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                 static object cache_lock = new object ();
  52
  53                 public static XPathExpression Get (string xpath, IStaticXsltContext ctx)
  54                 {
  55                         object ctxkey = ctx != null ? ctx : dummy;
  56
  57                         lock (cache_lock) {
  58                                 WeakReference wr = table_per_ctx [ctxkey] as WeakReference;
  59                                 if (wr == null)
  60                                         return null;
  61                                 Hashtable table = wr.Target as Hashtable;
  62                                 if (table == null) {
  63                                         table_per_ctx [ctxkey] = null;
  64                                         return null;
  65                                 }
  66
  67                                 wr = table [xpath] as WeakReference;
  68                                 if (wr != null) {
  69                                         XPathExpression e = wr.Target as XPathExpression;
  70                                         if (e != null)
  71                                                 return e;
  72                                         table [xpath] = null;
  73                                 }
  74                         }
  75                         return null;
  76                 }
  77
  78                 public static void Set (string xpath, IStaticXsltContext ctx, XPathExpression exp)
  79                 {
  80                         object ctxkey = ctx != null ? ctx : dummy;
  81
  82                         Hashtable table = null;
  83                         lock (cache_lock) {
  84                                 WeakReference wr = table_per_ctx [ctxkey] as WeakReference;
  85                                 if (wr != null && wr.IsAlive)
  86                                         table = (Hashtable) wr.Target;
  87                                 if (table == null) {
  88                                         table = new Hashtable ();
  89                                         table_per_ctx [ctxkey] = new WeakReference (table);
  90                                 }
  91                                 table [xpath] = new WeakReference (exp);
  92                         }
  93                 }
  94         }
  95
  96 #if XPATH_DEBUG
  97         internal class CompiledExpression : Test.Xml.XPath.XPathExpression
  98 #else
  99         internal class CompiledExpression : XPathExpression
 100 #endif
 101         {
 102                 protected NSResolver _nsm;
 103                 protected Expression _expr;
 104                 XPathSorters _sorters;
 105                 string rawExpression;
 106
 107                 public CompiledExpression (string raw, Expression expr)
 108                 {
 109                         _expr = expr.Optimize ();
 110                         rawExpression = raw;
 111                 }
 112                 private CompiledExpression (CompiledExpression other)
 113                 {
 114                         _nsm = other._nsm;
 115                         _expr = other._expr;
 116                         rawExpression = other.rawExpression;
 117                 }
 118 #if XPATH_DEBUG
 119                 public override Test.Xml.XPath.XPathExpression Clone () { return new CompiledExpression (this); }
 120 #else
 121                 public override XPathExpression Clone () { return new CompiledExpression (this); }
 122 #endif
 123
 124                 public Expression ExpressionNode { get { return _expr; }}
 125
 126                 public override void SetContext (XmlNamespaceManager nsManager)
 127                 {
 128                         _nsm = nsManager;
 129                 }
 130
 131 #if NET_2_0
 132                 public override void SetContext (IXmlNamespaceResolver nsResolver)
 133                 {
 134                         _nsm = nsResolver;
 135                 }
 136 #endif
 137
 138                 internal NSResolver NamespaceManager { get { return _nsm; } }
 139                 public override String Expression { get { return rawExpression; }}
 140                 public override XPathResultType ReturnType { get { return _expr.ReturnType; }}
 141
 142                 public object Evaluate (BaseIterator iter)
 143                 {
 144                         if (_sorters != null)
 145                                 return EvaluateNodeSet (iter);
 146
 147 #if false
 148                         return _expr.Evaluate (iter);
 149 #else
 150                         try {
 151                                 return _expr.Evaluate (iter);
 152                         }
 153                         catch (XPathException) {
 154                                 throw;
 155                         }
 156                         catch (XsltException) {
 157                                 throw;
 158                         }
 159                         catch (Exception e) {
 160                                 throw new XPathException ("Error during evaluation", e);
 161                         }
 162 #endif
 163                 }
 164                 public XPathNodeIterator EvaluateNodeSet (BaseIterator iter)
 165                 {
 166 #if false
 167                         try
 168                         {
 169 #endif
 170                                 BaseIterator iterResults = _expr.EvaluateNodeSet (iter);
 171                                 if (_sorters != null)
 172                                         return _sorters.Sort (iterResults);
 173                                 return iterResults;
 174 #if false
 175                         }
 176                         catch (XPathException)
 177                         {
 178                                 throw;
 179                         }
 180                         catch (Exception e)
 181                         {
 182                                 throw new XPathException ("Error during evaluation", e);
 183                         }
 184 #endif
 185                 }
 186                 public double EvaluateNumber (BaseIterator iter)
 187                 {
 188 #if true
 189                         return _expr.EvaluateNumber (iter);
 190 #else
 191                         try
 192                         {
 193                                 return _expr.EvaluateNumber (iter);
 194                         }
 195                         catch (XPathException)
 196                         {
 197                                 throw;
 198                         }
 199                         catch (Exception e)
 200                         {
 201                                 throw new XPathException ("Error during evaluation", e);
 202                         }
 203 #endif
 204                 }
 205                 public string EvaluateString (BaseIterator iter)
 206                 {
 207 #if true
 208                         return _expr.EvaluateString (iter);
 209 #else
 210                         try
 211                         {
 212                                 return _expr.EvaluateString (iter);
 213                         }
 214                         catch (XPathException)
 215                         {
 216                                 throw;
 217                         }
 218                         catch (Exception e)
 219                         {
 220                                 throw new XPathException ("Error during evaluation", e);
 221                         }
 222 #endif
 223                 }
 224                 public bool EvaluateBoolean (BaseIterator iter)
 225                 {
 226 #if true
 227                         return _expr.EvaluateBoolean (iter);
 228 #else
 229                         try
 230                         {
 231                                 return _expr.EvaluateBoolean (iter);
 232                         }
 233                         catch (XPathException)
 234                         {
 235                                 throw;
 236                         }
 237                         catch (Exception e)
 238                         {
 239                                 throw new XPathException ("Error during evaluation", e);
 240                         }
 241 #endif
 242                 }
 243
 244                 public override void AddSort (Object obj, IComparer cmp)
 245                 {
 246                         if (_sorters == null)
 247                                 _sorters = new XPathSorters ();
 248                         _sorters.Add (obj, cmp);
 249                 }
 250                 public override void AddSort(object expr, XmlSortOrder orderSort, XmlCaseOrder orderCase, string lang, XmlDataType dataType)
 251                 {
 252                         if (_sorters == null)
 253                                 _sorters = new XPathSorters ();
 254                         _sorters.Add (expr, orderSort, orderCase, lang, dataType);
 255                 }
 256
 257         }
 258
 259         class XPathSortElement
 260         {
 261                 public XPathNavigator Navigator;
 262                 public object [] Values;
 263         }
 264
 265         class XPathSorters : IComparer
 266         {
 267                 readonly ArrayList _rgSorters = new ArrayList ();
 268
 269                 public void Add (object expr, IComparer cmp)
 270                 {
 271                         _rgSorters.Add (new XPathSorter (expr, cmp));
 272                 }
 273
 274                 public void Add (object expr, XmlSortOrder orderSort, XmlCaseOrder orderCase, string lang, XmlDataType dataType)
 275                 {
 276                         _rgSorters.Add (new XPathSorter (expr, orderSort, orderCase, lang, dataType));
 277                 }
 278
 279                 public void CopyFrom (XPathSorter [] sorters)
 280                 {
 281                         _rgSorters.Clear ();
 282                         _rgSorters.AddRange (sorters);
 283                 }
 284
 285                 public BaseIterator Sort (BaseIterator iter)
 286                 {
 287                         ArrayList rgElts = ToSortElementList (iter);
 288                         return Sort (rgElts, iter.NamespaceManager);
 289                 }
 290
 291                 ArrayList ToSortElementList (BaseIterator iter)
 292                 {
 293                         ArrayList rgElts = new ArrayList ();
 294                         int cSorters = _rgSorters.Count;
 295                         while (iter.MoveNext ())
 296                         {
 297                                 XPathSortElement elt = new XPathSortElement ();
 298                                 elt.Navigator = iter.Current.Clone ();
 299                                 elt.Values = new object [cSorters];
 300                                 for (int iSorter = 0; iSorter < _rgSorters.Count; ++iSorter)
 301                                 {
 302                                         XPathSorter sorter = (XPathSorter) _rgSorters [iSorter];
 303                                         elt.Values [iSorter] = sorter.Evaluate (iter);
 304                                 }
 305                                 rgElts.Add (elt);
 306                         }
 307                         return rgElts;
 308                 }
 309
 310                 public BaseIterator Sort (ArrayList rgElts, NSResolver nsm)
 311                 {
 312                         rgElts.Sort (this);
 313                         XPathNavigator [] rgResults = new XPathNavigator [rgElts.Count];
 314                         for (int iResult = 0; iResult < rgElts.Count; ++iResult)
 315                         {
 316                                 XPathSortElement elt = (XPathSortElement) rgElts [iResult];
 317                                 rgResults [iResult] = elt.Navigator;
 318                         }
 319                         return new ListIterator (rgResults, nsm);
 320                 }
 321
 322                 int IComparer.Compare (object o1, object o2)
 323                 {
 324                         XPathSortElement elt1 = (XPathSortElement) o1;
 325                         XPathSortElement elt2 = (XPathSortElement) o2;
 326                         for (int iSorter = 0; iSorter < _rgSorters.Count; ++iSorter)
 327                         {
 328                                 XPathSorter sorter = (XPathSorter) _rgSorters [iSorter];
 329                                 int cmp = sorter.Compare (elt1.Values [iSorter], elt2.Values [iSorter]);
