The difference between comment and document about the parser

[Jonathan Gibbons]

For the comment in JavacParser.java, I suggest the phrase "with code 
derived systematically from an LL(1) grammar" is replaced by something 
like "according to the grammar described in the Java Language 
Specification", and for bonus points, possibly even give the URL 
https://docs.oracle.com/javase/specs/index.html. I would recommend not 
citing any specific version, because that would need to be updated on 
each release.  For additional pedantry, you could also include reference 
to the preview features, which are not part of JLS itself.

-- Jon

On 1/23/21 9:05 AM, Jonathan Gibbons wrote:
>
> Going back in the public record, I note that JLS 3rd Edition, chapter 
> 18[1] says:
>
> /The grammar presented in this chapter is the basis for the reference 
> implementation. Note that it is not an LL(1) grammar, though in many 
> cases it minimizes the necessary look ahead./
>
> -- Jon
>
> 1: https://docs.oracle.com/javase/specs/jls/se6/html/syntax.html
>
> On 1/22/21 12:49 AM, Guoxiong Li wrote:
>> Hi all,
>>
>> The comment at class 
>> jdk.compiler/com.sun.tools.javac.parser.JavacParser states it as below.
>>
>> ```
>> /** The parser maps a token sequence into an abstract syntax
>>  *  tree. It operates by recursive descent, with code derived
>>  *  systematically from an LL(1) grammar. For efficiency reasons, an
>>  *  operator precedence scheme is used for parsing binary operation
>>  *  expressions.
>> ```
>>
>> And the document of the project `Compiler Grammar`[1] states it as below.
>>
>> > The parser that is currently in the javac compiler is a 
>> hand-written LALR parser.
>>
>> We can see that one is  LL(1) and another is LALR. I think the 
>> comment may be right.
>> No matter which one is the right description, the difference is not 
>> acceptable and need to be unified.
>>
>> What is your opinion? Any idea is appreciated.
>>
>> [1] http://openjdk.java.net/projects/compiler-grammar/ 
>> <http://openjdk.java.net/projects/compiler-grammar/>
>>
>> Best Regards.
>>
>> -- xiong
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