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 // (C) Copyright Reimar Döffinger 2018.
 // Based on zstd.hpp by:
 // (C) Copyright Milan Svoboda 2008.
 // 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.
 
 #ifndef BOOST_IOSTREAMS_ZSTD_HPP_INCLUDED
 #define BOOST_IOSTREAMS_ZSTD_HPP_INCLUDED
 
 #if defined(_MSC_VER)
 # pragma once
 #endif
 
 #include <cassert>
 #include <iosfwd>            // streamsize.
 #include <memory>            // allocator, bad_alloc.
 #include <new>
 #include <boost/config.hpp>  // MSVC, STATIC_CONSTANT, DEDUCED_TYPENAME, DINKUM.
 #include <boost/detail/workaround.hpp>
 #include <boost/iostreams/constants.hpp>   // buffer size.
 #include <boost/iostreams/detail/config/auto_link.hpp>
 #include <boost/iostreams/detail/config/dyn_link.hpp>
 #include <boost/iostreams/detail/config/wide_streams.hpp>
 #include <boost/iostreams/detail/ios.hpp>  // failure, streamsize.
 #include <boost/iostreams/filter/symmetric.hpp>
 #include <boost/iostreams/pipeline.hpp>
 #include <boost/type_traits/is_same.hpp>
 
 // Must come last.
 #ifdef BOOST_MSVC
 # pragma warning(push)
 # pragma warning(disable:4251 4231 4660)         // Dependencies not exported.
 #endif
 #include <boost/config/abi_prefix.hpp>
 
 namespace boost { namespace iostreams {
 
 namespace zstd {
 
 typedef void* (*alloc_func)(void*, size_t, size_t);
 typedef void (*free_func)(void*, void*);
 
                     // Compression levels
 
 BOOST_IOSTREAMS_DECL extern const uint32_t best_speed;
 BOOST_IOSTREAMS_DECL extern const uint32_t best_compression;
 BOOST_IOSTREAMS_DECL extern const uint32_t default_compression;
 
                     // Status codes
 
 BOOST_IOSTREAMS_DECL extern const int okay;
 BOOST_IOSTREAMS_DECL extern const int stream_end;
 
                     // Flush codes
 
 BOOST_IOSTREAMS_DECL extern const int finish;
 BOOST_IOSTREAMS_DECL extern const int flush;
 BOOST_IOSTREAMS_DECL extern const int run;
 
                     // Code for current OS
 
                     // Null pointer constant.
 
 const int null                               = 0;
 
                     // Default values
 
 } // End namespace zstd.
 
 //
 // Class name: zstd_params.
 // Description: Encapsulates the parameters passed to zstddec_init
 //      to customize compression and decompression.
 //
 struct zstd_params {
 
     // Non-explicit constructor.
     zstd_params( uint32_t level = zstd::default_compression )
         : level(level)
         { }
     uint32_t level;
 };
 
 //
 // Class name: zstd_error.
 // Description: Subclass of std::ios::failure thrown to indicate
 //     zstd errors other than out-of-memory conditions.
 //
 class BOOST_IOSTREAMS_DECL zstd_error : public BOOST_IOSTREAMS_FAILURE {
 public:
     explicit zstd_error(size_t error);
     int error() const { return error_; }
     static void check BOOST_PREVENT_MACRO_SUBSTITUTION(size_t error);
 private:
     size_t error_;
 };
 
 namespace detail {
 
 template<typename Alloc>
 struct zstd_allocator_traits {
 #ifndef BOOST_NO_STD_ALLOCATOR
 #if defined(BOOST_NO_CXX11_ALLOCATOR)
     typedef typename Alloc::template rebind<char>::other type;
 #else
     typedef typename std::allocator_traits<Alloc>::template rebind_alloc<char> type;
 #endif
 #else
     typedef std::allocator<char> type;
 #endif
 };
 
 template< typename Alloc,
           typename Base = // VC6 workaround (C2516)
               BOOST_DEDUCED_TYPENAME zstd_allocator_traits<Alloc>::type >
 struct zstd_allocator : private Base {
 private:
 #if defined(BOOST_NO_CXX11_ALLOCATOR) || defined(BOOST_NO_STD_ALLOCATOR)
     typedef typename Base::size_type size_type;
 #else
     typedef typename std::allocator_traits<Base>::size_type size_type;
 #endif
 public:
     BOOST_STATIC_CONSTANT(bool, custom =
         (!is_same<std::allocator<char>, Base>::value));
     typedef typename zstd_allocator_traits<Alloc>::type allocator_type;
     static void* allocate(void* self, size_t items, size_t size);
     static void deallocate(void* self, void* address);
 };
 
