[antlr-interest] ANTLRWorks 2 (for ANTLR v4)

[Douglas Godfrey]

You still need a way to cause Antlr/AntlrWorks to recognize that you have
an error and unwind the parse state.

I.e. add Error("message") and Warning("message") both with Antlr symbol
substitution within the message.
     Error() and Warning() can be placed in any rule after any token or
predicate.

On 9/8/11 3:28 PM, "Terence Parr" <parrt at cs.usfca.edu> wrote:

>yes, That is of course something for ANTLR not AW. I called those error
>alternatives in my wish list, but then I realized that you can simply
>list them already without having to identify them as error alternatives.
>Then, in that rule, you can specify the appropriate error message.
>
>Ter
>On Sep 8, 2011, at 5:45 AM, Douglas Godfrey wrote:
>
>> How about a direct language feature to issue a warning or error on
>>parsing
>> a rule...
>> 
>> I.e. you have a grammar where certain improper syntax is expected. You
>> make a rule
>> that will recognize the improper syntax or semantics and issue a syntax
>> error with 
>> a better error description when the rule is matched. The side effect of
>> encountering
>> an error rule is the normal unwinding that occurs on a parse failure.
>> 
>> 
>> On 9/1/11 2:18 PM, "Terence Parr" <parrt at cs.usfca.edu> wrote:
>> 
>>> Hi, In parallel with the development of ANTLR v4, superstar Colin Bean
>>> will be building the new version of ANTLRWorks. We already have a great
>>> base in what Jean Bovet did for the 1st version. It's a known entity
>>>and
>>> has lots of bookkeeping code that we can cut and paste into the new one
>>> such as the automatic update facility and preferences. Because we've
>>>got
>>> something to play with, we have something to critique and also a basic
>>> target.
>>> 
>>> I can imagine the basic tool being missing but it would be great to get
>>> feedback from the antlr community.  Remember, that there are probably 2
>>> main communities: the people new to languages and/or ANTLR and the
>>>people
>>> very used to working with ANTLR grammars. For example, new people tend
>>>to
>>> like the syntax diagrams but many old-timers like myself prefer looking
>>> at the grammar because it's more terse.  Recognizing that we must serve
>>> both those communities, please comment with any thoughts on the
>>>following:
>>> 
>>> * What feature seemed like a good idea, but didn't end up being that
>>> valuable? You can say even heretical things like: " the single step
>>> feature in the debugger just didn't seem to be that useful beyond
>>> learning about parsing"
>>> 
>>> * Do you use the re-factoring? Keep in mind that v4 will automatically
>>> handle direct left recursion.
>>> 
>>> * What features do you think are really critical to add?
>>> 
>>> * What features could be really great if we improved them?
>>> 
>>> * Do we need better export facilities?   would you really use things
>>>like
>>> "export grammar as hyperlinked HTML", for example.
>>> 
>>> * What parts of the debugger did you use? There is a lot of stuff in
>>> there like: breakpoints on input tokens, step forward, step backward,
>>> jump to the end, break on specific kinds of events, break at specific
>>> line in the grammar, show the parse tree, show the AST constructed,
>>>list
>>> to the incoming events, etc...  Should we rethink the entire notion of
>>> the debugger at something that simply displays information about what
>>>it
>>> sees during the parse?  I.e., doesn't need to be a controller in the
>>> sense that you can single step the actual running parser over the usual
>>> socket connection?
>>> 
>>> You might include whether you are in the newbie or experienced camp or
>>> somewhere in between.
>>> 
>>> Udo Borkowski has already implemented a fantastic tree layout algorithm
>>> from an academic paper. The performance is extremely good and the
>>>results
>>> are tight.  Colin will probably implement his own syntax diagram viewer
>>> so that we can make it more than just a pretty picture. We want to
>>> highlight elements and step through etc.
>>> 
>>> Thanks!
>>> Ter
>>> 
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>> 
>
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