text: /*
   * 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 THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_STEP_H_
  #define THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_STEP_H_
  
  #include "base/macros.h"
  #include "third_party/blink/renderer/core/xml/xpath_expression_node.h"
  #include "third_party/blink/renderer/core/xml/xpath_node_set.h"
  
  namespace blink {
  
  class Node;
  
  namespace xpath {
  
  class Predicate;
  
  class Step final : public ParseNode {
   public:
    enum Axis {
      kAncestorAxis,
      kAncestorOrSelfAxis,
      kAttributeAxis,
      kChildAxis,
      kDescendantAxis,
      kDescendantOrSelfAxis,
      kFollowingAxis,
      kFollowingSiblingAxis,
      kNamespaceAxis,
      kParentAxis,
      kPrecedingAxis,
      kPrecedingSiblingAxis,
      kSelfAxis
    };
  
    class NodeTest final : public GarbageCollected<NodeTest> {
     public:
      enum Kind {
        kTextNodeTest,
        kCommentNodeTest,
        kProcessingInstructionNodeTest,
        kAnyNodeTest,
        kNameTest
      };
  
      NodeTest(Kind kind) : kind_(kind) {}
      NodeTest(Kind kind, const String& data) : kind_(kind), data_(data) {}
      NodeTest(Kind kind,
               const AtomicString& data,
               const AtomicString& namespace_uri)
          : kind_(kind), data_(data), namespace_uri_(namespace_uri) {}
  
      NodeTest(const NodeTest& o)
          : kind_(o.kind_), data_(o.data_), namespace_uri_(o.namespace_uri_) {
        DCHECK(o.merged_predicates_.IsEmpty());
      }
      NodeTest& operator=(const NodeTest& o) {
        kind_ = o.kind_;
        data_ = o.data_;
        namespace_uri_ = o.namespace_uri_;
        DCHECK(o.merged_predicates_.IsEmpty());
        return *this;
      }
      void Trace(Visitor* visitor) { visitor->Trace(merged_predicates_); }
  
      Kind GetKind() const { return kind_; }
      const AtomicString& Data() const { return data_; }
      const AtomicString& NamespaceURI() const { return namespace_uri_; }
      HeapVector<Member<Predicate>>& MergedPredicates() {
        return merged_predicates_;
      }
      const HeapVector<Member<Predicate>>& MergedPredicates() const {
        return merged_predicates_;
      }
  
     private:
      Kind kind_;
      AtomicString data_;
      AtomicString namespace_uri_;
  
      // When possible, we merge some or all predicates with node test for better
      // performance.
      HeapVector<Member<Predicate>> merged_predicates_;
    };
  
    Step(Axis, const NodeTest&);
    Step(Axis, const NodeTest&, HeapVector<Member<Predicate>>&);
    ~Step() override;
    void Trace(Visitor*) override;
  
    void Optimize();
  
    void Evaluate(EvaluationContext&, Node* context, NodeSet&) const;
  
    Axis GetAxis() const { return axis_; }
    const NodeTest& GetNodeTest() const { return *node_test_; }
  
   private:
    friend bool OptimizeStepPair(Step*, Step*);
    bool PredicatesAreContextListInsensitive() const;
    NodeTest& GetNodeTest() { return *node_test_; }
  
    void ParseNodeTest(const String&);
    void NodesInAxis(EvaluationContext&, Node* context, NodeSet&) const;
    String NamespaceFromNodetest(const String& node_test) const;
  
    Axis axis_;
    Member<NodeTest> node_test_;
    HeapVector<Member<Predicate>> predicates_;
    DISALLOW_COPY_AND_ASSIGN(Step);
  };
  
  bool OptimizeStepPair(Step*, Step*);
  
  }  // namespace xpath
  
  }  // namespace blink
  
  #endif  // THIRD_PARTY_BLINK_RENDERER_CORE_XML_XPATH_STEP_H_
  