Re: [RFAv3 1/6] Add previous_saved_command_line to allow a command to repeat a previous command.

Pedro Alves
2019-05-27T17:29:32Z

On 5/4/19 5:17 PM, Philippe Waroquiers wrote:
> Currently, a previous command can be repeated when the user types an
> empty line. This is implemented in handle_line_of_input by
> returning saved_command_line in case an empty line has been input.
>
> If we want a command to repeat the previous command, we need to save
> the previous saved_command_line, as when a command runs, the saved_command_line
> already contains the current command line of the command being executed.
>
> As suggested by Tom, the previous_saved_command_line is made static.
> At the same time, saved_command_line is also made static.
> The support functions/variables for the repeat command logic are now all
> located inside top.c.
>
> gdb/ChangeLog
> 2019-05-04 Philippe Waroquiers <philippe.waroquiers@skynet.be>
>
> * top.h (saved_command_line): Remove declaration.
> * top.c (previous_saved_command_line, previous_repeat_arguments):
> New variables.
> (saved_command_line): Make static, define together with other
> 'repeat variables'.
> (dont_repeat): Clear repeat_arguments.
> (repeat_previous, get_saved_command_line, save_command_line):
> New functions.
> (gdb_init): Initialize saved_command_line
> and previous_saved_command_line.
> * main.c (captured_main_1): Remove saved_command_line initialization.
> * event-top.c (handle_line_of_input): Update to use
> the new 'repeat' related functions instead of direct access to
> saved_command_line.
> * command.h (repeat_previous, get_saved_command_line,
> save_command_line): New declarations.
> (dont_repeat): Add comment.
> ---
> gdb/command.h | 36 ++++++++++++++++++++++++-
> gdb/event-top.c | 16 +++++------
> gdb/main.c | 2 --
> gdb/top.c | 70 +++++++++++++++++++++++++++++++++++++++++--------
> gdb/top.h | 1 -
> 5 files changed, 101 insertions(+), 24 deletions(-)
>
> diff --git a/gdb/command.h b/gdb/command.h
> index 4a239a7196..ea3a58f81c 100644
> --- a/gdb/command.h
> +++ b/gdb/command.h
> @@ -448,7 +448,29 @@ extern void cmd_show_list (struct cmd_list_element *, int, const char *);
>
> extern void error_no_arg (const char *) ATTRIBUTE_NORETURN;
>
> -extern void dont_repeat (void);
> +
> +/* Command line saving and repetition.
> + Each input line executed is saved for possibly be repeated either

s/saved for ... be/saved to ... be/

> + when the user types an empty line, or be repeated by a command
> + that wants to repeat the previously executed command. The below
> + functions are controlling command repetition. */

s/are controlling/control/

> +
> +/* Commands call dont_repeat if they do not want to be repeated by null
> + lines or by repeat_previous (). */
> +
> +extern void dont_repeat ();
> +
> +/* Command call repeat_previous if they want to repeat the previous command.

s/Command call/Commands call/

> + Such commands repeating the previous command must indicate

s/Such commands repeating/Such commands that repeat/

> + to not repeat themselves, to avoid recursive repeat.
> + repeat_previous will mark the current command as not repeating,
> + and will ensure get_saved_command_line returns the previous command,
> + so that the currently executing command can repeat it. */
> +
> +extern void repeat_previous ();
> +
> +/* Prevent dont_repeat from working, and return a cleanup that
> + restores the previous state. */
>
> extern scoped_restore_tmpl<int> prevent_dont_repeat (void);
>
> @@ -457,6 +479,18 @@ extern scoped_restore_tmpl<int> prevent_dont_repeat (void);
>
> extern void set_repeat_arguments (const char *args);
>
> +/* Returns the saved command line to repeat.
> + When a command is being executed, this is the currently executing
> + command line, unless the currently executing command has called
> + repeat_previous (): in this case, get_saved_command_line returns
> + the previously saved command line. */
> +
> +extern char *get_saved_command_line ();
> +
> +/* Takes a copy of CMD, for possible repetition. */
> +
> +extern void save_command_line (const char *cmd);
> +
> /* Used to mark commands that don't do anything. If we just leave the
> function field NULL, the command is interpreted as a help topic, or
> as a class of commands. */
> diff --git a/gdb/event-top.c b/gdb/event-top.c
> index 3ccf136ff1..b64b7462c7 100644
> --- a/gdb/event-top.c
> +++ b/gdb/event-top.c
> @@ -634,11 +634,10 @@ command_line_append_input_line (struct buffer *cmd_line_buffer, const char *rl)
> If REPEAT, handle command repetitions:
>
> - If the input command line is NOT empty, the command returned is
> - copied into the global 'saved_command_line' var so that it can
> - be repeated later.
> + saved using save_command_line () so that it can be repeated later.
>
> - - OTOH, if the input command line IS empty, return the previously
> - saved command instead of the empty input line.
> + - OTOH, if the input command line IS empty, return the saved
> + command instead of the empty input line.
> */
>
> char *
> @@ -673,7 +672,7 @@ handle_line_of_input (struct buffer *cmd_line_buffer,
> server_command = startswith (cmd, SERVER_COMMAND_PREFIX);
> if (server_command)
> {
> - /* Note that we don't set `saved_command_line'. Between this
> + /* Note that we don't call `save_command_line'. Between this
> and the check in dont_repeat, this insures that repeating
> will still do the right thing. */
> return cmd + strlen (SERVER_COMMAND_PREFIX);
> @@ -713,7 +712,7 @@ handle_line_of_input (struct buffer *cmd_line_buffer,
> for (p1 = cmd; *p1 == ' ' || *p1 == '\t'; p1++)
> ;
> if (repeat && *p1 == '\0')
> - return saved_command_line;
> + return get_saved_command_line ();
>
> /* Add command to history if appropriate. Note: lines consisting
> solely of comments are also added to the command history. This
> @@ -728,9 +727,8 @@ handle_line_of_input (struct buffer *cmd_line_buffer,
> /* Save into global buffer if appropriate. */
> if (repeat)
> {
> - xfree (saved_command_line);
> - saved_command_line = xstrdup (cmd);
> - return saved_command_line;
> + save_command_line (cmd);
> + return get_saved_command_line ();
> }
> else
> return cmd;
> diff --git a/gdb/main.c b/gdb/main.c
> index 35df1e497f..ef9bfe8fc6 100644
> --- a/gdb/main.c
> +++ b/gdb/main.c
> @@ -499,8 +499,6 @@ captured_main_1 (struct captured_main_args *context)
>
> notice_open_fds ();
>
> - saved_command_line = (char *) xstrdup ("");
> -
> #ifdef __MINGW32__
> /* Ensure stderr is unbuffered. A Cygwin pty or pipe is implemented
> as a Windows pipe, and Windows buffers on pipes. */
> diff --git a/gdb/top.c b/gdb/top.c
> index bacd684dba..70f685ffad 100644
> --- a/gdb/top.c
> +++ b/gdb/top.c
> @@ -134,8 +134,26 @@ show_confirm (struct ui_file *file, int from_tty,
> char *current_directory;
>
> /* The last command line executed on the console. Used for command
> - repetitions. */
> -char *saved_command_line;
> + repetitions when the user enters an empty line. */
> +
> +static char *saved_command_line;
> +
> +/* If not NULL, the arguments that should be passed if
> + saved_command_line is repeated. */
> +
> +static const char *repeat_arguments;
> +
> +/* The previous last command line executed on the console. Used for command
> + repetitions when a command want to relaunch the previously launched

