streamb1.cpp

C标准库源代码

/***
*streamb1.cpp - non-core functions for streambuf class.
*
*       Copyright (c) 1990-1997, Microsoft Corporation.  All rights reserved.
*
*Purpose:
*       None-core functions for streambuf class.
*
*******************************************************************************/

#include <cruntime.h>
#include <internal.h>
#include <iostream.h>
#pragma hdrstop


/***
*int streambuf::snextc() -
*
*Purpose:
*       Increments get_pointer and returns the character following the new
*       get_pointer.
*
*Entry:
*       None.
*
*Exit:
*       Returns the next character or EOF.
*
*Exceptions:
*       Returns EOF if error.
*
*******************************************************************************/
int streambuf::snextc()
{
    if (_fUnbuf)
        {
        if (x_lastc==EOF)
            underflow();                // skip 1st character
        return x_lastc = underflow();   // return next character, or EOF
        }
    else
        {
        if ((!egptr()) || (gptr()>=egptr()))
            underflow();                // make sure buffer

        if ((++_gptr) < egptr())
            return (int)(unsigned char) *gptr();
        return underflow();             // returns next character, or EOF
        }
}


/***
*int streambuf::sbumpc() -
*
*Purpose:
*       Increments get_pointer and returns the character that the previous
*       get_pointer pointed to.
*
*Entry:
*       None.
*
*Exit:
*       Returns current character before bumping get pointer.
*
*Exceptions:
*       Returns EOF if error.
*
*******************************************************************************/
int streambuf::sbumpc()
{
    int c;
    if (_fUnbuf) // no buffer
        {
        if (x_lastc==EOF)
            {
            c = underflow();
            }
        else
            {
            c = x_lastc;
            x_lastc = EOF;
            }
        }
    else
        {
        if( gptr() < egptr() )
            {
            c = (int)(unsigned char)*(gptr());
            }
        else
            {
            c = underflow();
            }
        _gptr++;
        }
    return c;
}

/***
*void streambuf::stossc() - advance get pointer
*
*Purpose:
*       Advances the get pointer.  Does not check for EOF.
*
*Entry:
*       None.
*
*Exit:
*       None.
*
*Exceptions:
*
*******************************************************************************/
void streambuf::stossc()
{
    if (_fUnbuf)
        {
        if (x_lastc==EOF)
            underflow();        // throw away current character
        else
            x_lastc=EOF;        // discard current cached character
        }
    else
        {
        if (gptr() >= egptr())
            underflow();
        if (gptr() < egptr())
            _gptr++;
        }
}

/***
*int streambuf::sgetc() -
*
*Purpose:
*       Returns the character that the previous get_pointer points to.
*       DOES NOT advance the get pointer.
*
*Entry:
*       None.
*
*Exit:
*       Returns current character or EOF if error.
*
*Exceptions:
*       Returns EOF if error.
*
*******************************************************************************/
int streambuf::sgetc()
{
    if (_fUnbuf)  // no buffer
        {
        if (x_lastc==EOF)
            x_lastc = underflow();
        return x_lastc;
        }
     else
        return underflow();
}