Fix handling of @root helper arguments

[majortom731]

I've noticed that using helper arguments in @root... notation causes an error.

This is an attempt to fix it by simply allowing '@' as first char in the $name_chunks regexp in Arguments->parse().

What do you think?

[fzerorubigd]

@majortom731 Thank you!

@JustBlackBird LGTM , could you verify this too? thank you.

[JustBlackBird]

Frankly, I'm not sure Handlebars.js allow to use @ character freely. @majortom731 could you please provide a JS fiddle that illustrates behavior of Handlebars.js?

[majortom731]

Right, @ is reserved for special variables like @key, @index or @root. We should make @root a real special variable then.

[JustBlackBird]

@majortom731 actually @ is used for private variables. See http://handlebarsjs.com/block_helpers.html#hash-arguments for details. I believe we should fix arguments parsing at the same time we add support for private variables.

[fzerorubigd]

@JustBlackBird, the private variables are already supported as special variables, do I miss something?

[JustBlackBird]

@fzerorubigd sorry for the late answer, I had no enough time to manage issues, but now I'm back.

As I see, the current implementation of Handlebars.php supports only limited set of private variables, namely @index, @key, @first and @last (correct me if I've missed something). At the same time, Handlebars.js allow to use own custom private variables by defining them in block helpers. So there is a certain amount of work we should do here.