mcs/class/System.ServiceModel/Mono.Xml.XPath/DTMXPathNavigator2.cs

   1 //
   2 // Mono.Xml.XPath.DTMXPathNavigator2
   3 //
   4 // Author:
   5 //      Atsushi Enomoto <atsushi@ximian.com>
   6 //
   7 // (C) 2004 Novell Inc.
   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.Collections;
  32 using System.Text;
  33 using System.Xml;
  34 using System.Xml.Schema;
  35 using System.Xml.XPath;
  36 using System.ServiceModel.Dispatcher;
  37
  38 namespace Mono.Xml.XPath
  39 {
  40 #if OUTSIDE_SYSTEM_XML
  41         public
  42 #else
  43         internal
  44 #endif
  45                 class SeekableDTMXPathNavigator2 : SeekableXPathNavigator, IXmlLineInfo
  46         {
  47
  48                 public SeekableDTMXPathNavigator2 (DTMXPathDocument2 document)
  49                 {
  50                         this.MoveToRoot ();
  51                         this.document = document;
  52                 }
  53
  54                 // Copy constructor including position informations.
  55                 public SeekableDTMXPathNavigator2 (SeekableDTMXPathNavigator2 org)
  56                 {
  57                         document = org.document;
  58                         currentIsNode = org.currentIsNode;
  59                         currentIsAttr = org.currentIsAttr;
  60
  61                         currentNode = org.currentNode;
  62                         currentAttr = org.currentAttr;
  63                         currentNs = org.currentNs;
  64                 }
  65
  66                 #region SeekableXPathNavigator members
  67
  68                 public override long CurrentPosition {
  69                         get { return currentIsNode ? currentNode : currentIsAttr ? nodes.Length + currentAttr : nodes.Length + attributes.Length + currentNs; }
  70                         set {
  71                                 int pos = (int) value;
  72                                 if (pos < nodes.Length) {
  73                                         currentIsAttr = false;
  74                                         currentIsNode = true;
  75                                         currentNode = pos;
  76                                 } else if (pos < nodes.Length + attributes.Length) {
  77                                         currentIsAttr = true;
  78                                         currentIsNode = false;
  79                                         currentAttr = pos - nodes.Length;
  80                                 } else if (pos < nodes.Length + attributes.Length + namespaces.Length) {
  81                                         currentIsAttr = false;
  82                                         currentIsNode = false;
  83                                         currentNs = pos - nodes.Length - attributes.Length;
  84                                 } else
  85                                         throw new ArgumentOutOfRangeException ();
  86                         }
  87                 }
  88
  89                 public override XPathNodeType GetNodeType (long nodePosition)
  90                 {
  91                         return
  92                                 nodePosition < nodes.Length ? nodes [nodePosition].NodeType :
  93                                 nodePosition < nodes.Length + attributes.Length ? XPathNodeType.Attribute :
  94                                 XPathNodeType.Namespace;
  95                 }
  96
  97                 public override string GetLocalName (long nodePosition)
  98                 {
  99                         switch (GetNodeType (nodePosition)) {
 100                         case XPathNodeType.Namespace:
 101                                 return atomicStringPool [namespaces [nodePosition - nodes.Length - attributes.Length].Name];
 102                         case XPathNodeType.Attribute:
 103                                 return atomicStringPool [attributes [nodePosition - nodes.Length].LocalName];
 104                         default:
 105                                 return atomicStringPool [nodes [nodePosition].LocalName];
 106                         }
 107                 }
 108
 109                 public override string GetName (long nodePosition)
 110                 {
 111                         switch (GetNodeType (nodePosition)) {
 112                         case XPathNodeType.Namespace:
 113                                 return atomicStringPool [namespaces [nodePosition - nodes.Length - attributes.Length].Name];
 114                         case XPathNodeType.Attribute:
 115                                 return atomicStringPool [attributes [nodePosition - nodes.Length].LocalName];
 116                         default:
 117                                 return atomicStringPool [nodes [nodePosition].LocalName];
 118                         }
 119                 }
 120
 121                 public override string GetNamespace (long nodePosition)
 122                 {
 123                         switch (GetNodeType (nodePosition)) {
 124                         case XPathNodeType.Namespace:
 125                                 return atomicStringPool [namespaces [nodePosition - nodes.Length - attributes.Length].Namespace];
 126                         case XPathNodeType.Attribute:
 127                                 return atomicStringPool [attributes [nodePosition - nodes.Length].NamespaceURI];
 128                         default:
 129                                 return atomicStringPool [nodes [nodePosition].NamespaceURI];
 130                         }
 131                 }
 132
 133                 public override string GetValue (long nodePosition)
 134                 {
 135                         switch (GetNodeType (nodePosition)) {
 136                         case XPathNodeType.Namespace:
 137                                 return atomicStringPool [namespaces [nodePosition - nodes.Length - attributes.Length].Namespace];
 138                         case XPathNodeType.Attribute:
 139                                 return nonAtomicStringPool [attributes [nodePosition - nodes.Length].Value];
 140                         default:
 141                                 return nonAtomicStringPool [nodes [nodePosition].Value];
 142                         }
 143                 }
 144
 145                 int GetOwnerPosition (long position)
 146                 {
 147                         int pos = (int) position;
 148                         return pos < nodes.Length ? pos :
 149                                 pos < nodes.Length + attributes.Length ?
