mcs/class/System.XML/System.Xml.XPath/Expression.cs

   1 //
   2 // System.Xml.XPath.XPathExpression support classes
   3 //
   4 // Author:
   5 //   Piers Haken (piersh@friskit.com)
   6 //
   7 // (C) 2002 Piers Haken
   8 //
   9
  10 //
  11 // Permission is hereby granted, free of charge, to any person obtaining
  12 // a copy of this software and associated documentation files (the
  13 // "Software"), to deal in the Software without restriction, including
  14 // without limitation the rights to use, copy, modify, merge, publish,
  15 // distribute, sublicense, and/or sell copies of the Software, and to
  16 // permit persons to whom the Software is furnished to do so, subject to
  17 // the following conditions:
  18 //
  19 // The above copyright notice and this permission notice shall be
  20 // included in all copies or substantial portions of the Software.
  21 //
  22 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  23 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  24 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  25 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  26 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  27 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  28 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  29 //
  30 using System;
  31 using System.IO;
  32 using System.Collections;
  33 using System.Xml;
  34 using System.Xml.XPath;
  35 using System.Xml.Xsl;
  36 using System.Globalization;
  37 using Mono.Xml.XPath;
  38
  39 #if NET_2_0
  40 using NSResolver = System.Xml.IXmlNamespaceResolver;
  41 #else
  42 using NSResolver = System.Xml.XmlNamespaceManager;
  43 #endif
  44
  45 namespace System.Xml.XPath
  46 {
  47         internal static class ExpressionCache
  48         {
  49                 static readonly Hashtable table_per_ctx = new Hashtable ();
  50                 static object dummy = new object ();
  51
  52                 public static XPathExpression Get (string xpath, IStaticXsltContext ctx)
  53                 {
  54                         object ctxkey = ctx != null ? ctx : dummy;
  55
  56                         WeakReference wr = table_per_ctx [ctxkey] as WeakReference;
  57                         if (wr == null)
  58                                 return null;
  59                         if (!wr.IsAlive) {
  60                                 table_per_ctx [ctxkey] = null;
  61                                 return null;
  62                         }
  63                         Hashtable table = (Hashtable) wr.Target;
  64
  65                         wr = table [xpath] as WeakReference;
  66                         if (wr != null) {
  67                                 if (wr.IsAlive)
  68                                         // it may return null (as it might be GC-ed), but we don't have to worrt about it here.
  69                                         return (XPathExpression) wr.Target;
  70                                 table [xpath] = null;
  71                         }
  72                         return null;
  73                 }
  74
  75                 public static void Set (string xpath, IStaticXsltContext ctx, XPathExpression exp)
  76                 {
  77                         object ctxkey = ctx != null ? ctx : dummy;
  78
  79                         Hashtable table = null;
  80
  81                         WeakReference wr = table_per_ctx [ctxkey] as WeakReference;
  82                         if (wr != null && wr.IsAlive)
  83                                 table = (Hashtable) wr.Target;
  84                         if (table == null) {
  85                                 table = new Hashtable ();
  86                                 table_per_ctx [ctxkey] = new WeakReference (table);
  87                         }
  88                         table [xpath] = new WeakReference (exp);
  89                 }
  90         }
  91
  92 #if XPATH_DEBUG
  93         internal class CompiledExpression : Test.Xml.XPath.XPathExpression
  94 #else
  95         internal class CompiledExpression : XPathExpression
  96 #endif
  97         {
  98                 protected NSResolver _nsm;
  99                 protected Expression _expr;
 100                 XPathSorters _sorters;
 101                 string rawExpression;
 102
 103                 public CompiledExpression (string raw, Expression expr)
 104                 {
 105                         _expr = expr.Optimize ();
 106                         rawExpression = raw;
 107                 }
 108                 private CompiledExpression (CompiledExpression other)
 109                 {
 110                         _nsm = other._nsm;
 111                         _expr = other._expr;
 112                         rawExpression = other.rawExpression;
 113                 }
 114 #if XPATH_DEBUG
 115                 public override Test.Xml.XPath.XPathExpression Clone () { return new CompiledExpression (this); }
 116 #else
 117                 public override XPathExpression Clone () { return new CompiledExpression (this); }
 118 #endif
 119
 120                 public Expression ExpressionNode { get { return _expr; }}
 121
 122                 public override void SetContext (XmlNamespaceManager nsManager)
 123                 {
 124                         _nsm = nsManager;
 125                 }
 126
 127 #if NET_2_0
 128                 public override void SetContext (IXmlNamespaceResolver nsResolver)
 129                 {
 130                         _nsm = nsResolver;
 131                 }
 132 #endif
 133
 134                 internal NSResolver NamespaceManager { get { return _nsm; } }
 135                 public override String Expression { get { return rawExpression; }}
 136                 public override XPathResultType ReturnType { get { return _expr.ReturnType; }}
 137
 138                 public object Evaluate (BaseIterator iter)
 139                 {
 140                         if (_sorters != null)
 141                                 return EvaluateNodeSet (iter);
 142
 143 #if false
 144                         return _expr.Evaluate (iter);
 145 #else
 146                         try {
 147                                 return _expr.Evaluate (iter);
 148                         }
 149                         catch (XPathException) {
 150                                 throw;
 151                         }
 152                         catch (XsltException) {
 153                                 throw;
 154                         }
 155                         catch (Exception e) {
 156                                 throw new XPathException ("Error during evaluation", e);
 157                         }
 158 #endif
 159                 }
 160                 public XPathNodeIterator EvaluateNodeSet (BaseIterator iter)
 161                 {
 162 #if false
 163                         try
 164                         {
 165 #endif
 166                                 BaseIterator iterResults = _expr.EvaluateNodeSet (iter);
 167                                 if (_sorters != null)
 168                                         return _sorters.Sort (iterResults);
 169                                 return iterResults;
 170 #if false
 171                         }
 172                         catch (XPathException)
 173                         {
 174                                 throw;
 175                         }
 176                         catch (Exception e)
 177                         {
 178                                 throw new XPathException ("Error during evaluation", e);
 179                         }
 180 #endif
 181                 }
 182                 public double EvaluateNumber (BaseIterator iter)
 183                 {
 184 #if true
 185                         return _expr.EvaluateNumber (iter);
 186 #else
 187                         try
 188                         {
 189                                 return _expr.EvaluateNumber (iter);
 190                         }
 191                         catch (XPathException)
 192                         {
 193                                 throw;
 194                         }
 195                         catch (Exception e)
 196                         {
 197                                 throw new XPathException ("Error during evaluation", e);
 198                         }
 199 #endif
 200                 }
 201                 public string EvaluateString (BaseIterator iter)
 202                 {
 203 #if true
 204                         return _expr.EvaluateString (iter);
 205 #else
 206                         try
 207                         {
 208                                 return _expr.EvaluateString (iter);
 209                         }
 210                         catch (XPathException)
 211                         {
 212                                 throw;
 213                         }
 214                         catch (Exception e)
 215                         {
 216                                 throw new XPathException ("Error during evaluation", e);
 217                         }
 218 #endif
 219                 }
 220                 public bool EvaluateBoolean (BaseIterator iter)
 221                 {
 222 #if true
 223                         return _expr.EvaluateBoolean (iter);
 224 #else
 225                         try
 226                         {
 227                                 return _expr.EvaluateBoolean (iter);
 228                         }
 229                         catch (XPathException)
 230                         {
 231                                 throw;
 232                         }
 233                         catch (Exception e)
 234                         {
 235                                 throw new XPathException ("Error during evaluation", e);
 236                         }
 237 #endif
 238                 }
 239
 240                 public override void AddSort (Object obj, IComparer cmp)
 241                 {
 242                         if (_sorters == null)
 243                                 _sorters = new XPathSorters ();
 244                         _sorters.Add (obj, cmp);
 245                 }
 246                 public override void AddSort(object expr, XmlSortOrder orderSort, XmlCaseOrder orderCase, string lang, XmlDataType dataType)
 247                 {
 248                         if (_sorters == null)
 249                                 _sorters = new XPathSorters ();
 250                         _sorters.Add (expr, orderSort, orderCase, lang, dataType);
 251                 }
 252
 253         }
 254
 255         class XPathSortElement
 256         {
 257                 public XPathNavigator Navigator;
 258                 public object [] Values;
 259         }
 260
 261         class XPathSorters : IComparer
 262         {
 263                 readonly ArrayList _rgSorters = new ArrayList ();
 264
 265                 public void Add (object expr, IComparer cmp)
 266                 {
 267                         _rgSorters.Add (new XPathSorter (expr, cmp));
 268                 }
 269
 270                 public void Add (object expr, XmlSortOrder orderSort, XmlCaseOrder orderCase, string lang, XmlDataType dataType)
 271                 {
 272                         _rgSorters.Add (new XPathSorter (expr, orderSort, orderCase, lang, dataType));
 273                 }
 274
 275                 public void CopyFrom (XPathSorter [] sorters)
 276                 {
 277                         _rgSorters.Clear ();
 278                         _rgSorters.AddRange (sorters);
 279                 }
 280
 281                 public BaseIterator Sort (BaseIterator iter)
 282                 {
 283                         ArrayList rgElts = ToSortElementList (iter);
 284                         return Sort (rgElts, iter.NamespaceManager);
 285                 }
 286
 287                 ArrayList ToSortElementList (BaseIterator iter)
 288                 {
 289                         ArrayList rgElts = new ArrayList ();
 290                         int cSorters = _rgSorters.Count;
 291                         while (iter.MoveNext ())
 292                         {
 293                                 XPathSortElement elt = new XPathSortElement ();
 294                                 elt.Navigator = iter.Current.Clone ();
 295                                 elt.Values = new object [cSorters];
 296                                 for (int iSorter = 0; iSorter < _rgSorters.Count; ++iSorter)
 297                                 {
 298                                         XPathSorter sorter = (XPathSorter) _rgSorters [iSorter];
 299                                         elt.Values [iSorter] = sorter.Evaluate (iter);
 300                                 }
 301                                 rgElts.Add (elt);
 302                         }
 303                         return rgElts;
