Johannes Luber wrote:
Jim Idle schrieb:
Johannes Luber wrote:
Jim Idle schrieb:
Andy Grove wrote:
Hi,
I need to generate C and Java from an ANTLR grammar containing
actions. Is there a preprocessor approach I can use rather than
maintaining two versions of the grammar?
I use perforce and maintain a base grammar that has no actions, then
change only the grammar base. When ready to test I integrate the changes
via a prestored branch spec. Other SCCS can do the same sort of thing,
though perforce is streets ahead of anything else at the merge process.
However, occasionally it is a pain to debug remotely when I want to just
use the ANTLR works debugger before integrating a change, so I have
written a pre-processor as an experiment (it is in ANTLR3 of course),
and am trying to decide between the C# lexer base approach and the VB/C
approach (albeit not having the stupidity of the VB pre-processor.)
Having a preprocessor would allow me to have a single grammar for C#,
while allowing to serve it my own needs and the general ones at once.
I've thought about using C#'s preprocessor, but that would at best allow
to circumvent the assignments, but not any initializations.
I was referring to the design pattern rather than the implementation. C#
has a minimalist approach to what you can do with the pre-processor, VB
has some weird and wonderful stuff, and the C pre-processor lets you
hang yourself. So, I personally would not want a pre-processor that you
can program as we are writing grammars, not pre-processor macros ;-0
I think you misunderstood me. Here is one rule in my grammar:
collection_initializer
: OPEN_BRACE element_initializer_list COMMA? CLOSE_BRACE
-> ^(OPEN_BRACE element_initializer_list ^(OPTIONAL COMMA?) CLOSE_BRACE)
;
A normal parser would maybe need only:
collection_initializer
: OPEN_BRACE element_initializer_list COMMA? CLOSE_BRACE
-> ^(element_initializer_list)
;
With a preprocessor one could combine them:
collection_initializer
: OPEN_BRACE element_initializer_list COMMA? CLOSE_BRACE
-> ^(
#ifdef ALL_TOKENS
OPEN_BRACE
#endif
element_initializer_list
#ifdef ALL_TOKENS
^(OPTIONAL COMMA?) CLOSE_BRACE
#endif
)
;
A bit ugly, but it gets the job done. Maybe you have another idea to
accomplish this goal?
Well, you should do this with runtime configuration (I show a parameter
here but you should use some grammar global config class set
externally):
collection_initializer[boolean allTokens]
: OPEN_BRACE element_initializer_list COMMA? CLOSE_BRACE
-> {allTokens}? ^(OPEN_BRACE element_initializer_list
^(OPTIONAL COMMA?) CLOSE_BRACE)
-> element_initializer_list
;
And you probably don't need that COMMA under a root node ;-)
But the general point is good.
Jim
--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "il-antlr-interest" group.
To post to this group, send email to [email protected]
To unsubscribe from this group, send email to [email protected]
For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en
-~----------~----~----~----~------~----~------~--~---
|
List: http://www.antlr.org/mailman/listinfo/antlr-interest
Unsubscribe:
http://www.antlr.org/mailman/options/antlr-interest/your-email-address
