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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, public Noncopyable {
     43         public:
     44             enum Axis {
     45                 AncestorAxis, AncestorOrSelfAxis, AttributeAxis,
     46                 ChildAxis, DescendantAxis, DescendantOrSelfAxis,
     47                 FollowingAxis, FollowingSiblingAxis, NamespaceAxis,
     48                 ParentAxis, PrecedingAxis, PrecedingSiblingAxis,
     49                 SelfAxis
     50             };
     51 
     52             class NodeTest : public FastAllocBase {
     53             public:
     54                 enum Kind {
     55                     TextNodeTest, CommentNodeTest, ProcessingInstructionNodeTest, AnyNodeTest, NameTest
     56                 };
     57 
     58                 NodeTest(Kind kind) : m_kind(kind) {}
     59                 NodeTest(Kind kind, const String& data) : m_kind(kind), m_data(data) {}
     60                 NodeTest(Kind kind, const String& data, const String& namespaceURI) : m_kind(kind), m_data(data), m_namespaceURI(namespaceURI) {}
     61 
     62                 Kind kind() const { return m_kind; }
     63                 const AtomicString& data() const { return m_data; }
     64                 const AtomicString& namespaceURI() const { return m_namespaceURI; }
     65                 Vector<Predicate*>& mergedPredicates() { return m_mergedPredicates; }
     66                 const Vector<Predicate*>& mergedPredicates() const { return m_mergedPredicates; }
     67 
     68             private:
     69                 Kind m_kind;
     70                 AtomicString m_data;
     71                 AtomicString m_namespaceURI;
     72 
     73                 // When possible, we merge some or all predicates with node test for better performance.
     74                 Vector<Predicate*> m_mergedPredicates;
     75             };
     76 
     77             Step(Axis, const NodeTest& nodeTest, const Vector<Predicate*>& predicates = Vector<Predicate*>());
     78             ~Step();
     79 
     80             void optimize();
     81 
     82             void evaluate(Node* context, NodeSet&) const;
     83 
     84             Axis axis() const { return m_axis; }
     85             const NodeTest& nodeTest() const { return m_nodeTest; }
     86 
     87         private:
     88             friend void optimizeStepPair(Step*, Step*, bool&);
     89             bool predicatesAreContextListInsensitive() const;
     90 
     91             void parseNodeTest(const String&);
     92             void nodesInAxis(Node* context, NodeSet&) const;
     93             String namespaceFromNodetest(const String& nodeTest) const;
     94 
     95             Axis m_axis;
     96             NodeTest m_nodeTest;
     97             Vector<Predicate*> m_predicates;
     98         };
     99 
    100         void optimizeStepPair(Step*, Step*, bool& dropSecondStep);
    101     }
    102 
    103 }
    104 
    105 #endif // ENABLE(XPATH)
    106 
    107 #endif // XPathStep_h
    108