ILSpy/ICSharpCode.Decompiler/CSharp/Syntax/PatternMatching/Repeat.cs

// Copyright (c) 2011-2013 AlphaSierraPapa for the SharpDevelop Team
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy of this
// software and associated documentation files (the "Software"), to deal in the Software
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// to whom the Software is furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in all copies or
// substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
// 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.Diagnostics;

namespace ICSharpCode.Decompiler.CSharp.Syntax.PatternMatching
{
	/// <summary>
	/// Represents an optional node.
	/// </summary>
	public class Repeat : Pattern
	{
		readonly INode childNode;

		public int MinCount { get; set; }
		public int MaxCount { get; set; }

		public INode ChildNode {
			get { return childNode; }
		}

		public Repeat(INode childNode)
		{
			if (childNode == null)
				throw new ArgumentNullException(nameof(childNode));
			this.childNode = childNode;
			this.MinCount = 0;
			this.MaxCount = int.MaxValue;
		}

		public override bool DoMatchCollection(Role role, INode pos, Match match, BacktrackingInfo backtrackingInfo)
		{
			var backtrackingStack = backtrackingInfo.backtrackingStack;
			Debug.Assert(pos == null || pos.Role == role);
			int matchCount = 0;
			if (this.MinCount <= 0)
				backtrackingStack.Push(new PossibleMatch(pos, match.CheckPoint()));
			while (matchCount < this.MaxCount && pos != null && childNode.DoMatch(pos, match))
			{
				matchCount++;
				do
				{
					pos = pos.NextSibling;
				} while (pos != null && pos.Role != role);
				if (matchCount >= this.MinCount)
					backtrackingStack.Push(new PossibleMatch(pos, match.CheckPoint()));
			}
			return false; // never do a normal (single-element) match; always make the caller look at the results on the back-tracking stack.
		}

		public override bool DoMatch(INode other, Match match)
		{
			if (other == null || other.IsNull)
				return this.MinCount <= 0;
			else
				return this.MaxCount >= 1 && childNode.DoMatch(other, match);
		}
	}
}