mirror of
https://github.com/libSDL2pp/libSDL2pp.git
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231 lines
7.5 KiB
C++
231 lines
7.5 KiB
C++
/*
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libSDL2pp - C++11 bindings/wrapper for SDL2
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Copyright (C) 2014-2016 Dmitry Marakasov <amdmi3@amdmi3.ru>
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This software is provided 'as-is', without any express or implied
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warranty. In no event will the authors be held liable for any damages
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arising from the use of this software.
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Permission is granted to anyone to use this software for any purpose,
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including commercial applications, and to alter it and redistribute it
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freely, subject to the following restrictions:
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1. The origin of this software must not be misrepresented; you must not
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claim that you wrote the original software. If you use this software
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in a product, an acknowledgment in the product documentation would be
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appreciated but is not required.
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2. Altered source versions must be plainly marked as such, and must not be
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misrepresented as being the original software.
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3. This notice may not be removed or altered from any source distribution.
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*/
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#ifndef SDL2PP_STREAMRWOPS_HH
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#define SDL2PP_STREAMRWOPS_HH
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#include <SDL2pp/RWops.hh>
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#include <stdexcept>
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#include <iostream>
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#include <type_traits>
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namespace SDL2pp {
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////////////////////////////////////////////////////////////
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/// \brief RWops adaptor for STL streams
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///
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/// \ingroup io
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///
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/// \headerfile SDL2pp/StreamRWops.hh
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///
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/// This class extends functionality of %RWops concept onto STL
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/// streams. With ContainerRWops, you may read from / write to
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/// STL streams with %SDL functions.
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///
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/// This template supports both input and output streams, but not
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/// at the same time, as separate input and output pointers of
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/// streams are not compatible with %RWops.
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///
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////////////////////////////////////////////////////////////
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template <class S>
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class StreamRWops : public CustomRWops {
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// since STL streams have different pointers for reading and writing,
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// supporting both at the same time is impossible
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static_assert(!(std::is_base_of<std::istream, S>::value && std::is_base_of<std::ostream, S>::value), "StreamRWops does not support reading and writing at the same time");
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protected:
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S& stream_; ///< Reference to stream
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private:
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template <class SS>
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typename std::enable_if<std::is_base_of<std::istream, SS>::value && !std::is_base_of<std::ostream, SS>::value, void>::type SeekHelper(typename SS::off_type off, std::ios_base::seekdir dir) {
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stream_.seekg(off, dir);
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}
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template <class SS>
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typename std::enable_if<!std::is_base_of<std::istream, SS>::value && std::is_base_of<std::ostream, SS>::value, void>::type SeekHelper(typename SS::off_type off, std::ios_base::seekdir dir) {
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stream_.seekp(off, dir);
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}
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template <class SS>
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typename std::enable_if<std::is_base_of<std::istream, SS>::value && !std::is_base_of<std::ostream, SS>::value, typename SS::off_type>::type TellHelper() {
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return stream_.tellg();
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}
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template <class SS>
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typename std::enable_if<!std::is_base_of<std::istream, SS>::value && std::is_base_of<std::ostream, SS>::value, typename SS::off_type>::type TellHelper() {
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return stream_.tellp();
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}
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template <class SS>
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typename std::enable_if<std::is_base_of<std::istream, SS>::value, size_t>::type ReadHelper(void* ptr, size_t size, size_t maxnum) {
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stream_.read(static_cast<char*>(ptr), size * maxnum);
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// http://en.cppreference.com/w/cpp/io/streamsize:
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// "Except in the constructors of std::strstreambuf,
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// negative values of std::streamsize are never used"
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size_t nread = static_cast<size_t>(stream_.gcount());
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// eof is OK
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if (stream_.rdstate() == (std::ios_base::eofbit | std::ios_base::failbit))
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stream_.clear();
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if (nread != size * maxnum) {
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// short read
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char* pos = static_cast<char*>(ptr);
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pos += nread;
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size_t count = nread % size;
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// put partially read object back into the stream
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while (count != 0) {
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stream_.putback(*--pos);
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--count;
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}
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}
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return nread / size;
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}
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template <class SS>
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typename std::enable_if<!std::is_base_of<std::istream, SS>::value, size_t>::type ReadHelper(void*, size_t, size_t) {
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return 0;
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}
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template <class SS>
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typename std::enable_if<std::is_base_of<std::ostream, SS>::value, size_t>::type WriteHelper(const void* ptr, size_t size, size_t num) {
