rdf/base/src/nsRDFXMLSerializer.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
   2  * vim: set ts=4 sw=4 et tw=80:
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   4  * ***** BEGIN LICENSE BLOCK *****
   5  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   6  *
   7  * The contents of this file are subject to the Mozilla Public License Version
   8  * 1.1 (the "License"); you may not use this file except in compliance with
   9  * the License. You may obtain a copy of the License at
  10  * http://www.mozilla.org/MPL/
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  12  * Software distributed under the License is distributed on an "AS IS" basis,
  13  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  14  * for the specific language governing rights and limitations under the
  15  * License.
  16  *
  17  * The Original Code is mozilla.org Code.
  18  *
  19  * The Initial Developer of the Original Code is
  20  * Netscape Communications Corporation.
  21  * Portions created by the Initial Developer are Copyright (C) 1999
  22  * the Initial Developer. All Rights Reserved.
  23  *
  24  * Contributor(s):
  25  *   Chris Waterson <waterson@netscape.com>
  26  *   Axel Hecht <axel@pike.org>
  27  *
  28  * Alternatively, the contents of this file may be used under the terms of
  29  * either of the GNU General Public License Version 2 or later (the "GPL"),
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  31  * in which case the provisions of the GPL or the LGPL are applicable instead
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  39  *
  40  * ***** END LICENSE BLOCK ***** */
  41
  42 #include "nsRDFXMLSerializer.h"
  43
  44 #include "nsIAtom.h"
  45 #include "nsIOutputStream.h"
  46 #include "nsIRDFService.h"
  47 #include "nsIRDFContainerUtils.h"
  48 #include "nsIServiceManager.h"
  49 #include "nsString.h"
  50 #include "nsXPIDLString.h"
  51 #include "nsVoidArray.h"
  52 #include "rdf.h"
  53 #include "rdfutil.h"
  54
  55 #include "rdfIDataSource.h"
  56
  57 #include "nsITimelineService.h"
  58
  59 PRInt32 nsRDFXMLSerializer::gRefCnt = 0;
  60 nsIRDFContainerUtils* nsRDFXMLSerializer::gRDFC;
  61 nsIRDFResource* nsRDFXMLSerializer::kRDF_instanceOf;
  62 nsIRDFResource* nsRDFXMLSerializer::kRDF_type;
  63 nsIRDFResource* nsRDFXMLSerializer::kRDF_nextVal;
  64 nsIRDFResource* nsRDFXMLSerializer::kRDF_Bag;
  65 nsIRDFResource* nsRDFXMLSerializer::kRDF_Seq;
  66 nsIRDFResource* nsRDFXMLSerializer::kRDF_Alt;
  67
  68 static const char kRDFDescriptionOpen[]      = "  <RDF:Description";
  69 static const char kIDAttr[]                  = " RDF:ID=\"";
  70 static const char kAboutAttr[]               = " RDF:about=\"";
  71 static const char kRDFDescriptionClose[]     = "  </RDF:Description>\n";
  72 static const char kRDFResource1[] = " RDF:resource=\"";
  73 static const char kRDFResource2[] = "\"/>\n";
  74 static const char kRDFParseTypeInteger[] = " NC:parseType=\"Integer\">";
  75 static const char kRDFParseTypeDate[] = " NC:parseType=\"Date\">";
  76 static const char kRDFUnknown[] = "><!-- unknown node type -->";
  77
  78 NS_IMETHODIMP
  79 nsRDFXMLSerializer::Create(nsISupports* aOuter, REFNSIID aIID, void** aResult)
  80 {
  81     if (aOuter)
  82         return NS_ERROR_NO_AGGREGATION;
  83
  84     nsCOMPtr<nsIRDFXMLSerializer> result = new nsRDFXMLSerializer();
  85     if (! result)
  86         return NS_ERROR_OUT_OF_MEMORY;
  87     // The serializer object is here, addref gRefCnt so that the
  88     // destructor can safely release it.
  89     gRefCnt++;
  90
  91     nsresult rv;
  92     rv = result->QueryInterface(aIID, aResult);
  93
  94     if (NS_FAILED(rv)) return rv;
  95
  96     if (gRefCnt == 1) do {
  97         nsCOMPtr<nsIRDFService> rdf = do_GetService("@mozilla.org/rdf/rdf-service;1", &rv);
  98         if (NS_FAILED(rv)) break;
  99
 100         rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "instanceOf"),
 101                               &kRDF_instanceOf);
 102         if (NS_FAILED(rv)) break;
 103
 104         rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "type"),
 105                               &kRDF_type);
 106         if (NS_FAILED(rv)) break;
 107
 108         rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "nextVal"),
 109                               &kRDF_nextVal);
 110         if (NS_FAILED(rv)) break;
 111
 112         rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "Bag"),
 113                               &kRDF_Bag);
 114         if (NS_FAILED(rv)) break;
 115
 116         rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "Seq"),
 117                               &kRDF_Seq);
 118         if (NS_FAILED(rv)) break;
 119
 120         rv = rdf->GetResource(NS_LITERAL_CSTRING(RDF_NAMESPACE_URI "Alt"),
 121                               &kRDF_Alt);
 122         if (NS_FAILED(rv)) break;
 123
 124         rv = CallGetService("@mozilla.org/rdf/container-utils;1", &gRDFC);
 125         if (NS_FAILED(rv)) break;
 126     } while (0);
 127
 128     return rv;
 129 }
 130
 131 nsRDFXMLSerializer::nsRDFXMLSerializer()
 132 {
 133     MOZ_COUNT_CTOR(nsRDFXMLSerializer);
 134 }
 135
 136 nsRDFXMLSerializer::~nsRDFXMLSerializer()
 137 {
 138     MOZ_COUNT_DTOR(nsRDFXMLSerializer);
 139
 140     if (--gRefCnt == 0) {
 141         NS_IF_RELEASE(kRDF_Bag);
 142         NS_IF_RELEASE(kRDF_Seq);
 143         NS_IF_RELEASE(kRDF_Alt);
 144         NS_IF_RELEASE(kRDF_instanceOf);
 145         NS_IF_RELEASE(kRDF_type);
 146         NS_IF_RELEASE(kRDF_nextVal);
 147         NS_IF_RELEASE(gRDFC);
 148     }
 149 }
 150
 151 NS_IMPL_ISUPPORTS2(nsRDFXMLSerializer, nsIRDFXMLSerializer, nsIRDFXMLSource)
 152
 153 NS_IMETHODIMP
 154 nsRDFXMLSerializer::Init(nsIRDFDataSource* aDataSource)
 155 {
 156     if (! aDataSource)
 157         return NS_ERROR_NULL_POINTER;
 158
 159     mDataSource = aDataSource;
 160     mDataSource->GetURI(getter_Copies(mBaseURLSpec));
 161
 162     // Add the ``RDF'' prefix, by default.
