10:58 a.m.
I have run into a number of problems using a domain specific language (DSL)
on processing DSLR files. My biggest frustration - and one I am hoping
people can provide a work-around or guidance on - is that often the Eclipse
plug-in does not allow the DRL pane, showing the DRL file, to be clicked on
(and shown.) This sometimes happens when there are no compilation errors:
the DLR file is simply not being generated.
I have run into issues where an error like "parsing problem: contact the
support team" occurs or a null pointer exception occurs, but no error is
shown. My approach has been to make small changes in working DSL files
(i.e., describing the translations) at a time, to minimize impact. Can
anyone offer better approaches to building the DSL grammar?
On a related issue, many documents cite using DSL and regular expressions
for code-rewriting and - while I find documentation on antlr 3 masks for
doing some regular expressions - is the common re-writing task of using "or"
- as in
My object (Car|Bus|Buyer|Salesman)
supported in any way other than seperate lines for "object Car", "object
Bus", etc? Thanks!
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11:14 a.m.
Trying to bind a variable on the left hand side is a specific example that
causes no error to be reported but no DRL to be generated. I can do the
binding if I have one re-writing statement per possibility,
i.e.,
There is a first object = object_1 : Car()
but not if I generalize it:
There is a {nth} object = object_{nth} : Car
I have seen limited cases where code seems to be able to be generated with
the generalized approach, but it seems to generally fail. My goal here is
to use one re-writing statement to handle any number of bindings on
variables and objects, as opposed to the cross-product. I.e., I want to
avoid
There is a first object with a first field {field} = object_1 : Car(
field_1_1 : {field} )
There is a second object with a first field {field} = object_2 : Car(
field_2_1 : {field} )
There is a first object with a second field {field} = object_1 : Car(
field_1_2 : {field} )
There is a second object with a second field {field} = object_1 : Car(
field_2_2 : {field} )
since I might have 4 matched objects with 5 matched fields - and there is
plenty of other matching logic to consider. Thanks!
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1:40 p.m.
On 21 March 2011 16:58, drdaveg <drdaveg(a)gmail.com> wrote:
I have run into a number of problems using a domain specific language
(DSL)
on processing DSLR files. My biggest frustration - and one I am hoping
people can provide a work-around or guidance on - is that often the Eclipse
plug-in does not allow the DRL pane, showing the DRL file, to be clicked on
(and shown.) This sometimes happens when there are no compilation errors:
the DLR file is simply not being generated.
I have run into issues where an error like "parsing problem: contact the
support team" occurs or a null pointer exception occurs, but no error is
shown. My approach has been to make small changes in working DSL files
(i.e., describing the translations) at a time, to minimize impact. Can
anyone offer better approaches to building the DSL grammar?
The upcoming version 5.2 will have better error reporting and new debug
facilities for DSL/DSLR expansion. Also, the substitution of partial names
for
binding variables should work with this new version.
On a related issue, many documents cite using DSL and regular
expressions
for code-rewriting and - while I find documentation on antlr 3 masks for
doing some regular expressions - is the common re-writing task of using
"or"
- as in
My object (Car|Bus|Buyer|Salesman)
supported in any way other than seperate lines for "object Car", "object
Bus", etc? Thanks!
I can't quite follow you here. From a user's point of view, antlr3 has
nothing
to do with DSL. If you could provide examples in DRL for what you want to
express in DSL/DSLR?
-W
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1:52 p.m.
I have some more incite into what might be causing the problem. Once I
remove the drools.package file - which shouldn't be needed since the imports
and expander are in the .dslr file - and have a trivial example - I can see
an "DSL Rule Translation: Array out of bounds" exception generated in
Eclipse several *minutes* later. My DSL makes no mention of arrays and, in
this simplest case, am generating
object1 : Car()
where object1 and Car are mappings. Once the exception is generated and the
dialog box clicked on, you can see the correct translation in the DLR file.
Thus, I believe
1. the translator is grinding in an infinite loop, probably just before the
file is closed and
2. The exception closes the (correctly translated) file.
Is there some token (other than "end") that should be included in the .dslr
file to ensure the file closes properly? I don't see any control characters
present in the file when I open it in a variety of editors.
On antlr, I was referring to an article at
http://blog.athico.com/search/label/DSL%20regexp%20antlr that discusses the
development of Drools. Thanks!
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1:55 p.m.
Sorry to not include this earlier, but the exeption (where I am developing on
another machine) disappeared before. It is exactly:
DSL Rule Translation Error!
Reason:
java.lang.ArrayIndexOutOfBoundsException: 16
and my .dslr file has exactlly 16 lines.
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