mcs/class/System.XML/Mono.Xml.Xsl/XslFunctions.cs

   1 //
   2 // XsltCompiledContext.cs
   3 //
   4 // Authors:
   5 //      Ben Maurer (bmaurer@users.sourceforge.net)
   6 //      Atsushi Enomoto (atsushi@ximian.com)
   7 // (C) 2003 Ben Maurer
   8 // (C) 2004 Atsushi Enomoto
   9 //
  10
  11 //
  12 // Permission is hereby granted, free of charge, to any person obtaining
  13 // a copy of this software and associated documentation files (the
  14 // "Software"), to deal in the Software without restriction, including
  15 // without limitation the rights to use, copy, modify, merge, publish,
  16 // distribute, sublicense, and/or sell copies of the Software, and to
  17 // permit persons to whom the Software is furnished to do so, subject to
  18 // the following conditions:
  19 //
  20 // The above copyright notice and this permission notice shall be
  21 // included in all copies or substantial portions of the Software.
  22 //
  23 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  27 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  28 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  29 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  30 //
  31 using System;
  32 using System.Collections;
  33 using System.Globalization;
  34 using System.Reflection;
  35 using System.Text;
  36 using System.Xml;
  37 using System.Xml.XPath;
  38 using System.Xml.Xsl;
  39 using Mono.Xml.Xsl;
  40
  41 using QName = System.Xml.XmlQualifiedName;
  42
  43 namespace Mono.Xml.Xsl
  44 {
  45         internal abstract class XPFuncImpl : IXsltContextFunction
  46         {
  47                 int minargs, maxargs;
  48                 XPathResultType returnType;
  49                 XPathResultType [] argTypes;
  50
  51                 public XPFuncImpl () {}
  52                 public XPFuncImpl (int minArgs, int maxArgs, XPathResultType returnType, XPathResultType[] argTypes)
  53                 {
  54                         this.Init(minArgs, maxArgs, returnType, argTypes);
  55                 }
  56
  57                 protected void Init (int minArgs, int maxArgs, XPathResultType returnType, XPathResultType[] argTypes)
  58                 {
  59                         this.minargs    = minArgs;
  60                         this.maxargs    = maxArgs;
  61                         this.returnType = returnType;
  62                         this.argTypes   = argTypes;
  63                 }
  64
  65                 public int Minargs { get { return this.minargs; }}
  66                 public int Maxargs { get { return this.maxargs; }}
  67                 public XPathResultType ReturnType { get { return this.returnType; }}
  68                 public XPathResultType [] ArgTypes { get { return this.argTypes; }}
  69                 public object Invoke (XsltContext xsltContext, object [] args, XPathNavigator docContext)
  70                 {
  71                         return Invoke ((XsltCompiledContext)xsltContext, args, docContext);
  72                 }
  73
  74                 public abstract object Invoke (XsltCompiledContext xsltContext, object [] args, XPathNavigator docContext);
  75
  76                 public static XPathResultType GetXPathType (Type type, XPathNavigator node) {
  77                         switch (Type.GetTypeCode(type)) {
  78                         case TypeCode.String:
  79                                 return XPathResultType.String;
  80                         case TypeCode.Boolean:
  81                                 return XPathResultType.Boolean;
  82                         case TypeCode.Object:
  83                                 if (typeof (XPathNavigator).IsAssignableFrom (type) || typeof (IXPathNavigable).IsAssignableFrom (type))
  84                                         return XPathResultType.Navigator;
  85
  86                                 if (typeof (XPathNodeIterator).IsAssignableFrom (type))
  87                                         return XPathResultType.NodeSet;
  88
  89                                 return XPathResultType.Any;
  90                         case TypeCode.DateTime :
  91                                 throw new XsltException ("Invalid type DateTime was specified.", null, node);
  92                         default: // Numeric
  93                                 return XPathResultType.Number;
  94                         }
  95                 }
  96         }
  97
  98         class XsltExtensionFunction : XPFuncImpl
  99         {
 100                 private object extension;
 101                 private MethodInfo method;
 102                 private TypeCode [] typeCodes;
 103
 104                 public XsltExtensionFunction (object extension, MethodInfo method, XPathNavigator currentNode)
 105                 {
 106                         this.extension = extension;
 107                         this.method = method;
 108
 109                         ParameterInfo [] parameters = method.GetParameters ();
 110                         int minArgs = parameters.Length;
 111                         int maxArgs = parameters.Length;
 112
 113                         this.typeCodes = new TypeCode [parameters.Length];
 114                         XPathResultType[] argTypes = new XPathResultType [parameters.Length];
 115
 116                         bool canBeOpt = true;
 117                         for (int i = parameters.Length - 1; 0 <= i; i--) { // optionals at the end
 118                                 typeCodes [i] = Type.GetTypeCode (parameters [i].ParameterType);
 119                                 argTypes [i] = GetXPathType (parameters [i].ParameterType, currentNode);