 330                                 if (cmp != 0)
 331                                         return cmp;
 332                         }
 333                         switch (elt1.Navigator.ComparePosition (elt2.Navigator)) {
 334                         case XmlNodeOrder.Same:
 335                                 return 0;
 336                         case XmlNodeOrder.After:
 337                                 return 1;
 338                         default:
 339                                 return -1;
 340                         }
 341                 }
 342         }
 343
 344         class XPathSorter
 345         {
 346                 readonly Expression _expr;
 347                 readonly IComparer _cmp;
 348                 readonly XmlDataType _type;
 349
 350                 public XPathSorter (object expr, IComparer cmp)
 351                 {
 352                         _expr = ExpressionFromObject (expr);
 353                         _cmp = cmp;
 354                         _type = XmlDataType.Text;
 355                 }
 356
 357                 public XPathSorter (object expr, XmlSortOrder orderSort, XmlCaseOrder orderCase, string lang, XmlDataType dataType)
 358                 {
 359                         _expr = ExpressionFromObject (expr);
 360                         _type = dataType;
 361                         if (dataType == XmlDataType.Number)
 362                                 _cmp = new XPathNumberComparer (orderSort);
 363                         else
 364                                 _cmp = new XPathTextComparer (orderSort, orderCase, lang);
 365                 }
 366
 367                 static Expression ExpressionFromObject (object expr)
 368                 {
 369                         if (expr is CompiledExpression)
 370                                 return ((CompiledExpression) expr).ExpressionNode;
 371                         if (expr is string)
 372                                 return new XPathParser ().Compile ((string)expr);
 373
 374                         throw new XPathException ("Invalid query object");
 375                 }
 376
 377                 public object Evaluate (BaseIterator iter)
 378                 {
 379                         if (_type == XmlDataType.Number)
 380                                 return _expr.EvaluateNumber (iter);
 381                         return _expr.EvaluateString (iter);
 382                 }
 383
 384                 public int Compare (object o1, object o2)
 385                 {
 386                         return _cmp.Compare (o1, o2);
 387                 }
 388
 389                 class XPathNumberComparer : IComparer
 390                 {
 391                         int _nMulSort;
 392
 393                         public XPathNumberComparer (XmlSortOrder orderSort)
 394                         {
 395                                 _nMulSort = (orderSort == XmlSortOrder.Ascending) ? 1 : -1;
 396                         }
 397
 398                         int IComparer.Compare (object o1, object o2)
 399                         {
 400                                 double num1 = (double) o1;
 401                                 double num2 = (double) o2;
 402                                 if (num1 < num2)
 403                                         return -_nMulSort;
 404                                 if (num1 > num2)
 405                                         return _nMulSort;
 406                                 if (num1 == num2)
 407                                         return 0;
 408                                 if (double.IsNaN (num1))
 409                                         return (double.IsNaN (num2)) ? 0 : -_nMulSort;
 410                                 return _nMulSort;
 411                         }
 412                 }
 413
 414                 class XPathTextComparer : IComparer
 415                 {
 416                         int _nMulSort;
 417                         int _nMulCase;
 418                         XmlCaseOrder _orderCase;
 419                         CultureInfo _ci;
 420
 421                         public XPathTextComparer (XmlSortOrder orderSort, XmlCaseOrder orderCase, string strLang)
 422                         {
 423                                 _orderCase = orderCase;
 424                                 // FIXME: We have to set this in
 425                                 // reverse order since currently
 426                                 // we don't support collation.
 427                                 _nMulCase = (orderCase == XmlCaseOrder.UpperFirst) ? -1 : 1;
 428                                 _nMulSort = (orderSort == XmlSortOrder.Ascending) ? 1 : -1;
 429
 430                                 if (strLang == null || strLang == "")
 431                                         _ci = CultureInfo.CurrentCulture;       // TODO: defer until evaluation?
 432                                 else
 433                                         _ci = new CultureInfo (strLang);
 434                         }
 435
 436                         int IComparer.Compare (object o1, object o2)
 437                         {
 438                                 string str1 = (string) o1;
 439                                 string str2 = (string) o2;
 440                                 int cmp = String.Compare (str1, str2, true, _ci);
 441                                 if (cmp != 0 || _orderCase == XmlCaseOrder.None)
 442                                         return cmp * _nMulSort;
 443                                 return _nMulSort * _nMulCase * String.Compare (str1, str2, false, _ci);
 444                         }
 445                 }
 446         }
 447
 448         /// <summary>
 449         /// Summary description for Expression.
 450         /// </summary>
 451         internal abstract class Expression
 452         {
 453                 public Expression ()
 454                 {
 455                 }
 456                 public abstract XPathResultType ReturnType { get; }
 457                 public virtual XPathResultType GetReturnType (BaseIterator iter) { return ReturnType; }
 458
 459                 public virtual Expression Optimize ()
 460                 {
 461                         return this;
 462                 }
 463
 464                 public virtual bool HasStaticValue {
 465                         get { return false; }
 466                 }
 467
 468                 public virtual object StaticValue {
 469                         get {
 470                                 switch (ReturnType) {
 471                                 case XPathResultType.String:
 472                                         return StaticValueAsString;
 473                                 case XPathResultType.Number:
 474                                         return StaticValueAsNumber;
 475                                 case XPathResultType.Boolean:
 476                                         return StaticValueAsBoolean;
 477                                 }
 478                                 return null;
 479                         }
 480                 }
 481
 482                 public virtual string StaticValueAsString {
 483                         get { return HasStaticValue ? XPathFunctions.ToString (StaticValue) : null; }
 484                 }
 485
 486                 public virtual double StaticValueAsNumber {
 487                         get { return HasStaticValue ? XPathFunctions.ToNumber (StaticValue) : 0; }
 488                 }
 489
 490                 public virtual bool StaticValueAsBoolean {
 491                         get { return HasStaticValue ? XPathFunctions.ToBoolean (StaticValue) : false; }
 492                 }
 493
 494                 public virtual XPathNavigator StaticValueAsNavigator {
 495                         get { return StaticValue as XPathNavigator; }
 496                 }
 497
 498                 public abstract object Evaluate (BaseIterator iter);
 499
 500                 public virtual BaseIterator EvaluateNodeSet (BaseIterator iter)
 501                 {
 502                         XPathResultType type = GetReturnType (iter);
 503                         switch (type) {
 504                         case XPathResultType.NodeSet:
 505                         case XPathResultType.Any:
 506                         case XPathResultType.Navigator: // FIXME: It may pass not-allowed use of RTF
 507                                 object o = Evaluate (iter);
 508                                 XPathNodeIterator xi = o as XPathNodeIterator;
 509                                 BaseIterator iterResult = null;
 510                                 if (xi != null) {
 511                                         iterResult = xi as BaseIterator;
 512                                         if (iterResult == null)
 513                                                 iterResult = new WrapperIterator (xi, iter.NamespaceManager);
 514                                         return iterResult;
 515                                 }
 516                                 XPathNavigator nav = o as XPathNavigator;
 517                                 if (nav != null) {
 518                                         XPathNodeIterator xiter = nav.SelectChildren (XPathNodeType.All);
 519                                         iterResult = xiter as BaseIterator;
 520                                         if (iterResult == null && xiter != null)
 521                                                 iterResult = new WrapperIterator (xiter, iter.NamespaceManager);
 522                                 }
 523                                 if (iterResult != null)
 524                                         return iterResult;
 525                                 if (o == null)
 526                                         return new NullIterator (iter);
 527                                 type = GetReturnType (o);
 528                                 break;
 529                         }
 530                         throw new XPathException (String.Format ("expected nodeset but was {1}: {0}", ToString (), type));
 531                 }
 532
 533                 protected static XPathResultType GetReturnType (object obj)
 534                 {
 535                         if (obj is string)
 536                                 return XPathResultType.String;
 537                         if (obj is bool)
 538                                 return XPathResultType.Boolean;
 539                         if (obj is XPathNodeIterator)
 540                                 return XPathResultType.NodeSet;
 541                         if (obj is double || obj is int)
 542                                 return XPathResultType.Number;
 543                         if (obj is XPathNavigator)
 544                                 return XPathResultType.Navigator;
 545                         throw new XPathException ("invalid node type: "+obj.GetType ().ToString ());
 546                 }
 547
 548                 internal virtual XPathNodeType EvaluatedNodeType {
 549                         get { return XPathNodeType.All; }
 550                 }
 551
 552                 internal virtual bool IsPositional {
 553                         get { return false; }
 554                 }
 555
 556                 // For "peer and subtree" optimization. see:
 557                 // http://idealliance.org/papers/dx_xmle04/papers/02-03-02/02-03-02.html
 558                 internal virtual bool Peer {
 559                         get { return false; }
 560                 }
 561
 562                 public virtual double EvaluateNumber (BaseIterator iter)
 563                 {
 564                         object result;
 565                         XPathResultType type = GetReturnType (iter);
 566                         if (type == XPathResultType.NodeSet)
 567                         {
 568                                 result = EvaluateString (iter);
 569                                 type = XPathResultType.String;
 570                         }
 571                         else
 572                                 result = Evaluate (iter);
 573
 574                         if (type == XPathResultType.Any)
 575                                 type = GetReturnType (result);
 576
 577                         switch (type) {
 578                         case XPathResultType.Number:
 579                                 if (result is double)
 580                                         return (double)result;
 581                                 else if (result is IConvertible)