 163     nsCOMPtr<nsIAtom> prefix;
 164
 165     prefix = do_GetAtom("RDF");
 166     AddNameSpace(prefix, NS_LITERAL_STRING("http://www.w3.org/1999/02/22-rdf-syntax-ns#"));
 167
 168     prefix = do_GetAtom("NC");
 169     AddNameSpace(prefix, NS_LITERAL_STRING("http://home.netscape.com/NC-rdf#"));
 170
 171     mQNames.Init();
 172     mPrefixID = 0;
 173
 174     return NS_OK;
 175 }
 176
 177 NS_IMETHODIMP
 178 nsRDFXMLSerializer::AddNameSpace(nsIAtom* aPrefix, const nsAString& aURI)
 179 {
 180     nsCOMPtr<nsIAtom> prefix = aPrefix;
 181     if (!prefix) {
 182         // Make up a prefix, we don't want default namespaces, so
 183         // that we can use QNames for elements and attributes alike.
 184         prefix = EnsureNewPrefix();
 185     }
 186     mNameSpaces.Put(aURI, prefix);
 187     return NS_OK;
 188 }
 189
 190 static nsresult
 191 rdf_BlockingWrite(nsIOutputStream* stream, const char* buf, PRUint32 size)
 192 {
 193     PRUint32 written = 0;
 194     PRUint32 remaining = size;
 195     while (remaining > 0) {
 196         nsresult rv;
 197         PRUint32 cb;
 198
 199         if (NS_FAILED(rv = stream->Write(buf + written, remaining, &cb)))
 200             return rv;
 201
 202         written += cb;
 203         remaining -= cb;
 204     }
 205     return NS_OK;
 206 }
 207
 208 static nsresult
 209 rdf_BlockingWrite(nsIOutputStream* stream, const nsCSubstring& s)
 210 {
 211     return rdf_BlockingWrite(stream, s.BeginReading(), s.Length());
 212 }
 213
 214 static nsresult
 215 rdf_BlockingWrite(nsIOutputStream* stream, const nsAString& s)
 216 {
 217     NS_ConvertUTF16toUTF8 utf8(s);
 218     return rdf_BlockingWrite(stream, utf8.get(), utf8.Length());
 219 }
 220
 221 already_AddRefed<nsIAtom>
 222 nsRDFXMLSerializer::EnsureNewPrefix()
 223 {
 224     nsCAutoString qname;
 225     nsCOMPtr<nsIAtom> prefix;
 226     PRBool isNewPrefix;
 227     do {
 228         isNewPrefix = PR_TRUE;
 229         qname.AssignLiteral("NS");
 230         qname.AppendInt(++mPrefixID, 10);
 231         prefix = do_GetAtom(qname);
 232         nsNameSpaceMap::const_iterator iter = mNameSpaces.first();
 233         while (iter != mNameSpaces.last() && isNewPrefix) {
 234             isNewPrefix = (iter->mPrefix != prefix);
 235             ++iter;
 236         }
 237     } while (!isNewPrefix);
 238     nsIAtom* outPrefix = nsnull;
 239     prefix.swap(outPrefix);
 240     return outPrefix;
 241 }
 242
 243 // This converts a property resource (like
 244 // "http://www.w3.org/TR/WD-rdf-syntax#Description") into a QName
 245 // ("RDF:Description"), and registers the namespace, if it's made up.
 246
 247 nsresult
 248 nsRDFXMLSerializer::RegisterQName(nsIRDFResource* aResource)
 249 {
 250     nsCAutoString uri, qname;
 251     aResource->GetValueUTF8(uri);
 252
 253     nsNameSpaceMap::const_iterator iter = mNameSpaces.GetNameSpaceOf(uri);
 254     if (iter != mNameSpaces.last()) {
 255         NS_ENSURE_TRUE(iter->mPrefix, NS_ERROR_UNEXPECTED);
 256         iter->mPrefix->ToUTF8String(qname);
 257         qname.Append(':');
 258         qname += StringTail(uri, uri.Length() - iter->mURI.Length());
 259         return mQNames.Put(aResource, qname) ? NS_OK : NS_ERROR_FAILURE;
 260     }
 261
 262     // Okay, so we don't have it in our map. Try to make one up. This
 263     // is very bogus.
 264     PRInt32 i = uri.RFindChar('#'); // first try a '#'
 265     if (i == -1) {
 266         i = uri.RFindChar('/');
 267         if (i == -1) {
 268             // Okay, just punt and assume there is _no_ namespace on
 269             // this thing...
 270             return mQNames.Put(aResource, uri) ? NS_OK : NS_ERROR_FAILURE;
 271         }
 272     }
 273
 274     // Take whatever is to the right of the '#' or '/' and call it the
 275     // local name, make up a prefix.
