1 /* 2 * Copyright (C) 2005 Frerich Raabe <raabe (at) kde.org> 3 * Copyright (C) 2006, 2009 Apple Inc. All rights reserved. 4 * Copyright (C) 2007 Alexey Proskuryakov <ap (at) webkit.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "config.h" 29 #include "XPathStep.h" 30 31 #if ENABLE(XPATH) 32 33 #include "Attr.h" 34 #include "Document.h" 35 #include "Element.h" 36 #include "NamedNodeMap.h" 37 #include "XMLNSNames.h" 38 #include "XPathParser.h" 39 #include "XPathUtil.h" 40 41 namespace WebCore { 42 namespace XPath { 43 44 Step::Step(Axis axis, const NodeTest& nodeTest, const Vector<Predicate*>& predicates) 45 : m_axis(axis) 46 , m_nodeTest(nodeTest) 47 , m_predicates(predicates) 48 { 49 } 50 51 Step::~Step() 52 { 53 deleteAllValues(m_predicates); 54 deleteAllValues(m_nodeTest.mergedPredicates()); 55 } 56 57 void Step::optimize() 58 { 59 // Evaluate predicates as part of node test if possible to avoid building unnecessary NodeSets. 60 // E.g., there is no need to build a set of all "foo" nodes to evaluate "foo[@bar]", we can check the predicate while enumerating. 61 // This optimization can be applied to predicates that are not context node list sensitive, or to first predicate that is only context position sensitive, e.g. foo[position() mod 2 = 0]. 62 Vector<Predicate*> remainingPredicates; 63 for (size_t i = 0; i < m_predicates.size(); ++i) { 64 Predicate* predicate = m_predicates[i]; 65 if ((!predicate->isContextPositionSensitive() || m_nodeTest.mergedPredicates().isEmpty()) && !predicate->isContextSizeSensitive() && remainingPredicates.isEmpty()) { 66 m_nodeTest.mergedPredicates().append(predicate); 67 } else 68 remainingPredicates.append(predicate); 69 } 70 swap(remainingPredicates, m_predicates); 71 } 72 73 void optimizeStepPair(Step* first, Step* second, bool& dropSecondStep) 74 { 75 dropSecondStep = false; 76 77 if (first->m_axis == Step::DescendantOrSelfAxis 78 && first->m_nodeTest.kind() == Step::NodeTest::AnyNodeTest 79 && !first->m_predicates.size() 80 && !first->m_nodeTest.mergedPredicates().size()) { 81 82 ASSERT(first->m_nodeTest.data().isEmpty()); 83 ASSERT(first->m_nodeTest.namespaceURI().isEmpty()); 84 85 // Optimize the common case of "//" AKA /descendant-or-self::node()/child::NodeTest to /descendant::NodeTest. 86 if (second->m_axis == Step::ChildAxis && second->predicatesAreContextListInsensitive()) { 87 first->m_axis = Step::DescendantAxis; 88 first->m_nodeTest = Step::NodeTest(second->m_nodeTest.kind(), second->m_nodeTest.data(), second->m_nodeTest.namespaceURI()); 89 swap(second->m_nodeTest.mergedPredicates(), first->m_nodeTest.mergedPredicates()); 90 swap(second->m_predicates, first->m_predicates); 91 first->optimize(); 92 dropSecondStep = true; 93 } 94 } 95 } 96 97 bool Step::predicatesAreContextListInsensitive() const 98 { 99 for (size_t i = 0; i < m_predicates.size(); ++i) { 100 Predicate* predicate = m_predicates[i]; 101 if (predicate->isContextPositionSensitive() || predicate->isContextSizeSensitive()) 102 return false; 103 } 104 105 for (size_t i = 0; i < m_nodeTest.mergedPredicates().size(); ++i) { 106 Predicate* predicate = m_nodeTest.mergedPredicates()[i]; 107 if (predicate->isContextPositionSensitive() || predicate->isContextSizeSensitive()) 108 return false; 109 } 110 111 return true; 