 304                 }
 305
 306                 public BaseIterator Sort (ArrayList rgElts, NSResolver nsm)
 307                 {
 308                         rgElts.Sort (this);
 309                         XPathNavigator [] rgResults = new XPathNavigator [rgElts.Count];
 310                         for (int iResult = 0; iResult < rgElts.Count; ++iResult)
 311                         {
 312                                 XPathSortElement elt = (XPathSortElement) rgElts [iResult];
 313                                 rgResults [iResult] = elt.Navigator;
 314                         }
 315                         return new ListIterator (rgResults, nsm);
 316                 }
 317
 318                 int IComparer.Compare (object o1, object o2)
 319                 {
 320                         XPathSortElement elt1 = (XPathSortElement) o1;
 321                         XPathSortElement elt2 = (XPathSortElement) o2;
 322                         for (int iSorter = 0; iSorter < _rgSorters.Count; ++iSorter)
 323                         {
 324                                 XPathSorter sorter = (XPathSorter) _rgSorters [iSorter];
 325                                 int cmp = sorter.Compare (elt1.Values [iSorter], elt2.Values [iSorter]);
 326                                 if (cmp != 0)
 327                                         return cmp;
 328                         }
 329                         switch (elt1.Navigator.ComparePosition (elt2.Navigator)) {
 330                         case XmlNodeOrder.Same:
 331                                 return 0;
 332                         case XmlNodeOrder.After:
 333                                 return 1;
 334                         default:
 335                                 return -1;
 336                         }
 337                 }
 338         }
 339
 340         class XPathSorter
 341         {
 342                 readonly Expression _expr;
 343                 readonly IComparer _cmp;
 344                 readonly XmlDataType _type;
 345
 346                 public XPathSorter (object expr, IComparer cmp)
 347                 {
 348                         _expr = ExpressionFromObject (expr);
 349                         _cmp = cmp;
 350                         _type = XmlDataType.Text;
 351                 }
 352
 353                 public XPathSorter (object expr, XmlSortOrder orderSort, XmlCaseOrder orderCase, string lang, XmlDataType dataType)
 354                 {
 355                         _expr = ExpressionFromObject (expr);
 356                         _type = dataType;
 357                         if (dataType == XmlDataType.Number)
 358                                 _cmp = new XPathNumberComparer (orderSort);
 359                         else
 360                                 _cmp = new XPathTextComparer (orderSort, orderCase, lang);
 361                 }
 362
 363                 static Expression ExpressionFromObject (object expr)
 364                 {
 365                         if (expr is CompiledExpression)
 366                                 return ((CompiledExpression) expr).ExpressionNode;
 367                         if (expr is string)
 368                                 return new XPathParser ().Compile ((string)expr);
 369
 370                         throw new XPathException ("Invalid query object");
 371                 }
 372
 373                 public object Evaluate (BaseIterator iter)
 374                 {
 375                         if (_type == XmlDataType.Number)
 376                                 return _expr.EvaluateNumber (iter);
 377                         return _expr.EvaluateString (iter);
 378                 }
 379
 380                 public int Compare (object o1, object o2)
 381                 {
 382                         return _cmp.Compare (o1, o2);
 383                 }
 384
 385                 class XPathNumberComparer : IComparer
 386                 {
 387                         int _nMulSort;
 388
 389                         public XPathNumberComparer (XmlSortOrder orderSort)
 390                         {
 391                                 _nMulSort = (orderSort == XmlSortOrder.Ascending) ? 1 : -1;
 392                         }
 393
 394                         int IComparer.Compare (object o1, object o2)
 395                         {
 396                                 double num1 = (double) o1;
 397                                 double num2 = (double) o2;
 398                                 if (num1 < num2)
 399                                         return -_nMulSort;
 400                                 if (num1 > num2)
 401                                         return _nMulSort;
 402                                 if (num1 == num2)
 403                                         return 0;
 404                                 if (double.IsNaN (num1))
 405                                         return (double.IsNaN (num2)) ? 0 : -_nMulSort;
 406                                 return _nMulSort;
 407                         }
 408                 }
 409
 410                 class XPathTextComparer : IComparer
 411                 {
 412                         int _nMulSort;
 413                         int _nMulCase;
 414                         XmlCaseOrder _orderCase;
 415                         CultureInfo _ci;
 416
 417                         public XPathTextComparer (XmlSortOrder orderSort, XmlCaseOrder orderCase, string strLang)
 418                         {
 419                                 _orderCase = orderCase;
 420                                 // FIXME: We have to set this in
 421                                 // reverse order since currently
 422                                 // we don't support collation.
 423                                 _nMulCase = (orderCase == XmlCaseOrder.UpperFirst) ? -1 : 1;
 424                                 _nMulSort = (orderSort == XmlSortOrder.Ascending) ? 1 : -1;
 425
 426                                 if (strLang == null || strLang == "")
 427                                         _ci = CultureInfo.CurrentCulture;       // TODO: defer until evaluation?
 428                                 else
 429                                         _ci = new CultureInfo (strLang);
 430                         }
 431
 432                         int IComparer.Compare (object o1, object o2)
 433                         {
 434                                 string str1 = (string) o1;
 435                                 string str2 = (string) o2;
 436                                 int cmp = String.Compare (str1, str2, true, _ci);
 437                                 if (cmp != 0 || _orderCase == XmlCaseOrder.None)
 438                                         return cmp * _nMulSort;
 439                                 return _nMulSort * _nMulCase * String.Compare (str1, str2, false, _ci);
 440                         }
 441                 }
 442         }
 443
 444         /// <summary>
 445         /// Summary description for Expression.
 446         /// </summary>
 447         internal abstract class Expression
 448         {
 449                 public Expression ()
 450                 {
 451                 }
 452                 public abstract XPathResultType ReturnType { get; }
 453                 public virtual XPathResultType GetReturnType (BaseIterator iter) { return ReturnType; }
 454
 455                 public virtual Expression Optimize ()
 456                 {
 457                         return this;
 458                 }
 459
 460                 public virtual bool HasStaticValue {
 461                         get { return false; }
 462                 }
 463
 464                 public virtual object StaticValue {
 465                         get {
 466                                 switch (ReturnType) {
 467                                 case XPathResultType.String:
 468                                         return StaticValueAsString;
 469                                 case XPathResultType.Number:
 470                                         return StaticValueAsNumber;
 471                                 case XPathResultType.Boolean:
 472                                         return StaticValueAsBoolean;
 473                                 }
 474                                 return null;
 475                         }
 476                 }
 477
 478                 public virtual string StaticValueAsString {
 479                         get { return HasStaticValue ? XPathFunctions.ToString (StaticValue) : null; }
 480                 }
 481
 482                 public virtual double StaticValueAsNumber {
 483                         get { return HasStaticValue ? XPathFunctions.ToNumber (StaticValue) : 0; }
 484                 }
 485
 486                 public virtual bool StaticValueAsBoolean {
 487                         get { return HasStaticValue ? XPathFunctions.ToBoolean (StaticValue) : false; }
 488                 }
 489
 490                 public virtual XPathNavigator StaticValueAsNavigator {
 491                         get { return StaticValue as XPathNavigator; }
 492                 }
 493
 494                 public abstract object Evaluate (BaseIterator iter);
 495
 496                 public virtual BaseIterator EvaluateNodeSet (BaseIterator iter)
 497                 {
 498                         XPathResultType type = GetReturnType (iter);
 499                         switch (type) {
 500                         case XPathResultType.NodeSet:
 501                         case XPathResultType.Any:
 502                         case XPathResultType.Navigator: // FIXME: It may pass not-allowed use of RTF
 503                                 object o = Evaluate (iter);
 504                                 XPathNodeIterator xi = o as XPathNodeIterator;
 505                                 BaseIterator iterResult = null;
 506                                 if (xi != null) {
 507                                         iterResult = xi as BaseIterator;
 508                                         if (iterResult == null)
 509                                                 iterResult = new WrapperIterator (xi, iter.NamespaceManager);
 510                                         return iterResult;
 511                                 }
 512                                 XPathNavigator nav = o as XPathNavigator;
 513                                 if (nav != null) {
 514                                         XPathNodeIterator xiter = nav.SelectChildren (XPathNodeType.All);
 515                                         iterResult = xiter as BaseIterator;
 516                                         if (iterResult == null && xiter != null)
 517                                                 iterResult = new WrapperIterator (xiter, iter.NamespaceManager);
 518                                 }
 519                                 if (iterResult != null)
 520                                         return iterResult;
 521                                 if (o == null)
 522                                         return new NullIterator (iter);
 523                                 type = GetReturnType (o);
 524                                 break;
 525                         }
 526                         throw new XPathException (String.Format ("expected nodeset but was {1}: {0}", ToString (), type));
 527                 }
 528
 529                 protected static XPathResultType GetReturnType (object obj)
 530                 {
 531                         if (obj is string)
 532                                 return XPathResultType.String;
 533                         if (obj is bool)
 534                                 return XPathResultType.Boolean;
 535                         if (obj is XPathNodeIterator)
 536                                 return XPathResultType.NodeSet;
 537                         if (obj is double || obj is int)
 538                                 return XPathResultType.Number;
 539                         if (obj is XPathNavigator)
 540                                 return XPathResultType.Navigator;
 541                         throw new XPathException ("invalid node type: "+obj.GetType ().ToString ());
 542                 }
 543
 544                 internal virtual XPathNodeType EvaluatedNodeType {
 545                         get { return XPathNodeType.All; }
 546                 }
 547
 548                 internal virtual bool IsPositional {
 549                         get { return false; }
 550                 }
 551
 552                 // For "peer and subtree" optimization. see:
 553                 // http://idealliance.org/papers/dx_xmle04/papers/02-03-02/02-03-02.html
 554                 internal virtual bool Peer {
 555                         get { return false; }
 556                 }
 557
 558                 public virtual double EvaluateNumber (BaseIterator iter)