 276     nsCOMPtr<nsIAtom> prefix = EnsureNewPrefix();
 277     mNameSpaces.Put(StringHead(uri, i+1), prefix);
 278     prefix->ToUTF8String(qname);
 279     qname.Append(':');
 280     qname += StringTail(uri, uri.Length() - (i + 1));
 281
 282     return mQNames.Put(aResource, qname) ? NS_OK : NS_ERROR_FAILURE;
 283 }
 284
 285 nsresult
 286 nsRDFXMLSerializer::GetQName(nsIRDFResource* aResource, nsCString& aQName)
 287 {
 288     return mQNames.Get(aResource, &aQName) ? NS_OK : NS_ERROR_UNEXPECTED;
 289 }
 290
 291 PRBool
 292 nsRDFXMLSerializer::IsContainerProperty(nsIRDFResource* aProperty)
 293 {
 294     // Return `true' if the property is an internal property related
 295     // to being a container.
 296     if (aProperty == kRDF_instanceOf)
 297         return PR_TRUE;
 298
 299     if (aProperty == kRDF_nextVal)
 300         return PR_TRUE;
 301
 302     PRBool isOrdinal = PR_FALSE;
 303     gRDFC->IsOrdinalProperty(aProperty, &isOrdinal);
 304     if (isOrdinal)
 305         return PR_TRUE;
 306
 307     return PR_FALSE;
 308 }
 309
 310
 311 // convert '&', '<', and '>' into "&amp;", "&lt;", and "&gt", respectively.
 312 static const char amp[] = "&amp;";
 313 static const char lt[] = "&lt;";
 314 static const char gt[] = "&gt;";
 315 static const char quot[] = "&quot;";
 316
 317 static void
 318 rdf_EscapeAmpersandsAndAngleBrackets(nsCString& s)
 319 {
 320     PRUint32 newLength, origLength;
 321     newLength = origLength = s.Length();
 322
 323     // Compute the length of the result string.
 324     const char* start = s.BeginReading();
 325     const char* end = s.EndReading();
 326     const char* c = start;
 327     while (c != end) {
 328         switch (*c) {
 329         case '&' :
 330             newLength += sizeof(amp) - 2;
 331             break;
 332         case '<':
 333         case '>':
 334             newLength += sizeof(gt) - 2;
 335             break;
 336         default:
 337             break;
 338         }
 339         ++c;
 340     }
 341     if (newLength == origLength) {
 342         // nothing to escape
 343         return;
 344     }
 345
 346     // escape the chars from the end back to the front.
 347     s.SetLength(newLength);
 348
 349     // Buffer might have changed, get the pointers again
 350     start = s.BeginReading(); // begin of string
 351     c = start + origLength - 1; // last char in original string
 352     char* w = s.EndWriting() - 1; // last char in grown buffer
 353     while (c >= start) {
 354         switch (*c) {
 355         case '&' :
 356             w -= 4;
 357             nsCharTraits<char>::copy(w, amp, sizeof(amp) - 1);
 358             break;
 359         case '<':
 360             w -= 3;
 361             nsCharTraits<char>::copy(w, lt, sizeof(lt) - 1);
 362             break;
 363         case '>':
 364             w -= 3;
 365             nsCharTraits<char>::copy(w, gt, sizeof(gt) - 1);
 366             break;
 367         default:
 368             *w = *c;
 369         }
 370         --w;
 371         --c;
 372     }
 373 }
 374
 375 // convert '"' to "&quot;"
 376 static void
 377 rdf_EscapeQuotes(nsCString& s)
 378 {
 379     PRInt32 i = 0;
 380     while ((i = s.FindChar('"', i)) != -1) {
 381         s.Replace(i, 1, quot, sizeof(quot) - 1);
 382         i += sizeof(quot) - 2;
 383     }
 384 }
 385
 386 static void
 387 rdf_EscapeAttributeValue(nsCString& s)
 388 {
 389     rdf_EscapeAmpersandsAndAngleBrackets(s);
 390     rdf_EscapeQuotes(s);
 391 }
 392
 393
 394 nsresult
 395 nsRDFXMLSerializer::SerializeInlineAssertion(nsIOutputStream* aStream,
 396                                              nsIRDFResource* aResource,
 397                                              nsIRDFResource* aProperty,
 398                                              nsIRDFLiteral* aValue)
 399 {
 400     nsresult rv;
 401     nsCString qname;
 402     rv = GetQName(aProperty, qname);
 403     NS_ENSURE_SUCCESS(rv, rv);
 404
 405     rv = rdf_BlockingWrite(aStream,
 406                            NS_LITERAL_CSTRING("\n                   "));
 407     if (NS_FAILED(rv)) return rv;
 408
 409     const PRUnichar* value;
 410     aValue->GetValueConst(&value);
 411     NS_ConvertUTF16toUTF8 s(value);
 412
 413     rdf_EscapeAttributeValue(s);
 414
 415     rv = rdf_BlockingWrite(aStream, qname);
 416     if (NS_FAILED(rv)) return rv;
 417     rv = rdf_BlockingWrite(aStream, "=\"", 2);
 418     if (NS_FAILED(rv)) return rv;
 419     s.Append('"');
 420     return rdf_BlockingWrite(aStream, s);
 421 }
 422
 423 nsresult
 424 nsRDFXMLSerializer::SerializeChildAssertion(nsIOutputStream* aStream,
 425                                             nsIRDFResource* aResource,
 426                                             nsIRDFResource* aProperty,
 427                                             nsIRDFNode* aValue)
 428 {
 429     nsCString qname;
 430     nsresult rv = GetQName(aProperty, qname);
 431     NS_ENSURE_SUCCESS(rv, rv);
 432
 433     rv = rdf_BlockingWrite(aStream, "    <", 5);
 434     if (NS_FAILED(rv)) return rv;
 435     rv = rdf_BlockingWrite(aStream, qname);
 436     if (NS_FAILED(rv)) return rv;
 437
 438     nsCOMPtr<nsIRDFResource> resource;
 439     nsCOMPtr<nsIRDFLiteral> literal;
 440     nsCOMPtr<nsIRDFInt> number;
 441     nsCOMPtr<nsIRDFDate> date;
 442
 443     if ((resource = do_QueryInterface(aValue)) != nsnull) {
 444         nsCAutoString uri;
 445         resource->GetValueUTF8(uri);
 446
 447         rdf_MakeRelativeRef(mBaseURLSpec, uri);
 448         rdf_EscapeAttributeValue(uri);
 449
 450         rv = rdf_BlockingWrite(aStream, kRDFResource1,
 451                                sizeof(kRDFResource1) - 1);
 452         if (NS_FAILED(rv)) return rv;
