Added support for mustaches beginning with @

[amiller-gh]

Because the handlebars parser treats mustaches beginning with @ differently (see @DaTa variables: http://handlebarsjs.com/reference.html), they do not have the string attribute assigned to them from the ast generated from handlebars. In order to allow other frameworks to support having their own @DaTa variables, modify hydration_opcode.js to accept either string or idName as the mustache identifier.

tl;dr:

• Mustaches beginning with @ dont have the string attribute defined in the handlebars ast.
• If a mustache does not have the string attribute present in hydration_opcode.js, use idName instead.
• Added missing semicolon for element cache in templates.

[mixonic]

@EpicMiller would definitely want to see some tests here. Not quite sure what role {{@index}} would play in the HTMLBars world, need to consider what this means for real-world APIs. It might be best to fail compilation if someone uses the {{@index}} syntax, just as it might be best to fail on unsupported syntaxes like {{../../someThing}}.

/cc @mmun

[mmun]

@EpicMiller What's your motivation behind this?

We're planning on implementing something more general than data for HTMLBars (which will likely need support in the Handlebars parser). Check out this RFC: emberjs/rfcs#3.

In the interim we could merge this so that we can at least treat @foo as a regular path instead of a parse error.

[amiller-gh]

Commented on the RFC with my thoughts on the larger block params problem, and hopefully with what counts as the motivation behind this. emberjs/rfcs#3

Tests can be added :)

[mmun]

This "just works" with the new Handlebars AST. @foo.bar and foo.bar are both PathExpressions, the first one simply has data: true on it. HTMLBars doesn't implement any special semantics for it though (yet?).