 559                 {
 560                         object result;
 561                         XPathResultType type = GetReturnType (iter);
 562                         if (type == XPathResultType.NodeSet)
 563                         {
 564                                 result = EvaluateString (iter);
 565                                 type = XPathResultType.String;
 566                         }
 567                         else
 568                                 result = Evaluate (iter);
 569
 570                         if (type == XPathResultType.Any)
 571                                 type = GetReturnType (result);
 572
 573                         switch (type) {
 574                         case XPathResultType.Number:
 575                                 return (double)result;
 576                         case XPathResultType.Boolean:
 577                                 return ((bool) result) ? 1.0 : 0.0;
 578                         case XPathResultType.NodeSet:
 579                                 return XPathFunctions.ToNumber (EvaluateString (iter));
 580                         case XPathResultType.String:
 581                                 return XPathFunctions.ToNumber ((string) result);
 582                         case XPathResultType.Navigator:
 583                                 return XPathFunctions.ToNumber (((XPathNavigator) (result)).Value);
 584                         default:
 585                                 throw new XPathException ("invalid node type");
 586                         }
 587                 }
 588
 589                 public virtual string EvaluateString (BaseIterator iter)
 590                 {
 591                         object result = Evaluate (iter);
 592                         XPathResultType type = GetReturnType (iter);
 593                         if (type == XPathResultType.Any)
 594                                 type = GetReturnType (result);
 595                         switch (type) {
 596                         case XPathResultType.Number:
 597                                 double d = (double) result;
 598                                 return XPathFunctions.ToString (d);
 599                         case XPathResultType.Boolean:
 600                                 return ((bool) result) ? "true" : "false";
 601                         case XPathResultType.String:
 602                                 return (string) result;
 603                         case XPathResultType.NodeSet:
 604                         {
 605                                 BaseIterator iterResult = (BaseIterator) result;
 606                                 if (iterResult == null || !iterResult.MoveNext ())
 607                                         return "";
 608                                 return iterResult.Current.Value;
 609                         }
 610                         case XPathResultType.Navigator:
 611                                 return ((XPathNavigator) result).Value;
 612                         default:
 613                                 throw new XPathException ("invalid node type");
 614                         }
 615                 }
 616
 617                 public virtual bool EvaluateBoolean (BaseIterator iter)
 618                 {
 619                         object result = Evaluate (iter);
 620                         XPathResultType type = GetReturnType (iter);
 621                         if (type == XPathResultType.Any)
 622                                 type = GetReturnType (result);
 623                         switch (type) {
 624                         case XPathResultType.Number:
 625                                 double num = Convert.ToDouble (result);
 626                                 return (num != 0.0 && num != -0.0 && !Double.IsNaN (num));
 627                         case XPathResultType.Boolean:
 628                                 return (bool) result;
 629                         case XPathResultType.String:
 630                                 return ((string) result).Length != 0;
 631                         case XPathResultType.NodeSet:
 632                                 BaseIterator iterResult = (BaseIterator) result;
 633                                 return (iterResult != null && iterResult.MoveNext ());
 634                         case XPathResultType.Navigator:
 635                                 return (((XPathNavigator) result).HasChildren);
 636                         default:
 637                                 throw new XPathException ("invalid node type");
 638                         }
 639                 }
 640
 641                 public object EvaluateAs (BaseIterator iter, XPathResultType type)
 642                 {
 643                         switch (type) {
 644                         case XPathResultType.Boolean:
 645                                 return EvaluateBoolean (iter);
 646                         case XPathResultType.NodeSet:
 647                                 return EvaluateNodeSet (iter);
 648                         case XPathResultType.String:
 649                                 return EvaluateString (iter);
 650                         case XPathResultType.Number:
 651                                 return EvaluateNumber (iter);
 652                         }
 653                         return Evaluate (iter);
 654                 }
 655
 656                 public virtual bool RequireSorting { get { return false; } }
 657         }
 658
 659         internal abstract class ExprBinary : Expression
 660         {
 661                 protected Expression _left, _right;
 662
 663                 public ExprBinary (Expression left, Expression right)
 664                 {
 665                         _left = left;
 666                         _right = right;
 667                 }
 668
 669                 public override Expression Optimize ()
 670                 {
 671                         _left = _left.Optimize ();
 672                         _right = _right.Optimize ();
 673                         return this;
 674                 }
 675
 676                 public override bool HasStaticValue {
 677                         get { return _left.HasStaticValue && _right.HasStaticValue; }
 678                 }
 679
 680                 public override String ToString ()
 681                 {
 682                         return _left.ToString () + ' ' + Operator + ' ' + _right.ToString ();
 683                 }
 684                 protected abstract String Operator { get; }
 685
 686                 internal override XPathNodeType EvaluatedNodeType {
 687                         get {
 688                                 if (_left.EvaluatedNodeType == _right.EvaluatedNodeType)
 689                                         return _left.EvaluatedNodeType;
 690                                 else
 691                                         return XPathNodeType.All;
 692                         }
 693                 }
 694
 695                 internal override bool IsPositional {
 696                         get { return _left.IsPositional || _right.IsPositional; }
 697                 }
 698
 699                 internal override bool Peer {
 700                         get { return _left.Peer && _right.Peer; }
 701                 }
 702         }
 703
 704         internal abstract class ExprBoolean : ExprBinary
 705         {
 706                 public ExprBoolean (Expression left, Expression right) : base (left, right) {}
 707
 708                 public override Expression Optimize ()
 709                 {
 710                         base.Optimize ();
 711                         if (!HasStaticValue)
 712                                 return this;
 713                         else if (StaticValueAsBoolean)
 714                                 return new XPathFunctionTrue (null);
 715                         else
 716                                 return new XPathFunctionFalse (null);
 717                 }
 718
 719                 public override XPathResultType ReturnType { get { return XPathResultType.Boolean; }}
 720                 public override object Evaluate (BaseIterator iter)
 721                 {
 722                         return EvaluateBoolean (iter);
 723                 }
 724                 public override double EvaluateNumber (BaseIterator iter)
 725                 {
 726                         return EvaluateBoolean (iter) ? 1 : 0;
 727                 }
 728
 729                 public override string EvaluateString (BaseIterator iter)
 730                 {
 731                         return EvaluateBoolean (iter) ? "true" : "false";
 732                 }
 733         }
 734
 735         internal class ExprOR : ExprBoolean
 736         {
 737                 public ExprOR (Expression left, Expression right) : base (left, right) {}
 738                 protected override String Operator { get { return "or"; }}
 739
 740                 public override bool StaticValueAsBoolean {
 741                         get { return HasStaticValue ? _left.StaticValueAsBoolean || _right.StaticValueAsBoolean : false; }
 742                 }
 743
 744                 public override bool EvaluateBoolean (BaseIterator iter)
 745                 {
 746                         if (_left.EvaluateBoolean (iter))
 747                                 return true;
 748                         return _right.EvaluateBoolean (iter);
 749                 }
 750         }
 751
 752         internal class ExprAND : ExprBoolean
 753         {
 754                 public ExprAND (Expression left, Expression right) : base (left, right) {}
 755                 protected override String Operator { get { return "and"; }}
 756
 757                 public override bool StaticValueAsBoolean {
 758                         get { return HasStaticValue ? _left.StaticValueAsBoolean && _right.StaticValueAsBoolean : false; }
 759                 }
 760
 761                 public override bool EvaluateBoolean (BaseIterator iter)
 762                 {
 763                         if (!_left.EvaluateBoolean (iter))
 764                                 return false;
 765                         return _right.EvaluateBoolean (iter);
 766                 }
 767         }
 768
 769         internal abstract class EqualityExpr : ExprBoolean
 770         {
 771                 bool trueVal;
 772                 public EqualityExpr (Expression left, Expression right, bool trueVal) : base (left, right)
 773                 {
 774                         this.trueVal = trueVal;
 775                 }
 776
 777                 public override bool StaticValueAsBoolean {
 778                         get {
 779                                 if (!HasStaticValue)
 780                                         return false;
 781                                 if ((_left.ReturnType == XPathResultType.Navigator || _right.ReturnType == XPathResultType.Navigator) && _left.ReturnType == _right.ReturnType)
 782                                         return (_left.StaticValueAsNavigator.IsSamePosition (
 783                                         _right.StaticValueAsNavigator))
 784                                          == trueVal;
 785                                 if (_left.ReturnType == XPathResultType.Boolean | _right.ReturnType == XPathResultType.Boolean)
 786                                         return (_left.StaticValueAsBoolean == _right.StaticValueAsBoolean) == trueVal;
 787                                 if (_left.ReturnType == XPathResultType.Number | _right.ReturnType == XPathResultType.Number)
 788                                         return (_left.StaticValueAsNumber == _right.StaticValueAsNumber) == trueVal;
 789                                 if (_left.ReturnType == XPathResultType.String | _right.ReturnType == XPathResultType.String)
 790                                         return (_left.StaticValueAsString == _right.StaticValueAsString) == trueVal;
 791                                 return _left.StaticValue == _right.StaticValue == trueVal;
 792                         }
 793                 }
 794
 795                 // FIXME: Avoid extraneous evaluation
 796                 public override bool EvaluateBoolean (BaseIterator iter)
 797                 {
 798                         XPathResultType typeL = _left.GetReturnType (iter);
 799                         XPathResultType typeR = _right.GetReturnType (iter);
 800
 801                         // TODO: avoid double evaluations
 802                         if (typeL == XPathResultType.Any)
 803                                 typeL = GetReturnType (_left.Evaluate (iter));
 804                         if (typeR == XPathResultType.Any)
 805                                 typeR = GetReturnType (_right.Evaluate (iter));
 806
 807                         // Regard RTF as string