 582                                         return ((IConvertible) result).ToDouble (CultureInfo.InvariantCulture);
 583                                 else
 584                                         return (double) result; // most likely invalid cast
 585                         case XPathResultType.Boolean:
 586                                 return ((bool) result) ? 1.0 : 0.0;
 587                         case XPathResultType.NodeSet:
 588                                 return XPathFunctions.ToNumber (EvaluateString (iter));
 589                         case XPathResultType.String:
 590                                 return XPathFunctions.ToNumber ((string) result);
 591                         case XPathResultType.Navigator:
 592                                 return XPathFunctions.ToNumber (((XPathNavigator) (result)).Value);
 593                         default:
 594                                 throw new XPathException ("invalid node type");
 595                         }
 596                 }
 597
 598                 public virtual string EvaluateString (BaseIterator iter)
 599                 {
 600                         object result = Evaluate (iter);
 601                         XPathResultType type = GetReturnType (iter);
 602                         if (type == XPathResultType.Any)
 603                                 type = GetReturnType (result);
 604                         switch (type) {
 605                         case XPathResultType.Number:
 606                                 double d = (double) result;
 607                                 return XPathFunctions.ToString (d);
 608                         case XPathResultType.Boolean:
 609                                 return ((bool) result) ? "true" : "false";
 610                         case XPathResultType.String:
 611                                 return (string) result;
 612                         case XPathResultType.NodeSet:
 613                         {
 614                                 BaseIterator iterResult = (BaseIterator) result;
 615                                 if (iterResult == null || !iterResult.MoveNext ())
 616                                         return "";
 617                                 return iterResult.Current.Value;
 618                         }
 619                         case XPathResultType.Navigator:
 620                                 return ((XPathNavigator) result).Value;
 621                         default:
 622                                 throw new XPathException ("invalid node type");
 623                         }
 624                 }
 625
 626                 public virtual bool EvaluateBoolean (BaseIterator iter)
 627                 {
 628                         object result = Evaluate (iter);
 629                         XPathResultType type = GetReturnType (iter);
 630                         if (type == XPathResultType.Any)
 631                                 type = GetReturnType (result);
 632                         switch (type) {
 633                         case XPathResultType.Number:
 634                                 double num = Convert.ToDouble (result);
 635                                 return (num != 0.0 && num != -0.0 && !Double.IsNaN (num));
 636                         case XPathResultType.Boolean:
 637                                 return (bool) result;
 638                         case XPathResultType.String:
 639                                 return ((string) result).Length != 0;
 640                         case XPathResultType.NodeSet:
 641                                 BaseIterator iterResult = (BaseIterator) result;
 642                                 return (iterResult != null && iterResult.MoveNext ());
 643                         case XPathResultType.Navigator:
 644                                 return (((XPathNavigator) result).HasChildren);
 645                         default:
 646                                 throw new XPathException ("invalid node type");
 647                         }
 648                 }
 649
 650                 public object EvaluateAs (BaseIterator iter, XPathResultType type)
 651                 {
 652                         switch (type) {
 653                         case XPathResultType.Boolean:
 654                                 return EvaluateBoolean (iter);
 655                         case XPathResultType.NodeSet:
 656                                 return EvaluateNodeSet (iter);
 657                         case XPathResultType.String:
 658                                 return EvaluateString (iter);
 659                         case XPathResultType.Number:
 660                                 return EvaluateNumber (iter);
 661                         }
 662                         return Evaluate (iter);
 663                 }
 664
 665                 public virtual bool RequireSorting { get { return false; } }
 666         }
 667
 668         internal abstract class ExprBinary : Expression
 669         {
 670                 protected Expression _left, _right;
 671
 672                 public ExprBinary (Expression left, Expression right)
 673                 {
 674                         _left = left;
 675                         _right = right;
 676                 }
 677
 678                 public override Expression Optimize ()
 679                 {
 680                         _left = _left.Optimize ();
 681                         _right = _right.Optimize ();
 682                         return this;
 683                 }
 684
 685                 public override bool HasStaticValue {
 686                         get { return _left.HasStaticValue && _right.HasStaticValue; }
 687                 }
 688
 689                 public override String ToString ()
 690                 {
 691                         return _left.ToString () + ' ' + Operator + ' ' + _right.ToString ();
 692                 }
 693                 protected abstract String Operator { get; }
 694
 695                 internal override XPathNodeType EvaluatedNodeType {
 696                         get {
 697                                 if (_left.EvaluatedNodeType == _right.EvaluatedNodeType)
 698                                         return _left.EvaluatedNodeType;
 699                                 else
 700                                         return XPathNodeType.All;
 701                         }
 702                 }
 703
 704                 internal override bool IsPositional {
 705                         get { return _left.IsPositional || _right.IsPositional; }
 706                 }
 707
 708                 internal override bool Peer {
 709                         get { return _left.Peer && _right.Peer; }
 710                 }
 711         }
 712
 713         internal abstract class ExprBoolean : ExprBinary
 714         {
 715                 public ExprBoolean (Expression left, Expression right) : base (left, right) {}
 716
 717                 public override Expression Optimize ()
 718                 {
 719                         base.Optimize ();
 720                         if (!HasStaticValue)
 721                                 return this;
 722                         else if (StaticValueAsBoolean)
 723                                 return new XPathFunctionTrue (null);
 724                         else
 725                                 return new XPathFunctionFalse (null);
 726                 }
 727
 728                 public override XPathResultType ReturnType { get { return XPathResultType.Boolean; }}
 729                 public override object Evaluate (BaseIterator iter)
 730                 {
 731                         return EvaluateBoolean (iter);
 732                 }
 733                 public override double EvaluateNumber (BaseIterator iter)
 734                 {
 735                         return EvaluateBoolean (iter) ? 1 : 0;
 736                 }
 737
 738                 public override string EvaluateString (BaseIterator iter)
 739                 {
 740                         return EvaluateBoolean (iter) ? "true" : "false";
 741                 }
 742         }
 743
 744         internal class ExprOR : ExprBoolean
 745         {
 746                 public ExprOR (Expression left, Expression right) : base (left, right) {}
 747                 protected override String Operator { get { return "or"; }}
 748
 749                 public override bool StaticValueAsBoolean {
 750                         get { return HasStaticValue ? _left.StaticValueAsBoolean || _right.StaticValueAsBoolean : false; }
 751                 }
 752
 753                 public override bool EvaluateBoolean (BaseIterator iter)
 754                 {
 755                         if (_left.EvaluateBoolean (iter))
 756                                 return true;
 757                         return _right.EvaluateBoolean (iter);
 758                 }
 759         }
 760
 761         internal class ExprAND : ExprBoolean
 762         {
 763                 public ExprAND (Expression left, Expression right) : base (left, right) {}
 764                 protected override String Operator { get { return "and"; }}
 765
 766                 public override bool StaticValueAsBoolean {
 767                         get { return HasStaticValue ? _left.StaticValueAsBoolean && _right.StaticValueAsBoolean : false; }
 768                 }
 769
 770                 public override bool EvaluateBoolean (BaseIterator iter)
 771                 {
 772                         if (!_left.EvaluateBoolean (iter))
 773                                 return false;
 774                         return _right.EvaluateBoolean (iter);
 775                 }
 776         }
 777
 778         internal abstract class EqualityExpr : ExprBoolean
 779         {
 780                 bool trueVal;
 781                 public EqualityExpr (Expression left, Expression right, bool trueVal) : base (left, right)
 782                 {
 783                         this.trueVal = trueVal;
 784                 }
 785
 786                 public override bool StaticValueAsBoolean {
 787                         get {
 788                                 if (!HasStaticValue)
 789                                         return false;
 790                                 if ((_left.ReturnType == XPathResultType.Navigator || _right.ReturnType == XPathResultType.Navigator) && _left.ReturnType == _right.ReturnType)
 791                                         return (_left.StaticValueAsNavigator.IsSamePosition (
 792                                         _right.StaticValueAsNavigator))
 793                                          == trueVal;
 794                                 if (_left.ReturnType == XPathResultType.Boolean | _right.ReturnType == XPathResultType.Boolean)
 795                                         return (_left.StaticValueAsBoolean == _right.StaticValueAsBoolean) == trueVal;
 796                                 if (_left.ReturnType == XPathResultType.Number | _right.ReturnType == XPathResultType.Number)
 797                                         return (_left.StaticValueAsNumber == _right.StaticValueAsNumber) == trueVal;
 798                                 if (_left.ReturnType == XPathResultType.String | _right.ReturnType == XPathResultType.String)
 799                                         return (_left.StaticValueAsString == _right.StaticValueAsString) == trueVal;
 800                                 return _left.StaticValue == _right.StaticValue == trueVal;
 801                         }
 802                 }
 803
 804                 // FIXME: Avoid extraneous evaluation
 805                 public override bool EvaluateBoolean (BaseIterator iter)
 806                 {
 807                         XPathResultType typeL = _left.GetReturnType (iter);
 808                         XPathResultType typeR = _right.GetReturnType (iter);
 809
 810                         // TODO: avoid double evaluations
 811                         if (typeL == XPathResultType.Any)
 812                                 typeL = GetReturnType (_left.Evaluate (iter));
 813                         if (typeR == XPathResultType.Any)
 814                                 typeR = GetReturnType (_right.Evaluate (iter));
 815
 816                         // Regard RTF as string
 817                         if (typeL == XPathResultType.Navigator)
 818                                 typeL = XPathResultType.String;
 819                         if (typeR == XPathResultType.Navigator)
 820                                 typeR = XPathResultType.String;
 821
