Re: [RFC PATCH v1] edit: add vi alias with vi-style bindings

[Roland Hieber <rhi@pengutronix.de>]

On Mon, Sep 09, 2019 at 10:02:13AM +0200, Ahmad Fatoum wrote:
> The edit command already supports a few key bindings for code
> navigation. To improve user experience for vi-impaired users, add a vi
> alias that maps traditional vi key bindings to the barebox edit ones.
> This is done by adding a mode-aware read_modal_key that maps vi
> normal-mode keys to barebox edit's. For operations that requires more
> than one barebox edit key, a backlog of two characters is additionally
> used.

Acked-by: Roland Hieber <rhi@pengutronix.de>

Thank you, I've been typing "vi" on the barebox console for three years
now!

> In interest of code size reduction, a command mode (and the associated
> readline overhead) are not implemented, the effect of the most common
> commands :q and :wq commands can be realized with vim-like ZQ and ZZ
> bindings instead.

You could also just handle ":q" and ":wq" like "ZZ" and "ZQ" and just
make them work without displaying them in the statusbar.

> This increases the size of a compressed THUMB2 barebox by 733 bytes.

If this is too big, you could always add a kconfig symbol for it. :)

 - Roland

> Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
> ---
>  commands/edit.c | 148 +++++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 139 insertions(+), 9 deletions(-)
> 
> diff --git a/commands/edit.c b/commands/edit.c
> index 290222ce152f..0dc19841f351 100644
> --- a/commands/edit.c
> +++ b/commands/edit.c
> @@ -378,8 +378,120 @@ static void getwinsize(void)
>  	pos(0, 0);
>  }
>  
> +static inline void statusbar(const char *str)
> +{
> +	pos(0, screenheight+1);
> +	printf("%*c\r", screenwidth, ' ');
> +	printf(str);
> +	pos(cursx, cursy);
> +}
> +
> +static int read_modal_key(bool is_modal)
> +{
> +	static enum { MODE_INSERT, MODE_NORMAL } mode = MODE_NORMAL;
> +	static int backlog[2] = { -1, -1 };
> +	int c;
> +
> +	if (backlog[0] >= 0) {
> +		/* pop a character */
> +		c = backlog[0];
> +		backlog[0] = backlog[1];
> +		backlog[1] = -1;
> +	} else {
> +		c = read_key();
> +	}
> +
> +	if (is_modal && mode == MODE_INSERT && (c == -1 || c == CTL_CH('c'))) {
> +		mode = MODE_NORMAL;
> +		statusbar("");
> +		return -EAGAIN;
> +	}
> +
> +	if (!is_modal || mode == MODE_INSERT)
> +		return c;
> +
> +	switch (c) {
> +	case -1: /* invalid escape, e.g. two escapes in a row */
> +		break;
> +	case 'i':
> +		statusbar("-- INSERT --");
> +		mode = MODE_INSERT;
> +		break;
> +	case 'h':
> +		return BB_KEY_LEFT;
> +	case 'j':
> +		return BB_KEY_DOWN;
> +	case 'k':
> +		return BB_KEY_UP;
> +	case 'a':
> +		statusbar("-- INSERT --");
> +		mode = MODE_INSERT;
> +		/* fall through */
> +	case 'l':
> +		return BB_KEY_RIGHT;
> +	case 'O':
> +		backlog[0] = '\n';
> +		backlog[1] = BB_KEY_UP;
> +		/* fall through */
> +	case 'I':
> +		statusbar("-- INSERT --");
> +		mode = MODE_INSERT;
> +		/* fall through */
> +	case '^':
> +	case '0':
> +		return BB_KEY_HOME;
> +	case 'g':
> +		c = read_key();
> +		if (c != 'g')
> +			break;
> +		backlog[0] = CTL_CH('u');
> +		backlog[1] = CTL_CH('u');
> +		/* fall through */
> +	case CTL_CH('u'):
> +		return BB_KEY_PAGEUP;
> +	case 'G':