 808                         if (typeL == XPathResultType.Navigator)
 809                                 typeL = XPathResultType.String;
 810                         if (typeR == XPathResultType.Navigator)
 811                                 typeR = XPathResultType.String;
 812
 813                         if (typeL == XPathResultType.NodeSet || typeR == XPathResultType.NodeSet)
 814                         {
 815                                 Expression left, right;
 816                                 if (typeL != XPathResultType.NodeSet)
 817                                 {
 818                                         left = _right;
 819                                         right = _left;
 820                                         XPathResultType typeTmp = typeL;
 821                                         typeL = typeR;
 822                                         typeR = typeTmp;
 823                                 }
 824                                 else
 825                                 {
 826                                         left = _left;
 827                                         right = _right;
 828                                 }
 829                                 if (typeR == XPathResultType.Boolean)
 830                                 {
 831                                         return left.EvaluateBoolean (iter) == right.EvaluateBoolean (iter) == trueVal;
 832                                 }
 833                                 else
 834                                 {
 835                                         BaseIterator iterL = left.EvaluateNodeSet (iter);
 836                                         if (typeR == XPathResultType.Number)
 837                                         {
 838                                                 double dR = right.EvaluateNumber (iter);
 839                                                 while (iterL.MoveNext ())
 840                                                         if (XPathFunctions.ToNumber (iterL.Current.Value) == dR == trueVal)
 841                                                                 return true;
 842                                         }
 843                                         else if (typeR == XPathResultType.String)
 844                                         {
 845                                                 string strR = right.EvaluateString (iter);
 846                                                 while (iterL.MoveNext ())
 847                                                         if (iterL.Current.Value == strR == trueVal)
 848                                                                 return true;
 849                                         }
 850                                         else if (typeR == XPathResultType.NodeSet)
 851                                         {
 852                                                 BaseIterator iterR = right.EvaluateNodeSet (iter);
 853                                                 ArrayList rgNodesL = new ArrayList ();
 854                                                 while (iterL.MoveNext ())
 855                                                         rgNodesL.Add (XPathFunctions.ToString (iterL.Current.Value));
 856                                                 while (iterR.MoveNext ())
 857                                                 {
 858                                                         string strR = XPathFunctions.ToString (iterR.Current.Value);
 859                                                         for (int l = 0; l < rgNodesL.Count; l++)
 860                                                                 if ((strR == (string) rgNodesL [l]) == trueVal)
 861                                                                         return true;
 862                                                 }
 863                                         }
 864                                         return false;
 865                                 }
 866                         }
 867                         else if (typeL == XPathResultType.Boolean || typeR == XPathResultType.Boolean)
 868                                 return _left.EvaluateBoolean (iter) == _right.EvaluateBoolean (iter) == trueVal;
 869                         else if (typeL == XPathResultType.Number || typeR == XPathResultType.Number)
 870                                 return _left.EvaluateNumber (iter) == _right.EvaluateNumber (iter) == trueVal;
 871                         else
 872                                 return _left.EvaluateString (iter) == _right.EvaluateString (iter) == trueVal;
 873                 }
 874         }
 875
 876         internal class ExprEQ : EqualityExpr
 877         {
 878                 public ExprEQ (Expression left, Expression right) : base (left, right, true) {}
 879                 protected override String Operator { get { return "="; }}
 880         }
 881
 882         internal class ExprNE : EqualityExpr
 883         {
 884                 public ExprNE (Expression left, Expression right) : base (left, right, false) {}
 885                 protected override String Operator { get { return "!="; }}
 886         }
 887
 888         internal abstract class RelationalExpr : ExprBoolean
 889         {
 890                 public RelationalExpr (Expression left, Expression right) : base (left, right) {}
 891
 892                 public override bool StaticValueAsBoolean {
 893                         get { return HasStaticValue ? Compare (_left.StaticValueAsNumber, _right.StaticValueAsNumber) : false; }
 894                 }
 895
 896                 // FIXME: Avoid extraneous evaluation.
 897                 public override bool EvaluateBoolean (BaseIterator iter)
 898                 {
 899                         XPathResultType typeL = _left.GetReturnType (iter);
 900                         XPathResultType typeR = _right.GetReturnType (iter);
 901
 902                         if (typeL == XPathResultType.Any)
 903                                 typeL = GetReturnType (_left.Evaluate (iter));
 904                         if (typeR == XPathResultType.Any)
 905                                 typeR = GetReturnType (_right.Evaluate (iter));
 906
 907                         // Regard RTF as string
 908                         if (typeL == XPathResultType.Navigator)
 909                                 typeL = XPathResultType.String;
 910                         if (typeR == XPathResultType.Navigator)
 911                                 typeR = XPathResultType.String;
 912
 913                         if (typeL == XPathResultType.NodeSet || typeR == XPathResultType.NodeSet)
 914                         {
 915                                 bool fReverse = false;
 916                                 Expression left, right;
 917                                 if (typeL != XPathResultType.NodeSet)
 918                                 {
 919                                         fReverse = true;
 920                                         left = _right;
 921                                         right = _left;
 922                                         XPathResultType typeTmp = typeL;
 923                                         typeL = typeR;
 924                                         typeR = typeTmp;
 925                                 }
 926                                 else
 927                                 {
 928                                         left = _left;
 929                                         right = _right;
 930                                 }
 931                                 if (typeR == XPathResultType.Boolean)
 932                                 {
 933                                         bool fL = left.EvaluateBoolean (iter);
 934                                         bool fR = right.EvaluateBoolean (iter);
 935                                         return Compare (Convert.ToDouble (fL), Convert.ToDouble (fR), fReverse);
 936                                 }
 937                                 else
 938                                 {
 939                                         BaseIterator iterL = left.EvaluateNodeSet (iter);
 940                                         if (typeR == XPathResultType.Number || typeR == XPathResultType.String)
 941                                         {
 942                                                 double dR = right.EvaluateNumber (iter);
 943                                                 while (iterL.MoveNext ())
 944                                                         if (Compare (XPathFunctions.ToNumber (iterL.Current.Value), dR, fReverse))
 945                                                                 return true;
 946                                         }
 947                                         else if (typeR == XPathResultType.NodeSet)
 948                                         {
 949                                                 BaseIterator iterR = right.EvaluateNodeSet (iter);
 950                                                 ArrayList rgNodesL = new ArrayList ();
 951                                                 while (iterL.MoveNext ())
 952                                                         rgNodesL.Add (XPathFunctions.ToNumber (iterL.Current.Value));
 953                                                 while (iterR.MoveNext ())
 954                                                 {
 955                                                         double numR = XPathFunctions.ToNumber (iterR.Current.Value);
 956                                                         for (int l = 0; l < rgNodesL.Count; l++)
 957                                                                 if (Compare ((double) rgNodesL [l], numR))
 958                                                                         return true;
 959                                                 }
 960                                         }
 961                                         return false;
 962                                 }
 963                         }
 964                         else
 965                                 return Compare (_left.EvaluateNumber (iter), _right.EvaluateNumber (iter));
 966                 }
 967                 public abstract bool Compare (double arg1, double arg2);
 968                 public bool Compare (double arg1, double arg2, bool fReverse)
 969                 {
 970                         if (fReverse)
 971                                 return Compare (arg2, arg1);
 972                         else
 973                                 return Compare (arg1, arg2);
 974                 }
 975         }
 976
 977         internal class ExprGT : RelationalExpr
 978         {
 979                 public ExprGT (Expression left, Expression right) : base (left, right) {}
 980                 protected override String Operator { get { return ">"; }}
 981                 public override bool Compare (double arg1, double arg2)
 982                 {
 983                         return arg1 > arg2;
 984                 }
 985         }
 986
 987         internal class ExprGE : RelationalExpr
 988         {
 989                 public ExprGE (Expression left, Expression right) : base (left, right) {}
 990                 protected override String Operator { get { return ">="; }}
 991                 public override bool Compare (double arg1, double arg2)
 992                 {
 993                         return arg1 >= arg2;
 994                 }
 995         }
 996
 997         internal class ExprLT : RelationalExpr
 998         {
 999                 public ExprLT (Expression left, Expression right) : base (left, right) {}
1000                 protected override String Operator { get { return "<"; }}
1001                 public override bool Compare (double arg1, double arg2)
1002                 {
1003                         return arg1 < arg2;
1004                 }
1005         }
1006
1007         internal class ExprLE : RelationalExpr
1008         {
1009                 public ExprLE (Expression left, Expression right) : base (left, right) {}
1010                 protected override String Operator { get { return "<="; }}
1011                 public override bool Compare (double arg1, double arg2)
1012                 {
1013                         return arg1 <= arg2;
1014                 }
1015         }
1016
1017         internal abstract class ExprNumeric : ExprBinary
1018         {
1019                 public ExprNumeric (Expression left, Expression right) : base (left, right) {}
1020                 public override XPathResultType ReturnType { get { return XPathResultType.Number; }}
1021
1022                 public override Expression Optimize ()
1023                 {
1024                         base.Optimize ();
1025                         return !HasStaticValue ?
