STL/stl/inc/streambuf

// streambuf standard header

// Copyright (c) Microsoft Corporation.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception

#pragma once
#ifndef _STREAMBUF_
#define _STREAMBUF_
#include <yvals_core.h>
#if _STL_COMPILER_PREPROCESSOR
#include <xiosbase>

#pragma pack(push, _CRT_PACKING)
#pragma warning(push, _STL_WARNING_LEVEL)
#pragma warning(disable : _STL_DISABLED_WARNINGS)
_STL_DISABLE_CLANG_WARNINGS
#pragma push_macro("new")
#undef new

_STD_BEGIN
template <class _Elem, class _Traits>
class basic_streambuf { // control read/write buffers
protected:
    __CLR_OR_THIS_CALL basic_streambuf() : _Plocale(new locale) {
        _Init();
    }

    __CLR_OR_THIS_CALL basic_streambuf(_Uninitialized) {}

    __CLR_OR_THIS_CALL basic_streambuf(const basic_streambuf& _Right) : _Plocale(new locale(_Right.getloc())) {
        _Init();
        setp(_Right.pbase(), _Right.pptr(), _Right.epptr());
        setg(_Right.eback(), _Right.gptr(), _Right.egptr());
    }

    basic_streambuf& __CLR_OR_THIS_CALL operator=(const basic_streambuf& _Right) {
        if (this != _STD addressof(_Right)) {
            setp(_Right.pbase(), _Right.pptr(), _Right.epptr());
            setg(_Right.eback(), _Right.gptr(), _Right.egptr());
            pubimbue(_Right.getloc());
        }
        return *this;
    }

    void __CLR_OR_THIS_CALL swap(basic_streambuf& _Right) {
        if (this != _STD addressof(_Right)) {
            _Elem* _Pfirst0 = pbase();
            _Elem* _Pnext0  = pptr();
            _Elem* _Pend    = epptr();
            _Elem* _Gfirst0 = eback();
            _Elem* _Gnext0  = gptr();
            _Elem* _Gend    = egptr();

            setp(_Right.pbase(), _Right.pptr(), _Right.epptr());
            _Right.setp(_Pfirst0, _Pnext0, _Pend);

            setg(_Right.eback(), _Right.gptr(), _Right.egptr());
            _Right.setg(_Gfirst0, _Gnext0, _Gend);

            _STD swap(_Plocale, _Right._Plocale);
        }
    }

public:
    using char_type   = _Elem;
    using traits_type = _Traits;

    virtual __CLR_OR_THIS_CALL ~basic_streambuf() noexcept {
        delete _Plocale;
    }

    using int_type = typename _Traits::int_type;
    using pos_type = typename _Traits::pos_type;
    using off_type = typename _Traits::off_type;

    pos_type __CLR_OR_THIS_CALL pubseekoff(off_type _Off, ios_base::seekdir _Way,
        ios_base::openmode _Mode = ios_base::in | ios_base::out) { // change position by _Off, according to _Way, _Mode
        return seekoff(_Off, _Way, _Mode);
    }

#if _HAS_OLD_IOSTREAMS_MEMBERS
    pos_type __CLR_OR_THIS_CALL pubseekoff(off_type _Off, ios_base::seek_dir _Way,
        ios_base::open_mode _Mode) { // change position by _Off, according to _Way, _Mode (old style)
        return pubseekoff(_Off, static_cast<ios_base::seekdir>(_Way), static_cast<ios_base::openmode>(_Mode));
    }
#endif // _HAS_OLD_IOSTREAMS_MEMBERS

    pos_type __CLR_OR_THIS_CALL pubseekpos(pos_type _Pos,
        ios_base::openmode _Mode = ios_base::in | ios_base::out) { // change position to _Pos, according to _Mode
        return seekpos(_Pos, _Mode);
    }

