Re: GDB/MI and ">" prompts

[Joel Brobecker <brobecker@adacore.com>]

On Sat, Apr 28, 2012 at 11:33:28AM +0300, Eli Zaretskii wrote:
> 
> Ping!  Is the patch below OK for committing?

I don't really know what the consequences would be to switch
temporarily to the CLI interpreter. I am hoping someone else might.
If not, there's only going to be one way to know, which it to give
it a try. Right now is a good time for this sort of attempt, as
we are still about 4 weeks away from 7.5 branching.

> 
> > Date: Sun, 22 Apr 2012 19:04:17 +0300
> > From: Eli Zaretskii <eliz@gnu.org>
> > Cc: gdb-patches@sourceware.org
> > 
> > [I moved this to gdb-patches, since I propose a patch below.]
> > 
> > > Date: Thu, 19 Apr 2012 22:24:53 +0300
> > > From: Eli Zaretskii <eliz@gnu.org>
> > > Cc: gdb@sourceware.org
> > > 
> > > The crux of my question was why non-interactive mode does display a
> > > prompt while the interactive one doesn't.
> > 
> > To answer my own question, here's why:
> > 
> >   char *
> >   command_line_input (char *prompt_arg, int repeat, char *annotation_suffix)
> >   {
> >     ...
> > 	/* Don't use fancy stuff if not talking to stdin.  */
> > 	if (deprecated_readline_hook && input_from_terminal_p ())
> > 	  {
> > 	    rl = (*deprecated_readline_hook) (local_prompt);
> > 	  }
> > 	else if (command_editing_p && input_from_terminal_p ())
> > 	  {
> > 	    rl = gdb_readline_wrapper (local_prompt);
> > 	  }
> > 	else
> > 	  {
> > 	    rl = gdb_readline (local_prompt);
> > 	  }
> > 
> > Now, the code is clear, but I cannot say I understand the logic.  If
> > the input is from terminal, we ask (inside gdb_readline_wrapper) the
> > current interpreter whether to show the prompt.  But if input is _not_
> > from terminal, we display the prompt unconditionally (inside
> > gdb_readline).  How does this make sense?
> > 
> > > Date: Thu, 19 Apr 2012 11:53:29 -0700
> > > From: Joel Brobecker <brobecker@adacore.com>
> > > Cc: gdb@sourceware.org
> > > 
> > > The other thing that occured to me was that, perhaps, we should instead
> > > be switching the interpreter while executing the console command,
> > 
> > I arrived to the same conclusion, eventually.  See below.
> > 
> > > but I doubt that would be correct.
> > 
> > Why not?  The patch below works for me.
> > 
> > --- gdb/interps.c~0	2012-01-06 06:43:17.000000000 +0200
> > +++ gdb/interps.c	2012-04-22 08:55:27.056588400 +0300
> > @@ -253,6 +253,18 @@ interp_ui_out (struct interp *interp)
> >    return current_interpreter->procs->ui_out_proc (current_interpreter);
> >  }
> >  
> > +/* Temporarily overrides the current interpreter.  */
> > +struct interp *
> > +interp_set_temp (const char *name)
> > +{
> > +  struct interp *interp = interp_lookup (name);
> > +  struct interp *old_interp = current_interpreter;
> > +
> > +  if (interp)
> > +    current_interpreter = interp;
> > +  return old_interp;
> > +}
> > +
> >  /* Returns the interpreter's cookie.  */
> >  
> >  void *
> > --- gdb/interps.h~0	2012-01-06 06:43:17.000000000 +0200
> > +++ gdb/interps.h	2012-04-22 08:42:05.687879800 +0300
> > @@ -69,6 +69,7 @@
> >  extern struct ui_out *interp_ui_out (struct interp *interp);
> >  extern void *interp_data (struct interp *interp);
> >  extern const char *interp_name (struct interp *interp);
> > +extern struct interp *interp_set_temp (const char *name);
> >  
> >  extern int current_interp_named_p (const char *name);
> >  extern int current_interp_display_prompt_p (void);
> > --- gdb/cli/cli-script.c~0	2012-01-06 06:43:32.000000000 +0200
> > +++ gdb/cli/cli-script.c	2012-04-22 09:04:23.533807200 +0300
> > @@ -1178,6 +1178,12 @@ recurse_read_control_structure (char * (
> >    return ret;
> >  }
> >  
> > +static void
> > +restore_interp (void *arg)
> > +{
> > +  interp_set_temp (interp_name ((struct interp *)arg));
> > +}
> > +
> >  /* Read lines from the input stream and accumulate them in a chain of
> >     struct command_line's, which is then returned.  For input from a
> >     terminal, the special command "end" is used to mark the end of the
> > @@ -1210,8 +1216,21 @@ read_command_lines (char *prompt_arg, in
> >  	}
> >      }
> >  
> > -  head = read_command_lines_1 (read_next_line, parse_commands,
> > -			       validator, closure);
> > +
> > +  /* Reading commands assumes the CLI behavior, so temporarily
> > +     override the current interpreter with CLI.  */
> > +  if (current_interp_named_p (INTERP_CONSOLE))
> > +    head = read_command_lines_1 (read_next_line, parse_commands,
> > +				 validator, closure);
> > +  else
> > +    {
> > +      struct interp *old_interp = interp_set_temp (INTERP_CONSOLE);
> > +      struct cleanup *old_chain = make_cleanup (restore_interp, old_interp);
> > +
> > +      head = read_command_lines_1 (read_next_line, parse_commands,
> > +				   validator, closure);
> > +      do_cleanups (old_chain);
> > +    }
> >  
> >    if (deprecated_readline_end_hook && from_tty && input_from_terminal_p ())
> >      {
> > 

-- 
Joel