1026                                 (Expression) this :
1027                                 new ExprNumber (StaticValueAsNumber);
1028                 }
1029
1030                 public override object Evaluate (BaseIterator iter)
1031                 {
1032                         return EvaluateNumber (iter);
1033                 }
1034         }
1035
1036         internal class ExprPLUS : ExprNumeric
1037         {
1038                 public ExprPLUS (Expression left, Expression right) : base (left, right) {}
1039                 protected override String Operator { get { return "+"; }}
1040
1041                 public override double StaticValueAsNumber {
1042                         get { return HasStaticValue ? _left.StaticValueAsNumber + _right.StaticValueAsNumber: 0; }
1043                 }
1044
1045                 public override double EvaluateNumber (BaseIterator iter)
1046                 {
1047                         return _left.EvaluateNumber (iter) + _right.EvaluateNumber (iter);
1048                 }
1049         }
1050
1051         internal class ExprMINUS : ExprNumeric
1052         {
1053                 public ExprMINUS (Expression left, Expression right) : base (left, right) {}
1054                 protected override String Operator { get { return "-"; }}
1055
1056                 public override double StaticValueAsNumber {
1057                         get { return HasStaticValue ? _left.StaticValueAsNumber - _right.StaticValueAsNumber: 0; }
1058                 }
1059
1060                 public override double EvaluateNumber (BaseIterator iter)
1061                 {
1062                         return _left.EvaluateNumber (iter) - _right.EvaluateNumber (iter);
1063                 }
1064         }
1065
1066         internal class ExprMULT : ExprNumeric
1067         {
1068                 public ExprMULT (Expression left, Expression right) : base (left, right) {}
1069                 protected override String Operator { get { return "*"; }}
1070
1071                 public override double StaticValueAsNumber {
1072                         get { return HasStaticValue ? _left.StaticValueAsNumber * _right.StaticValueAsNumber: 0; }
1073                 }
1074
1075                 public override double EvaluateNumber (BaseIterator iter)
1076                 {
1077                         return _left.EvaluateNumber (iter) * _right.EvaluateNumber (iter);
1078                 }
1079         }
1080
1081         internal class ExprDIV : ExprNumeric
1082         {
1083                 public ExprDIV (Expression left, Expression right) : base (left, right) {}
1084                 protected override String Operator { get { return " div "; }}
1085
1086                 public override double StaticValueAsNumber {
1087                         get { return HasStaticValue ? _left.StaticValueAsNumber / _right.StaticValueAsNumber: 0; }
1088                 }
1089
1090                 public override double EvaluateNumber (BaseIterator iter)
1091                 {
1092                         return _left.EvaluateNumber (iter) / _right.EvaluateNumber (iter);
1093                 }
1094         }
1095
1096         internal class ExprMOD : ExprNumeric
1097         {
1098                 public ExprMOD (Expression left, Expression right) : base (left, right) {}
1099                 protected override String Operator { get { return "%"; }}
1100
1101                 public override double StaticValueAsNumber {
1102                         get { return HasStaticValue ? _left.StaticValueAsNumber % _right.StaticValueAsNumber: 0; }
1103                 }
1104
1105                 public override double EvaluateNumber (BaseIterator iter)
1106                 {
1107                         return _left.EvaluateNumber (iter) % _right.EvaluateNumber (iter);
1108                 }
1109         }
1110
1111         internal class ExprNEG : Expression
1112         {
1113                 Expression _expr;
1114                 public ExprNEG (Expression expr)
1115                 {
1116                         _expr = expr;
1117                 }
1118                 public override String ToString () { return "- " + _expr.ToString (); }
1119                 public override XPathResultType ReturnType { get { return XPathResultType.Number; }}
1120
1121                 public override Expression Optimize ()
1122                 {
1123                         _expr = _expr.Optimize ();
1124                         return !HasStaticValue ?
1125                                 (Expression) this :
1126                                 new ExprNumber (StaticValueAsNumber);
1127                 }
1128
1129                 internal override bool Peer {
1130                         get { return _expr.Peer; }
1131                 }
1132
1133                 public override bool HasStaticValue {
1134                         get { return _expr.HasStaticValue; }
1135                 }
1136
1137                 public override double StaticValueAsNumber {
1138                         get { return _expr.HasStaticValue ? -1 * _expr.StaticValueAsNumber : 0; }
1139                 }
1140
1141                 public override object Evaluate (BaseIterator iter)
1142                 {
1143                         return - _expr.EvaluateNumber (iter);
1144                 }
1145
1146                 public override double EvaluateNumber (BaseIterator iter)
1147                 {
1148                         return - _expr.EvaluateNumber (iter);
1149                 }
1150
1151                 internal override bool IsPositional {
1152                         get { return _expr.IsPositional; }
1153                 }
1154         }
1155
1156
1157         internal abstract class NodeSet : Expression
1158         {
1159                 public override XPathResultType ReturnType { get { return XPathResultType.NodeSet; }}
1160
1161                 // For "peer and subtree" optimization. see:
1162                 // http://idealliance.org/papers/dx_xmle04/papers/02-03-02/02-03-02.html
1163                 internal abstract bool Subtree { get; }
1164         }
1165
1166         internal class ExprUNION : NodeSet
1167         {
1168                 internal Expression left, right;
1169                 public ExprUNION (Expression left, Expression right)
1170                 {
1171                         this.left = left;
1172                         this.right = right;
1173                 }
1174
1175                 public override Expression Optimize ()
1176                 {
1177                         left = left.Optimize ();
1178                         right = right.Optimize ();
1179                         return this;
1180                 }
1181
1182                 public override String ToString () { return left.ToString ()+ " | " + right.ToString (); }
1183                 public override object Evaluate (BaseIterator iter)
1184                 {
1185                         BaseIterator iterLeft = left.EvaluateNodeSet (iter);
1186                         BaseIterator iterRight = right.EvaluateNodeSet (iter);
1187                         return new UnionIterator (iter, iterLeft, iterRight);
1188                 }
1189
1190                 internal override XPathNodeType EvaluatedNodeType {
1191                         get { return left.EvaluatedNodeType == right.EvaluatedNodeType ? left.EvaluatedNodeType : XPathNodeType.All; }
1192                 }
1193
1194                 internal override bool IsPositional {
1195                         get { return left.IsPositional || right.IsPositional; }
1196                 }
1197
1198                 internal override bool Peer {
1199                         get { return left.Peer && right.Peer; }
1200                 }
1201
1202                 internal override bool Subtree {
1203                         get {
1204                                 NodeSet nl = left as NodeSet;
1205                                 NodeSet nr = right as NodeSet;
1206                                 return nl != null && nr != null && nl.Subtree && nr.Subtree;
1207                         }
1208                 }
1209         }
1210
1211         internal class ExprSLASH : NodeSet
1212         {
1213                 public Expression left;
1214                 public NodeSet right;
1215                 public ExprSLASH (Expression left, NodeSet right)
1216                 {
1217                         this.left = left;
1218                         this.right = right;
1219                 }
1220
1221                 public override Expression Optimize ()
1222                 {
1223                         left = left.Optimize ();
1224                         right = (NodeSet) right.Optimize ();
1225                         return this;
1226                 }
1227
1228                 public override String ToString () { return left.ToString ()+ "/" + right.ToString (); }
1229                 public override object Evaluate (BaseIterator iter)
1230                 {
1231                         // Peer and subtree optimization. see
1232                         // http://idealliance.org/papers/dx_xmle04/papers/02-03-02/02-03-02.html
1233                         BaseIterator iterLeft = left.EvaluateNodeSet (iter);
1234                         if (left.Peer && right.Subtree)
1235                                 return new SimpleSlashIterator (iterLeft, right);
1236                         BaseIterator si = new SlashIterator (iterLeft, right);
1237                         return new SortedIterator (si);
1238                 }
1239
1240                 public override bool RequireSorting { get { return left.RequireSorting || right.RequireSorting; } }
1241
1242                 internal override XPathNodeType EvaluatedNodeType {
1243                         get { return right.EvaluatedNodeType; }
1244                 }
1245
1246                 internal override bool IsPositional {
1247                         get { return left.IsPositional || right.IsPositional; }
1248                 }
1249
1250                 internal override bool Peer {
1251                         get { return left.Peer && right.Peer; }
1252                 }
1253
1254                 internal override bool Subtree {
1255                         get {
1256                                 NodeSet n = left as NodeSet;
1257                                 return n != null && n.Subtree && right.Subtree;
1258                         }
1259                 }
1260         }
1261
1262         internal class ExprSLASH2 : NodeSet {
1263                 public Expression left;
1264                 public NodeSet right;
1265
1266                 static NodeTest DescendantOrSelfStar = new NodeTypeTest (Axes.DescendantOrSelf, XPathNodeType.All);
1267
1268                 public ExprSLASH2 (Expression left, NodeSet right)
1269                 {
1270                         this.left = left;
1271                         this.right = right;
1272                 }
1273
1274                 public override Expression Optimize ()
1275                 {
1276                         left = left.Optimize ();
1277                         right = (NodeSet) right.Optimize ();
1278                         // Path A//B is equal to
1279                         // A/descendant-or-self::node()/child::B, which is
1280                         // equivalent to A/descendant::B. Unlike '//', '/'
1281                         // could be optimized by SimpleSlashIterator.
1282                         NodeTest rnt = right as NodeTest;
1283                         if (rnt != null && rnt.Axis.Axis == Axes.Child) {
1284                                 NodeNameTest nameTest = rnt as NodeNameTest;
1285                                 if (nameTest != null)
1286                                         return new ExprSLASH (left,
1287                                                 new NodeNameTest (nameTest, Axes.Descendant));
1288                                 NodeTypeTest typeTest = rnt as NodeTypeTest;
1289                                 if (typeTest != null)
1290                                         return new ExprSLASH (left,
1291                                                 new NodeTypeTest (typeTest, Axes.Descendant));
1292                         }
1293                         return this;
1294                 }
1295
1296                 public override String ToString () { return left.ToString ()+ "//" + right.ToString (); }
1297                 public override object Evaluate (BaseIterator iter)
1298                 {
1299                         BaseIterator il = left.EvaluateNodeSet (iter);
1300                         if (left.Peer && !left.RequireSorting)
1301                                 il = new SimpleSlashIterator (
1302                                         il, DescendantOrSelfStar);
1303                         else {
1304                                 BaseIterator bb = new SlashIterator (il, DescendantOrSelfStar);
1305                                 il = left.RequireSorting ? new SortedIterator (bb) : bb;
1306                         }
1307
1308                         // FIXME: there could be chances to introduce sort-less
1309                         // iterator, but no one could do it yet.
