Re: [PATCH v1 3/5] list-objects-filter: implement composite filters

[Matthew DeVore <matvore@comcast.net>]

On Tue, Jun 04, 2019 at 12:13:32PM -0400, Jeff King wrote:
> > -	return has_reserved_character(subspec, errbuf) ||
> > -		url_decode(subspec, errbuf) ||
> > -		gently_parse_list_objects_filter(
> > -			&filter_options->sub[new_index], subspec->buf, errbuf);
> > +	decoded = url_percent_decode(subspec->buf);
> 
> I think you can get rid of has_reserved_character() now, too.

The purpose of has_reserved_character is to allow for future
extensibility if someone decides to implement a more sophisticated DSL
and give meaning to these characters. That may be a long-shot, but it
seems worth it.

> The reserved character list is still used on the encoding side. But I
> think you could switch to strbuf_add_urlencode() there?

strbuf_addstr_urlencode will either escape or not escape all rfc3986
reserved characters, and that set includes both : and +. The former
should not require escaping since it's a common character in filter
specs, and I would like the hand-encoded combine specs to be relatively
easy to type and read. The + must be escaped since it is used as part of
the combine:... syntax to delimit sub filters. So
strbuf_addstr_url_encode would have to be more customizable to make it
work for this context. I'd like to add a parameterizable should_escape
predicate (iow function pointer) which strbuf_addstr_urlencode accepts.
I actually think this will be more readable than the current strbuf API.