 150                                 attributes [(int) pos].OwnerElement :
 151                                 namespaces [(int) pos].DeclaredElement;
 152                 }
 153
 154                 public override XmlNodeOrder ComparePosition (long firstPosition, long secondPosition)
 155                 {
 156                         if (firstPosition == secondPosition)
 157                                 return XmlNodeOrder.Same;
 158
 159                         int link1 = GetOwnerPosition (firstPosition);
 160                         int link2 = GetOwnerPosition (secondPosition);
 161                         if (link1 == link2)
 162                                 // on the same element. Comparison could be done numerically.
 163                                 return firstPosition < secondPosition ? XmlNodeOrder.Before :
 164                                         XmlNodeOrder.After;
 165                         else
 166                                 // on different linked nodes.
 167                                 return link1 < link2 ?
 168                                         XmlNodeOrder.Before :
 169                                         XmlNodeOrder.After;
 170                 }
 171
 172                 #endregion
 173
 174                 XmlNameTable nameTable {
 175                         get { return document.NameTable; }
 176                 }
 177
 178                 // Created XPathDocument. This is used to identify the origin of the navigator.
 179                 DTMXPathDocument2 document;
 180
 181                 DTMXPathLinkedNode2 [] nodes {
 182                         get { return document.Nodes; }
 183                 }
 184                 DTMXPathAttributeNode2 [] attributes {
 185                         get { return document.Attributes; }
 186                 }
 187                 DTMXPathNamespaceNode2 [] namespaces {
 188                         get { return document.Namespaces; }
 189                 }
 190                 string [] atomicStringPool {
 191                         get { return document.AtomicStringPool; }
 192                 }
 193                 string [] nonAtomicStringPool {
 194                         get { return document.NonAtomicStringPool; }
 195                 }
 196
 197                 // ID table
 198                 Hashtable idTable {
 199                         get { return document.IdTable; }
 200                 }
 201
 202                 bool currentIsNode;
 203                 bool currentIsAttr;
 204
 205                 int currentNode;
 206                 int currentAttr;
 207                 int currentNs;
 208
 209 #region Properties
 210
 211                 public override string BaseURI {
 212                         get { return atomicStringPool [nodes [currentNode].BaseURI]; }
 213                 }
 214
 215                 public override bool HasAttributes {
 216                         get { return currentIsNode ? nodes [currentNode].FirstAttribute != 0 : false; }
 217                 }
 218
 219                 public override bool HasChildren {
 220                         get { return currentIsNode ? nodes [currentNode].FirstChild != 0 : false; }
 221                 }
 222
 223                 public override bool IsEmptyElement {
 224                         get { return currentIsNode ? nodes [currentNode].IsEmptyElement : false; }
 225                 }
 226
 227                 int IXmlLineInfo.LineNumber {
 228                         get {
 229                                 return currentIsAttr ? attributes [currentAttr].LineNumber :
 230                                         nodes [currentNode].LineNumber;
 231                         }
 232                 }
 233
 234                 int IXmlLineInfo.LinePosition {
 235                         get {
 236                                 return currentIsAttr ? attributes [currentAttr].LinePosition :
 237                                         nodes [currentNode].LinePosition;
 238                         }
 239                 }
 240
 241                 public override string LocalName {
 242                         get {
 243                                 if (currentIsNode)
 244                                         return atomicStringPool [nodes [currentNode].LocalName];
 245                                 else if (currentIsAttr)
 246                                         return atomicStringPool [attributes [currentAttr].LocalName];
 247                                 else
 248                                         return atomicStringPool [namespaces [currentNs].Name];
 249                         }
 250                 }
 251
 252                 // It maybe scarcely used, so I decided to compute it always.