s/a command want/a command wants/

> + command. We need this as when a command is running, saved_command_line
> + already contains the line of the currently executing command. */
> +
> +char *previous_saved_command_line;
> +
> +/* If not NULL, the arguments that should be passed if the
> + previous_saved_command_line is repeated. */
> +
> +static const char *previous_repeat_arguments;
>
> /* Nonzero if the current command is modified by "server ". This
> affects things like recording into the command history, commands
> @@ -521,11 +539,6 @@ maybe_wait_sync_command_done (int was_sync)
> wait_sync_command_done ();
> }
>
> -/* If not NULL, the arguments that should be passed if the current
> - command is repeated. */
> -
> -static const char *repeat_arguments;
> -
> /* See command.h. */
>
> void
> @@ -695,7 +708,7 @@ execute_command_to_string (const char *p, int from_tty,
>
> static int suppress_dont_repeat = 0;
>
> -/* Commands call this if they do not want to be repeated by null lines. */
> +/* See command.h */
>
> void
> dont_repeat (void)
> @@ -709,11 +722,27 @@ dont_repeat (void)
> thing read from stdin in line and don't want to delete it. Null
> lines won't repeat here in any case. */
> if (ui->instream == ui->stdin_stream)
> - *saved_command_line = 0;
> + {
> + *saved_command_line = 0;
> + repeat_arguments = NULL;
> + }
> +}
> +
> +/* See command.h */
> +
> +void
> +repeat_previous ()
> +{
> + /* Do not repeat this command, as this command is a repeating command. */
> + dont_repeat ();
> +
> + /* We cannot free saved_command_line, as this line is being executed,
> + so swap it with previous_saved_command_line. */
> + std::swap (previous_saved_command_line, saved_command_line);
> + std::swap (previous_repeat_arguments, repeat_arguments);
> }
>
> -/* Prevent dont_repeat from working, and return a cleanup that
> - restores the previous state. */
> +/* See command.h. */
>
> scoped_restore_tmpl<int>
> prevent_dont_repeat (void)
> @@ -721,6 +750,22 @@ prevent_dont_repeat (void)
> return make_scoped_restore (&suppress_dont_repeat, 1);
> }
>
> +char *
> +get_saved_command_line ()

Add usual /* See foo.h */ comment.

> +{
> + return saved_command_line;
> +}
> +
> +void
> +save_command_line (const char *cmd)

Ditto.

> +{
> + xfree (previous_saved_command_line);
> + previous_saved_command_line = saved_command_line;
> + previous_repeat_arguments = repeat_arguments;
> + saved_command_line = xstrdup (cmd);
> + repeat_arguments = NULL;
> +}
> +
> \f
> /* Read a line from the stream "instream" without command line editing.
>
> @@ -2179,6 +2224,9 @@ The second argument is the terminal the UI runs on.\n"), &cmdlist);
> void
> gdb_init (char *argv0)
> {
> + saved_command_line = (char *) xstrdup ("");
> + previous_saved_command_line = (char *) xstrdup ("");

Drop the unnecessary casts.

> +
> if (pre_init_ui_hook)
> pre_init_ui_hook ();
>
> diff --git a/gdb/top.h b/gdb/top.h
> index 025d9389d6..aab03c13d6 100644
> --- a/gdb/top.h
> +++ b/gdb/top.h
> @@ -217,7 +217,6 @@ extern void ui_register_input_event_handler (struct ui *ui);
> extern void ui_unregister_input_event_handler (struct ui *ui);
>
> /* From top.c. */
> -extern char *saved_command_line;
> extern int confirm;
> extern int inhibit_gdbinit;
> extern const char gdbinit[];
>
Thanks,
Pedro Alves