iofgldfl.cpp

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C++ 代码 · 共 187 行

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*
*                            Open Watcom Project
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*    Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
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*  ========================================================================
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*    This file contains Original Code and/or Modifications of Original
*    Code as defined in and that are subject to the Sybase Open Watcom
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*    except in compliance with the License. BY USING THIS FILE YOU AGREE TO
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#ifdef __SW_FH
#include "iost.h"
#else
#include "variety.h"
#include <ctype.h>
#include <stdlib.h>
#include <iostream>
#include <streambu>
#endif
#include "ioutil.h"
#include "lock.h"
#include "iofhdr.h"

std::ios::iostate __getLDFsign( std::streambuf *sb, char *&bufptr, int is_exp ) {

    std::ios::iostate  state;
    int           c, sign;

    state = std::ios::goodbit;
    c = sb->speekc();
    if( c == EOF ) {
        state |= std::ios::eofbit;
        return( state );
    }
    if( !isdigit(c)  ) {
        if( c == '+'  ||  c == '-' ) {
            sign = sb->sbumpc();
            c = sb->speekc();
            if( !isdigit(c) ) {
                if( is_exp || c != '.' ) {
                    state |= std::ios::failbit;
                    sb->sputbackc( (char)sign );
                    return( state );
                }
            }
            *(bufptr++) = (char)sign;
            return( state );
        }
    }
    return( state );
}

std::ios::iostate __getLDFmantissa( std::streambuf *sb, char *&bufptr ) {

    std::ios::iostate  state;
    int           c, mant_digits;
    char          have_decimal;

    state = std::ios::goodbit;
    mant_digits  = 0;
    have_decimal = FALSE;
    for( ;; ) {
        c = sb->speekc();
        if( c == EOF ) {
            break;
        }
        if( isdigit( c ) ) {
            mant_digits++;
            sb->sbumpc();
        } else if( c == '.' ) {
            if( have_decimal ) {
                if ( mant_digits == 0 ) {
                    bufptr--;
                    sb->sputbackc( '.' );
                    state |= std::ios::failbit;
                    return( state );
                } else {
                    break;
                }
            }
            have_decimal = TRUE;
            sb->sbumpc();
        } else {
           break;
        }
        *(bufptr++) = (char)c;
    }
    if( mant_digits == 0 ) {
        state |= std::ios::failbit;
        if ( have_decimal ) {
            bufptr--;
            sb->sputbackc( '.' );
        }
    }
    return( state );
}

std::ios::iostate __getLDFexponent( std::streambuf *sb, char *&bufptr ) {

    std::ios::iostate  state;
    int           c, exp, exp_digits;

    state = std::ios::goodbit;
    exp_digits = 0;
    c = sb->speekc();
    if( tolower(c) != 'e' ) {
         return( state );
    }
    exp = sb->sbumpc();
    *(bufptr++) = (char)exp;  // keep the 'E'
    state |= __getLDFsign( sb, bufptr, TRUE );
    if ( state & std::ios::eofbit ) {
        bufptr--;             // discard the 'E'
        sb->sputbackc( (char)exp );
        return( std::ios::goodbit );
    }
    if ( !state ) {
        for( ;; ) {
            c = sb->speekc();
            if( isdigit( c ) ) {
                exp_digits++;
                sb->sbumpc();
            } else {
                if( exp_digits == 0 ) {
                    bufptr--;         // discard the 'E'
                    sb->sputbackc( (char)exp );
                    return( state );
                } else {
                    break;
                }
            }
            *(bufptr++) = (char)c;
        }
    }
    return( state );
}


// Read the input stream into buffer as long as it is a prefix of a
// floating point number. Return ios::failbit if something goes wrong in
// the format.

std::ios::iostate __GetLDFloat( std::streambuf *sb, char *buffer ) {

    char         *bufptr;
    std::ios::iostate  state;

    state = std::ios::goodbit;
    bufptr = buffer;
    state |= __getLDFsign( sb, bufptr, FALSE );
    if( state & std::ios::eofbit ) {
        state |= std::ios::failbit;
    }
    if( !state ) {
        state |= __getLDFmantissa( sb, bufptr );
    }
    if( !state ) {
        state |= __getLDFexponent( sb, bufptr );
    }
    if( state ) {
        buffer[0] = '\0';
    }
    *bufptr = '\0';
    return( state );
}