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

    Kind getKind() 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 getAxis() 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