 453         rv = rdf_BlockingWrite(aStream, uri);
 454         if (NS_FAILED(rv)) return rv;
 455         rv = rdf_BlockingWrite(aStream, kRDFResource2,
 456                                sizeof(kRDFResource2) - 1);
 457         if (NS_FAILED(rv)) return rv;
 458
 459         goto no_close_tag;
 460     }
 461     else if ((literal = do_QueryInterface(aValue)) != nsnull) {
 462         const PRUnichar *value;
 463         literal->GetValueConst(&value);
 464         NS_ConvertUTF16toUTF8 s(value);
 465
 466         rdf_EscapeAmpersandsAndAngleBrackets(s);
 467
 468         rv = rdf_BlockingWrite(aStream, ">", 1);
 469         if (NS_FAILED(rv)) return rv;
 470         rv = rdf_BlockingWrite(aStream, s);
 471         if (NS_FAILED(rv)) return rv;
 472     }
 473     else if ((number = do_QueryInterface(aValue)) != nsnull) {
 474         PRInt32 value;
 475         number->GetValue(&value);
 476
 477         nsCAutoString n;
 478         n.AppendInt(value);
 479
 480         rv = rdf_BlockingWrite(aStream, kRDFParseTypeInteger,
 481                                sizeof(kRDFParseTypeInteger) - 1);
 482         if (NS_FAILED(rv)) return rv;
 483         rv = rdf_BlockingWrite(aStream, n);
 484         if (NS_FAILED(rv)) return rv;
 485     }
 486     else if ((date = do_QueryInterface(aValue)) != nsnull) {
 487         PRTime value;
 488         date->GetValue(&value);
 489
 490         nsCAutoString s;
 491         rdf_FormatDate(value, s);
 492
 493         rv = rdf_BlockingWrite(aStream, kRDFParseTypeDate,
 494                                sizeof(kRDFParseTypeDate) - 1);
 495         if (NS_FAILED(rv)) return rv;
 496         rv = rdf_BlockingWrite(aStream, s);
 497         if (NS_FAILED(rv)) return rv;
 498     }
 499     else {
 500         // XXX it doesn't support nsIRDFResource _or_ nsIRDFLiteral???
 501         // We should serialize nsIRDFInt, nsIRDFDate, etc...
 502         NS_WARNING("unknown RDF node type");
 503
 504         rv = rdf_BlockingWrite(aStream, kRDFUnknown, sizeof(kRDFUnknown) - 1);
 505         if (NS_FAILED(rv)) return rv;
 506     }
 507
 508     rv = rdf_BlockingWrite(aStream, "</", 2);
 509     if (NS_FAILED(rv)) return rv;
 510     rv = rdf_BlockingWrite(aStream, qname);
 511     if (NS_FAILED(rv)) return rv;
 512     return rdf_BlockingWrite(aStream, ">\n", 2);
 513
 514  no_close_tag:
 515     return NS_OK;
 516 }
 517
 518 nsresult
 519 nsRDFXMLSerializer::SerializeProperty(nsIOutputStream* aStream,
 520                                       nsIRDFResource* aResource,
 521                                       nsIRDFResource* aProperty,
 522                                       PRBool aInline,
 523                                       PRInt32* aSkipped)
 524 {
 525     nsresult rv = NS_OK;
 526
 527     PRInt32 skipped = 0;
 528
 529     nsCOMPtr<nsISimpleEnumerator> assertions;
 530     mDataSource->GetTargets(aResource, aProperty, PR_TRUE, getter_AddRefs(assertions));
 531     if (! assertions)
 532         return NS_ERROR_FAILURE;
 533
 534     // Serializing the assertion inline is ok as long as the property has
 535     // only one target value, and it is a literal that doesn't include line
 536     // breaks.
 537     PRBool needsChild = PR_FALSE;
 538
 539     while (1) {
 540         PRBool hasMore = PR_FALSE;
 541         assertions->HasMoreElements(&hasMore);
 542         if (! hasMore)
 543             break;
 544
 545         nsCOMPtr<nsISupports> isupports;
 546         assertions->GetNext(getter_AddRefs(isupports));
 547         nsCOMPtr<nsIRDFLiteral> literal = do_QueryInterface(isupports);
 548         needsChild |= (!literal);
 549
 550         if (!needsChild) {
 551             assertions->HasMoreElements(&needsChild);
 552             if (!needsChild) {
 553                 const PRUnichar* literalVal = nsnull;
 554                 literal->GetValueConst(&literalVal);
 555                 if (literalVal) {
 556                     for (; *literalVal; literalVal++) {
 557                         if (*literalVal == PRUnichar('\n') ||
 558                             *literalVal == PRUnichar('\r')) {
 559                             needsChild = PR_TRUE;
 560                             break;
 561                         }
 562                     }
 563                 }
 564             }
 565         }
 566
 567         if (aInline && !needsChild) {
 568             rv = SerializeInlineAssertion(aStream, aResource, aProperty, literal);
 569         }
 570         else if (!aInline && needsChild) {
 571             nsCOMPtr<nsIRDFNode> value = do_QueryInterface(isupports);
 572             rv = SerializeChildAssertion(aStream, aResource, aProperty, value);
 573         }
 574         else {
 575             ++skipped;
 576             rv = NS_OK;
 577         }
 578
 579         if (NS_FAILED(rv))
 580             break;
 581     }
 582
 583     *aSkipped += skipped;
 584     return rv;
 585 }
 586
 587
 588 nsresult
 589 nsRDFXMLSerializer::SerializeDescription(nsIOutputStream* aStream,
 590                                          nsIRDFResource* aResource)
 591 {
 592     nsresult rv;
 593
 594     PRBool isTypedNode = PR_FALSE;
 595     nsCString typeQName;
 596
 597     nsCOMPtr<nsIRDFNode> typeNode;
 598     mDataSource->GetTarget(aResource, kRDF_type, PR_TRUE, getter_AddRefs(typeNode));
 599     if (typeNode) {
 600         nsCOMPtr<nsIRDFResource> type = do_QueryInterface(typeNode, &rv);
 601         if (type) {
 602             // Try to get a namespace prefix.  If none is available,
 603             // just treat the description as if it weren't a typed node
 604             // after all and emit rdf:type as a normal property.  This
 605             // seems preferable to using a bogus (invented) prefix.
