Re: [PATCH] client: handle wide chars for table rows

[James Prestwood <prestwoj@gmail.com>]

On Sat, 2022-10-08 at 15:55 +0800, Pinghao Wu wrote:
> Try to find out printing width of wide chars using current locale and
> its byte length before falling back to non-codepoint UTF-8 bytes
> method.
> ---
>  client/display.c | 16 +++++++++++++++-
>  client/main.c    |  3 +++
>  2 files changed, 18 insertions(+), 1 deletion(-)
> 
> diff --git a/client/display.c b/client/display.c
> index b729ad4c..dcbe11f8 100644
> --- a/client/display.c
> +++ b/client/display.c
> @@ -26,10 +26,13 @@
>  
>  #define _GNU_SOURCE
>  #include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
>  #include <signal.h>
>  #include <sys/stat.h>
>  #include <sys/ioctl.h>
>  #include <unistd.h>
> +#include <wchar.h>
>  
>  #include <readline/history.h>
>  #include <readline/readline.h>
> @@ -401,15 +404,26 @@ static char* next_line(char *s, unsigned int
> *max, char **color_out)
>         unsigned int i;
>         int last_space = -1;
>         int last_color = -1;
> +       int s_len = strlen(s);
>  
>         /* Find the last space before 'max', as well as any color */
> -       for (i = 0; i <= *max && s[i] != '\0'; i++) {
> +       for (i = 0; i <= *max && i != s_len; i++) {
>                 if (s[i] == ' ')
>                         last_space = i;
>                 else if (s[i] == 0x1b) {
>                         /* color escape won't count for column width
> */
>                         *max += color_end(s + i);
>                         last_color = i;
> +               /* Non-ASCII, try wchar */
> +               } else if (s[i] & 0x80) {
> +                       wchar_t w;
> +                       int w_mblen;
> +                       if ((w_mblen = mbtowc(&w, &s[i], s_len - i))

Instead of mbtowc() use l_utf8_get_codepoint() (an ELL utility). Since
we assume the input is going to be utf-8 always.

> > 0) {
> +                               /* Compensate max bytes for wide char
> */
> +                               *max += w_mblen - wcwidth(w);
> +                               /* Skip other bytes for this wchar */
> +                               i += w_mblen - 1;
> +                       }
>                 /* Add width for non-codepoint UTF-8 bytes */
>                 } else if (((uint8_t)s[i] >> 6) == 2)
>                         *max += 1;

And you can go ahead and remove this if-clause entirely since the above
case should now cover it. Plus the s[i] & 0x80 check above actually
prevents this branch from ever being taken.

> diff --git a/client/main.c b/client/main.c
> index df5c0a61..7e8dead4 100644
> --- a/client/main.c
> +++ b/client/main.c
> @@ -25,6 +25,7 @@
>  #endif
>  
>  #include <errno.h>
> +#include <locale.h>
>  #include <signal.h>
>  #include <ell/ell.h>
>  
> @@ -50,6 +51,8 @@ int main(int argc, char *argv[])
>  {
>         bool all_done;
>  
> +       setlocale(LC_CTYPE, "");
> +
>         if (!l_main_init())
>                 return EXIT_FAILURE;
>  

Thanks,
James