// (C) Copyright 2008 CodeRage, LLC (turkanis at coderage dot com)

// (C) Copyright 2003-2007 Jonathan Turkanis

// Distributed under 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.)

// See http://www.boost.org/libs/iostreams for documentation.



// This material is heavily indebted to the discussion and code samples in

// A. Langer and K. Kreft, "Standard C++ IOStreams and Locales",

// Addison-Wesley, 2000, pp. 228-43.



// User "GMSB" provided an optimization for small seeks.



#ifndef BOOST_IOSTREAMS_DETAIL_INDIRECT_STREAMBUF_HPP_INCLUDED

#define BOOST_IOSTREAMS_DETAIL_INDIRECT_STREAMBUF_HPP_INCLUDED



#include <algorithm>                             // min, max.

#include <cassert>

#include <exception>

#include <typeinfo>

#include <boost/config.hpp>                      // Member template friends.

#include <boost/detail/workaround.hpp>

#include <boost/iostreams/constants.hpp>

#include <boost/iostreams/detail/adapter/concept_adapter.hpp>

#include <boost/iostreams/detail/buffer.hpp>

#include <boost/iostreams/detail/config/wide_streams.hpp>

#include <boost/iostreams/detail/double_object.hpp> 

#include <boost/iostreams/detail/execute.hpp>

#include <boost/iostreams/detail/functional.hpp>

#include <boost/iostreams/detail/ios.hpp>

#include <boost/iostreams/detail/optional.hpp>

#include <boost/iostreams/detail/push.hpp>

#include <boost/iostreams/detail/streambuf/linked_streambuf.hpp>

#include <boost/iostreams/operations.hpp>

#include <boost/iostreams/positioning.hpp>

#include <boost/iostreams/traits.hpp>

#include <boost/iostreams/operations.hpp>

#include <boost/mpl/if.hpp>

#include <boost/type_traits/is_convertible.hpp>



// Must come last.

#include <boost/iostreams/detail/config/disable_warnings.hpp>  // MSVC, BCC 5.x



namespace boost { namespace iostreams { namespace detail {



//

// Description: The implementation of basic_streambuf used by chains.

//

template<typename T, typename Tr, typename Alloc, typename Mode>

class indirect_streambuf

    : public linked_streambuf<BOOST_DEDUCED_TYPENAME char_type_of<T>::type, Tr>

{

public:

    typedef typename char_type_of<T>::type                    char_type;

    BOOST_IOSTREAMS_STREAMBUF_TYPEDEFS(Tr)

private:

    typedef typename category_of<T>::type                     category;

    typedef concept_adapter<T>                                wrapper;

    typedef detail::basic_buffer<char_type, Alloc>            buffer_type;

    typedef indirect_streambuf<T, Tr, Alloc, Mode>            my_type;

    typedef detail::linked_streambuf<char_type, traits_type>  base_type;

    typedef linked_streambuf<char_type, Tr>                   streambuf_type;

public:

    indirect_streambuf();



    void open(const T& t BOOST_IOSTREAMS_PUSH_PARAMS());

    bool is_open() const;

    void close();

    bool auto_close() const;

    void set_auto_close(bool close);

    bool strict_sync();



    // Declared in linked_streambuf.

    T* component() { return &*obj(); }

protected:

#if !BOOST_WORKAROUND(__GNUC__, == 2)

    BOOST_IOSTREAMS_USING_PROTECTED_STREAMBUF_MEMBERS(base_type)

#endif



    //----------virtual functions---------------------------------------------//



#ifndef BOOST_IOSTREAMS_NO_LOCALE

    void imbue(const std::locale& loc);

#endif

#ifdef BOOST_IOSTREAMS_NO_STREAM_TEMPLATES

    public:

#endif

    int_type underflow();

    int_type pbackfail(int_type c);

    int_type overflow(int_type c);

    int sync();

    pos_type seekoff( off_type off, BOOST_IOS::seekdir way,

                      BOOST_IOS::openmode which );

    pos_type seekpos(pos_type sp, BOOST_IOS::openmode which);



