      BacktrackingInfo backtrackingInfo = new BacktrackingInfo();
      Stack<INode> patternStack = new Stack<INode>();
      Stack<PossibleMatch> stack = backtrackingInfo.backtrackingStack;
      patternStack.Push(firstPatternChild);
      stack.Push(new PossibleMatch(firstOtherChild, match.CheckPoint()));
      while (stack.Count > 0) {
        INode cur1 = patternStack.Pop();
        INode cur2 = stack.Peek().NextOther;
        match.RestoreCheckPoint(stack.Pop().Checkpoint);
        bool success = true;
        while (cur1 != null && success) {
          while (cur1 != null && cur1.Role != role)
            cur1 = cur1.NextSibling;
          while (cur2 != null && cur2.Role != role)
            cur2 = cur2.NextSibling;
          if (cur1 == null)
            break;
          
          Debug.Assert(stack.Count == patternStack.Count);
          success = cur1.DoMatchCollection(role, cur2, match, backtrackingInfo);
          Debug.Assert(stack.Count >= patternStack.Count);
          while (stack.Count > patternStack.Count)
            patternStack.Push(cur1.NextSibling);
          
          cur1 = cur1.NextSibling;
          if (cur2 != null)
            cur2 = cur2.NextSibling;
        }
        while (cur2 != null && cur2.Role != role)
          cur2 = cur2.NextSibling;
        if (success && cur2 == null)
          return true;
      }
      return false;
    }
  }
}