#if _HAS_OLD_IOSTREAMS_MEMBERS
    pos_type __CLR_OR_THIS_CALL pubseekpos(pos_type _Pos,
        ios_base::open_mode _Mode) { // change position to _Pos, according to _Mode (old style)
        return seekpos(_Pos, static_cast<ios_base::openmode>(_Mode));
    }
#endif // _HAS_OLD_IOSTREAMS_MEMBERS

    basic_streambuf* __CLR_OR_THIS_CALL pubsetbuf(_Elem* _Buffer,
        streamsize _Count) { // offer _Buffer to external agent
        return setbuf(_Buffer, _Count);
    }

    locale __CLR_OR_THIS_CALL pubimbue(const locale& _Newlocale) { // set locale to argument
        locale _Oldlocale = *_Plocale;
        imbue(_Newlocale);
        *_Plocale = _Newlocale;
        return _Oldlocale;
    }

    locale __CLR_OR_THIS_CALL getloc() const { // get locale
        return *_Plocale;
    }

    streamsize __CLR_OR_THIS_CALL in_avail() {
        streamsize _Res = _Gnavail();
        return 0 < _Res ? _Res : showmanyc();
    }

    int __CLR_OR_THIS_CALL pubsync() { // synchronize with external agent
        return sync();
    }

    int_type __CLR_OR_THIS_CALL sbumpc() { // get a character and point past it
        return 0 < _Gnavail() ? _Traits::to_int_type(*_Gninc()) : uflow();
    }

    int_type __CLR_OR_THIS_CALL sgetc() { // get a character and don't point past it
        return 0 < _Gnavail() ? _Traits::to_int_type(*gptr()) : underflow();
    }

    streamsize __CLR_OR_THIS_CALL sgetn(_Elem* _Ptr,
        streamsize _Count) { // get up to _Count characters into array beginning at _Ptr
        return xsgetn(_Ptr, _Count);
    }

    int_type __CLR_OR_THIS_CALL snextc() { // point to next character and return it
        return 1 < _Gnavail()                                 ? _Traits::to_int_type(*_Gnpreinc())
             : _Traits::eq_int_type(_Traits::eof(), sbumpc()) ? _Traits::eof()
                                                              : sgetc();
    }

    int_type __CLR_OR_THIS_CALL sputbackc(_Elem _Ch) { // put back _Ch
        if (gptr() && eback() < gptr() && _Traits::eq(_Ch, gptr()[-1])) {
            return _Traits::to_int_type(*_Gndec());
        }

        return pbackfail(_Traits::to_int_type(_Ch));
    }

#if _HAS_OLD_IOSTREAMS_MEMBERS
    void __CLR_OR_THIS_CALL stossc() { // point past a character
        if (0 < _Gnavail()) {
            _Gninc();
        } else {
            uflow();
        }
    }
#endif // _HAS_OLD_IOSTREAMS_MEMBERS

    int_type __CLR_OR_THIS_CALL sungetc() { // back up one position
        return gptr() && eback() < gptr() ? _Traits::to_int_type(*_Gndec()) : pbackfail();
    }

    int_type __CLR_OR_THIS_CALL sputc(_Elem _Ch) { // put a character
        return 0 < _Pnavail() ? _Traits::to_int_type(*_Pninc() = _Ch) : overflow(_Traits::to_int_type(_Ch));
    }

    streamsize __CLR_OR_THIS_CALL sputn(const _Elem* _Ptr,
        streamsize _Count) { // put _Count characters from array beginning at _Ptr
        return xsputn(_Ptr, _Count);
    }

    virtual void __CLR_OR_THIS_CALL _Lock() {} // set the thread lock (overridden by basic_filebuf)

    virtual void __CLR_OR_THIS_CALL _Unlock() {} // clear the thread lock (overridden by basic_filebuf)

protected:
    _Elem* __CLR_OR_THIS_CALL eback() const {
        return *_IGfirst;
    }

    _Elem* __CLR_OR_THIS_CALL gptr() const {
        return *_IGnext;
    }

    _Elem* __CLR_OR_THIS_CALL pbase() const {
        return *_IPfirst;
    }

    _Elem* __CLR_OR_THIS_CALL pptr() const {
        return *_IPnext;
    }

    _Elem* __CLR_OR_THIS_CALL egptr() const {
        return *_IGnext + *_IGcount;
    }

    void __CLR_OR_THIS_CALL gbump(int _Off) { // alter current position in read buffer by _Off
        *_IGcount -= _Off;
        *_IGnext += _Off;
    }

    void __CLR_OR_THIS_CALL setg(_Elem* _First, _Elem* _Next, _Elem* _Last) { // set pointers for read buffer
        *_IGfirst = _First;
        *_IGnext  = _Next;
        *_IGcount = static_cast<int>(_Last - _Next);
    }