 822                         if (typeL == XPathResultType.NodeSet || typeR == XPathResultType.NodeSet)
 823                         {
 824                                 Expression left, right;
 825                                 if (typeL != XPathResultType.NodeSet)
 826                                 {
 827                                         left = _right;
 828                                         right = _left;
 829                                         XPathResultType typeTmp = typeL;
 830                                         typeL = typeR;
 831                                         typeR = typeTmp;
 832                                 }
 833                                 else
 834                                 {
 835                                         left = _left;
 836                                         right = _right;
 837                                 }
 838                                 if (typeR == XPathResultType.Boolean)
 839                                 {
 840                                         return left.EvaluateBoolean (iter) == right.EvaluateBoolean (iter) == trueVal;
 841                                 }
 842                                 else
 843                                 {
 844                                         BaseIterator iterL = left.EvaluateNodeSet (iter);
 845                                         if (typeR == XPathResultType.Number)
 846                                         {
 847                                                 double dR = right.EvaluateNumber (iter);
 848                                                 while (iterL.MoveNext ())
 849                                                         if (XPathFunctions.ToNumber (iterL.Current.Value) == dR == trueVal)
 850                                                                 return true;
 851                                         }
 852                                         else if (typeR == XPathResultType.String)
 853                                         {
 854                                                 string strR = right.EvaluateString (iter);
 855                                                 while (iterL.MoveNext ())
 856                                                         if (iterL.Current.Value == strR == trueVal)
 857                                                                 return true;
 858                                         }
 859                                         else if (typeR == XPathResultType.NodeSet)
 860                                         {
 861                                                 BaseIterator iterR = right.EvaluateNodeSet (iter);
 862                                                 ArrayList rgNodesL = new ArrayList ();
 863                                                 while (iterL.MoveNext ())
 864                                                         rgNodesL.Add (XPathFunctions.ToString (iterL.Current.Value));
 865                                                 while (iterR.MoveNext ())
 866                                                 {
 867                                                         string strR = XPathFunctions.ToString (iterR.Current.Value);
 868                                                         for (int l = 0; l < rgNodesL.Count; l++)
 869                                                                 if ((strR == (string) rgNodesL [l]) == trueVal)
 870                                                                         return true;
 871                                                 }
 872                                         }
 873                                         return false;
 874                                 }
 875                         }
 876                         else if (typeL == XPathResultType.Boolean || typeR == XPathResultType.Boolean)
 877                                 return _left.EvaluateBoolean (iter) == _right.EvaluateBoolean (iter) == trueVal;
 878                         else if (typeL == XPathResultType.Number || typeR == XPathResultType.Number)
 879                                 return _left.EvaluateNumber (iter) == _right.EvaluateNumber (iter) == trueVal;
 880                         else
 881                                 return _left.EvaluateString (iter) == _right.EvaluateString (iter) == trueVal;
 882                 }
 883         }
 884
 885         internal class ExprEQ : EqualityExpr
 886         {
 887                 public ExprEQ (Expression left, Expression right) : base (left, right, true) {}
 888                 protected override String Operator { get { return "="; }}
 889         }
 890
 891         internal class ExprNE : EqualityExpr
 892         {
 893                 public ExprNE (Expression left, Expression right) : base (left, right, false) {}
 894                 protected override String Operator { get { return "!="; }}
 895         }
 896
 897         internal abstract class RelationalExpr : ExprBoolean
 898         {
 899                 public RelationalExpr (Expression left, Expression right) : base (left, right) {}
 900
 901                 public override bool StaticValueAsBoolean {
 902                         get { return HasStaticValue ? Compare (_left.StaticValueAsNumber, _right.StaticValueAsNumber) : false; }
 903                 }
 904
 905                 // FIXME: Avoid extraneous evaluation.
 906                 public override bool EvaluateBoolean (BaseIterator iter)
 907                 {
 908                         XPathResultType typeL = _left.GetReturnType (iter);
 909                         XPathResultType typeR = _right.GetReturnType (iter);
 910
 911                         if (typeL == XPathResultType.Any)
 912                                 typeL = GetReturnType (_left.Evaluate (iter));
 913                         if (typeR == XPathResultType.Any)
 914                                 typeR = GetReturnType (_right.Evaluate (iter));
 915
 916                         // Regard RTF as string
 917                         if (typeL == XPathResultType.Navigator)
 918                                 typeL = XPathResultType.String;
 919                         if (typeR == XPathResultType.Navigator)
 920                                 typeR = XPathResultType.String;
 921
 922                         if (typeL == XPathResultType.NodeSet || typeR == XPathResultType.NodeSet)
 923                         {
 924                                 bool fReverse = false;
 925                                 Expression left, right;
 926                                 if (typeL != XPathResultType.NodeSet)
 927                                 {
 928                                         fReverse = true;
 929                                         left = _right;
 930                                         right = _left;
 931                                         XPathResultType typeTmp = typeL;
 932                                         typeL = typeR;
 933                                         typeR = typeTmp;
 934                                 }
 935                                 else
 936                                 {
 937                                         left = _left;
 938                                         right = _right;
 939                                 }
 940                                 if (typeR == XPathResultType.Boolean)
 941                                 {
 942                                         bool fL = left.EvaluateBoolean (iter);
 943                                         bool fR = right.EvaluateBoolean (iter);
 944                                         return Compare (Convert.ToDouble (fL), Convert.ToDouble (fR), fReverse);
 945                                 }
 946                                 else
 947                                 {
 948                                         BaseIterator iterL = left.EvaluateNodeSet (iter);
 949                                         if (typeR == XPathResultType.Number || typeR == XPathResultType.String)
 950                                         {
 951                                                 double dR = right.EvaluateNumber (iter);
 952                                                 while (iterL.MoveNext ())
 953                                                         if (Compare (XPathFunctions.ToNumber (iterL.Current.Value), dR, fReverse))
 954                                                                 return true;
 955                                         }
 956                                         else if (typeR == XPathResultType.NodeSet)
 957                                         {
 958                                                 BaseIterator iterR = right.EvaluateNodeSet (iter);
 959                                                 ArrayList rgNodesL = new ArrayList ();
 960                                                 while (iterL.MoveNext ())
 961                                                         rgNodesL.Add (XPathFunctions.ToNumber (iterL.Current.Value));
 962                                                 while (iterR.MoveNext ())
 963                                                 {
 964                                                         double numR = XPathFunctions.ToNumber (iterR.Current.Value);
 965                                                         for (int l = 0; l < rgNodesL.Count; l++)
 966                                                                 if (Compare ((double) rgNodesL [l], numR))
 967                                                                         return true;
 968                                                 }
 969                                         }
 970                                         return false;
 971                                 }
 972                         }
 973                         else
 974                                 return Compare (_left.EvaluateNumber (iter), _right.EvaluateNumber (iter));
 975                 }
 976                 public abstract bool Compare (double arg1, double arg2);
 977                 public bool Compare (double arg1, double arg2, bool fReverse)
 978                 {
 979                         if (fReverse)
 980                                 return Compare (arg2, arg1);
 981                         else
 982                                 return Compare (arg1, arg2);
 983                 }
 984         }
 985
 986         internal class ExprGT : RelationalExpr
 987         {
 988                 public ExprGT (Expression left, Expression right) : base (left, right) {}
 989                 protected override String Operator { get { return ">"; }}
 990                 public override bool Compare (double arg1, double arg2)
 991                 {
 992                         return arg1 > arg2;
 993                 }
 994         }
 995
 996         internal class ExprGE : RelationalExpr
 997         {
 998                 public ExprGE (Expression left, Expression right) : base (left, right) {}
 999                 protected override String Operator { get { return ">="; }}
1000                 public override bool Compare (double arg1, double arg2)
1001                 {
1002                         return arg1 >= arg2;
1003                 }
1004         }
1005
1006         internal class ExprLT : RelationalExpr
1007         {
1008                 public ExprLT (Expression left, Expression right) : base (left, right) {}
1009                 protected override String Operator { get { return "<"; }}
1010                 public override bool Compare (double arg1, double arg2)
1011                 {
1012                         return arg1 < arg2;
1013                 }
1014         }
1015
1016         internal class ExprLE : RelationalExpr
1017         {
1018                 public ExprLE (Expression left, Expression right) : base (left, right) {}
1019                 protected override String Operator { get { return "<="; }}
1020                 public override bool Compare (double arg1, double arg2)
1021                 {
1022                         return arg1 <= arg2;
1023                 }
1024         }
1025
1026         internal abstract class ExprNumeric : ExprBinary
1027         {
1028                 public ExprNumeric (Expression left, Expression right) : base (left, right) {}
1029                 public override XPathResultType ReturnType { get { return XPathResultType.Number; }}
1030
1031                 public override Expression Optimize ()
1032                 {
1033                         base.Optimize ();
1034                         return !HasStaticValue ?