    // Declared in linked_streambuf.

    void set_next(streambuf_type* next);

    void close_impl(BOOST_IOS::openmode m);

    const std::type_info& component_type() const { return typeid(T); }

    void* component_impl() { return component(); }

private:



    //----------Accessor functions--------------------------------------------//



    wrapper& obj() { return *storage_; }

    streambuf_type* next() const { return next_; }

    buffer_type& in() { return buffer_.first(); }

    buffer_type& out() { return buffer_.second(); }

    bool can_read() const { return is_convertible<Mode, input>::value; }

    bool can_write() const { return is_convertible<Mode, output>::value; }

    bool output_buffered() const { return (flags_ & f_output_buffered) != 0; }

    bool shared_buffer() const { return is_convertible<Mode, seekable>::value; }

    void set_flags(int f) { flags_ = f; }



    //----------State changing functions--------------------------------------//



    virtual void init_get_area();

    virtual void init_put_area();



    //----------Utility function----------------------------------------------//



    pos_type seek_impl( stream_offset off, BOOST_IOS::seekdir way,

                        BOOST_IOS::openmode which );

    void sync_impl();



    enum flag_type {

        f_open             = 1,

        f_output_buffered  = f_open << 1,

        f_auto_close       = f_output_buffered << 1

    };



    optional<wrapper>           storage_;

    streambuf_type*             next_;

    double_object<

        buffer_type,

        is_convertible<

            Mode,

            two_sequence

        >

    >                           buffer_;

    std::streamsize             pback_size_;

    int                         flags_;

};



//--------------Implementation of indirect_streambuf--------------------------//



template<typename T, typename Tr, typename Alloc, typename Mode>

indirect_streambuf<T, Tr, Alloc, Mode>::indirect_streambuf()

    : next_(0), pback_size_(0), flags_(f_auto_close) { }



//--------------Implementation of open, is_open and close---------------------//



template<typename T, typename Tr, typename Alloc, typename Mode>

void indirect_streambuf<T, Tr, Alloc, Mode>::open

    (const T& t, int buffer_size, int pback_size)

{

    using namespace std;



    // Normalize buffer sizes.

    buffer_size =

        (buffer_size != -1) ?

        buffer_size :

        iostreams::optimal_buffer_size(t);

    pback_size =

        (pback_size != -1) ?

        pback_size :

        default_pback_buffer_size;



    // Construct input buffer.

    if (can_read()) {

        pback_size_ = (std::max)(2, pback_size); // STLPort needs 2.

        std::streamsize size =

            pback_size_ +

            ( buffer_size ? buffer_size: 1 );

        in().resize(size);

        if (!shared_buffer())

            init_get_area();

    }



    // Construct output buffer.

    if (can_write() && !shared_buffer()) {

        if (buffer_size != 0)

            out().resize(buffer_size);

        init_put_area();

    }



    storage_.reset(wrapper(t));

    flags_ |= f_open;

    if (can_write() && buffer_size > 1)

        flags_ |= f_output_buffered;

    this->set_true_eof(false);

}



template<typename T, typename Tr, typename Alloc, typename Mode>

inline bool indirect_streambuf<T, Tr, Alloc, Mode>::is_open() const

{ return (flags_ & f_open) != 0; }



template<typename T, typename Tr, typename Alloc, typename Mode>

void indirect_streambuf<T, Tr, Alloc, Mode>::close()

{

    using namespace std;

    base_type* self = this;

    detail::execute_all(

        detail::call_member_close(*self, BOOST_IOS::in),

        detail::call_member_close(*self, BOOST_IOS::out),

        detail::call_reset(storage_),

        detail::clear_flags(flags_)

    );

}



template<typename T, typename Tr, typename Alloc, typename Mode>

bool indirect_streambuf<T, Tr, Alloc, Mode>::auto_close() const

{ return (flags_ & f_auto_close) != 0; }



template<typename T, typename Tr, typename Alloc, typename Mode>

void indirect_streambuf<T, Tr, Alloc, Mode>::set_auto_close(bool close)

