src/xmlpatterns/expr/qexpressionfactory.cpp

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  41
  42 #include <QBuffer>
  43 #include <QByteArray>
  44
  45 #include "qcalltemplate_p.h"
  46 #include "qcommonsequencetypes_p.h"
  47 #include "qdebug_p.h"
  48 #include "qexpression_p.h"
  49 #include "qgenericstaticcontext_p.h"
  50 #include "qoperandsiterator_p.h"
  51 #include "qoptimizationpasses_p.h"
  52 #include "qparsercontext_p.h"
  53 #include "qpath_p.h"
  54 #include "qquerytransformparser_p.h"
  55 #include "qstaticfocuscontext_p.h"
  56 #include "qtokenrevealer_p.h"
  57 #include "qxquerytokenizer_p.h"
  58 #include "qxslttokenizer_p.h"
  59
  60 #include "qexpressionfactory_p.h"
  61
  62 QT_BEGIN_NAMESPACE
  63
  64 namespace QPatternist {
  65
  66 /**
  67  * @short The entry point to the parser.
  68  *
  69  * @param info supplies the information the parser & scanner
  70  * needs to create expressions. The created expression, if everything
  71  * succeeds, can be retrieved via the object @p info points to.
  72  * @returns non-negative if the parser fails.
  73  * @see ExpressionFactory::createExpression()
  74  */
  75 extern int XPathparse(QPatternist::ParserContext *const info);
  76
  77 Expression::Ptr ExpressionFactory::createExpression(const QString &expr,
  78                                                     const StaticContext::Ptr &context,
  79                                                     const QXmlQuery::QueryLanguage lang,
  80                                                     const SequenceType::Ptr &requiredType,
  81                                                     const QUrl &queryURI,
  82                                                     const QXmlName &initialTemplateName)
  83 {
  84     if(lang == QXmlQuery::XSLT20)
  85     {
  86         QByteArray query(expr.toUtf8());
  87         QBuffer buffer(&query);
  88         buffer.open(QIODevice::ReadOnly);
  89
  90         return createExpression(&buffer,
  91                                 context,
  92                                 lang,
  93                                 requiredType,
  94                                 queryURI,
  95                                 initialTemplateName);
  96     }
  97     else
  98     {
  99         return createExpression(Tokenizer::Ptr(new XQueryTokenizer(expr, queryURI)),
 100                                 context,
 101                                 lang,
 102                                 requiredType,
 103                                 queryURI,
 104                                 initialTemplateName);
 105     }
 106 }
 107
 108 Expression::Ptr ExpressionFactory::createExpression(QIODevice *const device,
 109                                                     const StaticContext::Ptr &context,
 110                                                     const QXmlQuery::QueryLanguage lang,
 111                                                     const SequenceType::Ptr &requiredType,
 112                                                     const QUrl &queryURI,
 113                                                     const QXmlName &initialTemplateName)
 114 {
 115     Q_ASSERT(device);
 116     Q_ASSERT(device->isReadable());
 117
 118     Tokenizer::Ptr tokenizer;
 119
 120     if(lang == QXmlQuery::XSLT20)
 121         tokenizer = Tokenizer::Ptr(new XSLTTokenizer(device, queryURI, context, context->namePool()));
 122     else
 123         tokenizer = Tokenizer::Ptr(new XQueryTokenizer(QString::fromUtf8(device->readAll()), queryURI));
 124
 125     return createExpression(tokenizer, context, lang, requiredType, queryURI, initialTemplateName);
 126 }
 127
 128 Expression::Ptr ExpressionFactory::createExpression(const Tokenizer::Ptr &tokenizer,
 129                                                     const StaticContext::Ptr &context,
 130                                                     const QXmlQuery::QueryLanguage lang,
 131                                                     const SequenceType::Ptr &requiredType,
 132                                                     const QUrl &queryURI,
 133                                                     const QXmlName &initialTemplateName)
 134 {
 135     Q_ASSERT(context);
 136     Q_ASSERT(requiredType);
 137     Q_ASSERT(queryURI.isValid());
 138
 139     Tokenizer::Ptr effectiveTokenizer(tokenizer);
 140 #ifdef Patternist_DEBUG
 141     effectiveTokenizer = Tokenizer::Ptr(new TokenRevealer(queryURI, tokenizer));
 142 #endif
 143
 144     OptimizationPasses::Coordinator::init();
 145
 146     const ParserContext::Ptr info(new ParserContext(context, lang, effectiveTokenizer.data()));
 147     info->initialTemplateName = initialTemplateName;
 148
 149     effectiveTokenizer->setParserContext(info);
 150
 151     const int bisonRetval = XPathparse(info.data());
 152
 153     Q_ASSERT_X(bisonRetval == 0, Q_FUNC_INFO,
 154                "We shouldn't be able to get an error, because we throw exceptions.");
 155     Q_UNUSED(bisonRetval); /* Needed when not compiled in debug mode, since bisonRetval won't
 156                             * be used in the Q_ASSERT_X above. */
 157
 158     Expression::Ptr result(info->queryBody);
 159
 160     if(!result)
 161     {
 162         context->error(QtXmlPatterns::tr("A library module cannot be evaluated "
 163                                          "directly. It must be imported from a "
 164                                          "main module."),
 165                        ReportContext::XPST0003,
 166                        QSourceLocation(queryURI, 1, 1));
 167     }
 168
 169     /* Optimization: I think many things are done in the wrong order below. We
 170      * probably want everything typechecked before compressing, since we can
 171      * have references all over the place(variable references, template
 172      * invocations, function callsites). This could even be a source to bugs.
