Re: [PATCH 06/11] built-in add -i: implement the main loop

[Jeff Hostetler <git@jeffhostetler.com>]

On 4/10/2019 1:37 PM, Johannes Schindelin via GitGitGadget wrote:
> From: Johannes Schindelin <johannes.schindelin@gmx.de>
> 
> The reason why we did not start with the main loop to begin with is that
> it is the first user of `list_and_choose()`, which uses the `list()`
> function that we conveniently introduced for use by the `status`
> command.
> 
> Apart from the "and choose" part, there are more differences between the
> way the `status` command calls the `list_and_choose()` function in the
> Perl version of `git add -i` compared to the other callers of said
> function. The most important ones:
> 
> - The list is not only shown, but the user is also asked to make a
>    choice, possibly selecting multiple entries.
> 
> - The list of items is prefixed with a marker indicating what items have
>    been selected, if multi-selection is allowed.
> 
> - Initially, for each item a unique prefix (if there exists any within
>    the given parameters) is determined, and shown in the list, and
>    accepted as a shortcut for the selection.
> 
> These features will be implemented later, except the part where the user
> can choose a command. At this stage, though, the built-in `git add -i`
> still only supports the `status` command, with the remaining commands to
> follow over the course of the next commits.
> 
> In addition, we also modify `list()` to support displaying the commands
> in columns, even if there is currently only one.
> 
> The Perl script `git-add--interactive.perl` mixed the purposes of the
> "list" and the "and choose" part into the same function. In the C
> version, we will keep them separate instead, calling the `list()`
> function from the `list_and_choose()` function.
> 
> Note that we only have a prompt ending in a single ">" at this stage;
> later commits will add commands that display a double ">>" to indicate
> that the user is in a different loop than the main one.
> 
> Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
> ---
>   add-interactive.c | 122 +++++++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 120 insertions(+), 2 deletions(-)
> 
> diff --git a/add-interactive.c b/add-interactive.c
> index 79adc58321..c8bd62369e 100644
> --- a/add-interactive.c
> +++ b/add-interactive.c
> @@ -58,6 +58,7 @@ struct item {
>   };
>   
>   struct list_options {
> +	int columns;
>   	const char *header;
>   	void (*print_item)(int i, struct item *item, void *print_item_data);
>   	void *print_item_data;
> @@ -65,7 +66,7 @@ struct list_options {
>   
>   static void list(struct item **list, size_t nr, struct list_options *opts)
>   {
> -	int i;
> +	int i, last_lf = 0;
>   
>   	if (!nr)
>   		return;
> @@ -77,8 +78,90 @@ static void list(struct item **list, size_t nr, struct list_options *opts)
>   
>   	for (i = 0; i < nr; i++) {
>   		opts->print_item(i, list[i], opts->print_item_data);
> +
> +		if ((opts->columns) && ((i + 1) % (opts->columns))) {
> +			putchar('\t');
> +			last_lf = 0;
> +		}
> +		else {
> +			putchar('\n');
> +			last_lf = 1;
> +		}
> +	}
> +
> +	if (!last_lf)
>   		putchar('\n');
> +}
> +struct list_and_choose_options {
> +	struct list_options list_opts;
> +
> +	const char *prompt;
> +};
> +
> +/*
> + * Returns the selected index.
> + */
> +static ssize_t list_and_choose(struct item **items, size_t nr,
> +			       struct list_and_choose_options *opts)
> +{
> +	struct strbuf input = STRBUF_INIT;
> +	ssize_t res = -1;
> +
> +	for (;;) {
> +		char *p, *endp;
> +
> +		strbuf_reset(&input);
> +
> +		list(items, nr, &opts->list_opts);
> +
> +		printf("%s%s", opts->prompt, "> ");
> +		fflush(stdout);
> +
> +		if (strbuf_getline(&input, stdin) == EOF) {
> +			putchar('\n');
> +			res = -2;

It would be nice to know what -1 and -2 mean if
they get returned to our caller.  Maybe a #define
for these??

> +			break;
> +		}
> +		strbuf_trim(&input);
> +
> +		if (!input.len)
> +			break;
> +
> +		p = input.buf;
> +		for (;;) {
> +			size_t sep = strcspn(p, " \t\r\n,");
> +			ssize_t index = -1;
> +
> +			if (!sep) {
> +				if (!*p)
> +					break;
> +				p++;
> +				continue;
> +			}
> +
> +			if (isdigit(*p)) {
> +				index = strtoul(p, &endp, 10) - 1;
> +				if (endp != p + sep)
> +					index = -1;
> +			}
> +
> +			p[sep] = '\0';
> +			if (index < 0 || index >= nr)
> +				printf(_("Huh (%s)?\n"), p);
> +			else {
> +				res = index;
> +				break;
> +			}
> +
> +			p += sep + 1;
> +		}
> +
> +		if (res >= 0)
> +			break;
>   	}
> +
> +	strbuf_release(&input);
> +	return res;
>   }
>   
>   struct adddel {
> @@ -292,16 +375,39 @@ static int run_status(struct repository *r, const struct pathspec *ps,
>   	return 0;
>   }
>   
> +static void print_command_item(int i, struct item *item,
> +			       void *print_command_item_data)
> +{
> +	printf(" %2d: %s", i + 1, item->name);
> +}
> +
> +struct command_item {
> +	struct item item;
> +	int (*command)(struct repository *r, const struct pathspec *ps,
> +		       struct file_list *files, struct list_options *opts);
> +};
> +
>   int run_add_i(struct repository *r, const struct pathspec *ps)
>   {
> +	struct list_and_choose_options main_loop_opts = {
> +		{ 4, N_("*** Commands ***"), print_command_item, NULL },
> +		N_("What now")
> +	};
> +	struct command_item
> +		status = { { "status" }, run_status };
> +	struct command_item *commands[] = {
> +		&status
> +	};
> +
>   	struct print_file_item_data print_file_item_data = {
>   		"%12s %12s %s", STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
>   	};
>   	struct list_options opts = {
> -		NULL, print_file_item, &print_file_item_data
> +		0, NULL, print_file_item, &print_file_item_data
>   	};
>   	struct strbuf header = STRBUF_INIT;
>   	struct file_list files = { NULL };
> +	ssize_t i;
>   	int res = 0;
>   
>   	strbuf_addstr(&header, "      ");
> @@ -313,6 +419,18 @@ int run_add_i(struct repository *r, const struct pathspec *ps)
>   	if (run_status(r, ps, &files, &opts) < 0)
>   		res = -1;
>   
> +	for (;;) {
> +		i = list_and_choose((struct item **)commands,
> +				    ARRAY_SIZE(commands), &main_loop_opts);
> +		if (i < -1) {
> +			printf(_("Bye.\n"));
> +			res = 0;
> +			break;
> +		}
> +		if (i >= 0)
> +			res = commands[i]->command(r, ps, &files, &opts);
> +	}
> +
>   	release_file_list(&files);
>   	strbuf_release(&print_file_item_data.buf);
>   	strbuf_release(&print_file_item_data.index);
>