1310                         SlashIterator b = new SlashIterator (il, right);
1311                         return new SortedIterator (b);
1312                 }
1313
1314                 public override bool RequireSorting { get { return left.RequireSorting || right.RequireSorting; } }
1315
1316                 internal override XPathNodeType EvaluatedNodeType {
1317                         get { return right.EvaluatedNodeType; }
1318                 }
1319
1320                 internal override bool IsPositional {
1321                         get { return left.IsPositional || right.IsPositional; }
1322                 }
1323
1324                 internal override bool Peer {
1325                         get { return false; }
1326                 }
1327
1328                 internal override bool Subtree {
1329                         get {
1330                                 NodeSet n = left as NodeSet;
1331                                 return n != null && n.Subtree && right.Subtree;
1332                         }
1333                 }
1334         }
1335
1336         internal class ExprRoot : NodeSet
1337         {
1338                 public override String ToString () { return ""; }
1339                 public override object Evaluate (BaseIterator iter)
1340                 {
1341                         if (iter.CurrentPosition == 0) {
1342                                 iter = (BaseIterator) iter.Clone ();
1343                                 iter.MoveNext ();
1344                         }
1345                         XPathNavigator navRoot = iter.Current.Clone ();
1346                         navRoot.MoveToRoot ();
1347                         return new SelfIterator (navRoot, iter.NamespaceManager);
1348                 }
1349
1350                 internal override XPathNodeType EvaluatedNodeType {
1351                         get { return XPathNodeType.Root; }
1352                 }
1353
1354                 internal override bool Peer {
1355                         get { return true; }
1356                 }
1357
1358                 internal override bool Subtree {
1359                         get { return false; }
1360                 }
1361         }
1362
1363         internal enum Axes
1364         {
1365                 Ancestor,
1366                 AncestorOrSelf,
1367                 Attribute,
1368                 Child,
1369                 Descendant,
1370                 DescendantOrSelf,
1371                 Following,
1372                 FollowingSibling,
1373                 Namespace,
1374                 Parent,
1375                 Preceding,
1376                 PrecedingSibling,
1377                 Self,
1378         }
1379
1380         internal class AxisSpecifier
1381         {
1382                 protected Axes _axis;
1383                 public AxisSpecifier (Axes axis)
1384                 {
1385                         _axis = axis;
1386                 }
1387                 public XPathNodeType NodeType
1388                 {
1389                         get
1390                         {
1391                                 switch (_axis) {
1392                                 case Axes.Namespace:
1393                                         return XPathNodeType.Namespace;
1394                                 case Axes.Attribute:
1395                                         return XPathNodeType.Attribute;
1396                                 default:
1397                                         return XPathNodeType.Element;
1398                                 }
1399                         }
1400                 }
1401                 public override string ToString ()
1402                 {
1403                         switch (_axis) {
1404                         case Axes.Ancestor:
1405                                 return "ancestor";
1406                         case Axes.AncestorOrSelf:
1407                                 return "ancestor-or-self";
1408                         case Axes.Attribute:
1409                                 return "attribute";
1410                         case Axes.Child:
1411                                 return "child";
1412                         case Axes.Descendant:
1413                                 return "descendant";
1414                         case Axes.DescendantOrSelf:
1415                                 return "descendant-or-self";
1416                         case Axes.Following:
1417                                 return "following";
1418                         case Axes.FollowingSibling:
1419                                 return "following-sibling";
1420                         case Axes.Namespace:
1421                                 return "namespace";
1422                         case Axes.Parent:
1423                                 return "parent";
1424                         case Axes.Preceding:
1425                                 return "preceding";
1426                         case Axes.PrecedingSibling:
1427                                 return "preceding-sibling";
1428                         case Axes.Self:
1429                                 return "self";
1430                         default:
1431                                 throw new IndexOutOfRangeException ();
1432                         }
1433                 }
1434                 public Axes Axis { get { return _axis; }}
1435                 public BaseIterator Evaluate (BaseIterator iter)
1436                 {
1437                         switch (_axis) {
1438                         case Axes.Ancestor:
1439                                 return new AncestorIterator (iter);
1440                         case Axes.AncestorOrSelf:
1441                                 return new AncestorOrSelfIterator (iter);
1442                         case Axes.Attribute:
1443                                 return new AttributeIterator (iter);
1444                         case Axes.Child:
1445                                 return new ChildIterator (iter);
1446                         case Axes.Descendant:
1447                                 return new DescendantIterator (iter);
1448                         case Axes.DescendantOrSelf:
1449                                 return new DescendantOrSelfIterator (iter);
1450                         case Axes.Following:
1451                                 return new FollowingIterator (iter);
1452                         case Axes.FollowingSibling:
1453                                 return new FollowingSiblingIterator (iter);
1454                         case Axes.Namespace:
1455                                 return new NamespaceIterator (iter);
1456                         case Axes.Parent:
1457                                 return new ParentIterator (iter);
1458                         case Axes.Preceding:
1459                                 return new PrecedingIterator (iter);
1460                         case Axes.PrecedingSibling:
1461                                 return new PrecedingSiblingIterator (iter);
1462                         case Axes.Self:
1463                                 return new SelfIterator (iter);
1464                         default:
1465                                 throw new IndexOutOfRangeException ();
1466                         }
1467                 }
1468         }
1469
1470         internal abstract class NodeTest : NodeSet
1471         {
1472                 protected AxisSpecifier _axis;
1473                 public NodeTest (Axes axis)
1474                 {
1475                         _axis = new AxisSpecifier (axis);
1476                 }
1477                 public abstract bool Match (NSResolver nsm, XPathNavigator nav);
1478                 public AxisSpecifier Axis { get { return _axis; }}
1479                 public override object Evaluate (BaseIterator iter)
1480                 {
1481                         BaseIterator iterAxis = _axis.Evaluate (iter);
1482                         return new AxisIterator (iterAxis, this);
1483                 }
1484
1485                 public abstract void GetInfo (out string name, out string ns, out XPathNodeType nodetype, NSResolver nsm);
1486
1487                 public override bool RequireSorting {
1488                         get {
1489                                 switch (_axis.Axis) {
1490                                 case Axes.Ancestor:
1491                                 case Axes.AncestorOrSelf:
1492                                 case Axes.Preceding:
1493                                 case Axes.PrecedingSibling:
1494                                 case Axes.Attribute:
1495                                 case Axes.Namespace:
1496                                         return true;
1497                                 default:
1498                                         return false;
1499                                 }
1500                         }
1501
1502                 }
1503
1504                 internal override bool Peer {
1505                         get {
1506                                 switch (_axis.Axis) {
1507                                 case Axes.Ancestor:
1508                                 case Axes.AncestorOrSelf:
1509                                 case Axes.DescendantOrSelf:
1510                                 case Axes.Descendant:
1511                                 case Axes.Preceding:
1512                                 case Axes.Following:
1513                                         return false;
1514                                 default:
1515                                         return true;
1516                                 }
1517                         }
1518                 }
1519
1520                 internal override bool Subtree {
1521                         get {
1522                                 switch (_axis.Axis) {
1523                                 case Axes.Parent:
1524                                 case Axes.Ancestor:
1525                                 case Axes.AncestorOrSelf:
1526                                 case Axes.Preceding:
1527                                 case Axes.PrecedingSibling:
1528                                 case Axes.Following:
1529                                 case Axes.FollowingSibling:
1530                                         return false;
1531                                 default:
1532                                         return true;
1533                                 }
1534                         }
1535
1536                 }
1537
1538                 internal override XPathNodeType EvaluatedNodeType {
1539                         get { return _axis.NodeType; }
1540                 }
1541         }
1542
1543         internal class NodeTypeTest : NodeTest
1544         {
1545                 public readonly XPathNodeType type;
1546                 protected String _param;
1547                 public NodeTypeTest (Axes axis) : base (axis)
1548                 {
1549                         this.type = _axis.NodeType;
1550                 }
1551                 public NodeTypeTest (Axes axis, XPathNodeType type) : base (axis)
1552                 {
1553                         this.type = type;
1554                 }
1555                 // FIXME: Better description
1556                 public NodeTypeTest (Axes axis, XPathNodeType type, String param) : base (axis)
1557                 {
1558                         this.type = type;
1559                         _param = param;
1560                         if (param != null && type != XPathNodeType.ProcessingInstruction)
1561                                 throw new XPathException ("No argument allowed for "+ToString (type)+"() test");        // TODO: better description
1562                 }
1563
1564                 // for optimizer use
1565                 internal NodeTypeTest (NodeTypeTest other, Axes axis)
1566                         : base (axis)
1567                 {
1568                         type = other.type;
1569                         _param = other._param;
1570                 }
1571
1572                 public override String ToString ()
1573                 {
1574                         String strType = ToString (type);
1575                         if (type == XPathNodeType.ProcessingInstruction && _param != null)
1576                                 strType += "('" + _param + "')";
1577                         else
1578                                 strType += "()";
1579
1580                         return _axis.ToString () + "::" + strType;
1581                 }
1582
1583                 private static String ToString (XPathNodeType type)
1584                 {
1585                         switch (type) {
1586                         case XPathNodeType.Comment:
1587                                 return "comment";
1588                         case XPathNodeType.Text:
1589                                 return "text";
1590                         case XPathNodeType.ProcessingInstruction:
1591                                 return "processing-instruction";
1592                         case XPathNodeType.All:
1593                         case XPathNodeType.Attribute:
