ClickHouse/base/poco/Foundation/include/Poco/Dynamic/VarIterator.h

//
// VarIterator.h
//
// Library: Foundation
// Package: Dynamic
// Module:  VarIterator
//
// Definition of the VarIterator class.
//
// Copyright (c) 2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_VarIterator_INCLUDED
#define Foundation_VarIterator_INCLUDED


#include <algorithm>
#include <iterator>
#include "Poco/Exception.h"


namespace Poco
{
namespace Dynamic
{


    class Var;


    class Foundation_API VarIterator
    /// VarIterator class.
    {
    public:
        typedef std::bidirectional_iterator_tag iterator_category;
        typedef Var value_type;
        typedef std::ptrdiff_t difference_type;
        typedef Var * pointer;
        typedef Var & reference;

        static const std::size_t POSITION_END;
        /// End position indicator.

        VarIterator(Var * pVar, bool positionEnd);
        /// Creates the VarIterator and positions it at the end of
        /// the recordset if positionEnd is true. Otherwise, it is
        /// positioned at the beginning.

        VarIterator(const VarIterator & other);
        /// Creates a copy of other VarIterator.

        ~VarIterator();
        /// Destroys the VarIterator.

        VarIterator & operator=(const VarIterator & other);
        /// Assigns the other VarIterator.

        bool operator==(const VarIterator & other) const;
        /// Equality operator.

        bool operator!=(const VarIterator & other) const;
        /// Inequality operator.

        Var & operator*() const;
        /// Returns value at the current position.

        Var * operator->() const;
        /// Returns pointer to the value at current position.

        const VarIterator & operator++() const;
        /// Advances by one position and returns current position.

        VarIterator operator++(int) const;
        /// Advances by one position and returns copy of the iterator with
        /// previous current position.

        const VarIterator & operator--() const;
        /// Goes back by one position and returns copy of the iterator with
        /// previous current position.

        VarIterator operator--(int) const;
        /// Goes back by one position and returns previous current position.

        VarIterator operator+(std::size_t diff) const;
        /// Returns a copy the VarIterator advanced by diff positions.

        VarIterator operator-(std::size_t diff) const;
        /// Returns a copy the VarIterator backed by diff positions.
        /// Throws RangeException if diff is larger than current position.

        void swap(VarIterator & other);
        /// Swaps the VarIterator with another one.

    private:
        VarIterator();

        void increment() const;
        /// Increments the iterator position by one.
        /// Throws RangeException if position is out of range.

        void decrement() const;
        /// Decrements the iterator position by one.
        /// Throws RangeException if position is out of range.

        void setPosition(std::size_t pos) const;
        /// Sets the iterator position.
        /// Throws RangeException if position is out of range.

        Var * _pVar;
        mutable std::size_t _position;

        friend class Var;
    };


    ///
    /// inlines
    ///


    inline bool VarIterator::operator==(const VarIterator & other) const
    {
        return _pVar == other._pVar && _position == other._position;
    }


    inline bool VarIterator::operator!=(const VarIterator & other) const
    {
        return _pVar != other._pVar || _position != other._position;
    }


}
} // namespace Poco::Dynamic


namespace std
{
template <>
inline void swap<Poco::Dynamic::VarIterator>(Poco::Dynamic::VarIterator & s1, Poco::Dynamic::VarIterator & s2)
/// Full template specialization of std:::swap for VarIterator
{
    s1.swap(s2);
}
}


#endif // Foundation_VarIterator_INCLUDED