context: //
  // System.Drawing.PrintingPermission.cs
  //
  // Authors:
  //	Dennis Hayes (dennish@Raytek.com)
  //	Herve Poussineau (hpoussineau@fr.st)
  //	Sebastien Pouliot  <sebastien@ximian.com>
  //
  // (C) 2002 Ximian, Inc
  // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  //
  // 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 without restriction, including
  // without limitation the rights to use, copy, modify, merge, 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 FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  //
  
  using System.Globalization;
  using System.Security;
  using System.Security.Permissions;
  
  namespace System.Drawing.Printing {
  
  	[Serializable]
  	public sealed class PrintingPermission : CodeAccessPermission, IUnrestrictedPermission {
  
  		private const int version = 1;
  
  		private PrintingPermissionLevel _Level;
  		
  		public PrintingPermission (PermissionState state) 
  		{
  			if (CheckPermissionState (state, true) == PermissionState.Unrestricted)
  				_Level = PrintingPermissionLevel.AllPrinting;
  		}
  
  		public PrintingPermission (PrintingPermissionLevel printingLevel) 
  		{
  			Level = printingLevel;
  		}
  		
  		// properties
  
  		public PrintingPermissionLevel Level{
  			get { return _Level; }
  			set {
  				if (!Enum.IsDefined (typeof (PrintingPermissionLevel), value)) {
  					string msg = Locale.GetText ("Invalid enum {0}");
  					throw new ArgumentException (String.Format (msg, value), "Level");
  				}
  				 _Level = value;
  			}
  		}
  
  		// methods
  
  		public override IPermission Copy ()
  		{
  			return new PrintingPermission (this.Level);
  		}
  		
  		public override void FromXml (SecurityElement esd)
  		{
  			CheckSecurityElement (esd, "esd", version, version);
  			// Note: we do not (yet) care about the return value 
  			// as we only accept version 1 (min/max values)
  
  			if (IsUnrestricted (esd))
  				_Level = PrintingPermissionLevel.AllPrinting;
  			else {
  				string level = esd.Attribute ("Level");
  				if (level != null) {
  					_Level = (PrintingPermissionLevel) Enum.Parse (
  						typeof (PrintingPermissionLevel), level);
  				}
  				else
  					_Level = PrintingPermissionLevel.NoPrinting;
  			}
  		}
  		
  		public override IPermission Intersect (IPermission target)
  		{
  			PrintingPermission pp = Cast (target);
  			if ((pp == null) || IsEmpty () || pp.IsEmpty ())
  				return null;
  
  			PrintingPermissionLevel level = (_Level <= pp.Level) ? _Level : pp.Level;
  			return new PrintingPermission (level);
  		}
  		
  		public override bool IsSubsetOf (IPermission target)
  		{
  			PrintingPermission pp = Cast (target);
  			if (pp == null)
  				return IsEmpty ();
  			
  			return (_Level <= pp.Level);
  		}
  		
  		public bool IsUnrestricted ()
  		{
  			return (_Level == PrintingPermissionLevel.AllPrinting);
  		}
  		
  		public override SecurityElement ToXml ()
  		{
  			SecurityElement se = Element (version);
  			if (IsUnrestricted ())
  				se.AddAttribute ("Unrestricted", "true");
  			else
  				se.AddAttribute ("Level", _Level.ToString ());
  			return se;
  		}
  		
  		public override IPermission Union (IPermission target)
  		{
  			PrintingPermission pp = Cast (target);
  			if (pp == null)
  				return new PrintingPermission (_Level);
  			if (IsUnrestricted () || pp.IsUnrestricted ())
  				return new PrintingPermission (PermissionState.Unrestricted);
  			if (IsEmpty () && pp.IsEmpty ())
  				return null;
  
  			PrintingPermissionLevel level = (_Level > pp.Level) ? _Level : pp.Level;
  			return new PrintingPermission (level);
  		}
  
  		// Internal helpers methods
  
  		private bool IsEmpty ()
  		{
  			return (_Level == PrintingPermissionLevel.NoPrinting);
  		}
  
  		private PrintingPermission Cast (IPermission target)
  		{
  			if (target == null)
  				return null;
  
  			PrintingPermission pp = (target as PrintingPermission);
  			if (pp == null) {
  				ThrowInvalidPermission (target, typeof (PrintingPermission));
  			}
  
  			return pp;
  		}
  
  		// NOTE: The following static methods should be moved out to a (static?) class 
  		// if (ever) System.Drawing.dll gets more than one permission in it's assembly.
  
  		// snippet moved from FileIOPermission (nickd) to be reused in all derived classes
  		internal SecurityElement Element (int version) 
  		{
  			SecurityElement se = new SecurityElement ("IPermission");
  			Type type = this.GetType ();
  			se.AddAttribute ("class", type.FullName + ", " + type.Assembly.ToString ().Replace ('\"', '\''));
  			se.AddAttribute ("version", version.ToString ());
  			return se;
  		}
  
  		internal static PermissionState CheckPermissionState (PermissionState state, bool allowUnrestricted)
  		{
  			string msg;
  			switch (state) {
  			case PermissionState.None:
  				break;
  			case PermissionState.Unrestricted:
  				if (!allowUnrestricted) {
  					msg = Locale.GetText ("Unrestricted isn't not allowed for identity permissions.");
  					throw new ArgumentException (msg, "state");
  				}
  				break;
  			default:
  				msg = String.Format (Locale.GetText ("Invalid enum {0}"), state);
  				throw new ArgumentException (msg, "state");
  			}
  			return state;
  		}
  
  		// logic isn't identical to CodeAccessPermission.CheckSecurityElement - see unit tests
  		internal static int CheckSecurityElement (SecurityElement se, string parameterName, int minimumVersion, int maximumVersion) 
  		{
  			if (se == null)
  				throw new ArgumentNullException (parameterName);
  
  			string c = se.Attribute ("class");
  #if NET_2_0
  
gt: 			if (c == null) {