 173      */
 174
 175     /* Here, we type check user declared functions and global variables. This
 176      * means that variables and functions that are not used are type
 177      * checked(which they otherwise wouldn't have been), and those which are
 178      * used, are type-checked twice, unfortunately. */
 179
 180     const bool hasExternalFocus = context->contextItemType();
 181
 182     if(lang == QXmlQuery::XSLT20)
 183     {
 184         /* Bind xsl:call-template instructions to their template bodies.
 185          *
 186          * We do this before type checking and compressing them, because a
 187          * CallTemplate obviously needs its template before being compressed.
 188          *
 189          * Also, we do this before type checking and compressing user
 190          * functions, since they can contain template call sites.
 191          */
 192         for(int i = 0; i < info->templateCalls.count(); ++i)
 193         {
 194             CallTemplate *const site = info->templateCalls.at(i)->as<CallTemplate>();
 195             const QXmlName targetName(site->name());
 196             const Template::Ptr t(info->namedTemplates.value(targetName));
 197
 198             if(t)
 199                 site->setTemplate(t);
 200             else
 201             {
 202                 context->error(QtXmlPatterns::tr("No template by name %1 exists.").arg(formatKeyword(context->namePool(), targetName)),
 203                                ReportContext::XTSE0650,
 204                                site);
 205             }
 206         }
 207     }
 208
 209     /* Type check and compress user functions. */
 210     {
 211         const UserFunction::List::const_iterator end(info->userFunctions.constEnd());
 212         UserFunction::List::const_iterator it(info->userFunctions.constBegin());
 213
 214         /* If the query has a focus(which is common, in the case of a
 215          * stylesheet), we must ensure that the focus isn't visible in the
 216          * function body. */
 217         StaticContext::Ptr effectiveContext;
 218
 219         if(hasExternalFocus)
 220         {
 221             effectiveContext = StaticContext::Ptr(new StaticFocusContext(ItemType::Ptr(),
 222                                                                          context));
 223         }
 224         else
 225             effectiveContext = context;
 226
 227         for(; it != end; ++it)
 228         {
 229             pDebug() << "-----      User Function Typecheck      -----";
 230             registerLastPath((*it)->body());
 231
 232             /* We will most likely call body()->typeCheck() again, once for
 233              * each callsite. That is, it will be called from
 234              * UserFunctionCallsite::typeCheck(), which will be called
 235              * indirectly when we check the query body. */
 236             const Expression::Ptr typeCheck((*it)->body()->typeCheck(effectiveContext,
 237                                                                      (*it)->signature()->returnType()));
 238             /* We don't have to call (*it)->setBody(typeCheck) here since it's
 239              * only used directly below. */
 240             processTreePass(typeCheck, UserFunctionTypeCheck);
 241             pDebug() << "------------------------------";
 242
 243             pDebug() << "-----      User Function Compress      -----";
 244             const Expression::Ptr comp(typeCheck->compress(effectiveContext));
 245             (*it)->setBody(comp);
 246             processTreePass(comp, UserFunctionCompression);
 247             pDebug() << "------------------------------";
 248         }
 249     }
 250
 251     /* Type check and compress global variables. */
 252     {
 253         const VariableDeclaration::Stack::const_iterator vend(info->variables.constEnd());
 254         VariableDeclaration::Stack::const_iterator vit(info->variables.constBegin());
 255         for(; vit != vend; ++vit)
 256         {
 257             Q_ASSERT(*vit);
 258             /* This is a bit murky, the global variable will have it
 259              * Expression::typeCheck() function called from all its references,
 260              * but we also want to check it here globally, so we do
 261              * typechecking using a proper focus. */
 262             if((*vit)->type == VariableDeclaration::ExternalVariable)
 263                 continue;
 264
 265             pDebug() << "-----      Global Variable Typecheck      -----";
 266             Q_ASSERT((*vit)->expression());
 267             /* We supply ZeroOrMoreItems, meaning the variable can evaluate to anything. */
 268             // FIXME which is a source to bugs
 269             // TODO What about compressing variables?
