On 02/02/2012 06:27 PM, Waldemar Horwat wrote:
On 02/02/2012 04:15 PM, Mark S. Miller wrote:
On Thu, Feb 2, 2012 at 2:00 PM, Waldemar Horwat <[email protected]
<mailto:[email protected]>> wrote:
OK. This introduces yet another lexing context, in which all productions
*except* QuasiMiddle and QuasiEnd are disallowed, and white space and comment
handling is funny. That works if the expressions must be one of the two forms:
$id
${expr}
Is that the exhaustive list, or are we looking at other forms such as $$, $id.id
<http://id.id>, $id[expr], etc.?
I'll let Mike speak for the details of what he really wants to propose. But
here are the answers from E:
escapes with the quasi literal text are taken care of by the QuasiChar
production, much like the existing definition of DoubleStringCharacter:
QuasiChar ::
SourceCharacter but not one of $ or `
$ $
$ `
$ \ EscapeSequence
So that `$$` === "$", `$`` === "`", and `$\n` === "\n", respectively.
Regarding `...$id.id...` and `...$id[expr]...`, only the first id in each case
in in the quasiHole. All the text afterwards is part of the QuasiClose.
Good. I'll have to think about this a bit more, but there's a chance you
converted me.
Note that this is more complex than just having the parser switch modes for the
treatment of / as division vs. regexp. Here comments and white space are also
affected, which can in turn the structure of the lexer upside down. The kinds
of cases I'm thinking of are:
`abc$/*comment*/identifier//
`
(here we have a /**/ comment and a // comment)
`abc$/**/{/**//re//**/}/**/def`
vs:
`abc$/**/{/**//re//**/}/*def`
(in the former all four "/**/"'s are comments. Not sure what the latter would
do.)
`abc$id def`
`abc$ id def`
(the lexer removes spaces before all tokens, so the quasi would not contain a space
before the "def")
Waldemar
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