 253                 public override string Name {
 254                         get {
 255                                 string prefix;
 256                                 string localName;
 257                                 if (currentIsNode) {
 258                                         prefix = atomicStringPool [nodes [currentNode].Prefix];
 259                                         localName = atomicStringPool [nodes [currentNode].LocalName];
 260                                 } else if (currentIsAttr) {
 261                                         prefix = atomicStringPool [attributes [currentAttr].Prefix];
 262                                         localName = atomicStringPool [attributes [currentAttr].LocalName];
 263                                 } else
 264                                         return atomicStringPool [namespaces [currentNs].Name];
 265
 266                                 if (prefix != "")
 267                                         return prefix + ':' + localName;
 268                                 else
 269                                         return localName;
 270                         }
 271                 }
 272
 273                 public override string NamespaceURI {
 274                         get {
 275                                 if (currentIsNode)
 276                                         return atomicStringPool [nodes [currentNode].NamespaceURI];
 277                                 if (currentIsAttr)
 278                                         return atomicStringPool [attributes [currentAttr].NamespaceURI];
 279                                 return String.Empty;
 280                         }
 281                 }
 282
 283                 public override XmlNameTable NameTable {
 284                         get { return nameTable; }
 285                 }
 286
 287                 public override XPathNodeType NodeType {
 288                         get {
 289                                 if (currentIsNode)
 290                                         return nodes [currentNode].NodeType;
 291                                 else if (currentIsAttr)
 292                                         return XPathNodeType.Attribute;
 293                                 else
 294                                         return XPathNodeType.Namespace;
 295                         }
 296                 }
 297
 298                 public override string Prefix {
 299                         get {
 300                                 if (currentIsNode)
 301                                         return atomicStringPool [nodes [currentNode].Prefix];
 302                                 else if (currentIsAttr)
 303                                         return atomicStringPool [attributes [currentAttr].Prefix];
 304                                 return String.Empty;
 305                         }
 306                 }
 307
 308                 public override string Value {
 309                         get {
 310                                 if (currentIsAttr)
 311                                         return nonAtomicStringPool [attributes [currentAttr].Value];
 312                                 else if (!currentIsNode)
 313                                         return atomicStringPool [namespaces [currentNs].Namespace];
 314
 315                                 switch (nodes [currentNode].NodeType) {
 316                                 case XPathNodeType.Comment:
 317                                 case XPathNodeType.ProcessingInstruction:
 318                                 case XPathNodeType.Text:
 319                                 case XPathNodeType.Whitespace:
 320                                 case XPathNodeType.SignificantWhitespace:
 321                                         return nonAtomicStringPool [nodes [currentNode].Value];
 322                                 }
 323
 324                                 // Element - collect all content values
 325                                 int iter = nodes [currentNode].FirstChild;
 326                                 if (iter == 0)
 327                                         return String.Empty;
 328
 329                                 StringBuilder builder = null;
 330                                 BuildValue (iter, ref builder);
 331                                 return builder == null ? String.Empty : builder.ToString ();
 332                         }
 333                 }
 334
 335                 void BuildValue (int iter, ref StringBuilder valueBuilder)
 336                 {
 337                         int end = nodes [currentNode].NextSibling;
 338                         if (end == 0) {
 339                                 int tmp = currentNode;
 340                                 do {
 341                                         tmp = nodes [tmp].Parent;
 342                                         end = nodes [tmp].NextSibling;
 343                                 } while (end == 0 && tmp != 0);
 344                                 if (end == 0)
 345                                         end = nodes.Length;
 346                         }
 347
 348                         while (iter < end) {
 349                                 switch (nodes [iter].NodeType) {
 350                                 case XPathNodeType.Text:
 351                                 case XPathNodeType.SignificantWhitespace:
 352                                 case XPathNodeType.Whitespace:
 353                                         if (valueBuilder == null)
 354                                                 valueBuilder = new StringBuilder ();
 355                                         valueBuilder.Append (nonAtomicStringPool [nodes [iter].Value]);
