third_party/WebKit/Source/core/xml/XPathStep.h

/*
 * Copyright (C) 2005 Frerich Raabe <raabe@kde.org>
 * Copyright (C) 2006, 2009 Apple Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef XPathStep_h
#define XPathStep_h

#include "core/xml/XPathExpressionNode.h"
#include "core/xml/XPathNodeSet.h"

namespace blink {

class Node;

namespace XPath {

class Predicate;

class Step final : public ParseNode {
    WTF_MAKE_NONCOPYABLE(Step);
public:
    enum Axis {
        AncestorAxis, AncestorOrSelfAxis, AttributeAxis,
        ChildAxis, DescendantAxis, DescendantOrSelfAxis,
        FollowingAxis, FollowingSiblingAxis, NamespaceAxis,
        ParentAxis, PrecedingAxis, PrecedingSiblingAxis,
        SelfAxis
    };

    class NodeTest : public GarbageCollectedFinalized<NodeTest> {
    public:
        enum Kind {
            TextNodeTest, CommentNodeTest, ProcessingInstructionNodeTest, AnyNodeTest, NameTest
        };

        NodeTest(Kind kind) : m_kind(kind) { }
        NodeTest(Kind kind, const String& data) : m_kind(kind), m_data(data) { }
        NodeTest(Kind kind, const AtomicString& data, const AtomicString& namespaceURI) : m_kind(kind), m_data(data), m_namespaceURI(namespaceURI) { }

        NodeTest(const NodeTest& o)
            : m_kind(o.m_kind)
            , m_data(o.m_data)
            , m_namespaceURI(o.m_namespaceURI)
        {
            ASSERT(o.m_mergedPredicates.isEmpty());
        }
        NodeTest& operator=(const NodeTest& o)
        {
            m_kind = o.m_kind;
            m_data = o.m_data;
            m_namespaceURI = o.m_namespaceURI;
            ASSERT(o.m_mergedPredicates.isEmpty());
            return *this;
        }
        DEFINE_INLINE_TRACE() { visitor->trace(m_mergedPredicates); }

        Kind kind() const { return m_kind; }
        const AtomicString& data() const { return m_data; }
        const AtomicString& namespaceURI() const { return m_namespaceURI; }
        HeapVector<Member<Predicate>>& mergedPredicates() { return m_mergedPredicates; }
        const HeapVector<Member<Predicate>>& mergedPredicates() const { return m_mergedPredicates; }

    private:
        Kind m_kind;
        AtomicString m_data;
        AtomicString m_namespaceURI;

        // When possible, we merge some or all predicates with node test for better performance.
        HeapVector<Member<Predicate>> m_mergedPredicates;
    };

    Step(Axis, const NodeTest&);
    Step(Axis, const NodeTest&, HeapVector<Member<Predicate>>&);
    ~Step() override;
    DECLARE_VIRTUAL_TRACE();

    void optimize();

    void evaluate(EvaluationContext&, Node* context, NodeSet&) const;

    Axis axis() const { return m_axis; }
    const NodeTest& nodeTest() const { return *m_nodeTest; }

private:
    friend bool optimizeStepPair(Step*, Step*);
    bool predicatesAreContextListInsensitive() const;
    NodeTest& nodeTest() { return *m_nodeTest; }

    void parseNodeTest(const String&);
    void nodesInAxis(EvaluationContext&, Node* context, NodeSet&) const;
    String namespaceFromNodetest(const String& nodeTest) const;

    Axis m_axis;
    Member<NodeTest> m_nodeTest;
    HeapVector<Member<Predicate>> m_predicates;
};

bool optimizeStepPair(Step*, Step*);

} // namespace XPath

} // namespace blink

#endif // XPathStep_h