    _Elem* __CLR_OR_THIS_CALL epptr() const {
        return *_IPnext + *_IPcount;
    }

    _Elem* __CLR_OR_THIS_CALL _Gndec() { // decrement current position in read buffer
        ++*_IGcount;
        return --*_IGnext;
    }

    _Elem* __CLR_OR_THIS_CALL _Gninc() { // increment current position in read buffer
        --*_IGcount;
        return (*_IGnext)++;
    }

    _Elem* __CLR_OR_THIS_CALL _Gnpreinc() { // preincrement current position in read buffer
        --*_IGcount;
        return ++(*_IGnext);
    }

    streamsize __CLR_OR_THIS_CALL _Gnavail() const { // count number of available elements in read buffer
        return *_IGnext ? *_IGcount : 0;
    }

    void __CLR_OR_THIS_CALL pbump(int _Off) { // alter current position in write buffer by _Off
        *_IPcount -= _Off;
        *_IPnext += _Off;
    }

    void __CLR_OR_THIS_CALL setp(_Elem* _First, _Elem* _Last) { // set pointers for write buffer
        *_IPfirst = _First;
        *_IPnext  = _First;
        *_IPcount = static_cast<int>(_Last - _First);
    }

    void __CLR_OR_THIS_CALL setp(
        _Elem* _First, _Elem* _Next, _Elem* _Last) { // set pointers for write buffer, extended version
        *_IPfirst = _First;
        *_IPnext  = _Next;
        *_IPcount = static_cast<int>(_Last - _Next);
    }

    _Elem* __CLR_OR_THIS_CALL _Pninc() { // increment current position in write buffer
        --*_IPcount;
        return (*_IPnext)++;
    }

    streamsize __CLR_OR_THIS_CALL _Pnavail() const { // count number of available positions in write buffer
        return *_IPnext ? *_IPcount : 0;
    }

    void __CLR_OR_THIS_CALL _Init() { // initialize buffer parameters for no buffers
        _IGfirst = &_Gfirst;
        _IPfirst = &_Pfirst;
        _IGnext  = &_Gnext;
        _IPnext  = &_Pnext;
        _IGcount = &_Gcount;
        _IPcount = &_Pcount;
        setp(nullptr, nullptr);
        setg(nullptr, nullptr, nullptr);
    }

    void __CLR_OR_THIS_CALL _Init(_Elem** _Gf, _Elem** _Gn, int* _Gc, _Elem** _Pf, _Elem** _Pn, int* _Pc) {
        // initialize buffer parameters as specified
        _IGfirst = _Gf;
        _IPfirst = _Pf;
        _IGnext  = _Gn;
        _IPnext  = _Pn;
        _IGcount = _Gc;
        _IPcount = _Pc;
    }

    virtual int_type __CLR_OR_THIS_CALL overflow(int_type = _Traits::eof()) { // put a character to stream (always fail)
        return _Traits::eof();
    }

    virtual int_type __CLR_OR_THIS_CALL pbackfail(int_type = _Traits::eof()) {
        // put a character back to stream (always fail)
        return _Traits::eof();
    }

    virtual streamsize __CLR_OR_THIS_CALL showmanyc() {
        return 0;
    }

    virtual int_type __CLR_OR_THIS_CALL underflow() { // get a character from stream, but don't point past it
        return _Traits::eof();
    }

    virtual int_type __CLR_OR_THIS_CALL uflow() { // get a character from stream, point past it
        return _Traits::eq_int_type(_Traits::eof(), underflow()) ? _Traits::eof() : _Traits::to_int_type(*_Gninc());
    }

    virtual streamsize __CLR_OR_THIS_CALL xsgetn(_Elem* _Ptr, streamsize _Count) { // get _Count characters from stream
        const streamsize _Start_count = _Count;

        while (0 < _Count) {
            streamsize _Size = _Gnavail();
            if (0 < _Size) { // copy from read buffer
                if (_Count < _Size) {
                    _Size = _Count;
                }

