Hello!
Gilles Detillieux wrote:
[skipped]
> > int
> > String::readLine(FILE *in)
> > {
> > Length = 0;
> > allocate_fix_space(2048);
> >
> > while (fgets(Data + Length, Allocated - Length, in))
> > {
> > Length += strlen(Data + Length);
> > if (Length == 0)
> > continue;
> > if (Data[Length - 1] == '\n')
> > {
> > //
> > // A full line has been read. Return it.
> > //
> > chop('\n');
> > return 1;
>
> I think instead of the chop() and return above, you just want a "break;",
> to be consistent with the >> operator below.
If there will be 'break' then line consiting of only '\n' will return 0
to calling function. I tried to make this function as close to
ExternalParser::readLine as possible to remove readLine from
ExternalParser.
> > }
> > if (Allocated > Length + 1)
> > {
> > //
> > // Not all available space filled. Probably EOF?
> > //
> >
> > continue;
> > }
> > //
> > // Only a partial line was read. Increase available space in
> > // string and read some more.
> > //
> >
> > reallocate_space(Allocated << 1);
> > }
> > chop('\n');
>
> I guess the chop() is a judgement call - some may prefer to leave the '\n'
> in the string, while some would prefer it taken out. I guess for our
> purposes, we always want it out, and it's easy to add it if we want.
See above for my reason to remove '\n'.
>
> >
> > return Length > 0;
>
> Should an empty line return 1 or 0? This code will return 0 on any empty
> line, not just at EOF.
No it will not. Because of return 1 above on empty line will be returned
1.
> > }
> >
> > istream &
> > operator >> (istream &in, String &line)
> > {
> > line.Length = 0;
> > line.allocate_fix_space(2048);
> >
> > while (in.get(line.Data + line.Length, line.Allocated - line.Length))
> > {
> > line.Length += strlen(line.Data + line.Length);
> > int c = in.get();
>
> I'm not clear on the semantics of ifstream::get() above, and why you need
> two calls to it. Wouldn't it make more sense to use in.getline() instead,
> and keep the logic of this operator as close to the readLine() method
> above as possible? I believe ifstream::getline()'s semantics are identical
IIRC getline will remove '\n' from buffer as well as from input stream.
So I won't be able to find out whether '\n' was read or just maximum
number of bytes read. istream::get(char *, int maxlen) reads input
stream
until '\n' or maxbytes read leaving '\n' in input stream.
> to fgets(), except that is works on an ifstream instead of a FILE. BTW,
> I think it's ifstream, and not istream.
IIRC ifstream is a subclass of istream. (I don't have GNU implementation
at hand, but it is so in Borland).
>
> > if (c == '\n')
> > {
> > //
> > // A full line has been read. Return it.
> > //
> > break;
> > }
> > if (line.Allocated > line.Length + 2)
> > {
> > //
> > // Not all available space filled. Probably EOF?
> > //
> >
>
> Will this code add EOF to the Data?
Oops. It can. In case if there is a 2048 bytes in input stream
exactly (or 4096 or ...). In other cases 'while' will exit by
condition. So condition above instead of 'if (c == '\n')'
should be 'if (c == '\n' || c == EOF)'.
Alexis
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