 120                                 if (canBeOpt) {
 121                                         if (parameters[i].IsOptional)
 122                                                 minArgs --;
 123                                         else
 124                                                 canBeOpt = false;
 125                                 }
 126                         }
 127                         base.Init (minArgs, maxArgs, GetXPathType (method.ReturnType, currentNode), argTypes);
 128                 }
 129
 130                 public override object Invoke (XsltCompiledContext xsltContext, object [] args, XPathNavigator docContext)
 131                 {
 132                         try {
 133                                 ParameterInfo [] pis = method.GetParameters ();
 134                                 object [] castedArgs = new object [pis.Length];
 135                                 for (int i = 0; i < args.Length; i++) {
 136                                         Type t = pis [i].ParameterType;
 137                                         switch (t.FullName) {
 138                                         case "System.Int16":
 139                                         case "System.UInt16":
 140                                         case "System.Int32":
 141                                         case "System.UInt32":
 142                                         case "System.Int64":
 143                                         case "System.UInt64":
 144                                         case "System.Single":
 145                                         case "System.Decimal":
 146                                                 castedArgs [i] = Convert.ChangeType (args [i], t);
 147                                                 break;
 148                                         default:
 149                                                 castedArgs [i] = args [i];
 150                                                 break;
 151                                         }
 152                                 }
 153
 154                                 object result = null;
 155                                 switch (method.ReturnType.FullName) {
 156                                 case "System.Int16":
 157                                 case "System.UInt16":
 158                                 case "System.Int32":
 159                                 case "System.UInt32":
 160                                 case "System.Int64":
 161                                 case "System.UInt64":
 162                                 case "System.Single":
 163                                 case "System.Decimal":
 164                                         result = (double) method.Invoke (extension, castedArgs);
 165                                         break;
 166                                 default:
 167                                         result = method.Invoke(extension, castedArgs);
 168                                         break;
 169                                 }
 170                                 IXPathNavigable navigable = result as IXPathNavigable;
 171                                 if (navigable != null)
 172                                         return navigable.CreateNavigator ();
 173
 174                                 return result;
 175                         } catch (Exception ex) {
 176                                 throw new XsltException ("Custom function reported an error.", ex);
 177 //                              Debug.WriteLine ("****** INCORRECT RESOLUTION **********");
 178                         }
 179                 }
 180         }
 181
 182         class XsltCurrent : XPathFunction
 183         {
 184                 public XsltCurrent (FunctionArguments args) : base (args)
 185                 {
 186                         if (args != null)
 187                                 throw new XPathException ("current takes 0 args");
 188                 }
 189
 190                 public override XPathResultType ReturnType { get { return XPathResultType.NodeSet; }}
 191
 192                 public override object Evaluate (BaseIterator iter)
 193                 {
 194                         return new SelfIterator ((iter.NamespaceManager as XsltCompiledContext).Processor.CurrentNode, null);
 195                 }
 196
 197                 internal override bool Peer {
 198                         get { return false; }
 199                 }
 200
 201                 public override string ToString ()
 202                 {
 203                         return "current()";
 204                 }
 205         }
 206
 207         class XsltDocument : XPathFunction
 208         {
 209                 Expression arg0, arg1;
 210                 XPathNavigator doc;
 211
 212                 public XsltDocument (FunctionArguments args, Compiler c) : base (args)
 213                 {
 214                         if (args == null || (args.Tail != null && args.Tail.Tail != null))
 215                                 throw new XPathException ("document takes one or two args");
 216
 217                         arg0 = args.Arg;
 218                         if (args.Tail != null)
 219                                 arg1 = args.Tail.Arg;
 220                         doc = c.Input.Clone ();
 221                 }
 222                 public override XPathResultType ReturnType { get { return XPathResultType.NodeSet; }}
 223
 224                 internal override bool Peer {
 225                         get { return arg0.Peer && (arg1 != null ? arg1.Peer : true); }