112 } 113 114 void Step::evaluate(Node* context, NodeSet& nodes) const 115 { 116 EvaluationContext& evaluationContext = Expression::evaluationContext(); 117 evaluationContext.position = 0; 118 119 nodesInAxis(context, nodes); 120 121 // Check predicates that couldn't be merged into node test. 122 for (unsigned i = 0; i < m_predicates.size(); i++) { 123 Predicate* predicate = m_predicates[i]; 124 125 NodeSet newNodes; 126 if (!nodes.isSorted()) 127 newNodes.markSorted(false); 128 129 for (unsigned j = 0; j < nodes.size(); j++) { 130 Node* node = nodes[j]; 131 132 evaluationContext.node = node; 133 evaluationContext.size = nodes.size(); 134 evaluationContext.position = j + 1; 135 if (predicate->evaluate()) 136 newNodes.append(node); 137 } 138 139 nodes.swap(newNodes); 140 } 141 } 142 143 static inline Node::NodeType primaryNodeType(Step::Axis axis) 144 { 145 switch (axis) { 146 case Step::AttributeAxis: 147 return Node::ATTRIBUTE_NODE; 148 case Step::NamespaceAxis: 149 return Node::XPATH_NAMESPACE_NODE; 150 default: 151 return Node::ELEMENT_NODE; 152 } 153 } 154 155 // Evaluate NodeTest without considering merged predicates. 156 static inline bool nodeMatchesBasicTest(Node* node, Step::Axis axis, const Step::NodeTest& nodeTest) 157 { 158 switch (nodeTest.kind()) { 159 case Step::NodeTest::TextNodeTest: 160 return node->nodeType() == Node::TEXT_NODE || node->nodeType() == Node::CDATA_SECTION_NODE; 161 case Step::NodeTest::CommentNodeTest: 162 return node->nodeType() == Node::COMMENT_NODE; 163 case Step::NodeTest::ProcessingInstructionNodeTest: { 164 const AtomicString& name = nodeTest.data(); 165 return node->nodeType() == Node::PROCESSING_INSTRUCTION_NODE && (name.isEmpty() || node->nodeName() == name); 166 } 167 case Step::NodeTest::AnyNodeTest: 168 return true; 169 case Step::NodeTest::NameTest: { 170 const AtomicString& name = nodeTest.data(); 171 const AtomicString& namespaceURI = nodeTest.namespaceURI(); 172 173 if (axis == Step::AttributeAxis) { 174 ASSERT(node->isAttributeNode()); 175 176 // In XPath land, namespace nodes are not accessible on the attribute axis. 177 if (node->namespaceURI() == XMLNSNames::xmlnsNamespaceURI) 178 return false; 179 180 if (name == starAtom) 181 return namespaceURI.isEmpty() || node->namespaceURI() == namespaceURI; 182 183 return node->localName() == name && node->namespaceURI() == namespaceURI; 184 } 185 186 // Node test on the namespace axis is not implemented yet, the caller has a check for it. 187 ASSERT(axis != Step::NamespaceAxis); 188 189 // For other axes, the principal node type is element. 190 ASSERT(primaryNodeType(axis) == Node::ELEMENT_NODE); 191 if (node->nodeType() != Node::ELEMENT_NODE) 192 return false; 193 194 if (name == starAtom) 195 return namespaceURI.isEmpty() || namespaceURI == node->namespaceURI(); 196 197 if (node->document()->isHTMLDocument()) { 198 if (node->isHTMLElement()) { 199 // Paths without namespaces should match HTML elements in HTML documents despite those having an XHTML namespace. Names are compared case-insensitively. 200 return equalIgnoringCase(static_cast<Element*>(node)->localName(), name) && (namespaceURI.isNull() || namespaceURI == node->namespaceURI()); 201 } 202 // An expression without any prefix shouldn't match no-namespace nodes (because HTML5 says so). 