 356                                         break;
 357                                 }
 358                                 iter++;
 359                         }
 360                 }
 361
 362                 public override string XmlLang {
 363                         get { return atomicStringPool [nodes [currentNode].XmlLang]; }
 364                 }
 365
 366 #endregion
 367
 368 #region Methods
 369
 370                 public override XPathNavigator Clone ()
 371                 {
 372                         return new SeekableDTMXPathNavigator2 (this);
 373                 }
 374
 375                 public override XmlNodeOrder ComparePosition (XPathNavigator nav)
 376                 {
 377                         SeekableDTMXPathNavigator2 another = nav as SeekableDTMXPathNavigator2;
 378
 379                         if (another == null || another.document != this.document)
 380                                 return XmlNodeOrder.Unknown;
 381
 382                         if (currentNode > another.currentNode)
 383                                 return XmlNodeOrder.After;
 384                         else if (currentNode < another.currentNode)
 385                                 return XmlNodeOrder.Before;
 386
 387                         // another may attr or ns,
 388                         // and this may be also attr or ns.
 389                         if (another.currentIsAttr) {
 390                                 if (this.currentIsAttr) {
 391                                         if (currentAttr > another.currentAttr)
 392                                                 return XmlNodeOrder.After;
 393                                         else if (currentAttr < another.currentAttr)
 394                                                 return XmlNodeOrder.Before;
 395                                         else
 396                                                 return XmlNodeOrder.Same;
 397                                 } else
 398                                         return XmlNodeOrder.Before;
 399                         } else if (!another.currentIsNode) {
 400                                 if (!this.currentIsNode) {
 401                                         if (currentNs > another.currentNs)
 402                                                 return XmlNodeOrder.After;
 403                                         else if (currentNs < another.currentNs)
 404                                                 return XmlNodeOrder.Before;
 405                                         else
 406                                                 return XmlNodeOrder.Same;
 407                                 } else
 408                                         return XmlNodeOrder.Before;
 409                         } else
 410                                 return !another.currentIsNode ? XmlNodeOrder.Before : XmlNodeOrder.Same;
 411                 }
 412
 413                 private int findAttribute (string localName, string namespaceURI)
 414                 {
 415                         if (currentIsNode && nodes [currentNode].NodeType == XPathNodeType.Element) {
 416                                 int cur = nodes [currentNode].FirstAttribute;
 417                                 while (cur != 0) {
 418                                         if (atomicStringPool [attributes [cur].LocalName] == localName && atomicStringPool [attributes [cur].NamespaceURI] == namespaceURI)
 419                                                 return cur;
 420                                         cur = attributes [cur].NextAttribute;
 421                                 }
 422                         }
 423                         return 0;
 424                 }
 425
 426                 public override string GetAttribute (string localName,
 427                         string namespaceURI)
 428                 {
 429                         int attr = findAttribute (localName, namespaceURI);
 430                         return (attr != 0) ? nonAtomicStringPool [attributes [attr].Value] : String.Empty;
 431                 }
 432
 433                 public override string GetNamespace (string name)
 434                 {
 435                         if (currentIsNode && nodes [currentNode].NodeType == XPathNodeType.Element) {
 436                                 int nsNode = nodes [currentNode].FirstNamespace;
 437                                 while (nsNode != 0) {
 438                                         if (atomicStringPool [namespaces [nsNode].Name] == name)
 439                                                 return atomicStringPool [namespaces [nsNode].Namespace];
 440                                         nsNode = namespaces [nsNode].NextNamespace;
 441                                 }
 442                         }
 443                         return String.Empty;
 444                 }
 445
 446                 bool IXmlLineInfo.HasLineInfo ()
 447                 {
 448                         return true;
 449                 }
 450
 451                 public override bool IsDescendant (XPathNavigator nav)
 452                 {
 453                         SeekableDTMXPathNavigator2 another = nav as SeekableDTMXPathNavigator2;
 454
 455                         if (another == null || another.document != this.document)
 456                                 return false;
 457
 458                         if (another.currentNode == currentNode)
 459                                 return !another.currentIsNode;
 460                         int tmp = nodes [another.currentNode].Parent;
 461
 462                         // ancestors must appear in prior on the node list.