 226                 }
 227
 228                 public override object Evaluate (BaseIterator iter)
 229                 {
 230                         string baseUri = null;
 231                         if (arg1 != null) {
 232                                 XPathNodeIterator it = arg1.EvaluateNodeSet (iter);
 233                                 if (it.MoveNext())
 234                                         baseUri = it.Current.BaseURI;
 235                                 else
 236                                         baseUri = VoidBaseUriFlag;
 237                         }
 238
 239                         object o = arg0.Evaluate (iter);
 240                         if (o is XPathNodeIterator)
 241                                 return GetDocument ((iter.NamespaceManager as XsltCompiledContext), (XPathNodeIterator)o, baseUri);
 242                         else
 243                                 return GetDocument ((iter.NamespaceManager as XsltCompiledContext), o is IFormattable ? ((IFormattable) o).ToString (null, CultureInfo.InvariantCulture) : o.ToString (), baseUri);
 244                 }
 245
 246                 static string VoidBaseUriFlag = "&^)(*&%*^$&$VOID!BASE!URI!";
 247
 248                 Uri Resolve (string thisUri, string baseUri, XslTransformProcessor p)
 249                 {
 250 //                      Debug.WriteLine ("THIS: " + thisUri);
 251 //                      Debug.WriteLine ("BASE: " + baseUri);
 252                         XmlResolver r = p.Resolver;
 253                         if (r == null)
 254                                 return null;
 255                         Uri uriBase = null;
 256                         if (! object.ReferenceEquals (baseUri, VoidBaseUriFlag) && baseUri != String.Empty)
 257                                 uriBase = r.ResolveUri (null, baseUri);
 258
 259                         return r.ResolveUri (uriBase, thisUri);
 260                 }
 261
 262                 XPathNodeIterator GetDocument (XsltCompiledContext xsltContext, XPathNodeIterator itr, string baseUri)
 263                 {
 264                         ArrayList list = new ArrayList ();
 265                         Hashtable got = new Hashtable ();
 266
 267                         while (itr.MoveNext()) {
 268                                 Uri uri = Resolve (itr.Current.Value, baseUri != null ? baseUri : /*itr.Current.BaseURI*/doc.BaseURI, xsltContext.Processor);
 269                                 if (!got.ContainsKey (uri)) {
 270                                         got.Add (uri, null);
 271                                         if (uri != null && uri.ToString () == "") {
 272                                                 XPathNavigator n = doc.Clone ();
 273                                                 n.MoveToRoot ();
 274                                                 list.Add (n);
 275                                         } else
 276                                                 list.Add (xsltContext.Processor.GetDocument (uri));
 277                                 }
 278                         }
 279
 280                         return new ListIterator (list, xsltContext);
 281                 }
 282
 283                 XPathNodeIterator GetDocument (XsltCompiledContext xsltContext, string arg0, string baseUri)
 284                 {
 285                         Uri uri = Resolve (arg0, baseUri != null ? baseUri : doc.BaseURI, xsltContext.Processor);
 286                         XPathNavigator n;
 287                         if (uri != null && uri.ToString () == "") {
 288                                 n = doc.Clone ();
 289                                 n.MoveToRoot ();
 290                         } else
 291                                 n = xsltContext.Processor.GetDocument (uri);
 292
 293                         return new SelfIterator (n, xsltContext);
 294                 }
 295
 296                 public override string ToString ()
 297                 {
 298                         return String.Concat ("document(",
 299                                 arg0.ToString (),
 300                                 arg1 != null ? "," : String.Empty,
 301                                 arg1 != null ? arg1.ToString () : String.Empty,
 302                                 ")");
 303                 }
 304         }
 305
 306         class XsltElementAvailable : XPathFunction
 307         {
 308                 Expression arg0;
 309                 IStaticXsltContext ctx;
 310
 311                 public XsltElementAvailable (FunctionArguments args, IStaticXsltContext ctx) : base (args)
 312                 {
 313                         if (args == null || args.Tail != null)
 314                                 throw new XPathException ("element-available takes 1 arg");
 315
 316                         arg0 = args.Arg;
 317                         this.ctx = ctx;
 318                 }
 319
 320                 public override XPathResultType ReturnType { get { return XPathResultType.Boolean; }}
 321
 322                 internal override bool Peer {
 323                         get { return arg0.Peer; }
 324                 }
 325
 326                 public override object Evaluate (BaseIterator iter)
 327                 {
 328                         QName name = XslNameUtil.FromString (arg0.EvaluateString (iter), ctx);
 329
 330                         return (
 331                                 (name.Namespace == Compiler.XsltNamespace) &&
 332                                 (
 333                                         //