203 return static_cast<Element*>(node)->hasLocalName(name) && namespaceURI == node->namespaceURI() && !namespaceURI.isNull(); 204 } 205 return static_cast<Element*>(node)->hasLocalName(name) && namespaceURI == node->namespaceURI(); 206 } 207 } 208 ASSERT_NOT_REACHED(); 209 return false; 210 } 211 212 static inline bool nodeMatches(Node* node, Step::Axis axis, const Step::NodeTest& nodeTest) 213 { 214 if (!nodeMatchesBasicTest(node, axis, nodeTest)) 215 return false; 216 217 EvaluationContext& evaluationContext = Expression::evaluationContext(); 218 219 // Only the first merged predicate may depend on position. 220 ++evaluationContext.position; 221 222 const Vector<Predicate*>& mergedPredicates = nodeTest.mergedPredicates(); 223 for (unsigned i = 0; i < mergedPredicates.size(); i++) { 224 Predicate* predicate = mergedPredicates[i]; 225 226 evaluationContext.node = node; 227 // No need to set context size - we only get here when evaluating predicates that do not depend on it. 228 if (!predicate->evaluate()) 229 return false; 230 } 231 232 return true; 233 } 234 235 // Result nodes are ordered in axis order. Node test (including merged predicates) is applied. 236 void Step::nodesInAxis(Node* context, NodeSet& nodes) const 237 { 238 ASSERT(nodes.isEmpty()); 239 switch (m_axis) { 240 case ChildAxis: 241 if (context->isAttributeNode()) // In XPath model, attribute nodes do not have children. 242 return; 243 244 for (Node* n = context->firstChild(); n; n = n->nextSibling()) 245 if (nodeMatches(n, ChildAxis, m_nodeTest)) 246 nodes.append(n); 247 return; 248 case DescendantAxis: 249 if (context->isAttributeNode()) // In XPath model, attribute nodes do not have children. 250 return; 251 252 for (Node* n = context->firstChild(); n; n = n->traverseNextNode(context)) 253 if (nodeMatches(n, DescendantAxis, m_nodeTest)) 254 nodes.append(n); 255 return; 256 case ParentAxis: 257 if (context->isAttributeNode()) { 258 Element* n = static_cast<Attr*>(context)->ownerElement(); 259 if (nodeMatches(n, ParentAxis, m_nodeTest)) 260 nodes.append(n); 261 } else { 262 ContainerNode* n = context->parentNode(); 263 if (n && nodeMatches(n, ParentAxis, m_nodeTest)) 264 nodes.append(n); 265 } 266 return; 267 case AncestorAxis: { 268 Node* n = context; 269 if (context->isAttributeNode()) { 270 n = static_cast<Attr*>(context)->ownerElement(); 271 if (nodeMatches(n, AncestorAxis, m_nodeTest)) 272 nodes.append(n); 273 } 274 for (n = n->parentNode(); n; n = n->parentNode()) 275 if (nodeMatches(n, AncestorAxis, m_nodeTest)) 276 nodes.append(n); 277 nodes.markSorted(false); 278 return; 279 } 280 case FollowingSiblingAxis: 281 if (context->nodeType() == Node::ATTRIBUTE_NODE || 282 context->nodeType() == Node::XPATH_NAMESPACE_NODE) 283 return; 284 285 for (Node* n = context->nextSibling(); n; n = n->nextSibling()) 286 if (nodeMatches(n, FollowingSiblingAxis, m_nodeTest)) 287 nodes.append(n); 288 return; 289 case PrecedingSiblingAxis: 290 if (context->nodeType() == Node::ATTRIBUTE_NODE || 291 context->nodeType() == Node::XPATH_NAMESPACE_NODE) 292 return; 293 294 for (Node* n = context->previousSibling(); n; n = n->previousSibling()) 295 if (nodeMatches(n, PrecedingSiblingAxis, m_nodeTest)) 296 nodes.append(n); 297 298 nodes.markSorted(false); 299 