ILSpy/ICSharpCode.Decompiler/CSharp/Syntax/PatternMatching/Choice.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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// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
// 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.Collections;
using System.Collections.Generic;

namespace ICSharpCode.Decompiler.CSharp.Syntax.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(nameof(alternative));
			alternatives.Add(new NamedNode(name, alternative));
		}

		public void Add(INode alternative)
		{
			if (alternative == null)
				throw new ArgumentNullException(nameof(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();
		}
	}
}