 334                                         // A list of all the instructions (does not include top-level-elements)
 335                                         //
 336                                         name.Name == "apply-imports" ||
 337                                         name.Name == "apply-templates" ||
 338                                         name.Name == "call-template" ||
 339                                         name.Name == "choose" ||
 340                                         name.Name == "comment" ||
 341                                         name.Name == "copy" ||
 342                                         name.Name == "copy-of" ||
 343                                         name.Name == "element" ||
 344                                         name.Name == "fallback" ||
 345                                         name.Name == "for-each" ||
 346                                         name.Name == "message" ||
 347                                         name.Name == "number" ||
 348                                         name.Name == "processing-instruction" ||
 349                                         name.Name == "text" ||
 350                                         name.Name == "value-of" ||
 351                                         name.Name == "variable"
 352                                 )
 353                         );
 354                 }
 355         }
 356
 357         class XsltFormatNumber : XPathFunction
 358         {
 359                 Expression arg0, arg1, arg2;
 360                 IStaticXsltContext ctx;
 361
 362                 public XsltFormatNumber (FunctionArguments args, IStaticXsltContext ctx) : base (args)
 363                 {
 364                         if (args == null || args.Tail == null || (args.Tail.Tail != null && args.Tail.Tail.Tail != null))
 365                                 throw new XPathException ("format-number takes 2 or 3 args");
 366
 367                         arg0 = args.Arg;
 368                         arg1 = args.Tail.Arg;
 369                         if (args.Tail.Tail != null) {
 370                                 arg2= args.Tail.Tail.Arg;
 371                                 this.ctx = ctx;
 372                         }
 373                 }
 374                 public override XPathResultType ReturnType { get { return XPathResultType.String; }}
 375
 376                 internal override bool Peer {
 377                         get { return arg0.Peer && arg1.Peer && (arg2 != null ? arg2.Peer : true); }
 378                 }
 379
 380                 public override object Evaluate (BaseIterator iter)
 381                 {
 382                         double d = arg0.EvaluateNumber (iter);
 383                         string s = arg1.EvaluateString (iter);
 384                         QName nm = QName.Empty;
 385
 386                         if (arg2 != null)
 387                                 nm = XslNameUtil.FromString (arg2.EvaluateString (iter), ctx);
 388
 389                         try {
 390                                 return (iter.NamespaceManager as XsltCompiledContext).Processor.CompiledStyle
 391                                 .LookupDecimalFormat (nm).FormatNumber (d, s);
 392                         } catch (ArgumentException ex) {
 393                                 throw new XsltException (ex.Message, ex, iter.Current);
 394                         }
 395                 }
 396         }
 397
 398         class XsltFunctionAvailable : XPathFunction
 399         {
 400                 Expression arg0;
 401                 IStaticXsltContext ctx;
 402
 403                 public XsltFunctionAvailable (FunctionArguments args, IStaticXsltContext ctx) : base (args)
 404                 {
 405                         if (args == null || args.Tail != null)
 406                                 throw new XPathException ("element-available takes 1 arg");
 407
 408                         arg0 = args.Arg;
 409                         this.ctx = ctx;
 410                 }
 411
 412                 public override XPathResultType ReturnType { get { return XPathResultType.Boolean; }}
 413
 414                 internal override bool Peer {
 415                         get { return arg0.Peer; }
 416                 }
 417
 418                 public override object Evaluate (BaseIterator iter)
 419                 {
 420
 421                         string name = arg0.EvaluateString (iter);
 422                         int colon = name.IndexOf (':');
 423                         // extension function
 424                         if (colon > 0)
 425                                 return (iter.NamespaceManager as XsltCompiledContext).ResolveFunction (
 426                                         XslNameUtil.FromString (name, ctx),
 427                                         null) != null;
 428
 429                         return (
 430                                 //
 431                                 // XPath
 432                                 //
 433                                 name == "boolean" ||
 434                                 name == "ceiling" ||
 435                                 name == "concat" ||
 436                                 name == "contains" ||
 437                                 name == "count" ||
 438                                 name == "false" ||
 439                                 name == "floor" ||
 440                                 name == "id"||
 441                                 name == "lang" ||
 442                                 name == "last" ||
