Nested Quasis

Waldemar Horwat waldemar at google.com
Wed Feb 1 17:33:36 PST 2012


On 02/01/2012 11:35 AM, Allen Wirfs-Brock wrote:
>
> On Feb 1, 2012, at 11:28 AM, Waldemar Horwat wrote:
>
>> On 01/31/2012 03:04 PM, Allen Wirfs-Brock wrote:
>>>
>>> On Jan 31, 2012, at 2:36 PM, Waldemar Horwat wrote:
>>>
>>>> On 01/28/2012 02:54 PM, Erik Arvidsson wrote:
>>>>> Under the open issues for Quasi Literals,
>>>>> http://wiki.ecmascript.org/doku.php?id=harmony:quasis#nesting , the
>>>>> topic of nesting is brought up.
>>>>>
>>>>> After implementing Quasi Literals in Traceur it is clear that
>>>>> supporting nested quasi literals is easier than not supporting them.
>>>>> What is the argument for not supporting nesting? Can we resolve this?
>>>>
>>>> This has been hashed out in committee before.  Do you have a solution to the grammar problems, such as having a full ECMAScript parser inside the lexer?  You can't just count parentheses because that breaks regexps.
>>>
>>> I would think the solution to this is pretty straightforward.  Basically, a Quasi is not a single token.   the grammar in the proposal can almost be read that way right now.   It should only take a little cleanup to factor it into a pure lexical part and a syntactic part.
>>
>> I'd love to see this little cleanup.  I thought about it for a while and couldn't come up with it myself; I'm not sure it can even be done.
>
> Was there some particular issue you were running into?

Here's one which I couldn't express in a lexer grammar: How to restart the quasi after an included expression is over.

     Waldemar


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