/*
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 * modification, are permitted provided that the following conditions are
 * met:
 *
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 * in the documentation and/or other materials provided with the
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 * this software without specific prior written permission.
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#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_EDITING_COMMANDS_UNDO_STACK_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_EDITING_COMMANDS_UNDO_STACK_H_

#include "base/macros.h"
#include "third_party/blink/renderer/platform/heap/handle.h"
#include "third_party/blink/renderer/platform/wtf/deque.h"
#include "third_party/blink/renderer/platform/wtf/forward.h"

namespace blink {

class LocalFrame;
class UndoStep;

// |UndoStack| is owned by and always 1:1 to |Editor|. Since |Editor| is 1:1 to
// |LocalFrame|, |UndoStack| is also 1:1 to |LocalFrame|.
class UndoStack final : public GarbageCollected<UndoStack> {
  using UndoStepStack = HeapDeque<Member<UndoStep>>;

 public:
  UndoStack();

  void RegisterUndoStep(UndoStep*);
  void RegisterRedoStep(UndoStep*);
  bool CanUndo() const;
  bool CanRedo() const;
  void Undo();
  void Redo();
  void Clear();

  class UndoStepRange {
    STACK_ALLOCATED();

   public:
    using ConstIterator = UndoStepStack::const_reverse_iterator;
    ConstIterator begin() { return step_stack_.rbegin(); }
    ConstIterator end() { return step_stack_.rend(); }

    explicit UndoStepRange(const UndoStepStack&);

   private:
    const UndoStepStack& step_stack_;
  };

  UndoStepRange UndoSteps() const;

  void Trace(Visitor*) const;

 private:
  bool in_redo_;
  UndoStepStack undo_stack_;
  UndoStepStack redo_stack_;

  DISALLOW_COPY_AND_ASSIGN(UndoStack);
};

}  // namespace blink

#endif