 443                                 name == "local-name" ||
 444                                 name == "name" ||
 445                                 name == "namespace-uri" ||
 446                                 name == "normalize-space" ||
 447                                 name == "not" ||
 448                                 name == "number" ||
 449                                 name == "position" ||
 450                                 name == "round" ||
 451                                 name == "starts-with" ||
 452                                 name == "string" ||
 453                                 name == "string-length" ||
 454                                 name == "substring" ||
 455                                 name == "substring-after" ||
 456                                 name == "substring-before" ||
 457                                 name == "sum" ||
 458                                 name == "translate" ||
 459                                 name == "true" ||
 460                                 // XSLT
 461                                 name == "document" ||
 462                                 name == "format-number" ||
 463                                 name == "function-available" ||
 464                                 name == "generate-id" ||
 465                                 name == "key" ||
 466                                 name == "current" ||
 467                                 name == "unparsed-entity-uri" ||
 468                                 name == "element-available" ||
 469                                 name == "system-property"
 470                         );
 471                 }
 472         }
 473
 474         class XsltGenerateId : XPathFunction
 475         {
 476                 //FIXME: generate short string, not the huge thing it makes now
 477                 Expression arg0;
 478                 public XsltGenerateId (FunctionArguments args) : base (args)
 479                 {
 480                         if (args != null) {
 481                                 if (args.Tail != null)
 482                                         throw new XPathException ("generate-id takes 1 or no args");
 483                                 arg0 = args.Arg;
 484                         }
 485                 }
 486
 487                 public override XPathResultType ReturnType { get { return XPathResultType.String; }}
 488
 489                 internal override bool Peer {
 490                         get { return arg0.Peer; }
 491                 }
 492
 493                 public override object Evaluate (BaseIterator iter)
 494                 {
 495                         XPathNavigator n;
 496                         if (arg0 != null) {
 497                                 XPathNodeIterator itr = arg0.EvaluateNodeSet (iter);
 498                                 if (itr.MoveNext ())
 499                                         n = itr.Current.Clone ();
 500                                 else
 501                                         return string.Empty; // empty nodeset == empty string
 502                         } else
 503                                 n = iter.Current.Clone ();
 504
 505                         StringBuilder sb = new StringBuilder ("Mono"); // Ensure begins with alpha
 506                         sb.Append (XmlConvert.EncodeLocalName (n.BaseURI));
 507                         sb.Replace ('_', 'm'); // remove underscores from EncodeLocalName
 508                         sb.Append (n.NodeType);
 509                         sb.Append ('m');
 510
 511                         do {
 512                                 sb.Append (IndexInParent (n));
 513                                 sb.Append ('m');
 514                         } while (n.MoveToParent ());
 515
 516                         return sb.ToString ();
 517                 }
 518
 519                 int IndexInParent (XPathNavigator nav)
 520                 {
 521                         int n = 0;
 522                         while (nav.MoveToPrevious ())
 523                                 n++;
 524
 525                         return n;
 526                 }
 527         }
 528
 529         class XsltKey : XPathFunction
 530         {
 531                 Expression arg0, arg1;
 532                 IStaticXsltContext staticContext;
 533
 534                 public XsltKey (FunctionArguments args, IStaticXsltContext ctx) : base (args)
 535                 {
 536                         staticContext = ctx;
 537                         if (args == null || args.Tail == null)
 538                                 throw new XPathException ("key takes 2 args");
 539                         arg0 = args.Arg;
 540                         arg1 = args.Tail.Arg;
 541                 }
 542                 public Expression KeyName { get { return arg0; } }
 543                 public Expression Field { get { return arg1; } }
 544                 public override XPathResultType ReturnType { get { return XPathResultType.NodeSet; }}
 545
 546                 internal override bool Peer {
 547                         get { return arg0.Peer && arg1.Peer; }
 548                 }
 549
 550                 public bool PatternMatches (XPathNavigator nav, XsltContext nsmgr)
 551                 {
 552                         XsltCompiledContext ctx = nsmgr as XsltCompiledContext;
 553                         // for key pattern, it must contain literal value
 554                         return ctx.MatchesKey (nav, staticContext,
 555                                 arg0.StaticValueAsString,
