Re: [PATCH] for strports.c: scm_c_eval_string_from_file_line

[Bruce Korb]

Marius Vollmer wrote:

>   void
>   scm_c_primitive_load_from_string (const char *str,
>                                     const char *filename, int line)
>   {
>     SCM port, exp;
> 
>     port = scm_open_input_string (scm_str2string (str));
>     scm_set_port_file_name_x (port, scm_str2string (filename));
>     scm_set_port_line_x (port, scm_int2num (line));
> 
>     while (!SCM_EOF_OBJECT_P (exp = scm_read (port)))
>       scm_primitive_eval_x (exp);
>   }
> 
> I think this quite straightforward, no?

No.

> But we might want to offer it ready-made, anyway.  Opinions?

Yes.  It is pretty close to what I wound up with, but I don't
track the preferred way to do things.  For Guile 1.4,
``scm_primitive_eval_x'' gets #define-d into ``scm_eval_x''
and it works.  I also try to avoid gratuitous creations of
string SCM's since the file name is generally invariant.
You omitted returning the final value, which is important :-).
It's easier to ignore if the caller doesn't want it.  And, no,
I didn't find that the research required to do this was obvious.
In fact, there is no ``scm_set_port_file_name_x'' in 1.6.3, so
you must be talking 1.7 here.  I'm still working with 1.4.
Therefore, I must directly assign to ``file_name''.  I may as
well assign the line number, too.

I'd rather it was ready made so I can just #define
my ``ag_scm_c_eval_string_from_file_line'' into
``scm_c_primitive_load_from_string''.  You might tweak it
a bit so a NULL file pointer bypasses the scm_set_port_file_name_x
call.  I'd also use "file_line" in the name, but that is your call.


EXPORT SCM
ag_scm_c_eval_string_from_file_line( tCC* pzExpr, tCC* pzFile, int line )
{
    SCM port;

    {
        tSCC zEx[] = "eval-string-from-file-line";
        SCM  expr  = scm_makfrom0str( pzExpr );
        port = scm_mkstrport( SCM_INUM0, expr, SCM_OPN | SCM_RDNG, zEx );
    }

    {
        static SCM file = SCM_UNDEFINED;
        scm_t_port* pt;

        if (  (file == SCM_UNDEFINED)
           || (strcmp( SCM_CHARS( file ), pzFile ) != 0) )
            file = scm_makfrom0str( pzFile );

        pt = SCM_PTAB_ENTRY( port );
        pt->line_number = line - 1;
        pt->file_name   = file;
    }

    {
        SCM ans = SCM_UNSPECIFIED;

        for (;;) {
            SCM form = scm_read( port );
            if (SCM_EOF_OBJECT_P( form ))
                break;
            ans = scm_primitive_eval_x( form );
        }

        return ans; // return the last answer
    }
}