                _Traits::copy(_Ptr, gptr(), static_cast<size_t>(_Size));
                _Ptr += _Size;
                _Count -= _Size;
                gbump(static_cast<int>(_Size));
            } else {
                const int_type _Meta = uflow();
                if (_Traits::eq_int_type(_Traits::eof(), _Meta)) {
                    break; // end of file, quit
                }

                // get a single character
                *_Ptr++ = _Traits::to_char_type(_Meta);
                --_Count;
            }
        }

        return _Start_count - _Count;
    }

    virtual streamsize __CLR_OR_THIS_CALL xsputn(const _Elem* _Ptr, streamsize _Count) {
        // put _Count characters to stream
        const streamsize _Start_count = _Count;
        while (0 < _Count) {
            streamsize _Size = _Pnavail();
            if (0 < _Size) { // copy to write buffer
                if (_Count < _Size) {
                    _Size = _Count;
                }

                _Traits::copy(pptr(), _Ptr, static_cast<size_t>(_Size));
                _Ptr += _Size;
                _Count -= _Size;
                pbump(static_cast<int>(_Size));
            } else if (_Traits::eq_int_type(_Traits::eof(), overflow(_Traits::to_int_type(*_Ptr)))) {
                break; // single character put failed, quit
            } else { // count character successfully put
                ++_Ptr;
                --_Count;
            }
        }

        return _Start_count - _Count;
    }

    virtual pos_type __CLR_OR_THIS_CALL seekoff(
        off_type, ios_base::seekdir, ios_base::openmode = ios_base::in | ios_base::out) {
        // change position by offset, according to way and mode
        return pos_type(off_type(-1));
    }

    virtual pos_type __CLR_OR_THIS_CALL seekpos(pos_type, ios_base::openmode = ios_base::in | ios_base::out) {
        // change to specified position, according to mode
        return pos_type(off_type(-1));
    }

    virtual basic_streambuf* __CLR_OR_THIS_CALL setbuf(_Elem*, streamsize) {
        // offer buffer to external agent (do nothing)
        return this;
    }

    virtual int __CLR_OR_THIS_CALL sync() { // synchronize with external agent (do nothing)
        return 0;
    }

    virtual void __CLR_OR_THIS_CALL imbue(const locale&) {} // set locale to argument (do nothing)

private:
    _Elem* _Gfirst; // beginning of read buffer
    _Elem* _Pfirst; // beginning of write buffer
    _Elem** _IGfirst; // pointer to beginning of read buffer
    _Elem** _IPfirst; // pointer to beginning of write buffer
    _Elem* _Gnext; // current position in read buffer
    _Elem* _Pnext; // current position in write buffer
    _Elem** _IGnext; // pointer to current position in read buffer
    _Elem** _IPnext; // pointer to current position in write buffer

    int _Gcount; // length of read buffer
    int _Pcount; // length of write buffer
    int* _IGcount; // pointer to length of read buffer
    int* _IPcount; // pointer to length of write buffer

protected:
    locale* _Plocale; // pointer to imbued locale object
};

#if defined(_DLL_CPPLIB)

#if !defined(_CRTBLD) || defined(__FORCE_INSTANCE)
template class _CRTIMP2_PURE_IMPORT basic_streambuf<char, char_traits<char>>;
template class _CRTIMP2_PURE_IMPORT basic_streambuf<wchar_t, char_traits<wchar_t>>;
#endif // !defined(_CRTBLD) || defined(__FORCE_INSTANCE)

#ifdef __FORCE_INSTANCE
template class _CRTIMP2_PURE_IMPORT basic_streambuf<unsigned short, char_traits<unsigned short>>;
#endif // __FORCE_INSTANCE
#endif // defined(_DLL_CPPLIB)
_STD_END

#pragma pop_macro("new")
_STL_RESTORE_CLANG_WARNINGS
#pragma warning(pop)
#pragma pack(pop)
#endif // _STL_COMPILER_PREPROCESSOR
#endif // _STREAMBUF_