 270             const Expression::Ptr
 271             nev((*vit)->expression()->typeCheck(context, CommonSequenceTypes::ZeroOrMoreItems));
 272             processTreePass(nev, GlobalVariableTypeCheck);
 273             pDebug() << "------------------------------";
 274         }
 275     }
 276
 277     /* Do all tests specific to XSL-T. */
 278     if(lang == QXmlQuery::XSLT20)
 279     {
 280         /* Type check and compress named templates. */
 281         {
 282             pDebug() << "Have " << info->namedTemplates.count() << "named templates";
 283
 284             QMutableHashIterator<QXmlName, Template::Ptr> it(info->namedTemplates);
 285
 286             while(it.hasNext())
 287             {
 288                 it.next();
 289                 processNamedTemplate(it.key(), it.value()->body, TemplateInitial);
 290
 291                 it.value()->body = it.value()->body->typeCheck(context, CommonSequenceTypes::ZeroOrMoreItems);
 292                 processNamedTemplate(it.key(), it.value()->body, TemplateTypeCheck);
 293
 294                 it.value()->body = it.value()->body->compress(context);
 295                 processNamedTemplate(it.key(), it.value()->body, TemplateCompress);
 296
 297                 it.value()->compileParameters(context);
 298             }
 299         }
 300
 301         /* Type check and compress template rules. */
 302         {
 303             QHashIterator<QXmlName, TemplateMode::Ptr> it(info->templateRules);
 304
 305             /* Since a pattern can exist of AxisStep, its typeCheck() stage
 306              * requires a focus. In the case that we're invoked with a name but
 307              * no focus, this will yield a compile error, unless we declare a
 308              * focus manually. This only needs to be done for the pattern
 309              * expression, since the static type of the pattern is used as the
 310              * static type for the focus of the template body. */
 311             StaticContext::Ptr patternContext;
 312             if(hasExternalFocus)
 313                 patternContext = context;
 314             else
 315                 patternContext = StaticContext::Ptr(new StaticFocusContext(BuiltinTypes::node, context));
 316
 317             /* For each template pattern. */
 318             while(it.hasNext())
 319             {
 320                 it.next();
 321                 const TemplateMode::Ptr &mode = it.value();
 322                 const int len = mode->templatePatterns.count();
 323                 TemplatePattern::ID currentTemplateID = -1;
 324                 bool hasDoneItOnce = false;
 325
 326                 /* For each template pattern. */
 327                 for(int i = 0; i < len; ++i)
 328                 {
 329                     /* We can't use references for these two members, since we
 330                      * assign to them. */
 331                     const TemplatePattern::Ptr &pattern = mode->templatePatterns.at(i);
 332                     Expression::Ptr matchPattern(pattern->matchPattern());
 333
 334                     processTemplateRule(pattern->templateTarget()->body,
 335                                         pattern, mode->name(), TemplateInitial);
 336
 337                     matchPattern = matchPattern->typeCheck(patternContext, CommonSequenceTypes::ZeroOrMoreItems);
 338                     matchPattern = matchPattern->compress(patternContext);
 339                     pattern->setMatchPattern(matchPattern);
 340
 341                     if(currentTemplateID == -1 && hasDoneItOnce)
 342                     {
 343                         currentTemplateID = pattern->id();
 344                         continue;
 345                     }
 346                     else if(currentTemplateID == pattern->id() && hasDoneItOnce)
 347                     {
 348                         hasDoneItOnce = false;
 349                         continue;
 350                     }
 351
 352                     hasDoneItOnce = true;
 353                     currentTemplateID = pattern->id();
 354                     Expression::Ptr body(pattern->templateTarget()->body);
 355
 356                     /* Patterns for a new template has started, we must
 357                      * deal with the body & parameters. */
 358                     {
 359                         /* TODO type is wrong, it has to be the union of all
 360                          * patterns. */
 361                         const StaticContext::Ptr focusContext(new StaticFocusContext(matchPattern->staticType()->itemType(),
 362                                                                                      context));
 363                         body = body->typeCheck(focusContext, CommonSequenceTypes::ZeroOrMoreItems);
 364
 365                         pattern->templateTarget()->compileParameters(focusContext);
 366                     }
 367
 368                     processTemplateRule(body, pattern, mode->name(), TemplateTypeCheck);
 369
 370                     body = body->compress(context);
 371
 372                     pattern->templateTarget()->body = body;
 373                     processTemplateRule(body, pattern, mode->name(), TemplateCompress);
 374                 }
 375
 376                 mode->finalize();
 377             }
 378         }
 379
 380         /* Add templates in mode #all to all other modes.