1035                                 (Expression) this :
1036                                 new ExprNumber (StaticValueAsNumber);
1037                 }
1038
1039                 public override object Evaluate (BaseIterator iter)
1040                 {
1041                         return EvaluateNumber (iter);
1042                 }
1043         }
1044
1045         internal class ExprPLUS : ExprNumeric
1046         {
1047                 public ExprPLUS (Expression left, Expression right) : base (left, right) {}
1048                 protected override String Operator { get { return "+"; }}
1049
1050                 public override double StaticValueAsNumber {
1051                         get { return HasStaticValue ? _left.StaticValueAsNumber + _right.StaticValueAsNumber: 0; }
1052                 }
1053
1054                 public override double EvaluateNumber (BaseIterator iter)
1055                 {
1056                         return _left.EvaluateNumber (iter) + _right.EvaluateNumber (iter);
1057                 }
1058         }
1059
1060         internal class ExprMINUS : ExprNumeric
1061         {
1062                 public ExprMINUS (Expression left, Expression right) : base (left, right) {}
1063                 protected override String Operator { get { return "-"; }}
1064
1065                 public override double StaticValueAsNumber {
1066                         get { return HasStaticValue ? _left.StaticValueAsNumber - _right.StaticValueAsNumber: 0; }
1067                 }
1068
1069                 public override double EvaluateNumber (BaseIterator iter)
1070                 {
1071                         return _left.EvaluateNumber (iter) - _right.EvaluateNumber (iter);
1072                 }
1073         }
1074
1075         internal class ExprMULT : ExprNumeric
1076         {
1077                 public ExprMULT (Expression left, Expression right) : base (left, right) {}
1078                 protected override String Operator { get { return "*"; }}
1079
1080                 public override double StaticValueAsNumber {
1081                         get { return HasStaticValue ? _left.StaticValueAsNumber * _right.StaticValueAsNumber: 0; }
1082                 }
1083
1084                 public override double EvaluateNumber (BaseIterator iter)
1085                 {
1086                         return _left.EvaluateNumber (iter) * _right.EvaluateNumber (iter);
1087                 }
1088         }
1089
1090         internal class ExprDIV : ExprNumeric
1091         {
1092                 public ExprDIV (Expression left, Expression right) : base (left, right) {}
1093                 protected override String Operator { get { return " div "; }}
1094
1095                 public override double StaticValueAsNumber {
1096                         get { return HasStaticValue ? _left.StaticValueAsNumber / _right.StaticValueAsNumber: 0; }
1097                 }
1098
1099                 public override double EvaluateNumber (BaseIterator iter)
1100                 {
1101                         return _left.EvaluateNumber (iter) / _right.EvaluateNumber (iter);
1102                 }
1103         }
1104
1105         internal class ExprMOD : ExprNumeric
1106         {
1107                 public ExprMOD (Expression left, Expression right) : base (left, right) {}
1108                 protected override String Operator { get { return "%"; }}
1109
1110                 public override double StaticValueAsNumber {
1111                         get { return HasStaticValue ? _left.StaticValueAsNumber % _right.StaticValueAsNumber: 0; }
1112                 }
1113
1114                 public override double EvaluateNumber (BaseIterator iter)
1115                 {
1116                         return _left.EvaluateNumber (iter) % _right.EvaluateNumber (iter);
1117                 }
1118         }
1119
1120         internal class ExprNEG : Expression
1121         {
1122                 Expression _expr;
1123                 public ExprNEG (Expression expr)
1124                 {
1125                         _expr = expr;
1126                 }
1127                 public override String ToString () { return "- " + _expr.ToString (); }
1128                 public override XPathResultType ReturnType { get { return XPathResultType.Number; }}
1129
1130                 public override Expression Optimize ()
1131                 {
1132                         _expr = _expr.Optimize ();
1133                         return !HasStaticValue ?
1134                                 (Expression) this :
1135                                 new ExprNumber (StaticValueAsNumber);
1136                 }
1137
1138                 internal override bool Peer {
1139                         get { return _expr.Peer; }
1140                 }
1141
1142                 public override bool HasStaticValue {
1143                         get { return _expr.HasStaticValue; }
1144                 }
1145
1146                 public override double StaticValueAsNumber {
1147                         get { return _expr.HasStaticValue ? -1 * _expr.StaticValueAsNumber : 0; }
1148                 }
1149
1150                 public override object Evaluate (BaseIterator iter)
1151                 {
1152                         return - _expr.EvaluateNumber (iter);
1153                 }
1154
1155                 public override double EvaluateNumber (BaseIterator iter)
1156                 {
1157                         return - _expr.EvaluateNumber (iter);
1158                 }
1159
1160                 internal override bool IsPositional {
1161                         get { return _expr.IsPositional; }
1162                 }
1163         }
1164
1165
1166         internal abstract class NodeSet : Expression
1167         {
1168                 public override XPathResultType ReturnType { get { return XPathResultType.NodeSet; }}
1169
1170                 // For "peer and subtree" optimization. see:
1171                 // http://idealliance.org/papers/dx_xmle04/papers/02-03-02/02-03-02.html
1172                 internal abstract bool Subtree { get; }
1173         }
1174
1175         internal class ExprUNION : NodeSet
1176         {
1177                 internal Expression left, right;
1178                 public ExprUNION (Expression left, Expression right)
1179                 {
1180                         this.left = left;
1181                         this.right = right;
1182                 }
1183
1184                 public override Expression Optimize ()
1185                 {
1186                         left = left.Optimize ();
1187                         right = right.Optimize ();
1188                         return this;
1189                 }
1190
1191                 public override String ToString () { return left.ToString ()+ " | " + right.ToString (); }
1192                 public override object Evaluate (BaseIterator iter)
1193                 {
1194                         BaseIterator iterLeft = left.EvaluateNodeSet (iter);
1195                         BaseIterator iterRight = right.EvaluateNodeSet (iter);
1196                         return new UnionIterator (iter, iterLeft, iterRight);
1197                 }
1198
1199                 internal override XPathNodeType EvaluatedNodeType {
1200                         get { return left.EvaluatedNodeType == right.EvaluatedNodeType ? left.EvaluatedNodeType : XPathNodeType.All; }
1201                 }
1202
1203                 internal override bool IsPositional {
1204                         get { return left.IsPositional || right.IsPositional; }
1205                 }
1206
1207                 internal override bool Peer {
1208                         get { return left.Peer && right.Peer; }
1209                 }
1210
1211                 internal override bool Subtree {
1212                         get {
1213                                 NodeSet nl = left as NodeSet;
1214                                 NodeSet nr = right as NodeSet;
1215                                 return nl != null && nr != null && nl.Subtree && nr.Subtree;
1216                         }
1217                 }
1218         }
1219
1220         internal class ExprSLASH : NodeSet
1221         {
1222                 public Expression left;
1223                 public NodeSet right;
1224                 public ExprSLASH (Expression left, NodeSet right)
1225                 {
1226                         this.left = left;
1227                         this.right = right;
1228                 }
1229
1230                 public override Expression Optimize ()
1231                 {
1232                         left = left.Optimize ();
1233                         right = (NodeSet) right.Optimize ();
1234                         return this;
1235                 }
1236
1237                 public override String ToString () { return left.ToString ()+ "/" + right.ToString (); }
1238                 public override object Evaluate (BaseIterator iter)
1239                 {
1240                         // Peer and subtree optimization. see
1241                         // http://idealliance.org/papers/dx_xmle04/papers/02-03-02/02-03-02.html
1242                         BaseIterator iterLeft = left.EvaluateNodeSet (iter);
1243                         if (left.Peer && right.Subtree)
1244                                 return new SimpleSlashIterator (iterLeft, right);
1245                         BaseIterator si = new SlashIterator (iterLeft, right);
1246                         return new SortedIterator (si);
1247                 }
1248
1249                 public override bool RequireSorting { get { return left.RequireSorting || right.RequireSorting; } }
1250
1251                 internal override XPathNodeType EvaluatedNodeType {
1252                         get { return right.EvaluatedNodeType; }
1253                 }
1254
1255                 internal override bool IsPositional {
1256                         get { return left.IsPositional || right.IsPositional; }
1257                 }
1258
1259                 internal override bool Peer {
1260                         get { return left.Peer && right.Peer; }
1261                 }
1262
1263                 internal override bool Subtree {
1264                         get {
1265                                 NodeSet n = left as NodeSet;
1266                                 return n != null && n.Subtree && right.Subtree;
1267                         }
1268                 }
1269         }
1270
1271         internal class ExprSLASH2 : NodeSet {
1272                 public Expression left;
1273                 public NodeSet right;
1274
1275                 static NodeTest DescendantOrSelfStar = new NodeTypeTest (Axes.DescendantOrSelf, XPathNodeType.All);
1276
1277                 public ExprSLASH2 (Expression left, NodeSet right)
1278                 {
1279                         this.left = left;
1280                         this.right = right;
1281                 }
1282
1283                 public override Expression Optimize ()
1284                 {
1285                         left = left.Optimize ();
1286                         right = (NodeSet) right.Optimize ();
1287                         // Path A//B is equal to
1288                         // A/descendant-or-self::node()/child::B, which is
1289                         // equivalent to A/descendant::B. Unlike '//', '/'
1290                         // could be optimized by SimpleSlashIterator.
1291                         NodeTest rnt = right as NodeTest;
1292                         if (rnt != null && rnt.Axis.Axis == Axes.Child) {
1293                                 NodeNameTest nameTest = rnt as NodeNameTest;
1294                                 if (nameTest != null)
1295                                         return new ExprSLASH (left,
1296                                                 new NodeNameTest (nameTest, Axes.Descendant));
1297                                 NodeTypeTest typeTest = rnt as NodeTypeTest;
1298                                 if (typeTest != null)
1299                                         return new ExprSLASH (left,
1300                                                 new NodeTypeTest (typeTest, Axes.Descendant));
1301                         }
1302                         return this;
1303                 }
1304
1305                 public override String ToString () { return left.ToString ()+ "//" + right.ToString (); }
1306                 public override object Evaluate (BaseIterator iter)
1307                 {
1308                         BaseIterator il = left.EvaluateNodeSet (iter);
1309                         if (left.Peer && !left.RequireSorting)
1310                                 il = new SimpleSlashIterator (
1311                                         il, DescendantOrSelfStar);
1312                         else {
1313                                 BaseIterator bb = new SlashIterator (il, DescendantOrSelfStar);
1314                                 il = left.RequireSorting ? new SortedIterator (bb) : bb;
1315                         }
1316
1317                         // FIXME: there could be chances to introduce sort-less
1318                         // iterator, but no one could do it yet.