1594                         case XPathNodeType.Element:
1595                         case XPathNodeType.Namespace:
1596                                 return "node";
1597                         default:
1598                                 return "node-type [" + type.ToString () + "]";
1599                         }
1600                 }
1601
1602                 public override bool Match (NSResolver nsm, XPathNavigator nav)
1603                 {
1604                         XPathNodeType nodeType = nav.NodeType;
1605                         switch (type) {
1606                         case XPathNodeType.All:
1607                                 return true;
1608
1609                         case XPathNodeType.ProcessingInstruction:
1610                                 if (nodeType != XPathNodeType.ProcessingInstruction)
1611                                         return false;
1612                                 if (_param != null && nav.Name != _param)
1613                                         return false;
1614                                 return true;
1615
1616                         case XPathNodeType.Text:
1617                                 switch (nodeType) {
1618                                 case XPathNodeType.Text:
1619                                 case XPathNodeType.Whitespace:
1620                                 case XPathNodeType.SignificantWhitespace:
1621                                         return true;
1622                                 default:
1623                                         return false;
1624                                 }
1625                         default:
1626                                 return type == nodeType;
1627                         }
1628                 }
1629
1630                 public override void GetInfo (out string name, out string ns, out XPathNodeType nodetype, NSResolver nsm)
1631                 {
1632                         name = _param;
1633                         ns = null;
1634                         nodetype = type;
1635                 }
1636         }
1637
1638         internal class NodeNameTest : NodeTest
1639         {
1640                 protected XmlQualifiedName _name;
1641                 protected readonly bool resolvedName = false;
1642                 public NodeNameTest (Axes axis, XmlQualifiedName name, IStaticXsltContext ctx) : base (axis)
1643                 {
1644                         if (ctx != null) {
1645                                 name = ctx.LookupQName (name.ToString ());
1646                                 resolvedName = true;
1647                         }
1648                         _name = name;
1649                 }
1650
1651                 public NodeNameTest (Axes axis, XmlQualifiedName name, bool resolvedName) : base (axis)
1652                 {
1653                         _name = name;
1654                         this.resolvedName = resolvedName;
1655                 }
1656
1657                 // for optimized path rewrite
1658                 internal NodeNameTest (NodeNameTest source, Axes axis)
1659                         : base (axis)
1660                 {
1661                         _name = source._name;
1662                         resolvedName = source.resolvedName;
1663                 }
1664
1665                 public override String ToString () { return _axis.ToString () + "::" + _name.ToString (); }
1666
1667                 public XmlQualifiedName Name { get { return _name; } }
1668
1669                 public override bool Match (NSResolver nsm, XPathNavigator nav)
1670                 {
1671                         // must be the correct node type
1672                         if (nav.NodeType != _axis.NodeType)
1673                                 return false;
1674
1675                         if (_name.Name != "")
1676                         {
1677                                 // test the local part of the name first
1678                                 if (_name.Name != nav.LocalName)
1679                                         return false;
1680                         }
1681
1682                         // get the prefix for the given name
1683                         String strURI1 = "";
1684                         if (_name.Namespace != "")
1685                         {
1686                                 if (resolvedName)
1687                                         strURI1 = _name.Namespace;
1688                                 else if (nsm != null)
1689 // We still need to have such tricky switch, because the behavior is
1690 // inconsistent between .NET 1.x and 2.0 when the argument is not
1691 // atomic string.
1692 #if NET_2_0
1693                                         strURI1 = nsm.LookupNamespace (_name.Namespace);
1694 #else
1695                                         strURI1 = nsm.LookupNamespace (_name.Namespace, false);
1696 #endif
1697                                 if (strURI1 == null)
1698                                         throw new XPathException ("Invalid namespace prefix: "+_name.Namespace);
1699                         }
1700
1701                         // test the prefixes
1702                         return strURI1 == nav.NamespaceURI;
1703                 }
1704
1705                 public override void GetInfo (out string name, out string ns, out XPathNodeType nodetype, NSResolver nsm)
1706                 {
1707                         // must be the correct node type
1708                         nodetype = _axis.NodeType;
1709
1710                         if (_name.Name != "")
1711                                 name = _name.Name;
1712                         else
1713                                 name = null;
1714                         ns = "";
1715                         if (nsm != null && _name.Namespace != "") {
1716                                 if (resolvedName)
1717                                         ns = _name.Namespace;
1718                                 else
1719 // We still need to have such tricky switch, because the behavior is
1720 // inconsistent between .NET 1.x and 2.0 when the argument is not
1721 // atomic string.
1722 #if NET_2_0
1723                                         ns = nsm.LookupNamespace (_name.Namespace);     // TODO: check to see if this returns null or ""
1724 #else
1725                                         ns = nsm.LookupNamespace (_name.Namespace, false);      // TODO: check to see if this returns null or ""
1726 #endif
1727                                 if (ns == null)
1728                                         throw new XPathException ("Invalid namespace prefix: "+_name.Namespace);
1729                         }
1730                 }
1731         }
1732
1733         internal class ExprFilter : NodeSet
1734         {
1735                 internal Expression expr, pred;
1736
1737                 public ExprFilter (Expression expr, Expression pred)
1738                 {
1739                         this.expr = expr;
1740                         this.pred = pred;
1741                 }
1742
1743                 public override Expression Optimize ()
1744                 {
1745                         expr = expr.Optimize ();
1746                         pred = pred.Optimize ();
1747                         return this;
1748                 }
1749
1750                 internal Expression LeftHandSide {get{return expr;}}
1751                 public override String ToString () { return "(" + expr.ToString () + ")[" + pred.ToString () + "]"; }
1752                 public override object Evaluate (BaseIterator iter)
1753                 {
1754                         BaseIterator iterExpr = expr.EvaluateNodeSet (iter);
1755                         return new PredicateIterator (iterExpr, pred);
1756                 }
1757
1758                 internal override XPathNodeType EvaluatedNodeType {
1759                         get { return expr.EvaluatedNodeType; }
1760                 }
1761
1762                 internal override bool IsPositional {
1763                         get {
1764                                 if (pred.ReturnType == XPathResultType.Number)
1765                                         return true;
1766                                 return expr.IsPositional || pred.IsPositional;
1767                         }
1768                 }
1769
1770                 internal override bool Peer {
1771                         get { return expr.Peer && pred.Peer; }
1772                 }
1773
1774                 internal override bool Subtree {
1775                         get {
1776                                 NodeSet n = expr as NodeSet;
1777                                 return n != null && n.Subtree;
1778                         }
1779                 }
1780         }
1781
1782         internal class ExprNumber : Expression
1783         {
1784                 protected double _value;
1785                 public ExprNumber (double value)
1786                 {
1787                         _value = value;
1788                 }
1789                 public override String ToString () { return _value.ToString (); }
1790                 public override XPathResultType ReturnType { get { return XPathResultType.Number; }}
1791
1792                 internal override bool Peer {
1793                         get { return true; }
1794                 }
1795
1796                 public override bool HasStaticValue {
1797                         get { return true; }
1798                 }
1799
1800                 public override double StaticValueAsNumber {
1801                         get { return XPathFunctions.ToNumber (_value); }
1802                 }
1803
1804                 public override object Evaluate (BaseIterator iter)
1805                 {
1806                         return _value;
1807                 }
1808
1809                 public override double EvaluateNumber (BaseIterator iter)
1810                 {
1811                         return _value;
1812                 }
1813
1814                 internal override bool IsPositional {
1815                         get { return false; }
1816                 }
1817         }
1818
1819         internal class BooleanConstant : Expression
1820         {
1821                 bool _value;
1822
1823                 public BooleanConstant (bool value)
1824                 {
1825                         _value = value;
1826                 }
1827
1828                 public override String ToString () { return _value ? "true()" : "false()"; }
1829                 public override XPathResultType ReturnType { get { return XPathResultType.Boolean; }}
1830
1831                 internal override bool Peer {
1832                         get { return true; }
1833                 }
1834
1835                 public override bool HasStaticValue {
1836                         get { return true; }
1837                 }
1838
1839                 public override bool StaticValueAsBoolean {
1840                         get { return _value; }
1841                 }
1842
1843                 public override object Evaluate (BaseIterator iter)
1844                 {
1845                         return _value;
1846                 }
1847
1848                 public override bool EvaluateBoolean (BaseIterator iter)
1849                 {
1850                         return _value;
1851                 }
1852         }
1853
1854         internal class ExprLiteral : Expression
1855         {
1856                 protected String _value;
1857                 public ExprLiteral (String value)
1858                 {
1859                         _value = value;
1860                 }
1861                 public string Value { get { return _value; } }
1862                 public override String ToString () { return "'" + _value + "'"; }
1863                 public override XPathResultType ReturnType { get { return XPathResultType.String; }}
1864
1865                 internal override bool Peer {
1866                         get { return true; }
1867                 }
1868
1869                 public override bool HasStaticValue {
1870                         get { return true; }
1871                 }
1872
1873                 public override string StaticValueAsString {
1874                         get { return _value; }
1875                 }
1876
1877                 public override object Evaluate (BaseIterator iter)
1878                 {
1879                         return _value;
1880                 }
1881
1882                 public override string EvaluateString (BaseIterator iter)
1883                 {
1884                         return _value;
1885                 }
1886         }
1887
1888         internal class ExprVariable : Expression
1889         {
1890                 protected XmlQualifiedName _name;
1891                 protected bool resolvedName = false;
1892                 public ExprVariable (XmlQualifiedName name, IStaticXsltContext ctx)
1893                 {
1894                         if (ctx != null) {
1895                                 name = ctx.LookupQName (name.ToString ());
1896                                 resolvedName = true;
1897                         }
1898
