context: // NameFilter.cs
  //
  // Copyright 2005 John Reilly
  //
  // This program is free software; you can redistribute it and/or
  // modify it under the terms of the GNU General Public License
  // as published by the Free Software Foundation; either version 2
  // of the License, or (at your option) any later version.
  //
  // This program is distributed in the hope that it will be useful,
  // but WITHOUT ANY WARRANTY; without even the implied warranty of
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  // GNU General Public License for more details.
  //
  // You should have received a copy of the GNU General Public License
  // along with this program; if not, write to the Free Software
  // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
  //
  // Linking this library statically or dynamically with other modules is
  // making a combined work based on this library.  Thus, the terms and
  // conditions of the GNU General Public License cover the whole
  // combination.
  // 
  // As a special exception, the copyright holders of this library give you
  // permission to link this library with independent modules to produce an
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  // exception statement from your version.
  
  
  using System;
  using System.Collections;
  using System.Text.RegularExpressions;
  
  namespace ICSharpCode.SharpZipLib.Core
  {
  	/// <summary>
  	/// NameFilter is a string matching class which allows for both positive and negative
  	/// matching.
  	/// A filter is a sequence of independant <see cref="Regex">regular expressions</see> separated by semi-colons ';'
  	/// Each expression can be prefixed by a plus '+' sign or a minus '-' sign to denote the expression
  	/// is intended to include or exclude names.  If neither a plus or minus sign is found include is the default
  	/// A given name is tested for inclusion before checking exclusions.  Only names matching an include spec 
  	/// and not matching an exclude spec are deemed to match the filter.
  	/// An empty filter matches any name.
  	/// </summary>
  	/// <example>The following expression includes all name ending in '.dat' with the exception of 'dummy.dat'
  	/// "+\.dat$;-^dummy\.dat$"
  	/// </example>
  	public class NameFilter : IScanFilter
  	{
  		#region Constructors
  		/// <summary>
  		/// Construct an instance based on the filter expression passed
  		/// </summary>
  		/// <param name="filter">The filter expression.</param>
  		public NameFilter(string filter)
  		{
  			filter_ = filter;
  			inclusions_ = new ArrayList();
  			exclusions_ = new ArrayList();
  			Compile();
  		}
  		#endregion
  
  		/// <summary>
  		/// Test a string to see if it is a valid regular expression.
  		/// </summary>
  		/// <param name="expression">The expression to test.</param>
  		/// <returns>True if expression is a valid <see cref="System.Text.RegularExpressions.Regex"/> false otherwise.</returns>
  		public static bool IsValidExpression(string expression)
  		{
  			bool result = true;
  			try
  			{
  				Regex exp = new Regex(expression, RegexOptions.IgnoreCase | RegexOptions.Singleline);
  			}
  			catch
  			{
  				result = false;
  			}
  			return result;
  		}
  
  		/// <summary>
  		/// Test an expression to see if it is valid as a filter.
  		/// </summary>
  		/// <param name="toTest">The filter expression to test.</param>
  		/// <returns>True if the expression is valid, false otherwise.</returns>
  		public static bool IsValidFilterExpression(string toTest)
  		{
  			if ( toTest == null )
  			{
  				throw new ArgumentNullException("toTest");
  			}
  
  			bool result = true;
  
  			try
  			{
  				string[] items = toTest.Split(';');
  				for ( int i = 0; i < items.Length; ++i )
  				{
  					if ( items[i] != null && items[i].Length > 0 )
  					{
  						string toCompile;
  
  						if ( items[i][0] == '+' )
  						{
  							toCompile = items[i].Substring(1, items[i].Length - 1);
  						}
  						else if ( items[i][0] == '-' )
  						{
  							toCompile = items[i].Substring(1, items[i].Length - 1);
  						}
  						else
  						{
  							toCompile = items[i];
  						}
  
  						Regex testRegex = new Regex(toCompile, RegexOptions.IgnoreCase | RegexOptions.Singleline);
  					}
  				}
  			}
  			catch ( Exception )
  			{
  				result = false;
  			}
  
  			return result;
  		}
  
  		/// <summary>
  		/// Convert this filter to its string equivalent.
  		/// </summary>
  		/// <returns>The string equivalent for this filter.</returns>
  		public override string ToString()
  		{
  			return filter_;
  		}
  
  		/// <summary>
  		/// Test a value to see if it is included by the filter.
  		/// </summary>
  		/// <param name="name">The value to test.</param>
  		/// <returns>True if the value is included, false otherwise.</returns>
  		public bool IsIncluded(string name)
  		{
  			bool result = false;
  			if ( inclusions_.Count == 0 )
  			{
  				result = true;
  			}
  			else
  			{
  				foreach ( Regex r in inclusions_ )
  				{
  					if ( r.IsMatch(name) )
  					{
  						result = true;
  						break;
  					}
  				}
  			}
  			return result;
  		}
  
  		/// <summary>
  		/// Test a value to see if it is excluded by the filter.
  		/// </summary>
  		/// <param name="name">The value to test.</param>
  		/// <returns>True if the value is excluded, false otherwise.</returns>
  		public bool IsExcluded(string name)
  		{
  			bool result = false;
  			foreach ( Regex r in exclusions_ )
  			{
  				if ( r.IsMatch(name) )
  				{
  					result = true;
  					break;
  				}
  			}
  			return result;
  		}
  
  		#region IScanFilter Members
  		/// <summary>
  		/// Test a value to see if it matches the filter.
  		/// </summary>
  		/// <param name="name">The value to test.</param>
  		/// <returns>True if the value matches, false otherwise.</returns>
  		public bool IsMatch(string name)
  		{
  			return (IsIncluded(name) == true) && (IsExcluded(name) == false);
  		}
  		#endregion
  
  		/// <summary>
  		/// Compile this filter.
  		/// </summary>
  		void Compile()
  		{
  			// TODO: Check to see if combining RE's makes it faster/smaller.
  			// simple scheme would be to have one RE for inclusion and one for exclusion.
  			if ( filter_ == null )
  			{
  				return;
  			}
  
  			// TODO: Allow for paths to include ';'
  
gt: 			string[] items = filter_.Split(';');