 381          *
 382          * We do this after the templates has been typechecked and compressed,
 383          * since otherwise it will be done N times for the built-in templates,
 384          * where N is the count of different templates, instead of once. */
 385         {
 386             const QXmlName nameModeAll(QXmlName(StandardNamespaces::InternalXSLT,
 387                                                 StandardLocalNames::all));
 388             const TemplateMode::Ptr &modeAll = info->templateRules[nameModeAll];
 389
 390             Q_ASSERT_X(modeAll, Q_FUNC_INFO,
 391                        "We should at least have the builtin templates.");
 392             QHashIterator<QXmlName, TemplateMode::Ptr> it(info->templateRules);
 393
 394             while(it.hasNext())
 395             {
 396                 it.next();
 397
 398                 /* Don't add mode #all to mode #all. */
 399                 if(it.key()  == nameModeAll)
 400                     continue;
 401
 402                 it.value()->addMode(modeAll);
 403             }
 404         }
 405     }
 406
 407     /* Type check and compress the query body. */
 408     {
 409         pDebug() << "----- Initial AST build. -----";
 410         processTreePass(result, QueryBodyInitial);
 411         pDebug() << "------------------------------";
 412
 413         pDebug() << "-----     Type Check     -----";
 414         registerLastPath(result);
 415         result->rewrite(result, result->typeCheck(context, requiredType), context);
 416         processTreePass(result, QueryBodyTypeCheck);
 417         pDebug() << "------------------------------";
 418
 419         pDebug() << "-----      Compress      -----";
 420         result->rewrite(result, result->compress(context), context);
 421         processTreePass(result, QueryBodyCompression);
 422         pDebug() << "------------------------------";
 423     }
 424
 425     return result;
 426 }
 427
 428 void ExpressionFactory::registerLastPath(const Expression::Ptr &operand)
 429 {
 430     OperandsIterator it(operand, OperandsIterator::IncludeParent);
 431     Expression::Ptr next(it.next());
 432
 433     while(next)
 434     {
 435         if(next->is(Expression::IDPath))
 436         {
 437             next->as<Path>()->setLast();
 438             next = it.skipOperands();
 439         }
 440         else
 441             next = it.next();
 442     }
 443 }
 444
 445 void ExpressionFactory::processTreePass(const Expression::Ptr &,
 446                                         const CompilationStage)
 447 {
 448 }
 449
 450 void ExpressionFactory::processTemplateRule(const Expression::Ptr &body,
 451                                             const TemplatePattern::Ptr &pattern,
 452                                             const QXmlName &mode,
 453                                             const TemplateCompilationStage stage)
 454 {
 455     Q_UNUSED(body);
 456     Q_UNUSED(pattern);
 457     Q_UNUSED(mode);
 458     Q_UNUSED(stage);
 459 }
 460
 461 void ExpressionFactory::processNamedTemplate(const QXmlName &name,
 462                                              const Expression::Ptr &tree,
 463                                              const TemplateCompilationStage stage)
 464 {
 465     Q_UNUSED(name);
 466     Q_UNUSED(tree);
 467     Q_UNUSED(stage);
 468 }
 469
 470 } // namespace QPatternist
 471
 472 QT_END_NAMESPACE
 473