C++的流basic_streambuf

關鍵字：basic_streambufC++的流basic_streambuf
不是個抽象類,但是他是C++流的基類.它提供了基本的緩沖區管理.它包含六個緩存區指針,三個分別是讀指針(開頭,結尾,當前),另外三個是寫指針(開頭,結尾,當前)
 
    讀開始指針                            當前讀指針                                    讀結尾指針
_M_gbegin                          _M_gnext                      _M_gend
         
         =========================================================     
              ^                                                      ^                                              ^
       _M_pbegin                          _M_pnext                      _M_pend
           寫開始指針                            當前寫指針                           寫結尾指針
 
template <class_CharT, class_Traits>
classbasic_streambuf
{
 friendclassbasic_istream<_CharT, _Traits>;
 friendclassbasic_ostream<_CharT, _Traits>;
public:                         // Typedefs.
 typedef_CharT                   char_type;
 typedeftypename_Traits::int_type        int_type;
 typedeftypename_Traits::pos_type     pos_type;
 typedeftypename_Traits::off_type       off_type;
 typedef_Traits                    traits_type;
 
public:                         // Destructor.
 virtual ~basic_streambuf() {}
 
public:                         // Locale-related functions.
 localepubimbue(constlocale& __loc) {
    this->imbue(__loc);
    locale__tmp = _M_locale;
    _M_locale = __loc;
    return__tmp;
 }
 localegetloc() const { return_M_locale; }
 
public:                         // Buffer management.
 //設置緩沖區和長度
 basic_streambuf* pubsetbuf(char_type* __s, streamsize__n) 
    { returnthis->setbuf(__s, __n); }
 
 //設置緩沖區偏移量,簡單調用seekoff()函數
 pos_typepubseekoff(off_type__offset, ios_base::seekdir__way,
                      ios_base::openmode__mod = ios_base::in | ios_base::out)
    { returnthis->seekoff(__offset, __way, __mod); }
//設置緩沖區位置,簡單調用seekpos()函數
 pos_typepubseekpos(pos_type__sp,
                      ios_base::openmode__mod = ios_base::in | ios_base::out)
    { returnthis->seekpos(__sp, __mod); }
 
//放置緩沖區同步,簡單調用sync()函數
 intpubsync() { returnthis->sync(); }

原文轉自：http://www.kjueaiud.com