 606             isTypedNode = NS_SUCCEEDED(GetQName(type, typeQName));
 607         }
 608     }
 609
 610     nsCAutoString uri;
 611     rv = aResource->GetValueUTF8(uri);
 612     if (NS_FAILED(rv)) return rv;
 613
 614     rdf_MakeRelativeRef(mBaseURLSpec, uri);
 615     rdf_EscapeAttributeValue(uri);
 616
 617     // Emit an open tag and the subject
 618     if (isTypedNode) {
 619         rv = rdf_BlockingWrite(aStream, NS_LITERAL_STRING("  <"));
 620         if (NS_FAILED(rv)) return rv;
 621         // Watch out for the default namespace!
 622         rv = rdf_BlockingWrite(aStream, typeQName);
 623         if (NS_FAILED(rv)) return rv;
 624     }
 625     else {
 626         rv = rdf_BlockingWrite(aStream, kRDFDescriptionOpen,
 627                                sizeof(kRDFDescriptionOpen) - 1);
 628         if (NS_FAILED(rv)) return rv;
 629     }
 630     if (uri[0] == PRUnichar('#')) {
 631         uri.Cut(0, 1);
 632         rv = rdf_BlockingWrite(aStream, kIDAttr, sizeof(kIDAttr) - 1);
 633     }
 634     else {
 635         rv = rdf_BlockingWrite(aStream, kAboutAttr, sizeof(kAboutAttr) - 1);
 636     }
 637     if (NS_FAILED(rv)) return rv;
 638
 639     uri.Append('"');
 640     rv = rdf_BlockingWrite(aStream, uri);
 641     if (NS_FAILED(rv)) return rv;
 642
 643     // Any value that's a literal we can write out as an inline
 644     // attribute on the RDF:Description
 645     nsAutoVoidArray visited;
 646     PRInt32 skipped = 0;
 647
 648     nsCOMPtr<nsISimpleEnumerator> arcs;
 649     mDataSource->ArcLabelsOut(aResource, getter_AddRefs(arcs));
 650
 651     if (arcs) {
 652         // Don't re-serialize rdf:type later on
 653         if (isTypedNode)
 654             visited.AppendElement(kRDF_type);
 655
 656         while (1) {
 657             PRBool hasMore = PR_FALSE;
 658             arcs->HasMoreElements(&hasMore);
 659             if (! hasMore)
 660                 break;
 661
 662             nsCOMPtr<nsISupports> isupports;
 663             arcs->GetNext(getter_AddRefs(isupports));
 664
 665             nsCOMPtr<nsIRDFResource> property = do_QueryInterface(isupports);
 666             if (! property)
 667                 continue;
 668
 669             // Ignore properties that pertain to containers; we may be
 670             // called from SerializeContainer() if the container resource
 671             // has been assigned non-container properties.
 672             if (IsContainerProperty(property))
 673                 continue;
 674
 675             // Only serialize values for the property once.
 676             if (visited.IndexOf(property.get()) >= 0)
 677                 continue;
 678
 679             visited.AppendElement(property.get());
 680
 681             SerializeProperty(aStream, aResource, property, PR_TRUE, &skipped);
 682         }
 683     }
 684
 685     if (skipped) {
 686         // Close the RDF:Description tag.
 687         rv = rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING(">\n"));
 688         if (NS_FAILED(rv)) return rv;
 689
 690         // Now write out resources (which might have their own
 691         // substructure) as children.
 692         mDataSource->ArcLabelsOut(aResource, getter_AddRefs(arcs));
 693
 694         if (arcs) {
 695             // Forget that we've visited anything
 696             visited.Clear();
 697             // ... except for rdf:type
 698             if (isTypedNode)
 699                 visited.AppendElement(kRDF_type);
 700
 701             while (1) {
 702                 PRBool hasMore = PR_FALSE;
 703                 arcs->HasMoreElements(&hasMore);
 704                 if (! hasMore)
 705                     break;
 706
 707                 nsCOMPtr<nsISupports> isupports;
 708                 arcs->GetNext(getter_AddRefs(isupports));
 709
 710                 nsCOMPtr<nsIRDFResource> property = do_QueryInterface(isupports);
 711                 if (! property)
 712                     continue;
 713
 714                 // Ignore properties that pertain to containers; we may be
 715                 // called from SerializeContainer() if the container
 716                 // resource has been assigned non-container properties.
 717                 if (IsContainerProperty(property))
 718                     continue;
 719
 720                 // have we already seen this property?  If so, don't write it
 721                 // out again; serialize property will write each instance.
 722                 if (visited.IndexOf(property.get()) >= 0)
 723                     continue;
 724
 725                 visited.AppendElement(property.get());
 726
 727                 SerializeProperty(aStream, aResource, property, PR_FALSE, &skipped);
 728             }
 729         }
 730
 731         // Emit a proper close-tag.
 732         if (isTypedNode) {
 733             rv = rdf_BlockingWrite(aStream,  NS_LITERAL_CSTRING("  </"));
 734             if (NS_FAILED(rv)) return rv;
 735             // Watch out for the default namespace!