 class BOOST_IOSTREAMS_DECL zstd_base {
 public:
     typedef char char_type;
 protected:
     zstd_base();
     ~zstd_base();
     template<typename Alloc>
     void init( const zstd_params& p,
                bool compress,
                zstd_allocator<Alloc>& zalloc )
         {
             bool custom = zstd_allocator<Alloc>::custom;
             do_init( p, compress,
                      custom ? zstd_allocator<Alloc>::allocate : 0,
                      custom ? zstd_allocator<Alloc>::deallocate : 0,
                      &zalloc );
         }
     void before( const char*& src_begin, const char* src_end,
                  char*& dest_begin, char* dest_end );
     void after( const char*& src_begin, char*& dest_begin,
                 bool compress );
     int deflate(int action);
     int inflate(int action);
     void reset(bool compress, bool realloc);
 private:
     void do_init( const zstd_params& p, bool compress,
                   zstd::alloc_func,
                   zstd::free_func,
                   void* derived );
     void*         cstream_;         // Actual type: ZSTD_CStream *
     void*         dstream_;         // Actual type: ZSTD_DStream *
     void*         in_;              // Actual type: ZSTD_inBuffer *
     void*         out_;             // Actual type: ZSTD_outBuffer *
     int eof_;
     uint32_t level;
 };
 
 //
 // Template name: zstd_compressor_impl
 // Description: Model of C-Style Filter implementing compression by
 //      delegating to the zstd function deflate.
 //
 template<typename Alloc = std::allocator<char> >
 class zstd_compressor_impl : public zstd_base, public zstd_allocator<Alloc> {
 public:
     zstd_compressor_impl(const zstd_params& = zstd::default_compression);
     ~zstd_compressor_impl();
     bool filter( const char*& src_begin, const char* src_end,
                  char*& dest_begin, char* dest_end, bool flush );
     void close();
 };
 
 //
 // Template name: zstd_compressor_impl
 // Description: Model of C-Style Filte implementing decompression by
 //      delegating to the zstd function inflate.
 //
 template<typename Alloc = std::allocator<char> >
 class zstd_decompressor_impl : public zstd_base, public zstd_allocator<Alloc> {
 public:
     zstd_decompressor_impl(const zstd_params&);
     zstd_decompressor_impl();
     ~zstd_decompressor_impl();
     bool filter( const char*& begin_in, const char* end_in,
                  char*& begin_out, char* end_out, bool flush );
     void close();
 };
 
 } // End namespace detail.
 
 //
 // Template name: zstd_compressor
 // Description: Model of InputFilter and OutputFilter implementing
 //      compression using zstd.
 //
 template<typename Alloc = std::allocator<char> >
 struct basic_zstd_compressor
     : symmetric_filter<detail::zstd_compressor_impl<Alloc>, Alloc>
 {
 private:
     typedef detail::zstd_compressor_impl<Alloc> impl_type;
     typedef symmetric_filter<impl_type, Alloc>  base_type;
 public:
     typedef typename base_type::char_type               char_type;
     typedef typename base_type::category                category;
     basic_zstd_compressor( const zstd_params& = zstd::default_compression,
                            std::streamsize buffer_size = default_device_buffer_size );
 };
 BOOST_IOSTREAMS_PIPABLE(basic_zstd_compressor, 1)
 
 typedef basic_zstd_compressor<> zstd_compressor;
 
 //
 // Template name: zstd_decompressor
 // Description: Model of InputFilter and OutputFilter implementing
 //      decompression using zstd.
 //
 template<typename Alloc = std::allocator<char> >
 struct basic_zstd_decompressor
     : symmetric_filter<detail::zstd_decompressor_impl<Alloc>, Alloc>
 {
 private:
     typedef detail::zstd_decompressor_impl<Alloc> impl_type;
     typedef symmetric_filter<impl_type, Alloc>    base_type;
 public:
     typedef typename base_type::char_type               char_type;
     typedef typename base_type::category                category;
     basic_zstd_decompressor( std::streamsize buffer_size = default_device_buffer_size );
     basic_zstd_decompressor( const zstd_params& p,
                              std::streamsize buffer_size = default_device_buffer_size );
 };
 BOOST_IOSTREAMS_PIPABLE(basic_zstd_decompressor, 1)
 
 typedef basic_zstd_decompressor<> zstd_decompressor;
 