{ flags_ = (flags_ & ~f_auto_close) | (close ? f_auto_close : 0); }



//--------------Implementation virtual functions------------------------------//



#ifndef BOOST_IOSTREAMS_NO_LOCALE

template<typename T, typename Tr, typename Alloc, typename Mode>

void indirect_streambuf<T, Tr, Alloc, Mode>::imbue(const std::locale& loc)

{

    if (is_open()) {

        obj().imbue(loc);

        if (next_)

            next_->pubimbue(loc);

    }

}

#endif



template<typename T, typename Tr, typename Alloc, typename Mode>

typename indirect_streambuf<T, Tr, Alloc, Mode>::int_type

indirect_streambuf<T, Tr, Alloc, Mode>::underflow()

{

    using namespace std;

    if (!gptr()) init_get_area();

    buffer_type& buf = in();

    if (gptr() < egptr()) return traits_type::to_int_type(*gptr());



    // Fill putback buffer.

    std::streamsize keep = 

        (std::min)( static_cast<std::streamsize>(gptr() - eback()),

                    pback_size_ );

    if (keep)

        traits_type::move( buf.data() + (pback_size_ - keep),

                           gptr() - keep, keep );



    // Set pointers to reasonable values in case read throws.

    setg( buf.data() + pback_size_ - keep,

          buf.data() + pback_size_,

          buf.data() + pback_size_ );



    // Read from source.

    std::streamsize chars =

        obj().read(buf.data() + pback_size_, buf.size() - pback_size_, next_);

    if (chars == -1) {

        this->set_true_eof(true);

        chars = 0;

    }

    setg(eback(), gptr(), buf.data() + pback_size_ + chars);

    return chars != 0 ?

        traits_type::to_int_type(*gptr()) :

        traits_type::eof();

}



template<typename T, typename Tr, typename Alloc, typename Mode>

typename indirect_streambuf<T, Tr, Alloc, Mode>::int_type

indirect_streambuf<T, Tr, Alloc, Mode>::pbackfail(int_type c)

{

    if (gptr() != eback()) {

        gbump(-1);

        if (!traits_type::eq_int_type(c, traits_type::eof()))

            *gptr() = traits_type::to_char_type(c);

        return traits_type::not_eof(c);

    } else {

        throw bad_putback();

    }

}



template<typename T, typename Tr, typename Alloc, typename Mode>

typename indirect_streambuf<T, Tr, Alloc, Mode>::int_type

indirect_streambuf<T, Tr, Alloc, Mode>::overflow(int_type c)

{

    if ( output_buffered() && pptr() == 0 ||

         shared_buffer() && gptr() != 0 )

    {

        init_put_area();

    }

    if (!traits_type::eq_int_type(c, traits_type::eof())) {

        if (output_buffered()) {

            if (pptr() == epptr()) {

                sync_impl();

                if (pptr() == epptr())

                    return traits_type::eof();

            }

            *pptr() = traits_type::to_char_type(c);

            pbump(1);

        } else {

            char_type d = traits_type::to_char_type(c);

            if (obj().write(&d, 1, next_) != 1)

                return traits_type::eof();

        }

    }

    return traits_type::not_eof(c);

}



template<typename T, typename Tr, typename Alloc, typename Mode>

int indirect_streambuf<T, Tr, Alloc, Mode>::sync()

{

    try { // sync() is no-throw.

        sync_impl();

        obj().flush(next_);

        return 0;

    } catch (...) { return -1; }

}



template<typename T, typename Tr, typename Alloc, typename Mode>

bool indirect_streambuf<T, Tr, Alloc, Mode>::strict_sync()

{

    try { // sync() is no-throw.

        sync_impl();

        return obj().flush(next_);

    } catch (...) { return false; }

}



template<typename T, typename Tr, typename Alloc, typename Mode>

inline typename indirect_streambuf<T, Tr, Alloc, Mode>::pos_type

indirect_streambuf<T, Tr, Alloc, Mode>::seekoff

    (off_type off, BOOST_IOS::seekdir way, BOOST_IOS::openmode which)

