Dollar symbols were failing to parse when not followed by a non-brace,
non-dollar, non-EOF token and causing expected tests to fail. This
simplifies the rules to allow the remaining tests to succeed.
Fix and reinstate the final few failing tests, and add another.
Allow any escape sequence to be matched so that invalid sequences
produce a meaningful error message instead of a generic "cannot parse":
ast: interpolate: interpolating: V: \?
unhandled escape sequence token: \?
Tidy the related Makefile rule for generating the ragel parser.
Signed-off-by: Joe Groocock <me@frebib.net>
The original string interpolation was based on hil which didn't allow
proper escaping, since they used a different escape pattern. Secondly,
the golang Unquote function didn't deal with the variable substitution,
which meant it had to be performed in a second step.
Most importantly, because we did this partial job in Unquote (the fact
that is strips the leading and trailing quotes tricked me into thinking
I was done with interpolation!) it was impossible to remedy the
remaining parts in a second pass with hil. Both operations needs to be
done in a single step. This is logical when you aren't tunnel visioned.
This patch replaces both of these so that string interpolation works
properly. This removes the ability to allow inline function calls in a
string, however this was an incidental feature, and it's not clear that
having it is a good idea. It also requires you wrap the var name with
curly braces. (They are not optional.)
This comes with a load of tests, but I think I got some of it wrong,
since I'm quite new at ragel. If you find something, please say so =D In
any case, this is much better than the original hil implementation, and
easy for a new contributor to patch to make the necessary fixes.