1899                         _name = name;
1900                 }
1901                 public override String ToString () { return "$" + _name.ToString (); }
1902                 public override XPathResultType ReturnType { get { return XPathResultType.Any; }}
1903                 public override XPathResultType GetReturnType (BaseIterator iter)
1904                 {
1905                         return XPathResultType.Any;
1906                 }
1907
1908                 public override object Evaluate (BaseIterator iter)
1909                 {
1910                         IXsltContextVariable var = null;
1911
1912                         XsltContext context = iter.NamespaceManager as XsltContext;
1913                         if (context != null) {
1914                                 if (resolvedName)
1915                                         var = context.ResolveVariable (_name);
1916                                 else
1917                                         var = context.ResolveVariable (new XmlQualifiedName (_name.Name, _name.Namespace));
1918                         }
1919                         else
1920                                 throw new XPathException (String.Format ("XSLT context is required to resolve variable. Current namespace manager in current node-set '{0}' is '{1}'", iter.GetType (), iter.NamespaceManager != null ? iter.NamespaceManager.GetType () : null));
1921
1922                         if (var == null)
1923                                 throw new XPathException ("variable "+_name.ToString ()+" not found");
1924                         object objResult = var.Evaluate (context);
1925                         XPathNodeIterator iterResult = objResult as XPathNodeIterator;
1926                         if (iterResult != null)
1927                                 return iterResult is BaseIterator ? iterResult : new WrapperIterator (iterResult, iter.NamespaceManager);
1928                         return objResult;
1929                 }
1930
1931                 internal override bool Peer {
1932                         get { return false; }
1933                 }
1934         }
1935
1936         internal class ExprParens : Expression
1937         {
1938                 protected Expression _expr;
1939                 public ExprParens (Expression expr)
1940                 {
1941                         _expr = expr;
1942                 }
1943
1944                 public override Expression Optimize ()
1945                 {
1946                         _expr.Optimize ();
1947                         return this;
1948                 }
1949
1950                 public override bool HasStaticValue {
1951                         get { return _expr.HasStaticValue; }
1952                 }
1953
1954                 public override object StaticValue {
1955                         get { return _expr.StaticValue; }
1956                 }
1957
1958                 public override string StaticValueAsString {
1959                         get { return _expr.StaticValueAsString; }
1960                 }
1961
1962                 public override double StaticValueAsNumber {
1963                         get { return _expr.StaticValueAsNumber; }
1964                 }
1965
1966                 public override bool StaticValueAsBoolean {
1967                         get { return _expr.StaticValueAsBoolean; }
1968                 }
1969
1970                 public override String ToString () { return "(" + _expr.ToString () + ")"; }
1971                 public override XPathResultType ReturnType { get { return _expr.ReturnType; }}
1972                 public override object Evaluate (BaseIterator iter)
1973                 {
1974                         object o = (_expr.Evaluate (iter));
1975                         XPathNodeIterator xi = o as XPathNodeIterator;
1976                         BaseIterator predBase = xi as BaseIterator;
1977                         if (predBase == null && xi != null)
1978                                 predBase = new WrapperIterator (xi, iter.NamespaceManager);
1979                         if (predBase != null)
1980                                 return new ParensIterator (predBase);
1981                         else
1982                                 return o;
1983                 }
1984
1985                 internal override XPathNodeType EvaluatedNodeType {
1986                         get { return _expr.EvaluatedNodeType; }
1987                 }
1988
1989                 internal override bool IsPositional {
1990                         get { return _expr.IsPositional; }
1991                 }
1992
1993                 internal override bool Peer {
1994                         get { return _expr.Peer; }
1995                 }
1996         }
1997
1998         internal class FunctionArguments
1999         {
2000                 protected Expression _arg;
2001                 protected FunctionArguments _tail;
2002                 public FunctionArguments (Expression arg, FunctionArguments tail)
2003                 {
2004                         _arg = arg;
2005                         _tail = tail;
2006                 }
2007                 public Expression Arg
2008                 {
2009                         get { return _arg; }
2010                 }
2011                 public FunctionArguments Tail
2012                 {
2013                         get { return _tail; }
2014                 }
2015
2016                 public void ToArrayList (ArrayList a)
2017                 {
2018                         FunctionArguments cur = this;
2019
2020                         do {
2021                                 a.Add (cur._arg);
2022                                 cur = cur._tail;
2023                         } while (cur != null);
2024
2025                 }
2026         }
2027
2028         internal class ExprFunctionCall : Expression
2029         {
2030                 protected readonly XmlQualifiedName _name;
2031                 protected readonly bool resolvedName = false;
2032                 protected readonly ArrayList _args = new ArrayList ();
2033                 public ExprFunctionCall (XmlQualifiedName name, FunctionArguments args, IStaticXsltContext ctx)
2034                 {
2035                         if (ctx != null) {
2036                                 name = ctx.LookupQName (name.ToString ());
2037                                 resolvedName = true;
2038                         }
2039
2040                         _name = name;
2041                         if (args != null)
2042                                 args.ToArrayList (_args);
2043                 }
2044
2045                 public static Expression Factory (XmlQualifiedName name, FunctionArguments args, IStaticXsltContext ctx)
2046                 {
2047                         if (name.Namespace != null && name.Namespace != "")
2048                                 return new ExprFunctionCall (name, args, ctx);
2049
2050                         switch (name.Name) {
2051                         case "last": return new XPathFunctionLast (args);
2052                         case "position": return new XPathFunctionPosition (args);
2053                         case "count": return new XPathFunctionCount (args);
2054                         case "id": return new XPathFunctionId (args);
2055                         case "local-name": return new XPathFunctionLocalName (args);
2056                         case "namespace-uri": return new XPathFunctionNamespaceUri (args);
2057                         case "name": return new XPathFunctionName (args);
2058                         case "string": return new XPathFunctionString (args);
2059                         case "concat": return new XPathFunctionConcat (args);
2060                         case "starts-with": return new XPathFunctionStartsWith (args);
2061                         case "contains": return new XPathFunctionContains (args);
2062                         case "substring-before": return new XPathFunctionSubstringBefore (args);
2063                         case "substring-after": return new XPathFunctionSubstringAfter (args);
2064                         case "substring": return new XPathFunctionSubstring (args);
2065                         case "string-length": return new XPathFunctionStringLength (args);
2066                         case "normalize-space": return new XPathFunctionNormalizeSpace (args);
2067                         case "translate": return new XPathFunctionTranslate (args);
2068                         case "boolean": return new XPathFunctionBoolean (args);
2069                         case "not": return new XPathFunctionNot (args);
2070                         case "true": return new XPathFunctionTrue (args);
2071                         case "false": return new XPathFunctionFalse (args);
2072                         case "lang": return new XPathFunctionLang (args);
2073                         case "number": return new XPathFunctionNumber (args);
2074                         case "sum": return new XPathFunctionSum (args);
2075                         case "floor": return new XPathFunctionFloor (args);
2076                         case "ceiling": return new XPathFunctionCeil (args);
2077                         case "round": return new XPathFunctionRound (args);
2078                         }
2079                         return new ExprFunctionCall (name, args, ctx);
2080                 }
2081
2082                 public override String ToString ()
2083                 {
2084                         String strArgs = "";
2085                         for (int i = 0; i < _args.Count; i++) {
2086                                 Expression arg = (Expression) _args [i];
2087                                 if (strArgs != "")
2088                                         strArgs += ", ";
2089                                 strArgs += arg.ToString ();
2090                         }
2091                         return _name.ToString () + '(' + strArgs + ')';
2092                 }
2093                 public override XPathResultType ReturnType { get { return XPathResultType.Any; }}
2094                 public override XPathResultType GetReturnType (BaseIterator iter)
2095                 {
2096                         return XPathResultType.Any;
2097                 }
2098
2099                 private XPathResultType [] GetArgTypes (BaseIterator iter)
2100                 {
2101                         // TODO: can we cache these? what if the types depend on the nsm?
2102                         XPathResultType [] rgArgs = new XPathResultType [_args.Count];
2103                         for (int iArg = 0; iArg < _args.Count; iArg++)
2104                                 rgArgs [iArg] = ((Expression) _args [iArg]).GetReturnType (iter);
2105                         return rgArgs;
2106                 }
2107                 public override object Evaluate (BaseIterator iter)
2108                 {
2109                         XPathResultType [] rgTypes = GetArgTypes (iter);
2110                         IXsltContextFunction func = null;
2111                         XsltContext context = iter.NamespaceManager as XsltContext;
2112                         if (context != null) {
2113                                 if (resolvedName)
2114                                         func = context.ResolveFunction (_name, rgTypes);
2115                                 else
2116                                         func = context.ResolveFunction (_name.Namespace, _name.Name, rgTypes);
2117                         }
2118
2119                         if (func == null)
2120                                 throw new XPathException ("function "+_name.ToString ()+" not found");
2121
2122                         object [] rgArgs = new object [_args.Count];
2123                         if (func.Maxargs != 0)
2124                         {
2125                                 XPathResultType [] rgFuncTypes = func.ArgTypes;
2126                                 for (int iArg = 0; iArg < _args.Count; iArg ++)
2127                                 {
2128                                         XPathResultType typeArg;
2129                                         if (rgFuncTypes == null)
2130                                                 typeArg = XPathResultType.Any;
2131                                         else if (iArg < rgFuncTypes.Length)
2132                                                 typeArg = rgFuncTypes [iArg];
2133                                         else
2134                                                 typeArg = rgFuncTypes [rgFuncTypes.Length - 1];
2135
2136                                         Expression arg = (Expression) _args [iArg];
2137                                         object result = arg.EvaluateAs (iter, typeArg);
2138                                         rgArgs [iArg] = result;
2139                                 }
2140                         }
2141                         return func.Invoke (context, rgArgs, iter.Current);
2142                 }
2143
2144                 internal override bool Peer {
2145                         get { return false; }
2146                 }
2147         }
2148 }