1319                         SlashIterator b = new SlashIterator (il, right);
1320                         return new SortedIterator (b);
1321                 }
1322
1323                 public override bool RequireSorting { get { return left.RequireSorting || right.RequireSorting; } }
1324
1325                 internal override XPathNodeType EvaluatedNodeType {
1326                         get { return right.EvaluatedNodeType; }
1327                 }
1328
1329                 internal override bool IsPositional {
1330                         get { return left.IsPositional || right.IsPositional; }
1331                 }
1332
1333                 internal override bool Peer {
1334                         get { return false; }
1335                 }
1336
1337                 internal override bool Subtree {
1338                         get {
1339                                 NodeSet n = left as NodeSet;
1340                                 return n != null && n.Subtree && right.Subtree;
1341                         }
1342                 }
1343         }
1344
1345         internal class ExprRoot : NodeSet
1346         {
1347                 public override String ToString () { return ""; }
1348                 public override object Evaluate (BaseIterator iter)
1349                 {
1350                         if (iter.CurrentPosition == 0) {
1351                                 iter = (BaseIterator) iter.Clone ();
1352                                 iter.MoveNext ();
1353                         }
1354                         XPathNavigator navRoot = iter.Current.Clone ();
1355                         navRoot.MoveToRoot ();
1356                         return new SelfIterator (navRoot, iter.NamespaceManager);
1357                 }
1358
1359                 internal override XPathNodeType EvaluatedNodeType {
1360                         get { return XPathNodeType.Root; }
1361                 }
1362
1363                 internal override bool Peer {
1364                         get { return true; }
1365                 }
1366
1367                 internal override bool Subtree {
1368                         get { return false; }
1369                 }
1370         }
1371
1372         internal enum Axes
1373         {
1374                 Ancestor,
1375                 AncestorOrSelf,
1376                 Attribute,
1377                 Child,
1378                 Descendant,
1379                 DescendantOrSelf,
1380                 Following,
1381                 FollowingSibling,
1382                 Namespace,
1383                 Parent,
1384                 Preceding,
1385                 PrecedingSibling,
1386                 Self,
1387         }
1388
1389         internal class AxisSpecifier
1390         {
1391                 protected Axes _axis;
1392                 public AxisSpecifier (Axes axis)
1393                 {
1394                         _axis = axis;
1395                 }
1396                 public XPathNodeType NodeType
1397                 {
1398                         get
1399                         {
1400                                 switch (_axis) {
1401                                 case Axes.Namespace:
1402                                         return XPathNodeType.Namespace;
1403                                 case Axes.Attribute:
1404                                         return XPathNodeType.Attribute;
1405                                 default:
1406                                         return XPathNodeType.Element;
1407                                 }
1408                         }
1409                 }
1410                 public override string ToString ()
1411                 {
1412                         switch (_axis) {
1413                         case Axes.Ancestor:
1414                                 return "ancestor";
1415                         case Axes.AncestorOrSelf:
1416                                 return "ancestor-or-self";
1417                         case Axes.Attribute:
1418                                 return "attribute";
1419                         case Axes.Child:
1420                                 return "child";
1421                         case Axes.Descendant:
1422                                 return "descendant";
1423                         case Axes.DescendantOrSelf:
1424                                 return "descendant-or-self";
1425                         case Axes.Following:
1426                                 return "following";
1427                         case Axes.FollowingSibling:
1428                                 return "following-sibling";
1429                         case Axes.Namespace:
1430                                 return "namespace";
1431                         case Axes.Parent:
1432                                 return "parent";
1433                         case Axes.Preceding:
1434                                 return "preceding";
1435                         case Axes.PrecedingSibling:
1436                                 return "preceding-sibling";
1437                         case Axes.Self:
1438                                 return "self";
1439                         default:
1440                                 throw new IndexOutOfRangeException ();
1441                         }
1442                 }
1443                 public Axes Axis { get { return _axis; }}
1444                 public BaseIterator Evaluate (BaseIterator iter)
1445                 {
1446                         switch (_axis) {
1447                         case Axes.Ancestor:
1448                                 return new AncestorIterator (iter);
1449                         case Axes.AncestorOrSelf:
1450                                 return new AncestorOrSelfIterator (iter);
1451                         case Axes.Attribute:
1452                                 return new AttributeIterator (iter);
1453                         case Axes.Child:
1454                                 return new ChildIterator (iter);
1455                         case Axes.Descendant:
1456                                 return new DescendantIterator (iter);
1457                         case Axes.DescendantOrSelf:
1458                                 return new DescendantOrSelfIterator (iter);
1459                         case Axes.Following:
1460                                 return new FollowingIterator (iter);
1461                         case Axes.FollowingSibling:
1462                                 return new FollowingSiblingIterator (iter);
1463                         case Axes.Namespace:
1464                                 return new NamespaceIterator (iter);
1465                         case Axes.Parent:
1466                                 return new ParentIterator (iter);
1467                         case Axes.Preceding:
1468                                 return new PrecedingIterator (iter);
1469                         case Axes.PrecedingSibling:
1470                                 return new PrecedingSiblingIterator (iter);
1471                         case Axes.Self:
1472                                 return new SelfIterator (iter);
1473                         default:
1474                                 throw new IndexOutOfRangeException ();
1475                         }
1476                 }
1477         }
1478
1479         internal abstract class NodeTest : NodeSet
1480         {
1481                 protected AxisSpecifier _axis;
1482                 public NodeTest (Axes axis)
1483                 {
1484                         _axis = new AxisSpecifier (axis);
1485                 }
1486                 public abstract bool Match (NSResolver nsm, XPathNavigator nav);
1487                 public AxisSpecifier Axis { get { return _axis; }}
1488                 public override object Evaluate (BaseIterator iter)
1489                 {
1490                         BaseIterator iterAxis = _axis.Evaluate (iter);
1491                         return new AxisIterator (iterAxis, this);
1492                 }
1493
1494                 public abstract void GetInfo (out string name, out string ns, out XPathNodeType nodetype, NSResolver nsm);
1495
1496                 public override bool RequireSorting {
1497                         get {
1498                                 switch (_axis.Axis) {
1499                                 case Axes.Ancestor:
1500                                 case Axes.AncestorOrSelf:
1501                                 case Axes.Preceding:
1502                                 case Axes.PrecedingSibling:
1503                                 case Axes.Attribute:
1504                                 case Axes.Namespace:
1505                                         return true;
1506                                 default:
1507                                         return false;
1508                                 }
1509                         }
1510
1511                 }
1512
1513                 internal override bool Peer {
1514                         get {
1515                                 switch (_axis.Axis) {
1516                                 case Axes.Ancestor:
1517                                 case Axes.AncestorOrSelf:
1518                                 case Axes.DescendantOrSelf:
1519                                 case Axes.Descendant:
1520                                 case Axes.Preceding:
1521                                 case Axes.Following:
1522                                         return false;
1523                                 default:
1524                                         return true;
1525                                 }
1526                         }
1527                 }
1528
1529                 internal override bool Subtree {
1530                         get {
1531                                 switch (_axis.Axis) {
1532                                 case Axes.Parent:
1533                                 case Axes.Ancestor:
1534                                 case Axes.AncestorOrSelf:
1535                                 case Axes.Preceding:
1536                                 case Axes.PrecedingSibling:
1537                                 case Axes.Following:
1538                                 case Axes.FollowingSibling:
1539                                         return false;
1540                                 default:
1541                                         return true;
1542                                 }
1543                         }
1544
1545                 }
1546
1547                 internal override XPathNodeType EvaluatedNodeType {
1548                         get { return _axis.NodeType; }
1549                 }
1550         }
1551
1552         internal class NodeTypeTest : NodeTest
1553         {
1554                 public readonly XPathNodeType type;
1555                 protected String _param;
1556                 public NodeTypeTest (Axes axis) : base (axis)
1557                 {
1558                         this.type = _axis.NodeType;
1559                 }
1560                 public NodeTypeTest (Axes axis, XPathNodeType type) : base (axis)
1561                 {
1562                         this.type = type;
1563                 }
1564                 // FIXME: Better description
1565                 public NodeTypeTest (Axes axis, XPathNodeType type, String param) : base (axis)
1566                 {
1567                         this.type = type;
1568                         _param = param;
1569                         if (param != null && type != XPathNodeType.ProcessingInstruction)
1570                                 throw new XPathException ("No argument allowed for "+ToString (type)+"() test");        // TODO: better description
1571                 }
1572
1573                 // for optimizer use
1574                 internal NodeTypeTest (NodeTypeTest other, Axes axis)
1575                         : base (axis)
1576                 {
1577                         type = other.type;
1578                         _param = other._param;
1579                 }
1580
1581                 public override String ToString ()
1582                 {
1583                         String strType = ToString (type);
1584                         if (type == XPathNodeType.ProcessingInstruction && _param != null)
1585                                 strType += "('" + _param + "')";
1586                         else
1587                                 strType += "()";
1588
1589                         return _axis.ToString () + "::" + strType;
1590                 }
1591
1592                 private static String ToString (XPathNodeType type)
1593                 {
1594                         switch (type) {
1595                         case XPathNodeType.Comment:
1596                                 return "comment";
1597                         case XPathNodeType.Text:
1598                                 return "text";
1599                         case XPathNodeType.ProcessingInstruction:
1600                                 return "processing-instruction";
1601                         case XPathNodeType.All:
1602                         case XPathNodeType.Attribute:
1603                         case XPathNodeType.Element:
1604                         case XPathNodeType.Namespace:
1605                                 return "node";
1606                         default:
1607                                 return "node-type [" + type.ToString () + "]";
1608                         }
1609                 }
1610
1611                 public override bool Match (NSResolver nsm, XPathNavigator nav)
1612                 {
1613                         XPathNodeType nodeType = nav.NodeType;
1614                         switch (type) {
1615                         case XPathNodeType.All:
1616                                 return true;
1617
1618                         case XPathNodeType.ProcessingInstruction:
1619                                 if (nodeType != XPathNodeType.ProcessingInstruction)
1620                                         return false;
1621                                 if (_param != null && nav.Name != _param)
1622                                         return false;
1623                                 return true;
1624
1625                         case XPathNodeType.Text:
1626                                 switch (nodeType) {
1627                                 case XPathNodeType.Text:
1628                                 case XPathNodeType.Whitespace:
1629                                 case XPathNodeType.SignificantWhitespace:
1630                                         return true;
1631                                 default:
1632                                         return false;
1633                                 }
1634                         default:
1635                                 return type == nodeType;
1636                         }
1637                 }
1638
1639                 public override void GetInfo (out string name, out string ns, out XPathNodeType nodetype, NSResolver nsm)
1640                 {
1641                         name = _param;
1642                         ns = null;
1643                         nodetype = type;
1644                 }
1645         }
1646
1647         internal class NodeNameTest : NodeTest
1648         {
1649                 protected XmlQualifiedName _name;
1650                 protected readonly bool resolvedName = false;
1651                 public NodeNameTest (Axes axis, XmlQualifiedName name, IStaticXsltContext ctx) : base (axis)
1652                 {
1653                         if (ctx != null) {
1654                                 name = ctx.LookupQName (name.ToString ());
1655                                 resolvedName = true;
1656                         }
1657                         _name = name;
1658                 }
1659
1660                 public NodeNameTest (Axes axis, XmlQualifiedName name, bool resolvedName) : base (axis)
1661                 {
1662                         _name = name;
1663                         this.resolvedName = resolvedName;
1664                 }
1665
1666                 // for optimized path rewrite
1667                 internal NodeNameTest (NodeNameTest source, Axes axis)
1668                         : base (axis)
1669                 {
1670                         _name = source._name;
1671                         resolvedName = source.resolvedName;
1672                 }
1673
1674                 public override String ToString () { return _axis.ToString () + "::" + _name.ToString (); }
1675
1676                 public XmlQualifiedName Name { get { return _name; } }
1677
1678                 public override bool Match (NSResolver nsm, XPathNavigator nav)
1679                 {
1680                         // must be the correct node type
1681                         if (nav.NodeType != _axis.NodeType)
1682                                 return false;
1683
1684                         if (_name.Name != "")
1685                         {
1686                                 // test the local part of the name first
1687                                 if (_name.Name != nav.LocalName)
1688                                         return false;
1689                         }
1690
1691                         // get the prefix for the given name
1692                         String strURI1 = "";
1693                         if (_name.Namespace != "")
1694                         {
1695                                 if (resolvedName)
1696                                         strURI1 = _name.Namespace;
1697                                 else if (nsm != null)
1698 // We still need to have such tricky switch, because the behavior is
1699 // inconsistent between .NET 1.x and 2.0 when the argument is not
1700 // atomic string.
1701 #if NET_2_0
1702                                         strURI1 = nsm.LookupNamespace (_name.Namespace);
1703 #else
1704                                         strURI1 = nsm.LookupNamespace (_name.Namespace, false);
1705 #endif
1706                                 if (strURI1 == null)
1707                                         throw new XPathException ("Invalid namespace prefix: "+_name.Namespace);
1708                         }
1709
1710                         // test the prefixes
1711                         return strURI1 == nav.NamespaceURI;
1712                 }
1713
1714                 public override void GetInfo (out string name, out string ns, out XPathNodeType nodetype, NSResolver nsm)
1715                 {
1716                         // must be the correct node type
1717                         nodetype = _axis.NodeType;
1718
1719                         if (_name.Name != "")
1720                                 name = _name.Name;
1721                         else
1722                                 name = null;
1723                         ns = "";
1724                         if (nsm != null && _name.Namespace != "") {
1725                                 if (resolvedName)
1726                                         ns = _name.Namespace;
1727                                 else
1728 // We still need to have such tricky switch, because the behavior is
1729 // inconsistent between .NET 1.x and 2.0 when the argument is not
1730 // atomic string.
1731 #if NET_2_0
1732                                         ns = nsm.LookupNamespace (_name.Namespace);     // TODO: check to see if this returns null or ""
1733 #else
1734                                         ns = nsm.LookupNamespace (_name.Namespace, false);      // TODO: check to see if this returns null or ""
1735 #endif
1736                                 if (ns == null)
1737                                         throw new XPathException ("Invalid namespace prefix: "+_name.Namespace);
1738                         }
1739                 }
1740         }
1741
1742         internal class ExprFilter : NodeSet
1743         {
1744                 internal Expression expr, pred;
1745
1746                 public ExprFilter (Expression expr, Expression pred)
1747                 {
1748                         this.expr = expr;
1749                         this.pred = pred;
1750                 }
1751
1752                 public override Expression Optimize ()
1753                 {
1754                         expr = expr.Optimize ();
1755                         pred = pred.Optimize ();
1756                         return this;
1757                 }
1758
1759                 internal Expression LeftHandSide {get{return expr;}}
1760                 public override String ToString () { return "(" + expr.ToString () + ")[" + pred.ToString () + "]"; }
1761                 public override object Evaluate (BaseIterator iter)
1762                 {
1763                         BaseIterator iterExpr = expr.EvaluateNodeSet (iter);
1764                         return new PredicateIterator (iterExpr, pred);
1765                 }
1766
1767                 internal override XPathNodeType EvaluatedNodeType {
1768                         get { return expr.EvaluatedNodeType; }
1769                 }
1770
1771                 internal override bool IsPositional {
1772                         get {
1773                                 if (pred.ReturnType == XPathResultType.Number)
1774                                         return true;
1775                                 return expr.IsPositional || pred.IsPositional;
1776                         }
1777                 }
1778
1779                 internal override bool Peer {
1780                         get { return expr.Peer && pred.Peer; }
1781                 }
1782
1783                 internal override bool Subtree {
1784                         get {
1785                                 NodeSet n = expr as NodeSet;
1786                                 return n != null && n.Subtree;
1787                         }
1788                 }
1789         }
1790
1791         internal class ExprNumber : Expression
1792         {
1793                 protected double _value;
1794                 public ExprNumber (double value)
1795                 {
1796                         _value = value;
1797                 }
1798                 public override String ToString () { return _value.ToString (); }
1799                 public override XPathResultType ReturnType { get { return XPathResultType.Number; }}
1800
1801                 internal override bool Peer {
1802                         get { return true; }
1803                 }
1804
1805                 public override bool HasStaticValue {
1806                         get { return true; }
1807                 }
1808
1809                 public override double StaticValueAsNumber {
1810                         get { return XPathFunctions.ToNumber (_value); }
1811                 }
1812
1813                 public override object Evaluate (BaseIterator iter)
1814                 {
1815                         return _value;
1816                 }
1817
1818                 public override double EvaluateNumber (BaseIterator iter)
1819                 {
1820                         return _value;
1821                 }
1822
1823                 internal override bool IsPositional {
1824                         get { return false; }
1825                 }
1826         }
1827
1828         internal class BooleanConstant : Expression
1829         {
1830                 bool _value;
1831
1832                 public BooleanConstant (bool value)
1833                 {
1834                         _value = value;
1835                 }
1836
1837                 public override String ToString () { return _value ? "true()" : "false()"; }
1838                 public override XPathResultType ReturnType { get { return XPathResultType.Boolean; }}
1839
1840                 internal override bool Peer {
1841                         get { return true; }
1842                 }
1843
1844                 public override bool HasStaticValue {
1845                         get { return true; }
1846                 }
1847
1848                 public override bool StaticValueAsBoolean {
1849                         get { return _value; }
1850                 }
1851
1852                 public override object Evaluate (BaseIterator iter)
1853                 {
1854                         return _value;
1855                 }
1856
1857                 public override bool EvaluateBoolean (BaseIterator iter)
1858                 {
1859                         return _value;
1860                 }
1861         }
1862
1863         internal class ExprLiteral : Expression
1864         {
1865                 protected String _value;
1866                 public ExprLiteral (String value)
1867                 {
1868                         _value = value;
1869                 }
1870                 public string Value { get { return _value; } }
1871                 public override String ToString () { return "'" + _value + "'"; }
1872                 public override XPathResultType ReturnType { get { return XPathResultType.String; }}
1873
1874                 internal override bool Peer {
1875                         get { return true; }
1876                 }
1877
1878                 public override bool HasStaticValue {
1879                         get { return true; }
1880                 }
1881
1882                 public override string StaticValueAsString {
1883                         get { return _value; }
1884                 }
1885
1886                 public override object Evaluate (BaseIterator iter)
1887                 {
1888                         return _value;
1889                 }
1890
1891                 public override string EvaluateString (BaseIterator iter)
1892                 {
1893                         return _value;
1894                 }
1895         }
1896
1897         internal class ExprVariable : Expression
1898         {
1899                 protected XmlQualifiedName _name;
1900                 protected bool resolvedName = false;
1901                 public ExprVariable (XmlQualifiedName name, IStaticXsltContext ctx)
1902                 {
1903                         if (ctx != null) {
1904                                 name = ctx.LookupQName (name.ToString ());