 556                                 arg1.StaticValueAsString);
 557                 }
 558
 559                 public override object Evaluate (BaseIterator iter)
 560                 {
 561                         XsltCompiledContext ctx = iter.NamespaceManager
 562                                 as XsltCompiledContext;
 563                         return ctx.EvaluateKey (staticContext, iter, arg0, arg1);
 564                 }
 565         }
 566
 567         class XsltSystemProperty : XPathFunction
 568         {
 569                 Expression arg0;
 570                 IStaticXsltContext ctx;
 571
 572                 public XsltSystemProperty (FunctionArguments args, IStaticXsltContext ctx) : base (args)
 573                 {
 574                         if (args == null || args.Tail != null)
 575                                 throw new XPathException ("system-property takes 1 arg");
 576
 577                         arg0 = args.Arg;
 578                         this.ctx = ctx;
 579                 }
 580
 581                 public override XPathResultType ReturnType { get { return XPathResultType.String; }}
 582
 583                 internal override bool Peer {
 584                         get { return arg0.Peer; }
 585                 }
 586
 587                 public override object Evaluate (BaseIterator iter)
 588                 {
 589                         QName name = XslNameUtil.FromString (arg0.EvaluateString (iter), ctx);
 590
 591                         if (name.Namespace == Compiler.XsltNamespace) {
 592                                 switch (name.Name) {
 593                                         case "version": return "1.0";
 594                                         case "vendor": return "Mono";
 595                                         case "vendor-url": return "http://www.go-mono.com/";
 596                                 }
 597                         }
 598
 599                         return "";
 600                 }
 601         }
 602
 603         class XsltUnparsedEntityUri : XPathFunction
 604         {
 605                 Expression arg0;
 606
 607                 public XsltUnparsedEntityUri (FunctionArguments args) : base (args)
 608                 {
 609                         if (args == null || args.Tail != null)
 610                                 throw new XPathException ("unparsed-entity-uri takes 1 arg");
 611
 612                         arg0 = args.Arg;
 613                 }
 614
 615                 public override XPathResultType ReturnType { get { return XPathResultType.String; }}
 616
 617                 internal override bool Peer {
 618                         get { return arg0.Peer; }
 619                 }
 620
 621                 public override object Evaluate (BaseIterator iter)
 622                 {
 623                         IHasXmlNode xn = iter.Current as IHasXmlNode;
 624                         if (xn == null)
 625                                 return String.Empty;
 626                         XmlNode n = xn.GetNode ();
 627                         if (n.OwnerDocument == null)
 628                                 return String.Empty;
 629                         XmlDocumentType doctype = n.OwnerDocument.DocumentType;
 630                         if (doctype == null)
 631                                 return String.Empty;
 632                         XmlEntity ent = doctype.Entities.GetNamedItem (arg0.EvaluateString (iter)) as XmlEntity;
 633                         if (ent == null)
 634                                 return String.Empty;
 635                         return ent.SystemId != null ? ent.SystemId : String.Empty;
 636                 }
 637         }
 638
 639         class MSXslNodeSet : XPathFunction
 640         {
 641                 Expression arg0;
 642
 643                 public MSXslNodeSet (FunctionArguments args) : base (args)
 644                 {
 645                         if (args == null || args.Tail != null)
 646                                 throw new XPathException ("element-available takes 1 arg");
 647
 648                         arg0 = args.Arg;
 649                 }
 650
 651                 public override XPathResultType ReturnType {
 652                         get {
 653                                 return XPathResultType.NodeSet;
 654                         }
 655                 }
 656
 657                 internal override bool Peer {
 658                         get { return arg0.Peer; }
 659                 }
 660
 661                 public override object Evaluate (BaseIterator iter)
 662                 {
 663                         XsltCompiledContext ctx = iter.NamespaceManager as XsltCompiledContext;
 664                         XPathNavigator loc = iter.Current != null ? iter.Current.Clone () : null;
 665                         XPathNavigator nav = arg0.EvaluateAs (iter, XPathResultType.Navigator) as XPathNavigator;
 666                         if (nav == null) {
 667                                 if (loc != null)
 668                                         return new XsltException ("Cannot convert the XPath argument to a result tree fragment.", null, loc);
 669                                 else
 670                                         return new XsltException ("Cannot convert the XPath argument to a result tree fragment.", null);
 671                         }
 672                         ArrayList al = new ArrayList ();
 673                         al.Add (nav);
 674                         return new ListIterator (al, ctx);
 675                 }
 676         }
 677 }