 //----------------------------------------------------------------------------//
 
 //------------------Implementation of zstd_allocator--------------------------//
 
 namespace detail {
 
 template<typename Alloc, typename Base>
 void* zstd_allocator<Alloc, Base>::allocate
     (void* self, size_t items, size_t size)
 {
     size_type len = items * size;
     char* ptr =
         static_cast<allocator_type*>(self)->allocate
             (len + sizeof(size_type)
             #if BOOST_WORKAROUND(BOOST_DINKUMWARE_STDLIB, == 1)
                 , (char*)0
             #endif
             );
     *reinterpret_cast<size_type*>(ptr) = len;
     return ptr + sizeof(size_type);
 }
 
 template<typename Alloc, typename Base>
 void zstd_allocator<Alloc, Base>::deallocate(void* self, void* address)
 {
     char* ptr = reinterpret_cast<char*>(address) - sizeof(size_type);
     size_type len = *reinterpret_cast<size_type*>(ptr) + sizeof(size_type);
     static_cast<allocator_type*>(self)->deallocate(ptr, len);
 }
 
 //------------------Implementation of zstd_compressor_impl--------------------//
 
 template<typename Alloc>
 zstd_compressor_impl<Alloc>::zstd_compressor_impl(const zstd_params& p)
 { init(p, true, static_cast<zstd_allocator<Alloc>&>(*this)); }
 
 template<typename Alloc>
 zstd_compressor_impl<Alloc>::~zstd_compressor_impl()
 { reset(true, false); }
 
 template<typename Alloc>
 bool zstd_compressor_impl<Alloc>::filter
     ( const char*& src_begin, const char* src_end,
       char*& dest_begin, char* dest_end, bool flush )
 {
     before(src_begin, src_end, dest_begin, dest_end);
     int result = deflate(flush ? zstd::finish : zstd::run);
     after(src_begin, dest_begin, true);
     return result != zstd::stream_end;
 }
 
 template<typename Alloc>
 void zstd_compressor_impl<Alloc>::close() { reset(true, true); }
 
 //------------------Implementation of zstd_decompressor_impl------------------//
 
 template<typename Alloc>
 zstd_decompressor_impl<Alloc>::zstd_decompressor_impl(const zstd_params& p)
 { init(p, false, static_cast<zstd_allocator<Alloc>&>(*this)); }
 
 template<typename Alloc>
 zstd_decompressor_impl<Alloc>::~zstd_decompressor_impl()
 { reset(false, false); }
 
 template<typename Alloc>
 zstd_decompressor_impl<Alloc>::zstd_decompressor_impl()
 {
     zstd_params p;
     init(p, false, static_cast<zstd_allocator<Alloc>&>(*this));
 }
 
 template<typename Alloc>
 bool zstd_decompressor_impl<Alloc>::filter
     ( const char*& src_begin, const char* src_end,
       char*& dest_begin, char* dest_end, bool flush )
 {
     before(src_begin, src_end, dest_begin, dest_end);
     int result = inflate(flush ? zstd::finish : zstd::run);
     after(src_begin, dest_begin, false);
     return result != zstd::stream_end;
 }
 
 template<typename Alloc>
 void zstd_decompressor_impl<Alloc>::close() { reset(false, true); }
 
 } // End namespace detail.
 
 //------------------Implementation of zstd_compressor-----------------------//
 
 template<typename Alloc>
 basic_zstd_compressor<Alloc>::basic_zstd_compressor
     (const zstd_params& p, std::streamsize buffer_size)
     : base_type(buffer_size, p) { }
 
 //------------------Implementation of zstd_decompressor-----------------------//
 
 template<typename Alloc>
 basic_zstd_decompressor<Alloc>::basic_zstd_decompressor
     (std::streamsize buffer_size)
     : base_type(buffer_size) { }
 
 template<typename Alloc>
 basic_zstd_decompressor<Alloc>::basic_zstd_decompressor
     (const zstd_params& p, std::streamsize buffer_size)
     : base_type(buffer_size, p) { }
 
 //----------------------------------------------------------------------------//
 
 } } // End namespaces iostreams, boost.
 
 #include <boost/config/abi_suffix.hpp> // Pops abi_suffix.hpp pragmas.
 #ifdef BOOST_MSVC
 # pragma warning(pop)
 #endif
 
 #endif // #ifndef BOOST_IOSTREAMS_ZSTD_HPP_INCLUDED