1905                                 resolvedName = true;
1906                         }
1907
1908                         _name = name;
1909                 }
1910                 public override String ToString () { return "$" + _name.ToString (); }
1911                 public override XPathResultType ReturnType { get { return XPathResultType.Any; }}
1912                 public override XPathResultType GetReturnType (BaseIterator iter)
1913                 {
1914                         return XPathResultType.Any;
1915                 }
1916
1917                 public override object Evaluate (BaseIterator iter)
1918                 {
1919                         IXsltContextVariable var = null;
1920
1921                         XsltContext context = iter.NamespaceManager as XsltContext;
1922                         if (context != null) {
1923                                 if (resolvedName)
1924                                         var = context.ResolveVariable (_name);
1925                                 else
1926                                         var = context.ResolveVariable (new XmlQualifiedName (_name.Name, _name.Namespace));
1927                         }
1928                         else
1929                                 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));
1930
1931                         if (var == null)
1932                                 throw new XPathException ("variable "+_name.ToString ()+" not found");
1933                         object objResult = var.Evaluate (context);
1934                         XPathNodeIterator iterResult = objResult as XPathNodeIterator;
1935                         if (iterResult != null)
1936                                 return iterResult is BaseIterator ? iterResult : new WrapperIterator (iterResult, iter.NamespaceManager);
1937                         return objResult;
1938                 }
1939
1940                 internal override bool Peer {
1941                         get { return false; }
1942                 }
1943         }
1944
1945         internal class ExprParens : Expression
1946         {
1947                 protected Expression _expr;
1948                 public ExprParens (Expression expr)
1949                 {
1950                         _expr = expr;
1951                 }
1952
1953                 public override Expression Optimize ()
1954                 {
1955                         _expr.Optimize ();
1956                         return this;
1957                 }
1958
1959                 public override bool HasStaticValue {
1960                         get { return _expr.HasStaticValue; }
1961                 }
1962
1963                 public override object StaticValue {
1964                         get { return _expr.StaticValue; }
1965                 }
1966
1967                 public override string StaticValueAsString {
1968                         get { return _expr.StaticValueAsString; }
1969                 }
1970
1971                 public override double StaticValueAsNumber {
1972                         get { return _expr.StaticValueAsNumber; }
1973                 }
1974
1975                 public override bool StaticValueAsBoolean {
1976                         get { return _expr.StaticValueAsBoolean; }
1977                 }
1978
1979                 public override String ToString () { return "(" + _expr.ToString () + ")"; }
1980                 public override XPathResultType ReturnType { get { return _expr.ReturnType; }}
1981                 public override object Evaluate (BaseIterator iter)
1982                 {
1983                         object o = (_expr.Evaluate (iter));
1984                         XPathNodeIterator xi = o as XPathNodeIterator;
1985                         BaseIterator predBase = xi as BaseIterator;
1986                         if (predBase == null && xi != null)
1987                                 predBase = new WrapperIterator (xi, iter.NamespaceManager);
1988                         if (predBase != null)
1989                                 return new ParensIterator (predBase);
1990                         else
1991                                 return o;
1992                 }
1993
1994                 internal override XPathNodeType EvaluatedNodeType {
1995                         get { return _expr.EvaluatedNodeType; }
1996                 }
1997
1998                 internal override bool IsPositional {
1999                         get { return _expr.IsPositional; }
2000                 }
2001
2002                 internal override bool Peer {
2003                         get { return _expr.Peer; }
2004                 }
2005         }
2006
2007         internal class FunctionArguments
2008         {
2009                 protected Expression _arg;
2010                 protected FunctionArguments _tail;
2011                 public FunctionArguments (Expression arg, FunctionArguments tail)
2012                 {
2013                         _arg = arg;
2014                         _tail = tail;
2015                 }
2016                 public Expression Arg
2017                 {
2018                         get { return _arg; }
2019                 }
2020                 public FunctionArguments Tail
2021                 {
2022                         get { return _tail; }
2023                 }
2024
2025                 public void ToArrayList (ArrayList a)
2026                 {
2027                         FunctionArguments cur = this;
2028
2029                         do {
2030                                 a.Add (cur._arg);
2031                                 cur = cur._tail;
2032                         } while (cur != null);
2033
2034                 }
2035         }
2036
2037         internal class ExprFunctionCall : Expression
2038         {
2039                 protected readonly XmlQualifiedName _name;
2040                 protected readonly bool resolvedName = false;
2041                 protected readonly ArrayList _args = new ArrayList ();
2042                 public ExprFunctionCall (XmlQualifiedName name, FunctionArguments args, IStaticXsltContext ctx)
2043                 {
2044                         if (ctx != null) {
2045                                 name = ctx.LookupQName (name.ToString ());
2046                                 resolvedName = true;
2047                         }
2048
2049                         _name = name;
2050                         if (args != null)
2051                                 args.ToArrayList (_args);
2052                 }
2053
2054                 public static Expression Factory (XmlQualifiedName name, FunctionArguments args, IStaticXsltContext ctx)
2055                 {
2056                         if (name.Namespace != null && name.Namespace != "")
2057                                 return new ExprFunctionCall (name, args, ctx);
2058
2059                         switch (name.Name) {
2060                         case "last": return new XPathFunctionLast (args);
2061                         case "position": return new XPathFunctionPosition (args);
2062                         case "count": return new XPathFunctionCount (args);
2063                         case "id": return new XPathFunctionId (args);
2064                         case "local-name": return new XPathFunctionLocalName (args);
2065                         case "namespace-uri": return new XPathFunctionNamespaceUri (args);
2066                         case "name": return new XPathFunctionName (args);
2067                         case "string": return new XPathFunctionString (args);
2068                         case "concat": return new XPathFunctionConcat (args);
2069                         case "starts-with": return new XPathFunctionStartsWith (args);
2070                         case "contains": return new XPathFunctionContains (args);
2071                         case "substring-before": return new XPathFunctionSubstringBefore (args);
2072                         case "substring-after": return new XPathFunctionSubstringAfter (args);
2073                         case "substring": return new XPathFunctionSubstring (args);
2074                         case "string-length": return new XPathFunctionStringLength (args);
2075                         case "normalize-space": return new XPathFunctionNormalizeSpace (args);
2076                         case "translate": return new XPathFunctionTranslate (args);
2077                         case "boolean": return new XPathFunctionBoolean (args);
2078                         case "not": return new XPathFunctionNot (args);
2079                         case "true": return new XPathFunctionTrue (args);
2080                         case "false": return new XPathFunctionFalse (args);
2081                         case "lang": return new XPathFunctionLang (args);
2082                         case "number": return new XPathFunctionNumber (args);
2083                         case "sum": return new XPathFunctionSum (args);
2084                         case "floor": return new XPathFunctionFloor (args);
2085                         case "ceiling": return new XPathFunctionCeil (args);
2086                         case "round": return new XPathFunctionRound (args);
2087                         }
2088                         return new ExprFunctionCall (name, args, ctx);
2089                 }
2090
2091                 public override String ToString ()
2092                 {
2093                         String strArgs = "";
2094                         for (int i = 0; i < _args.Count; i++) {
2095                                 Expression arg = (Expression) _args [i];
2096                                 if (strArgs != "")
2097                                         strArgs += ", ";
2098                                 strArgs += arg.ToString ();
2099                         }
2100                         return _name.ToString () + '(' + strArgs + ')';
2101                 }
2102                 public override XPathResultType ReturnType { get { return XPathResultType.Any; }}
2103                 public override XPathResultType GetReturnType (BaseIterator iter)
2104                 {
2105                         return XPathResultType.Any;
2106                 }
2107
2108                 private XPathResultType [] GetArgTypes (BaseIterator iter)
2109                 {
2110                         // TODO: can we cache these? what if the types depend on the nsm?
2111                         XPathResultType [] rgArgs = new XPathResultType [_args.Count];
2112                         for (int iArg = 0; iArg < _args.Count; iArg++)
2113                                 rgArgs [iArg] = ((Expression) _args [iArg]).GetReturnType (iter);
2114                         return rgArgs;
2115                 }
2116                 public override object Evaluate (BaseIterator iter)
2117                 {
2118                         XPathResultType [] rgTypes = GetArgTypes (iter);
2119                         IXsltContextFunction func = null;
2120                         XsltContext context = iter.NamespaceManager as XsltContext;
2121                         if (context != null) {
2122                                 if (resolvedName)
2123                                         func = context.ResolveFunction (_name, rgTypes);
2124                                 else
2125                                         func = context.ResolveFunction (_name.Namespace, _name.Name, rgTypes);
2126                         }
2127
2128                         if (func == null)
2129                                 throw new XPathException ("function "+_name.ToString ()+" not found");
2130
2131                         object [] rgArgs = new object [_args.Count];
2132                         if (func.Maxargs != 0)
2133                         {
2134                                 XPathResultType [] rgFuncTypes = func.ArgTypes;
2135                                 for (int iArg = 0; iArg < _args.Count; iArg ++)
2136                                 {
2137                                         XPathResultType typeArg;
2138                                         if (rgFuncTypes == null)
2139                                                 typeArg = XPathResultType.Any;
2140                                         else if (iArg < rgFuncTypes.Length)
2141                                                 typeArg = rgFuncTypes [iArg];
2142                                         else
2143                                                 typeArg = rgFuncTypes [rgFuncTypes.Length - 1];
2144
2145                                         Expression arg = (Expression) _args [iArg];
2146                                         object result = arg.EvaluateAs (iter, typeArg);
2147                                         rgArgs [iArg] = result;
2148                                 }
2149                         }
2150                         return func.Invoke (context, rgArgs, iter.Current);
2151                 }
2152
2153                 internal override bool Peer {
2154                         get { return false; }
2155                 }
2156         }
2157 }