SharpDevelop/ICSharpCode.NRefactory.CSharp/Refactoring/PatternHelper.cs

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using System;
using ICSharpCode.NRefactory.PatternMatching;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
	/// <summary>
	/// Helper class for constructing pattern ASTs.
	/// </summary>
	public class PatternHelper
	{
		/// <summary>
		/// Produces a choice pattern for <c>expr1 op expr2</c> or <c>expr2 op expr1</c>.
		/// </summary>
		public static Expression CommutativeOperator(Expression expr1, BinaryOperatorType op, Expression expr2)
		{
			return new Choice {
				new BinaryOperatorExpression(expr1, op, expr2),
				new BinaryOperatorExpression(expr2.Clone(), op, expr1.Clone())
			};
		}
		
		/// <summary>
		/// Optionally allows parentheses around the given expression.
		/// </summary>
		public static Expression OptionalParentheses(Expression expr)
		{
			return new OptionalParenthesesPattern(expr);
		}
		
		sealed class OptionalParenthesesPattern : Pattern
		{
			readonly INode child;
			
			public OptionalParenthesesPattern(INode child)
			{
				this.child = child;
			}
			
			public override bool DoMatch(INode other, Match match)
			{
				INode unpacked = ParenthesizedExpression.UnpackParenthesizedExpression(other as Expression);
				return child.DoMatch(unpacked, match);
			}
		}
	}
}