RFR: 8276124: Provide snippet support for properties files [v2]

[Pavel Rappo]

On Mon, 22 Nov 2021 23:23:35 GMT, Jonathan Gibbons <jjg at openjdk.org> wrote:

>> I'm going to answer both of your comments, this and that one above:
>> 
>>> I think you can simplify the code by reducing `CoarseParser` down to a language-specific regular expression with "standard" named groups for the payload and markup.
>> 
>> Regular expressions with named groups were the initial design. However, I changed it to `CoarseParser` halfway through the implementation, when saw how bulky the named regex were becoming. As you also note, "end-of-line comments" and "comment lines" differ. I couldn't quickly come up with a regex that accounts for both of them.
>
> You may be somewhat missing the point I was trying to make.
> 
> You have two impls of `CoarseParser`, both of which contain a regular expression for the parsing, hidden inside their private matcher field.
> 
> The only other functionality of `CoarseParser` is `payloadEnd` and `markupStart`.
> 
> My suggestion is to start by updating each of the regex with named groups for the payload and markup parts of the line, such that you can derive `payloadEnd` and `markupStart` from the appropriate named groups.
> 
> At that point, the only thing unique about the impls of `CoarseParser` is their regex, and that regex could become a property of the `Language` object.
> 
>> As you also note, "end-of-line comments" and "comment lines" differ. I couldn't quickly come up with a regex that accounts for both of them.
> 
> To be clear, I am _not_ suggesting a single regex.  I am suggesting a regex per supported language.

I abstracted out the mechanics behind the `CoarseParser` precisely because I couldn't come up with a simple way to derive `payloadEnd` and `markupStart` using only groups, be they named or otherwise. My regex fu is not strong enough. If you could find a way that does not look too ugly and passes the added `TestLangProperties` test, be my guest.

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PR: https://git.openjdk.java.net/jdk/pull/6397