/*=============================================================================
    Copyright (c) 2001, Daniel C. Nuffer
    Copyright (c) 2003, Hartmut Kaiser
    http://spirit.sourceforge.net/

    Use, modification and distribution is subject to the Boost Software
    License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
    http://www.boost.org/LICENSE_1_0.txt)
=============================================================================*/
#ifndef FIXED_SIZE_QUEUE
#define FIXED_SIZE_QUEUE

#include <cstdlib>
#include <iterator>
#include <cstddef>

#include <boost/spirit/core/assert.hpp> // for BOOST_SPIRIT_ASSERT

// FIXES for broken compilers
#include <boost/config.hpp>
#include <boost/iterator_adaptors.hpp>

#define BOOST_SPIRIT_ASSERT_FSQ_SIZE \
    BOOST_SPIRIT_ASSERT(((m_tail + N + 1) - m_head) % (N+1) == m_size % (N+1)) \
    /**/

///////////////////////////////////////////////////////////////////////////////
namespace boost { namespace spirit {

///////////////////////////////////////////////////////////////////////////////
namespace impl {

#if !defined(BOOST_ITERATOR_ADAPTORS_VERSION) || \
    BOOST_ITERATOR_ADAPTORS_VERSION < 0x0200
#error "Please use at least Boost V1.31.0 while compiling the fixed_size_queue class!"
#else // BOOST_ITERATOR_ADAPTORS_VERSION < 0x0200

template <typename QueueT, typename T, typename PointerT>
class fsq_iterator
:   public boost::iterator_adaptor<
        fsq_iterator<QueueT, T, PointerT>, 
        PointerT,
        T,
        std::random_access_iterator_tag
    >
{
public:
    typedef typename QueueT::position_t position;
    typedef boost::iterator_adaptor<
            fsq_iterator<QueueT, T, PointerT>, PointerT, T,
            std::random_access_iterator_tag
        > base_t;

    fsq_iterator() {}
    fsq_iterator(position const &p_) : p(p_) {}
    
    position const &get_position() const { return p; }
    
private:
    friend class boost::iterator_core_access;
    
    typename base_t::reference dereference() const
    {
        return p.self->m_queue[p.pos];
    }

    void increment()
    {
        ++p.pos;
        if (p.pos == QueueT::MAX_SIZE+1)
            p.pos = 0;
    }

    void decrement()
    {
        if (p.pos == 0)
            p.pos = QueueT::MAX_SIZE;
        else
            --p.pos;
    }

    template <
        typename OtherDerivedT, typename OtherIteratorT, 
        typename V, typename C, typename R, typename D
    >   
    bool equal(iterator_adaptor<OtherDerivedT, OtherIteratorT, V, C, R, D> 
        const &x) const
    {
        position const &rhs_pos = 
            static_cast<OtherDerivedT const &>(x).get_position();
        return (p.self == rhs_pos.self) && (p.pos == rhs_pos.pos);
    }

    template <
        typename OtherDerivedT, typename OtherIteratorT, 
        typename V, typename C, typename R, typename D
    >   
    typename base_t::difference_type distance_to(
        iterator_adaptor<OtherDerivedT, OtherIteratorT, V, C, R, D> 
        const &x) const
    {
        typedef typename base_t::difference_type diff_t;

        position const &p2 = 
            static_cast<OtherDerivedT const &>(x).get_position();
        std::size_t pos1 = p.pos;
        std::size_t pos2 = p2.pos;

        // Undefined behaviour if the iterators come from different
        //  containers
        BOOST_SPIRIT_ASSERT(p.self == p2.self);

        if (pos1 < p.self->m_head)
            pos1 += QueueT::MAX_SIZE;
        if (pos2 < p2.self->m_head)
            pos2 += QueueT::MAX_SIZE;

        if (pos2 > pos1)
            return diff_t(pos2 - pos1);
        else
            return -diff_t(pos1 - pos2);
    }

    void advance(typename base_t::difference_type n)
    {
        // Notice that we don't care values of n that can
        //  wrap around more than one time, since it would
        //  be undefined behaviour anyway (going outside
        //  the begin/end range). Negative wrapping is a bit
        //  cumbersome because we don't want to case p.pos
        //  to signed.
        if (n < 0)
        {
            n = -n;
            if (p.pos < (std::size_t)n)
                p.pos = QueueT::MAX_SIZE+1 - (n - p.pos);
            else
                p.pos -= n;
        }
        else
        {
            p.pos += n;
            if (p.pos >= QueueT::MAX_SIZE+1)
                p.pos -= QueueT::MAX_SIZE+1;
        }
    }
    
private:
    position p;
};