 736             rdf_BlockingWrite(aStream, typeQName);
 737             if (NS_FAILED(rv)) return rv;
 738             rdf_BlockingWrite(aStream, ">\n", 2);
 739             if (NS_FAILED(rv)) return rv;
 740         }
 741         else {
 742             rv = rdf_BlockingWrite(aStream, kRDFDescriptionClose,
 743                                    sizeof(kRDFDescriptionClose) - 1);
 744             if (NS_FAILED(rv)) return rv;
 745         }
 746     }
 747     else {
 748         // If we saw _no_ child properties, then we can don't need a
 749         // close-tag.
 750         rv = rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING(" />\n"));
 751         if (NS_FAILED(rv)) return rv;
 752     }
 753
 754     return NS_OK;
 755 }
 756
 757 nsresult
 758 nsRDFXMLSerializer::SerializeMember(nsIOutputStream* aStream,
 759                                       nsIRDFResource* aContainer,
 760                                       nsIRDFNode* aMember)
 761 {
 762     // If it's a resource, then output a "<RDF:li RDF:resource=... />"
 763     // tag, because we'll be dumping the resource separately. (We
 764     // iterate thru all the resources in the datasource,
 765     // remember?) Otherwise, output the literal value.
 766
 767     nsCOMPtr<nsIRDFResource> resource;
 768     nsCOMPtr<nsIRDFLiteral> literal;
 769     nsCOMPtr<nsIRDFInt> number;
 770     nsCOMPtr<nsIRDFDate> date;
 771
 772 static const char kRDFLIOpen[] = "    <RDF:li";
 773     nsresult rv = rdf_BlockingWrite(aStream, kRDFLIOpen,
 774                                     sizeof(kRDFLIOpen) - 1);
 775     if (NS_FAILED(rv)) return rv;
 776
 777     if ((resource = do_QueryInterface(aMember)) != nsnull) {
 778         nsCAutoString uri;
 779         resource->GetValueUTF8(uri);
 780
 781         rdf_MakeRelativeRef(mBaseURLSpec, uri);
 782         rdf_EscapeAttributeValue(uri);
 783
 784         rv = rdf_BlockingWrite(aStream, kRDFResource1,
 785                                sizeof(kRDFResource1) - 1);
 786         if (NS_FAILED(rv)) return rv;
 787         rv = rdf_BlockingWrite(aStream, uri);
 788         if (NS_FAILED(rv)) return rv;
 789         rv = rdf_BlockingWrite(aStream, kRDFResource2,
 790                                sizeof(kRDFResource2) - 1);
 791         if (NS_FAILED(rv)) return rv;
 792
 793         goto no_close_tag;
 794     }
 795     else if ((literal = do_QueryInterface(aMember)) != nsnull) {
 796         const PRUnichar *value;
 797         literal->GetValueConst(&value);
 798 static const char kRDFLIOpenGT[] = ">";
 799         // close the '<RDF:LI' before adding the literal
 800         rv = rdf_BlockingWrite(aStream, kRDFLIOpenGT,
 801                                sizeof(kRDFLIOpenGT) - 1);
 802         if (NS_FAILED(rv)) return rv;
 803
 804         NS_ConvertUTF16toUTF8 s(value);
 805         rdf_EscapeAmpersandsAndAngleBrackets(s);
 806
 807         rv = rdf_BlockingWrite(aStream, s);
 808         if (NS_FAILED(rv)) return rv;
 809     }
 810     else if ((number = do_QueryInterface(aMember)) != nsnull) {
 811         PRInt32 value;
 812         number->GetValue(&value);
 813
 814         nsCAutoString n;
 815         n.AppendInt(value);
 816
 817         rv = rdf_BlockingWrite(aStream, kRDFParseTypeInteger,
 818                                sizeof(kRDFParseTypeInteger) - 1);
 819         if (NS_FAILED(rv)) return rv;
 820         rv = rdf_BlockingWrite(aStream, n);
 821         if (NS_FAILED(rv)) return rv;
 822     }
 823     else if ((date = do_QueryInterface(aMember)) != nsnull) {
 824         PRTime value;
 825         date->GetValue(&value);
 826
 827         nsCAutoString s;
 828         rdf_FormatDate(value, s);
 829
 830         rv = rdf_BlockingWrite(aStream, kRDFParseTypeDate,
 831                                sizeof(kRDFParseTypeDate) - 1);
 832         if (NS_FAILED(rv)) return rv;
 833         rv = rdf_BlockingWrite(aStream, s);
 834         if (NS_FAILED(rv)) return rv;
 835     }
 836     else {
 837         // XXX it doesn't support nsIRDFResource _or_ nsIRDFLiteral???
 838         // We should serialize nsIRDFInt, nsIRDFDate, etc...
 839         NS_WARNING("unknown RDF node type");
 840
 841         rv = rdf_BlockingWrite(aStream, kRDFUnknown, sizeof(kRDFUnknown) - 1);
 842         if (NS_FAILED(rv)) return rv;
 843     }
 844
 845     {
 846 static const char kRDFLIClose[] = "</RDF:li>\n";
 847         rv = rdf_BlockingWrite(aStream, kRDFLIClose, sizeof(kRDFLIClose) - 1);
 848         if (NS_FAILED(rv)) return rv;
 849     }
 850
 851  no_close_tag:
 852     return NS_OK;
 853 }
 854
 855
 856 nsresult
 857 nsRDFXMLSerializer::SerializeContainer(nsIOutputStream* aStream,
 858                                          nsIRDFResource* aContainer)
 859 {
 860     nsresult rv;
 861     nsCAutoString tag;
 862
 863     // Decide if it's a sequence, bag, or alternation, and print the
 864     // appropriate tag-open sequence
 865
 866     if (IsA(mDataSource, aContainer, kRDF_Bag)) {
 867         tag.AssignLiteral("RDF:Bag");
 868     }
 869     else if (IsA(mDataSource, aContainer, kRDF_Seq)) {
 870         tag.AssignLiteral("RDF:Seq");
 871     }
 872     else if (IsA(mDataSource, aContainer, kRDF_Alt)) {
 873         tag.AssignLiteral("RDF:Alt");
 874     }
 875     else {
 876         NS_ASSERTION(PR_FALSE, "huh? this is _not_ a container.");
 877         return NS_ERROR_UNEXPECTED;
 878     }
 879
 880     rv = rdf_BlockingWrite(aStream, "  <", 3);
 881     if (NS_FAILED(rv)) return rv;
 882     rv = rdf_BlockingWrite(aStream, tag);
 883     if (NS_FAILED(rv)) return rv;
 884
 885
 886     // Unfortunately, we always need to print out the identity of the
 887     // resource, even if was constructed "anonymously". We need to do
 888     // this because we never really know who else might be referring
 889     // to it...