 463                         if (tmp < currentNode)
 464                                 return false;
 465
 466                         while (tmp != 0) {
 467                                 if (tmp == currentNode)
 468                                         return true;
 469                                 tmp = nodes [tmp].Parent;
 470                         }
 471                         return false;
 472                 }
 473
 474                 public override bool IsSamePosition (XPathNavigator other)
 475                 {
 476                         SeekableDTMXPathNavigator2 another = other as SeekableDTMXPathNavigator2;
 477
 478                         if (another == null || another.document != this.document)
 479                                 return false;
 480
 481                         if (this.currentNode != another.currentNode ||
 482                                 this.currentIsAttr != another.currentIsAttr ||
 483                                 this.currentIsNode != another.currentIsNode)
 484                                 return false;
 485
 486                         if (currentIsAttr)
 487                                 return this.currentAttr == another.currentAttr;
 488                         else if (!currentIsNode)
 489                                 return this.currentNs == another.currentNs;
 490                         return true;
 491                 }
 492
 493                 public override bool MoveTo (XPathNavigator other)
 494                 {
 495                         SeekableDTMXPathNavigator2 another = other as SeekableDTMXPathNavigator2;
 496
 497                         if (another == null || another.document != this.document)
 498                                 return false;
 499
 500                         this.currentNode = another.currentNode;
 501                         this.currentAttr = another.currentAttr;
 502                         this.currentNs = another.currentNs;
 503                         this.currentIsNode = another.currentIsNode;
 504                         this.currentIsAttr = another.currentIsAttr;
 505                         return true;
 506                 }
 507
 508                 public override bool MoveToAttribute (string localName,
 509                         string namespaceURI)
 510                 {
 511                         int attr = findAttribute (localName, namespaceURI);
 512                         if (attr == 0)
 513                                 return false;
 514
 515                         currentAttr = attr;
 516                         currentIsAttr = true;
 517                         currentIsNode = false;
 518                         return true;
 519                 }
 520
 521                 public override bool MoveToFirst ()
 522                 {
 523                         if (currentIsAttr)
 524                                 return false;
 525
 526                         int cur = nodes [currentNode].PreviousSibling;
 527                         if (cur == 0)
 528                                 return false;
 529
 530                         cur = nodes [cur].Parent;
 531                         cur = nodes [cur].FirstChild;
 532                         currentNode = cur;
 533                         currentIsNode = true;
 534                         return true;
 535                 }
 536
 537                 public override bool MoveToFirstAttribute ()
 538                 {
 539                         if (!currentIsNode)
 540                                 return false;
 541
 542                         int first = nodes [currentNode].FirstAttribute;
 543                         if (first == 0)
 544                                 return false;
 545
 546                         currentAttr = first;
 547                         currentIsAttr = true;
 548                         currentIsNode = false;
 549                         return true;
 550                 }
 551
 552                 public override bool MoveToFirstChild ()
 553                 {
 554                         if (!currentIsNode)
 555                                 return false;
 556
 557                         int first = nodes [currentNode].FirstChild;
 558                         if (first == 0)
 559                                 return false;
 560
 561                         currentNode = first;
 562                         return true;
 563                 }
 564
 565                 private bool moveToSpecifiedNamespace (int cur,
 566                         XPathNamespaceScope namespaceScope)
 567                 {
 568                         if (cur == 0)
 569                                 return false;
 570
 571                         if (namespaceScope == XPathNamespaceScope.Local &&
 572                                         namespaces [cur].DeclaredElement != currentNode)
 573                                 return false;
 574
 575                         if (namespaceScope != XPathNamespaceScope.All
 576                                 && namespaces [cur].Namespace == XmlNamespaces.IndexXML)
 577                                 return false;
 578
 579                         if (cur != 0) {
 580                                 moveToNamespace (cur);
 581                                 return true;
 582                         }
 583                         else
 584                                 return false;
 585                 }
 586
 587                 public override bool MoveToFirstNamespace (
 588                         XPathNamespaceScope namespaceScope)
 589                 {
 590                         if (!currentIsNode)
 591                                 return false;
 592                         int cur = nodes [currentNode].FirstNamespace;
 593                         return moveToSpecifiedNamespace (cur, namespaceScope);
 594                 }
 595
 596                 // Note that this support is extension to XPathDocument.