return; 300 case FollowingAxis: 301 if (context->isAttributeNode()) { 302 Node* p = static_cast<Attr*>(context)->ownerElement(); 303 while ((p = p->traverseNextNode())) 304 if (nodeMatches(p, FollowingAxis, m_nodeTest)) 305 nodes.append(p); 306 } else { 307 for (Node* p = context; !isRootDomNode(p); p = p->parentNode()) { 308 for (Node* n = p->nextSibling(); n; n = n->nextSibling()) { 309 if (nodeMatches(n, FollowingAxis, m_nodeTest)) 310 nodes.append(n); 311 for (Node* c = n->firstChild(); c; c = c->traverseNextNode(n)) 312 if (nodeMatches(c, FollowingAxis, m_nodeTest)) 313 nodes.append(c); 314 } 315 } 316 } 317 return; 318 case PrecedingAxis: { 319 if (context->isAttributeNode()) 320 context = static_cast<Attr*>(context)->ownerElement(); 321 322 Node* n = context; 323 while (ContainerNode* parent = n->parentNode()) { 324 for (n = n->traversePreviousNode(); n != parent; n = n->traversePreviousNode()) 325 if (nodeMatches(n, PrecedingAxis, m_nodeTest)) 326 nodes.append(n); 327 n = parent; 328 } 329 nodes.markSorted(false); 330 return; 331 } 332 case AttributeAxis: { 333 if (context->nodeType() != Node::ELEMENT_NODE) 334 return; 335 336 // Avoid lazily creating attribute nodes for attributes that we do not need anyway. 337 if (m_nodeTest.kind() == NodeTest::NameTest && m_nodeTest.data() != starAtom) { 338 RefPtr<Node> n = static_cast<Element*>(context)->getAttributeNodeNS(m_nodeTest.namespaceURI(), m_nodeTest.data()); 339 if (n && n->namespaceURI() != XMLNSNames::xmlnsNamespaceURI) { // In XPath land, namespace nodes are not accessible on the attribute axis. 340 if (nodeMatches(n.get(), AttributeAxis, m_nodeTest)) // Still need to check merged predicates. 341 nodes.append(n.release()); 342 } 343 return; 344 } 345 346 NamedNodeMap* attrs = context->attributes(); 347 if (!attrs) 348 return; 349 350 for (unsigned i = 0; i < attrs->length(); ++i) { 351 RefPtr<Attr> attr = attrs->attributeItem(i)->createAttrIfNeeded(static_cast<Element*>(context)); 352 if (nodeMatches(attr.get(), AttributeAxis, m_nodeTest)) 353 nodes.append(attr.release()); 354 } 355 return; 356 } 357 case NamespaceAxis: 358 // XPath namespace nodes are not implemented yet. 359 return; 360 case SelfAxis: 361 if (nodeMatches(context, SelfAxis, m_nodeTest)) 362 nodes.append(context); 363 return; 364 case DescendantOrSelfAxis: 365 if (nodeMatches(context, DescendantOrSelfAxis, m_nodeTest)) 366 nodes.append(context); 367 if (context->isAttributeNode()) // In XPath model, attribute nodes do not have children. 368 return; 369 370 for (Node* n = context->firstChild(); n; n = n->traverseNextNode(context)) 371 if (nodeMatches(n, DescendantOrSelfAxis, m_nodeTest)) 372 nodes.append(n); 373 return; 374 case AncestorOrSelfAxis: { 375 if (nodeMatches(context, AncestorOrSelfAxis, m_nodeTest)) 376 nodes.append(context); 377 Node* n = context; 378 if (context->isAttributeNode()) { 379 n = static_cast<Attr*>(context)->ownerElement(); 380 if (nodeMatches(n, AncestorOrSelfAxis, m_nodeTest)) 381 nodes.append(n); 382 } 383 for (n = n->parentNode(); n; n = n->parentNode()) 384 if (nodeMatches(n, AncestorOrSelfAxis, m_nodeTest)) 385 nodes.append(n); 386 387 nodes.markSorted(false); 388 return; 389 } 390 } 391 ASSERT_NOT_REACHED(); 392 } 393 394 395 } 396 } 397 398 #endif // ENABLE(XPATH) 399
