OpenEuphoria

Re: Proposal for a (small) enhancement to the value() function.

• Posted by CChris <christian.cuvier at agriculture.gouv.fr> Jun 29, 2007
• 711 views

Robert Craig wrote:
> 
> CChris wrote:
> > I just looked at be_execute.c in this respect.
> > 
> > If getc() was defined as an inline function, you could remove this problem
> > by
> > 
> > * having a one char buffer for each open file (handle)
> > * having getc() to update this buffer on each read
> > * having one excess_read flag per file which says whether a character is to
> > be physically read from the file if clear
> > * causing Get() (or Get2() in my version) to attempt to back up using seek()
> > if it reads a pure number in a file as a top level object, and set the above
> > flag using a machine_proc() interface on failure to back up
> > * if the excess_read flag for a file is set, getc() clears it and returns
> > the
> > buffered char, which was read in excess. Otherwise it behaves as usual.
> > * having where() to adjust its return value according to the excess_read
> > status
> > for the requested file.
> > * having seek() to clear the flag for the file for which it is called
> > 
> > I am not sure whether the above can be done as getc() is a macro.
> > And, even if it can be done, is it worth the effort, and is there any chance
> > of a performance penalty in this sensitive area? I don't know C well enough,
> > you probably have a clearer idea. And the final answer may depend on the
> > compiler
> > too.
> 
> I thought about adding an ungetc() several years ago,
> but I didn't go ahead with it because:
>   - there would be added complexity and chance of subtle bugs
>   - Watcom had a bug in this area
>   - no one had ever asked for it
>   - there would be a tiny loss of performance
> 
> Regards,
>    Rob Craig
>    Rapid Deployment Software
>    <a href="http://www.RapidEuphoria.com">http://www.RapidEuphoria.com</a>

Understandable.
Do you think the mod above, which is a virtual ungetc() not relying on the
compiler's library, and with very restricted capabilities, would be useful? At
least, it would correct the issue of the extra space get() reads.
I forgot to mention that EOpen() should clear the flag for the concened file.

CChris