#endif // BOOST_ITERATOR_ADAPTORS_VERSION < 0x0200

///////////////////////////////////////////////////////////////////////////////
} /* namespace impl */

template <typename T, std::size_t N>
class fixed_size_queue
{
private:
    struct position
    {
        fixed_size_queue* self;
        std::size_t pos;

        position() : self(0), pos(0) {}

        // The const_cast here is just to avoid to have two different
        //  position structures for the const and non-const case.
        // The const semantic is guaranteed by the iterator itself
        position(const fixed_size_queue* s, std::size_t p)
            : self(const_cast<fixed_size_queue*>(s)), pos(p)
        {}
    };

public:
    // Declare the iterators
    typedef impl::fsq_iterator<fixed_size_queue<T, N>, T, T*> iterator;
    typedef impl::fsq_iterator<fixed_size_queue<T, N>, T const, T const*> 
        const_iterator;
    typedef position position_t;

    friend class impl::fsq_iterator<fixed_size_queue<T, N>, T, T*>;
    friend class impl::fsq_iterator<fixed_size_queue<T, N>, T const, T const*>;
    
    fixed_size_queue();
    fixed_size_queue(const fixed_size_queue& x);
    fixed_size_queue& operator=(const fixed_size_queue& x);
    ~fixed_size_queue();

    void push_back(const T& e);
    void push_front(const T& e);
    void serve(T& e);
    void pop_front();

    bool empty() const
    {
        return m_size == 0;
    }

    bool full() const
    {
        return m_size == N;
    }

    iterator begin()
    {
        return iterator(position(this, m_head));
    }

    const_iterator begin() const
    {
        return const_iterator(position(this, m_head));
    }

    iterator end()
    {
        return iterator(position(this, m_tail));
    }

    const_iterator end() const
    {
        return const_iterator(position(this, m_tail));
    }

    std::size_t size() const
    {
        return m_size;
    }

    T& front()
    {
        return m_queue[m_head];
    }

    const T& front() const
    {
        return m_queue[m_head];
    }

private:
    // Redefine the template parameters to avoid using partial template
    //  specialization on the iterator policy to extract N.
    BOOST_STATIC_CONSTANT(std::size_t, MAX_SIZE = N);

    std::size_t m_head;
    std::size_t m_tail;
    std::size_t m_size;
    T m_queue[N+1];
};

template <typename T, std::size_t N>
inline
fixed_size_queue<T, N>::fixed_size_queue()
    : m_head(0)
    , m_tail(0)
    , m_size(0)
{
    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);
}

template <typename T, std::size_t N>
inline
fixed_size_queue<T, N>::fixed_size_queue(const fixed_size_queue& x)
    : m_head(x.m_head)
    , m_tail(x.m_tail)
    , m_size(x.m_size)
{
    copy(x.begin(), x.end(), begin());
    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);
}

template <typename T, std::size_t N>
inline fixed_size_queue<T, N>&
fixed_size_queue<T, N>::operator=(const fixed_size_queue& x)
{
    if (this != &x)
    {
        m_head = x.m_head;
        m_tail = x.m_tail;
        m_size = x.m_size;
        copy(x.begin(), x.end(), begin());
    }
    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);

    return *this;
}

template <typename T, std::size_t N>
inline
fixed_size_queue<T, N>::~fixed_size_queue()
{
    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);
}

template <typename T, std::size_t N>
inline void
fixed_size_queue<T, N>::push_back(const T& e)
{
    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);

    BOOST_SPIRIT_ASSERT(!full());

    m_queue[m_tail] = e;
    ++m_size;
    ++m_tail;
    if (m_tail == N+1)
        m_tail = 0;


    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);
}

template <typename T, std::size_t N>
inline void
fixed_size_queue<T, N>::push_front(const T& e)
{
    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);

    BOOST_SPIRIT_ASSERT(!full());

    if (m_head == 0)
        m_head = N;
    else
        --m_head;

    m_queue[m_head] = e;
    ++m_size;

    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);
}


template <typename T, std::size_t N>
inline void
fixed_size_queue<T, N>::serve(T& e)
{
    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);

    e = m_queue[m_head];
    pop_front();
}



template <typename T, std::size_t N>
inline void
fixed_size_queue<T, N>::pop_front()
{
    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);

    ++m_head;
    if (m_head == N+1)
        m_head = 0;
    --m_size;

    BOOST_SPIRIT_ASSERT(m_size <= N+1);
    BOOST_SPIRIT_ASSERT_FSQ_SIZE;
    BOOST_SPIRIT_ASSERT(m_head <= N+1);
    BOOST_SPIRIT_ASSERT(m_tail <= N+1);
}

///////////////////////////////////////////////////////////////////////////////
}} // namespace boost::spirit

#undef BOOST_SPIRIT_ASSERT_FSQ_SIZE

#endif
