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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 #include "core/xml/XPathExpressionNode.h"
     31 #include "core/xml/XPathNodeSet.h"
     32 
     33 namespace WebCore {
     34 
     35 class Node;
     36 
     37 namespace XPath {
     38 
     39 class Predicate;
     40 
     41 class Step : public ParseNode {
     42     WTF_MAKE_NONCOPYABLE(Step);
     43     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 AtomicString& data, const AtomicString& namespaceURI) : m_kind(kind), m_data(data), m_namespaceURI(namespaceURI) { }
     63 
     64         NodeTest(const NodeTest& o)
     65             : m_kind(o.m_kind)
     66             , m_data(o.m_data)
     67             , m_namespaceURI(o.m_namespaceURI)
     68         {
     69             ASSERT(o.m_mergedPredicates.isEmpty());
     70         }
     71         NodeTest& operator=(const NodeTest& o)
     72         {
     73             m_kind = o.m_kind;
     74             m_data = o.m_data;
     75             m_namespaceURI = o.m_namespaceURI;
     76             ASSERT(o.m_mergedPredicates.isEmpty());
     77             return *this;
     78         }
     79 
     80         Kind kind() const { return m_kind; }
     81         const AtomicString& data() const { return m_data; }
     82         const AtomicString& namespaceURI() const { return m_namespaceURI; }
     83         Vector<OwnPtr<Predicate> >& mergedPredicates() { return m_mergedPredicates; }
     84         const Vector<OwnPtr<Predicate> >& mergedPredicates() const { return m_mergedPredicates; }
     85 
     86     private:
     87         Kind m_kind;
     88         AtomicString m_data;
     89         AtomicString m_namespaceURI;
     90 
     91         // When possible, we merge some or all predicates with node test for better performance.
     92         Vector<OwnPtr<Predicate> > m_mergedPredicates;
     93     };
     94 
     95     Step(Axis, const NodeTest&);
     96     Step(Axis, const NodeTest&, Vector<OwnPtr<Predicate> >&);
     97     ~Step();
     98 
     99     void optimize();
    100 
    101     void evaluate(Node* context, NodeSet&) const;
    102 
    103     Axis axis() const { return m_axis; }
    104     const NodeTest& nodeTest() const { return m_nodeTest; }
    105 
    106 private:
    107     friend void optimizeStepPair(Step*, Step*, bool&);
    108     bool predicatesAreContextListInsensitive() const;
    109 
    110     void parseNodeTest(const String&);
    111     void nodesInAxis(Node* context, NodeSet&) const;
    112     String namespaceFromNodetest(const String& nodeTest) const;
    113 
    114     Axis m_axis;
    115     NodeTest m_nodeTest;
    116     Vector<OwnPtr<Predicate> > m_predicates;
    117 };
    118 
    119 void optimizeStepPair(Step*, Step*, bool& dropSecondStep);
    120 
    121 } // namespace XPath
    122 
    123 } // namespace WebCore
    124 
    125 #endif // XPathStep_h
    126