{ return seek_impl(off, way, which); }



template<typename T, typename Tr, typename Alloc, typename Mode>

inline typename indirect_streambuf<T, Tr, Alloc, Mode>::pos_type

indirect_streambuf<T, Tr, Alloc, Mode>::seekpos

    (pos_type sp, BOOST_IOS::openmode which)

{ 

    return seek_impl(position_to_offset(sp), BOOST_IOS::beg, which); 

}



template<typename T, typename Tr, typename Alloc, typename Mode>

typename indirect_streambuf<T, Tr, Alloc, Mode>::pos_type

indirect_streambuf<T, Tr, Alloc, Mode>::seek_impl

    (stream_offset off, BOOST_IOS::seekdir way, BOOST_IOS::openmode which)

{

    if ( gptr() != 0 && way == BOOST_IOS::cur && which == BOOST_IOS::in && 

         eback() - gptr() <= off && off <= egptr() - gptr() ) 

    {   // Small seek optimization

        gbump(off);

        return obj().seek(0, BOOST_IOS::cur, BOOST_IOS::in, next_) -

               static_cast<off_type>(egptr() - gptr());

    }

    if (pptr() != 0) 

        this->BOOST_IOSTREAMS_PUBSYNC(); // sync() confuses VisualAge 6.

    if (way == BOOST_IOS::cur && gptr())

        off -= static_cast<off_type>(egptr() - gptr());

    setg(0, 0, 0);

    setp(0, 0);

    return obj().seek(off, way, which, next_);

}



template<typename T, typename Tr, typename Alloc, typename Mode>

inline void indirect_streambuf<T, Tr, Alloc, Mode>::set_next

    (streambuf_type* next)

{ next_ = next; }



template<typename T, typename Tr, typename Alloc, typename Mode>

inline void indirect_streambuf<T, Tr, Alloc, Mode>::close_impl

    (BOOST_IOS::openmode which)

{

    if (which == BOOST_IOS::in && is_convertible<Mode, input>::value) {

        setg(0, 0, 0);

    }

    if (which == BOOST_IOS::out && is_convertible<Mode, output>::value) {

        sync();

        setp(0, 0);

    }

    if ( !is_convertible<category, dual_use>::value ||

         is_convertible<Mode, input>::value == (which == BOOST_IOS::in) )

    {

        obj().close(which, next_);

    }

}



//----------State changing functions------------------------------------------//



template<typename T, typename Tr, typename Alloc, typename Mode>

void indirect_streambuf<T, Tr, Alloc, Mode>::sync_impl()

{

    std::streamsize avail, amt;

    if ((avail = static_cast<std::streamsize>(pptr() - pbase())) > 0) {

        if ((amt = obj().write(pbase(), avail, next())) == avail)

            setp(out().begin(), out().end());

        else {

            const char_type* ptr = pptr();

            setp(out().begin() + amt, out().end());

            pbump(ptr - pptr());

        }

    }

}



template<typename T, typename Tr, typename Alloc, typename Mode>

void indirect_streambuf<T, Tr, Alloc, Mode>::init_get_area()

{

    if (shared_buffer() && pptr() != 0) {

        sync_impl();

        setp(0, 0);

    }

    setg(in().begin(), in().begin(), in().begin());

}



template<typename T, typename Tr, typename Alloc, typename Mode>

void indirect_streambuf<T, Tr, Alloc, Mode>::init_put_area()

{

    using namespace std;

    if (shared_buffer() && gptr() != 0)

        setg(0, 0, 0);

    if (output_buffered())

        setp(out().begin(), out().end());

    else

        setp(0, 0);

}



//----------------------------------------------------------------------------//



} } } // End namespaces detail, iostreams, boost.



#include <boost/iostreams/detail/config/enable_warnings.hpp> // MSVC, BCC 5.x



#endif // #ifndef BOOST_IOSTREAMS_DETAIL_INDIRECT_STREAMBUF_HPP_INCLUDED