> +		backlog[0] = CTL_CH('d');
> +		backlog[1] = CTL_CH('d');
> +		/* fall through */
> +	case CTL_CH('d'):
> +		return BB_KEY_PAGEDOWN;
> +	case 'o':
> +		backlog[0] = '\n';
> +		/* fall through */
> +	case 'A':
> +		statusbar("-- INSERT --");
> +		mode = MODE_INSERT;
> +		/* fall through */
> +	case '$':
> +		return BB_KEY_END;
> +	case CTL_CH('c'):
> +		statusbar("Type ZQ to abandon all changes and exit vi."
> +			  "Type ZZ to exit whilesaving them.");
> +		break;
> +	case ':':
> +		statusbar("ERROR: command mode not supported");
> +		break;
> +	case 'Z':
> +		c = read_key();
> +		if (c == 'Z')
> +			return CTL_CH('d');
> +		if (c == 'Q')
> +			return CTL_CH('c');
> +	case 'x':
> +		return BB_KEY_DEL;
> +	case 'X':
> +		return '\b';
> +	default:
> +		statusbar("ERROR: not implemented");
> +		break;
> +	}
> +
> +	return -EAGAIN;
> +}
> +
>  static int do_edit(int argc, char *argv[])
>  {
> +	bool is_vi = false;
>  	int lastscrcol;
>  	int i;
>  	int linepos;
> @@ -401,10 +513,14 @@ static int do_edit(int argc, char *argv[])
>  	else
>  		screenheight = 25;
>  
> -	/* check if we are called as "sedit" instead of "edit" */
> -	if (*argv[0] == 's') {
> +	/* check if we are not called as "edit" */
> +	if (*argv[0] != 'e') {
>  		smartscroll = 1;
>  		getwinsize();
> +
> +		/* check if we are called as "vi" */
> +		if (*argv[0] == 'v')
> +			is_vi = true;
>  	}
>  
>  	buffer = NULL;
> @@ -424,14 +540,24 @@ static int do_edit(int argc, char *argv[])
>  
>  	pos(0, -1);
>  
> -	printf("%c[7m %-25s <ctrl-d>: Save and quit <ctrl-c>: quit %c[0m",
> -			27, argv[1], 27);
> -	printf("%c[2;%dr", 27, screenheight);
> -
> -	screenheight--; /* status line */
> +	if (is_vi) {
> +		screenheight -= 2;
> +		printf("%c[7m%*c%c[0m", 27, screenwidth , ' ', 27);
> +		pos(0, screenheight-1);
> +		printf("%c[7m%*c%c[0m", 27, screenwidth , ' ', 27);
> +		printf("\r%c[7m%-25s%c[0m", 27, argv[1], 27);
> +		printf("%c[2;%dr", 27, screenheight);
> +	} else {
> +		pos(0, -1);
> +		printf("%c[7m %-25s <ctrl-d>: Save and quit <ctrl-c>: quit %c[0m",
> +		       27, argv[1], 27);
> +		printf("%c[2;%dr", 27, screenheight);
> +	}
>  
>  	pos(0, 0);
>  
> +	screenheight--; /* status line */
> +
>  	refresh(1);
>  
>  	while (1) {
> @@ -469,7 +595,11 @@ static int do_edit(int argc, char *argv[])
>  		lastscrline = scrline;
>  		pos(cursx, cursy);
>  
> -		c = read_key();
> +again:
> +		c = read_modal_key(is_vi);
> +		if (c == -EAGAIN)
> +			goto again;
> +
>  		switch (c) {
>  		case BB_KEY_UP:
>  			if (!curline->prev)
> @@ -559,7 +689,7 @@ out:
>  	return ret;
>  }
>  
> -static const char * const edit_aliases[] = { "sedit", NULL};
> +static const char * const edit_aliases[] = { "sedit", "vi", NULL};
>  
>  BAREBOX_CMD_HELP_START(edit)
>  BAREBOX_CMD_HELP_TEXT("Use cursor keys, Ctrl-C to exit and Ctrl-D to exit-with-save.")
> -- 
> 2.20.1
> 
> 
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> 

-- 
Roland Hieber                     | r.hieber@pengutronix.de     |
Pengutronix e.K.                  | https://www.pengutronix.de/ |
Peiner Str. 6-8, 31137 Hildesheim | Phone: +49-5121-206917-5086 |
Amtsgericht Hildesheim, HRA 2686  | Fax:   +49-5121-206917-5555 |

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