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stream_.write(static_cast<const char*>(ptr), size * num);
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// XXX: there seem to be no reliable way to tell how much
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// was actually written
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if (stream_.rdstate() & std::ios_base::badbit)
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return 0;
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return num;
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}
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template <class SS>
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typename std::enable_if<!std::is_base_of<std::ostream, SS>::value, size_t>::type WriteHelper(const void*, size_t, size_t) {
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return 0;
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}
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template <class SS>
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typename std::enable_if<std::is_base_of<std::ostream, SS>::value, int>::type CloseHelper() {
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stream_.flush();
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return (stream_.rdstate() & std::ios_base::badbit) ? -1 : 0;
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}
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template <class SS>
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typename std::enable_if<!std::is_base_of<std::ostream, SS>::value, int>::type CloseHelper() {
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return 0;
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}
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public:
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////////////////////////////////////////////////////////////
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/// \brief Construct StreamRWops for specified stream
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///
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/// \param[in] stream Stream to use
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///
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////////////////////////////////////////////////////////////
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StreamRWops(S& stream) : stream_(stream) {
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}
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////////////////////////////////////////////////////////////
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/// \brief Seek within the stream
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///
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/// \param[in] offset Offset in bytes, relative to whence location; can
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/// be negative
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/// \param[in] whence Any of RW_SEEK_SET, RW_SEEK_CUR, RW_SEEK_END
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///
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/// \returns Final offset in the stream after the seek or -1 on error
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///
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/// \see SDL2pp::RWops::Seek
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/// \see http://wiki.libsdl.org/SDL_RWseek
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///
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////////////////////////////////////////////////////////////
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virtual Sint64 Seek(Sint64 offset, int whence) override {
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switch (whence) {
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case RW_SEEK_SET:
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SeekHelper<S>(offset, std::ios_base::beg);
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break;
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case RW_SEEK_CUR:
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SeekHelper<S>(offset, std::ios_base::cur);
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break;
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case RW_SEEK_END:
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SeekHelper<S>(offset, std::ios_base::end);
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break;
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default:
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throw std::logic_error("Unexpected whence value for StreamRWops::Seek");
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}
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return TellHelper<S>();
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}
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////////////////////////////////////////////////////////////
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/// \brief Read from a stream
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///
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/// \param[in] ptr Pointer to a buffer to read data into
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/// \param[in] size Size of each object to read, in bytes
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/// \param[in] maxnum Maximum number of objects to be read
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///
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/// \returns Number of objects read, or 0 at error or end of file
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///
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/// \see SDL2pp::RWops::Read
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/// \see http://wiki.libsdl.org/SDL_RWread
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///
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////////////////////////////////////////////////////////////
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virtual size_t Read(void* ptr, size_t size, size_t maxnum) override {
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return ReadHelper<S>(ptr, size, maxnum);
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}
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////////////////////////////////////////////////////////////
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/// \brief Write to a stream
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///
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/// \param[in] ptr Pointer to a buffer containing data to write
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/// \param[in] size Size of each object to write, in bytes
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/// \param[in] num Number of objects to be write
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///
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/// \returns Number of objects written
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///
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/// \see SDL2pp::RWops::Write
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/// \see http://wiki.libsdl.org/SDL_RWwrite
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///
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////////////////////////////////////////////////////////////
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virtual size_t Write(const void* ptr, size_t size, size_t num) override {
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return WriteHelper<S>(ptr, size, num);
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}
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////////////////////////////////////////////////////////////
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/// \brief Close stream
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///
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/// \returns 0 on success or a negative error code on failure
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///
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/// \see SDL2pp::RWops::Close
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/// \see http://wiki.libsdl.org/SDL_RWclose
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///
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////////////////////////////////////////////////////////////
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virtual int Close() override {
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return CloseHelper<S>();
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}
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};
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}
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#endif
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