 890
 891     nsCAutoString uri;
 892     if (NS_SUCCEEDED(aContainer->GetValueUTF8(uri))) {
 893         rdf_MakeRelativeRef(mBaseURLSpec, uri);
 894
 895         rdf_EscapeAttributeValue(uri);
 896
 897         if (uri.First() == '#') {
 898             // Okay, it's actually identified as an element in the
 899             // current document, not trying to decorate some absolute
 900             // URI. We can use the 'ID=' attribute...
 901
 902             uri.Cut(0, 1); // chop the '#'
 903             rv = rdf_BlockingWrite(aStream, kIDAttr, sizeof(kIDAttr) - 1);
 904             if (NS_FAILED(rv)) return rv;
 905         }
 906         else {
 907             // We need to cheat and spit out an illegal 'about=' on
 908             // the sequence.
 909             rv = rdf_BlockingWrite(aStream, kAboutAttr,
 910                                    sizeof(kAboutAttr) - 1);
 911             if (NS_FAILED(rv)) return rv;
 912         }
 913
 914         rv = rdf_BlockingWrite(aStream, uri);
 915         if (NS_FAILED(rv)) return rv;
 916         rv = rdf_BlockingWrite(aStream, "\"", 1);
 917         if (NS_FAILED(rv)) return rv;
 918     }
 919
 920     rv = rdf_BlockingWrite(aStream, ">\n", 2);
 921     if (NS_FAILED(rv)) return rv;
 922
 923     // First iterate through each of the ordinal elements (the RDF/XML
 924     // syntax doesn't allow us to place properties on RDF container
 925     // elements).
 926     nsCOMPtr<nsISimpleEnumerator> elements;
 927     rv = NS_NewContainerEnumerator(mDataSource, aContainer, getter_AddRefs(elements));
 928
 929     if (NS_SUCCEEDED(rv)) {
 930         while (1) {
 931             PRBool hasMore;
 932             rv = elements->HasMoreElements(&hasMore);
 933             if (NS_FAILED(rv)) break;
 934
 935             if (! hasMore)
 936                 break;
 937
 938             nsCOMPtr<nsISupports> isupports;
 939             elements->GetNext(getter_AddRefs(isupports));
 940
 941             nsCOMPtr<nsIRDFNode> element = do_QueryInterface(isupports);
 942             NS_ASSERTION(element != nsnull, "not an nsIRDFNode");
 943             if (! element)
 944                 continue;
 945
 946             SerializeMember(aStream, aContainer, element);
 947         }
 948     }
 949
 950     // close the container tag
 951     rv = rdf_BlockingWrite(aStream, "  </", 4);
 952     if (NS_FAILED(rv)) return rv;
 953     tag.Append(">\n", 2);
 954     rv = rdf_BlockingWrite(aStream, tag);
 955     if (NS_FAILED(rv)) return rv;
 956
 957     // Now, we iterate through _all_ of the arcs, in case someone has
 958     // applied properties to the bag itself. These'll be placed in a
 959     // separate RDF:Description element.
 960     nsCOMPtr<nsISimpleEnumerator> arcs;
 961     mDataSource->ArcLabelsOut(aContainer, getter_AddRefs(arcs));
 962
 963     PRBool wroteDescription = PR_FALSE;
 964     while (! wroteDescription) {
 965         PRBool hasMore = PR_FALSE;
 966         rv = arcs->HasMoreElements(&hasMore);
 967         if (NS_FAILED(rv)) break;
 968
 969         if (! hasMore)
 970             break;
 971
 972         nsIRDFResource* property;
 973         rv = arcs->GetNext((nsISupports**) &property);
 974         if (NS_FAILED(rv)) break;
 975
 976         // If it's a membership property, then output a "LI"
 977         // tag. Otherwise, output a property.
