ArrayBuffer.h

// Copyright eeGeo Ltd (2012-2015), All Rights Reserved

#pragma once

#include "Types.h"

#include <cstring>
#include <streambuf>
#include <cstring>

namespace Eegeo
{
    template<typename T>
    class ArrayBuffer : public std::streambuf
    {
        typedef T type;
    public:
        ArrayBuffer(const type *begin, const type *end) :
            m_pBegin(begin),
            m_pEnd(end),
            m_pCurrent(m_pBegin)
        {
            Eegeo_ASSERT(std::less_equal<const type *>()(m_pBegin, m_pEnd), "The end pointer is less than the begin pointer");
        }

        explicit ArrayBuffer(const type *str) :
            m_pBegin(str),
            m_pEnd(m_pBegin + std::strlen(str)),
            m_pCurrent(m_pBegin)
        {
        }

    private:
        int_type underflow()
        {
            if (m_pCurrent == m_pEnd)
                return traits_type::eof();

            return traits_type::to_int_type(*m_pCurrent);
        }

        int_type uflow()
        {
            if (m_pCurrent == m_pEnd)
                return traits_type::eof();

            return traits_type::to_int_type(*m_pCurrent++);
        }

        int_type pbackfail(int_type ch)
        {
            if (m_pCurrent == m_pBegin || (ch != traits_type::eof() && ch != m_pCurrent[-1]))
                return traits_type::eof();

            return traits_type::to_int_type(*--m_pCurrent);
        }

        std::streamsize showmanyc()
        {
            Eegeo_ASSERT(std::less_equal<const type *>()(m_pCurrent, m_pEnd), "The end pointer is less than the begin pointer")
                return m_pEnd - m_pCurrent;
        }

        pos_type seekoff(std::streamoff off, std::ios_base::seekdir way, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out)
        {
            if (way == std::ios_base::beg)
            {
                m_pCurrent = m_pBegin + off;
            }
            else if (way == std::ios_base::cur)
            {
                m_pCurrent += off;
            }
            else if (way == std::ios_base::end)
            {
                m_pCurrent = m_pEnd + off;
            }

            if (m_pCurrent < m_pBegin || m_pCurrent > m_pEnd)
            {
                return static_cast<pos_type>(-1);
            }

            return static_cast<pos_type>(m_pCurrent - m_pBegin);
        }

        pos_type seekpos(pos_type sp, std::ios_base::openmode which = std::ios_base::in | std::ios_base::out)
        {
            m_pCurrent = m_pBegin + sp;

            if (m_pCurrent < m_pBegin || m_pCurrent > m_pEnd)
            {
                return static_cast<pos_type>(-1);
            }

            return static_cast<pos_type>(m_pCurrent - m_pBegin);
        }

    private:
        const type * const m_pBegin;
        const type * const m_pEnd;
        const type * m_pCurrent;
    };
}