 597                 // XPathDocument does not support ID reference.
 598                 public override bool MoveToId (string id)
 599                 {
 600                         if (idTable.ContainsKey (id)) {
 601                                 currentNode = (int) idTable [id];
 602                                 currentIsNode = true;
 603                                 currentIsAttr = false;
 604                                 return true;
 605                         }
 606                         else
 607                                 return false;
 608                 }
 609
 610                 private void moveToNamespace (int nsNode)
 611                 {
 612                         currentIsNode = currentIsAttr = false;
 613                         currentNs = nsNode;
 614                 }
 615
 616                 public override bool MoveToNamespace (string name)
 617                 {
 618                         int cur = nodes [currentNode].FirstNamespace;
 619                         if (cur == 0)
 620                                 return false;
 621
 622                         while (cur != 0) {
 623                                 if (atomicStringPool [namespaces [cur].Name] == name) {
 624                                         moveToNamespace (cur);
 625                                         return true;
 626                                 }
 627                                 cur = namespaces [cur].NextNamespace;
 628                         }
 629                         return false;
 630                 }
 631
 632                 public override bool MoveToNext ()
 633                 {
 634                         if (currentIsAttr)
 635                                 return false;
 636
 637                         int next = nodes [currentNode].NextSibling;
 638                         if (next == 0)
 639                                 return false;
 640                         currentNode = next;
 641                         currentIsNode = true;
 642                         return true;
 643                 }
 644
 645                 public override bool MoveToNextAttribute ()
 646                 {
 647                         if (!currentIsAttr)
 648                                 return false;
 649
 650                         int next = attributes [currentAttr].NextAttribute;
 651                         if (next == 0)
 652                                 return false;
 653                         currentAttr = next;
 654                         return true;
 655                 }
 656
 657                 public override bool MoveToNextNamespace (
 658                         XPathNamespaceScope namespaceScope)
 659                 {
 660                         if (currentIsAttr || currentIsNode)
 661                                 return false;
 662
 663                         int cur = namespaces [currentNs].NextNamespace;
 664                         return moveToSpecifiedNamespace (cur, namespaceScope);
 665                 }
 666
 667                 public override bool MoveToParent ()
 668                 {
 669                         if (!currentIsNode) {
 670                                 currentIsNode = true;
 671                                 currentIsAttr = false;
 672                                 return true;
 673                         }
 674
 675                         int parent = nodes [currentNode].Parent;
 676                         if (parent == 0)        // It is root itself.
 677                                 return false;
 678
 679                         currentNode = parent;
 680                         return true;
 681                 }
 682
 683                 public override bool MoveToPrevious ()
 684                 {
 685                         if (currentIsAttr)
 686                                 return false;
 687
 688                         int previous = nodes [currentNode].PreviousSibling;
 689                         if (previous == 0)
 690                                 return false;
 691                         currentNode = previous;
 692                         currentIsNode = true;
 693                         return true;
 694                 }
 695
 696                 public override void MoveToRoot ()
 697                 {
 698                         currentNode = 1;        // root is 1.
 699                         currentIsNode = true;
 700                         currentIsAttr = false;
 701                 }
 702
 703 #endregion
 704         }
 705
 706         class XmlNamespaces
 707         {
 708                 public const string XML = "http://www.w3.org/XML/1998/namespace";
 709                 public const string XMLNS = "http://www.w3.org/2000/xmlns/";
 710                 public const int IndexXML = 2;
 711                 public const int IndexXMLNS = 3;
 712         }
 713 }