 978         if (! IsContainerProperty(property)) {
 979             rv = SerializeDescription(aStream, aContainer);
 980             wroteDescription = PR_TRUE;
 981         }
 982
 983         NS_RELEASE(property);
 984         if (NS_FAILED(rv))
 985             break;
 986     }
 987
 988     return NS_OK;
 989 }
 990
 991
 992 nsresult
 993 nsRDFXMLSerializer::SerializePrologue(nsIOutputStream* aStream)
 994 {
 995 static const char kXMLVersion[] = "<?xml version=\"1.0\"?>\n";
 996
 997     nsresult rv;
 998     rv = rdf_BlockingWrite(aStream, kXMLVersion, sizeof(kXMLVersion) - 1);
 999     if (NS_FAILED(rv)) return rv;
1000
1001     // global name space declarations
1002     rv = rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING("<RDF:RDF "));
1003     if (NS_FAILED(rv)) return rv;
1004
1005     nsNameSpaceMap::const_iterator first = mNameSpaces.first();
1006     nsNameSpaceMap::const_iterator last = mNameSpaces.last();
1007     for (nsNameSpaceMap::const_iterator entry = first; entry != last; ++entry) {
1008         if (entry != first) {
1009             rv = rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING("\n         "));
1010             if (NS_FAILED(rv)) return rv;
1011         }
1012         rv = rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING("xmlns"));
1013         if (NS_FAILED(rv)) return rv;
1014
1015         if (entry->mPrefix) {
1016             rv = rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING(":"));
1017             if (NS_FAILED(rv)) return rv;
1018             nsCAutoString prefix;
1019             entry->mPrefix->ToUTF8String(prefix);
1020             rv = rdf_BlockingWrite(aStream, prefix);
1021             if (NS_FAILED(rv)) return rv;
1022         }
1023
1024         rv = rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING("=\""));
1025         if (NS_FAILED(rv)) return rv;
1026         nsCAutoString uri(entry->mURI);
1027         rdf_EscapeAttributeValue(uri);
1028         rv = rdf_BlockingWrite(aStream, uri);
1029         if (NS_FAILED(rv)) return rv;
1030         rv = rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING("\""));
1031         if (NS_FAILED(rv)) return rv;
1032     }
1033
1034     return rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING(">\n"));
1035 }
1036
1037
1038 nsresult
1039 nsRDFXMLSerializer::SerializeEpilogue(nsIOutputStream* aStream)
1040 {
1041     return rdf_BlockingWrite(aStream, NS_LITERAL_CSTRING("</RDF:RDF>\n"));
1042 }
1043
1044 class QNameCollector : public rdfITripleVisitor {
1045 public:
1046     NS_DECL_ISUPPORTS
1047     NS_DECL_RDFITRIPLEVISITOR
1048     QNameCollector(nsRDFXMLSerializer* aParent)
1049         : mParent(aParent){}
1050 private:
1051     nsRDFXMLSerializer* mParent;
1052 };
1053
1054 NS_IMPL_ISUPPORTS1(QNameCollector, rdfITripleVisitor)
1055 nsresult
1056 QNameCollector::Visit(nsIRDFNode* aSubject, nsIRDFResource* aPredicate,
1057                       nsIRDFNode* aObject, PRBool aTruthValue)
1058 {
1059     if (aPredicate == mParent->kRDF_type) {
1060         // try to get a type QName for aObject, should be a resource
1061         nsCOMPtr<nsIRDFResource> resType = do_QueryInterface(aObject);
1062         if (!resType) {
1063             // ignore error
1064             return NS_OK;
1065         }
1066         if (mParent->mQNames.Get(resType, nsnull)) {
1067             return NS_OK;
1068         }
1069         mParent->RegisterQName(resType);
1070         return NS_OK;
1071     }
1072
1073     if (mParent->mQNames.Get(aPredicate, nsnull)) {
1074         return NS_OK;
1075     }
1076     if (aPredicate == mParent->kRDF_instanceOf ||
1077         aPredicate == mParent->kRDF_nextVal)
1078         return NS_OK;
1079     PRBool isOrdinal = PR_FALSE;
1080     mParent->gRDFC->IsOrdinalProperty(aPredicate, &isOrdinal);
1081     if (isOrdinal)
1082         return NS_OK;
1083
1084     mParent->RegisterQName(aPredicate);
1085
1086     return NS_OK;
1087 }
1088
1089 nsresult
1090 nsRDFXMLSerializer::CollectNamespaces()
1091 {
1092     // Iterate over all Triples to get namespaces for subject resource types
1093     // and Predicates and cache all the QNames we want to use.
1094     nsCOMPtr<rdfITripleVisitor> collector =
1095         new QNameCollector(this);
1096     nsCOMPtr<rdfIDataSource> ds = do_QueryInterface(mDataSource); // XXX API
1097     NS_ENSURE_TRUE(collector && ds, NS_ERROR_FAILURE);
1098     return ds->VisitAllTriples(collector);
1099 }
1100
1101 //----------------------------------------------------------------------
1102
1103 NS_IMETHODIMP
1104 nsRDFXMLSerializer::Serialize(nsIOutputStream* aStream)
1105 {
1106     nsresult rv;
1107     NS_TIMELINE_START_TIMER("rdf/xml-ser");
1108
1109     rv = CollectNamespaces();
1110     if (NS_FAILED(rv)) return rv;
1111
1112     nsCOMPtr<nsISimpleEnumerator> resources;
1113     rv = mDataSource->GetAllResources(getter_AddRefs(resources));
1114     if (NS_FAILED(rv)) return rv;
1115
1116     rv = SerializePrologue(aStream);
1117     if (NS_FAILED(rv))
1118         return rv;
1119
1120     while (1) {
1121         PRBool hasMore = PR_FALSE;
1122         resources->HasMoreElements(&hasMore);
1123         if (! hasMore)
1124             break;
1125
1126         nsCOMPtr<nsISupports> isupports;
1127         resources->GetNext(getter_AddRefs(isupports));
1128
1129         nsCOMPtr<nsIRDFResource> resource = do_QueryInterface(isupports);
1130         if (! resource)
1131             continue;
1132
1133         if (IsA(mDataSource, resource, kRDF_Bag) ||
1134             IsA(mDataSource, resource, kRDF_Seq) ||
1135             IsA(mDataSource, resource, kRDF_Alt)) {
1136             rv = SerializeContainer(aStream, resource);
1137         }
1138         else {
1139             rv = SerializeDescription(aStream, resource);
1140         }
1141
1142         if (NS_FAILED(rv))
1143             break;
1144     }
1145
1146     rv = SerializeEpilogue(aStream);
1147     NS_TIMELINE_STOP_TIMER("rdf/xml-ser");
1148     NS_TIMELINE_MARK("rdf/xml-ser");
1149
1150     return rv;
1151 }
1152
1153
1154 PRBool
1155 nsRDFXMLSerializer::IsA(nsIRDFDataSource* aDataSource, nsIRDFResource* aResource, nsIRDFResource* aType)
1156 {
1157     nsresult rv;
1158
1159     PRBool result;
1160     rv = aDataSource->HasAssertion(aResource, kRDF_instanceOf, aType, PR_TRUE, &result);
1161     if (NS_FAILED(rv)) return PR_FALSE;
1162
1163     return result;
1164 }