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      1 /*
      2  * Copyright (C) 2005 Frerich Raabe <raabe (at) kde.org>
      3  * Copyright (C) 2006, 2009 Apple Inc.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *
      9  * 1. Redistributions of source code must retain the above copyright
     10  *    notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  *    notice, this list of conditions and the following disclaimer in the
     13  *    documentation and/or other materials provided with the distribution.
     14  *
     15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     25  */
     26 
     27 #ifndef XPathStep_h
     28 #define XPathStep_h
     29 
     30 #if ENABLE(XPATH)
     31 
     32 #include "Node.h"
     33 #include "XPathExpressionNode.h"
     34 #include "XPathNodeSet.h"
     35 
     36 namespace WebCore {
     37 
     38     namespace XPath {
     39 
     40         class Predicate;
     41 
     42         class Step : public ParseNode {
     43             WTF_MAKE_NONCOPYABLE(Step); WTF_MAKE_FAST_ALLOCATED;
     44         public:
     45             enum Axis {
     46                 AncestorAxis, AncestorOrSelfAxis, AttributeAxis,
     47                 ChildAxis, DescendantAxis, DescendantOrSelfAxis,
     48                 FollowingAxis, FollowingSiblingAxis, NamespaceAxis,
     49                 ParentAxis, PrecedingAxis, PrecedingSiblingAxis,
     50                 SelfAxis
     51             };
     52 
     53             class NodeTest {
     54                 WTF_MAKE_FAST_ALLOCATED;
     55             public:
     56                 enum Kind {
     57                     TextNodeTest, CommentNodeTest, ProcessingInstructionNodeTest, AnyNodeTest, NameTest
     58                 };
     59 
     60                 NodeTest(Kind kind) : m_kind(kind) {}
     61                 NodeTest(Kind kind, const String& data) : m_kind(kind), m_data(data) {}
     62                 NodeTest(Kind kind, const String& data, const String& namespaceURI) : m_kind(kind), m_data(data), m_namespaceURI(namespaceURI) {}
     63 
     64                 Kind kind() const { return m_kind; }
     65                 const AtomicString& data() const { return m_data; }
     66                 const AtomicString& namespaceURI() const { return m_namespaceURI; }
     67                 Vector<Predicate*>& mergedPredicates() { return m_mergedPredicates; }
     68                 const Vector<Predicate*>& mergedPredicates() const { return m_mergedPredicates; }
     69 
     70             private:
     71                 Kind m_kind;
     72                 AtomicString m_data;
     73                 AtomicString m_namespaceURI;
     74 
     75                 // When possible, we merge some or all predicates with node test for better performance.
     76                 Vector<Predicate*> m_mergedPredicates;
     77             };
     78 
     79             Step(Axis, const NodeTest& nodeTest, const Vector<Predicate*>& predicates = Vector<Predicate*>());
     80             ~Step();
     81 
     82             void optimize();
     83 
     84             void evaluate(Node* context, NodeSet&) const;
     85 
     86             Axis axis() const { return m_axis; }
     87             const NodeTest& nodeTest() const { return m_nodeTest; }
     88 
     89         private:
     90             friend void optimizeStepPair(Step*, Step*, bool&);
     91             bool predicatesAreContextListInsensitive() const;
     92 
     93             void parseNodeTest(const String&);
     94             void nodesInAxis(Node* context, NodeSet&) const;
     95             String namespaceFromNodetest(const String& nodeTest) const;
     96 
     97             Axis m_axis;
     98             NodeTest m_nodeTest;
     99             Vector<Predicate*> m_predicates;
    100         };
    101 
    102         void optimizeStepPair(Step*, Step*, bool& dropSecondStep);
    103     }
    104 
    105 }
    106 
    107 #endif // ENABLE(XPATH)
    108 
    109 #endif // XPathStep_h
    110