Re: [PATCH 2/2] Use obstack in ada_encode_1

[Simon Marchi <simark@simark.ca>]

On 2020-10-02 4:26 p.m., Tom Tromey wrote:
> I'd eventually like to get rid of the GROW_VECT macro; and since I had
> already touched ada_encode_1 I decided to start here.  This patch
> removes the use of the macro in favor of using an obstack in this
> function.
>
> 2020-10-02  Tom Tromey  <tromey@adacore.com>
>
> 	* ada-lang.c (ada_encode_1): Use an obstack.
> ---
>  gdb/ChangeLog  |  4 ++++
>  gdb/ada-lang.c | 26 +++++++-------------------
>  2 files changed, 11 insertions(+), 19 deletions(-)
>
> diff --git a/gdb/ada-lang.c b/gdb/ada-lang.c
> index 2502d2847b2..dfe9d44959f 100644
> --- a/gdb/ada-lang.c
> +++ b/gdb/ada-lang.c
> @@ -926,25 +926,17 @@ const struct ada_opname_map ada_opname_table[] = {
>  static const char *
>  ada_encode_1 (const char *decoded, bool throw_errors)
>  {
> -  static char *encoding_buffer = NULL;
> -  static size_t encoding_buffer_size = 0;
> +  static auto_obstack encoding_buffer;
>    const char *p;
> -  int k;
>
>    if (decoded == NULL)
>      return NULL;
>
> -  GROW_VECT (encoding_buffer, encoding_buffer_size,
> -             2 * strlen (decoded) + 10);
> -
> -  k = 0;
> +  encoding_buffer.clear ();
>    for (p = decoded; *p != '\0'; p += 1)
>      {
>        if (*p == '.')
> -        {
> -          encoding_buffer[k] = encoding_buffer[k + 1] = '_';
> -          k += 2;
> -        }
> +	obstack_grow_str (&encoding_buffer, "__");
>        else if (*p == '"')
>          {
>            const struct ada_opname_map *mapping;
> @@ -960,19 +952,15 @@ ada_encode_1 (const char *decoded, bool throw_errors)
>  	      else
>  		return NULL;
>  	    }
> -          strcpy (encoding_buffer + k, mapping->encoded);
> -          k += strlen (mapping->encoded);
> +	  obstack_grow_str (&encoding_buffer, mapping->encoded);
>            break;
>          }
>        else
> -        {
> -          encoding_buffer[k] = *p;
> -          k += 1;
> -        }
> +	obstack_1grow (&encoding_buffer, *p);
>      }
>
> -  encoding_buffer[k] = '\0';
> -  return encoding_buffer;
> +  obstack_1grow (&encoding_buffer, '\0');
> +  return (const char *) obstack_finish (&encoding_buffer);
>  }
>
>  /* The "encoded" form of DECODED, according to GNAT conventions.
> --
> 2.26.2
>

I think the same could be achieved using a static std::string instead of
an obstack, and it would be a bit more C++-y, but either way is fine
with me.

Simon