Re: [Cgdb-devel] cgdb and readline

[Bob R. <bob...@co...>]

Wow, I must have looked right over that. Thanks Peter! This is exactly
what we need.

Bobby

On Wed, Feb 19, 2003 at 10:21:57PM -0500, Peter Kovacs wrote:
> I was just searching through the readline info pages and I found this
> entry:
>=20
>     Alternate Interface
>     -------------------
>=20
>        An alternate interface is available to plain `readline()'.  Some
>     applications need to interleave keyboard I/O with file, device, or wi=
ndow
>     system I/O, typically by using a main loop to `select()' on various f=
ile
>     descriptors.  To accomodate this need, readline can also be invoked a=
s a
>     `callback' function from an event loop.  There are functions availabl=
e to
>     make this easy.
>=20
>      - Function: void rl_callback_handler_install (const char *prompt,
>             rl_vcpfunc_t *lhandler)
>          Set up the terminal for readline I/O and display the initial exp=
anded
>          value of PROMPT.  Save the value of LHANDLER to use as a functio=
n to
>          call when a complete line of input has been entered.  The functi=
on
>          takes the text of the line as an argument.
>=20
>      - Function: void rl_callback_read_char (void)
>          Whenever an application determines that keyboard input is availa=
ble,
>          it should call `rl_callback_read_char()', which will read the ne=
xt
>          character from the current input source.  If that character comp=
letes
>          the line, `rl_callback_read_char' will invoke the LHANDLER funct=
ion
>          saved by `rl_callback_handler_install' to process the line.  `EO=
F' is
>          indicated by calling LHANDLER with a `NULL' line.
>=20
>      - Function: void rl_callback_handler_remove (void)
>          Restore the terminal to its initial state and remove the line ha=
ndler.
>          This may be called from within a callback as well as independent=
ly.
>=20
> That seems to be exactly what we need doesn't it?  I'm not sure how we
> would integrate this into our main loop, but at least its a good start.
>=20
> - Peter
>=20
> On Wed, Feb 19, 2003 at 10:12:36PM -0500, Bob Rossi wrote:
> > Hey guys,
> >=20
> > Look at this small example. It reads a line at a time and prints it.
> >=20
> >    #include <readline/readline.h>
> >    #include <readline/history.h>
> >    #include <stdlib.h>
> >=20
> >    /* Gets called when the user hits '\t' */
> >    int rl_complete (int ignore, int invoking_key) {
> >        fprintf(stderr, "complete\n");
> >        return 0;
> >    }
> >=20
> >    int main(int argc, char **argv){
> >        static char *line;
> >        while(1) {
> >            line =3D readline("PROMPT:");
> >            fprintf(stderr, "LINE=3D(%s)\n", line);
> >        }
> >        return 0;
> >    }
> >=20
> > I am trying to integrate readline into cgdb and ran into a problem.
> > Readline has a function called 'readline' that gets a line of input from
> > stdin. This is great, however, it is a blocking call ( It reads a whole
> > line and then returns). This is not good, since cgdb should also be able
> > to receive input if the user is in cgdb mode.=20
> >=20
> > For example, the users types 'info sour' and the ESC 'j' ( to go down a=
 line )=20
> > and then 'i' ( to get back into gdb mode ) and then 'e<CR>'.=20
> >=20
> > How would we get readline to give up control? Or feed it a char at a
> > time? I don't know how to resolve this problem.
> >=20
> > By the way, currently cgdb sits in a select loop reading from stdin,
> > gdb's stdout, and the debugged programs stdout (tty). How could we make
> > readline be a part of this?
> >=20
> > Any suggestions?
> >=20
> > Thanks,
> > Bobby
>=20
>=20
>=20
> --=20
> Peter D. Kovacs <pe...@ko...>