Home » Modeling » TMF (Xtext) » [Xtext] Serializing an expression DSL with parentheses and different operator priorities
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| Re: [Xtext] Serializing an expression DSL with parentheses and different operator priorities [message #642023 is a reply to message #642018] |
Mon, 29 November 2010 15:24   |
 Cédric Vidal
Messages: 101
Registered: July 2009 |
Senior Member |
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Actually, I just realized that in the sample, the parentheses are
actually correctly serialized.
It's in the bigger DSL that they are not. I have to figure out what is
the difference between the two that makes the serialization fail.
Le 29/11/2010 15:54, Cédric Vidal a écrit :
> Hi Meinte,
>
> Actually, the sample expression DSL is just a snippet to illustrate my
> case. It is part of a much larger DSL and I can't afford going the code
> generation template way.
>
> I really need to find a way to customize the serialization process to
> handle that case.
>
> Le 29/11/2010 15:22, Meinte Boersma a écrit :
>> If there's no need to go with the usual serializer, you could always use
>> an "old-fashioned" Xpand template to serialize it in a way which makes
>> sense, possibly combining it with some Xtend to "look ahead" to see
>> whether higher-precedence binary operators following the current AST
>> node require parentheses around the latter. (Or you just hack it
>> together in even more old-fashioned Java ;) After all, the grammar isn't
>> very big.)
>
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| Re: [Xtext] Serializing an expression DSL with parentheses and different operator priorities [message #642081 is a reply to message #642030] |
Mon, 29 November 2010 18:08 |
Cédric Vidal
Messages: 101
Registered: July 2009 |
Senior Member |
|
|
Hi Sebastian, thanx for the clarification, indeed, my grammar was
erroneous in respect to associativity. But sadly, the problem is
elsewhere. I've investigated and narrowed the issue.
The following grammar serializes correctly:
Expression : Addition;
Addition returns Expression :
Multiplication ({Operation.left=current} op=OPERATOR_ADD
right=Multiplication) *
;
Multiplication returns Expression :
Literal ({Operation.left=current} op=OPERATOR_MUL right=Literal) *
;
Literal returns Expression:
'(' Expression ')'
| {IntLiteral} value=INT
;
terminal OPERATOR_MUL : '*'|'/';
terminal OPERATOR_ADD : '+'|'-';
When using rules instead of terminals, serialization fails to include
parentheses:
Expression : Addition;
Addition returns Expression :
Multiplication ({Operation.left=current} op=OPERATOR_ADD
right=Multiplication) *
;
Multiplication returns Expression :
Literal ({Operation.left=current} op=OPERATOR_MUL right=Literal) *
;
Literal returns Expression:
'(' Expression ')'
| {IntLiteral} value=INT
;
OPERATOR_MUL : '*'|'/'; // <-- using rules instead of terminals
OPERATOR_ADD : '+'|'-';
--> parentheses are not serialized
When operators are specific meta classes which are referenced, it also
fails. The following DSL illustrates that. It adds the possibility to
define operators and reference them.
Evaluation:
(ops+=Operator ';') *
'exp' exp=Expression
;
Expression : Addition;
Addition returns Expression :
Multiplication ({Operation.left=current} op=[Operator|OPERATOR_ADD]
right=Multiplication) *
;
Multiplication returns Expression :
Literal ({Operation.left=current} op=[Operator|OPERATOR_MUL]
right=Literal) *
;
Literal returns Expression:
'(' Expression ')'
| {IntLiteral} value=INT
;
terminal OPERATOR_MUL : '*'|'/';
terminal OPERATOR_ADD : '+'|'-';
Operator :
'op' name=(OPERATOR_ADD|OPERATOR_MUL)
;
--> fails with "org.eclipse.xtext.conversion.ValueConverterException:
The value '*' is an invalid OPERATOR_ADD"
Regards,
Cédric
Le 29/11/2010 16:36, Sebastian Zarnekow a écrit :
> That was to fast. The expression should read:
>
> Addition returns Expression :
> Multiplication ({Operation.left=current} op=('+'|'-')
> right=Multiplication/* <- !!*/) * /* <- !! */
> ;
>
> Regards,
> Sebastian
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| Re: [Xtext] Serializing an expression DSL with parentheses and different operator priorities [message #642082 is a reply to message #642081] |
Mon, 29 November 2010 18:10 |
Cédric Vidal
Messages: 101
Registered: July 2009 |
Senior Member |
|
|
Note that I'm using Xtext 1.0.0, it might work in Xtext 1.0.1
Le 29/11/2010 19:08, Cédric Vidal a écrit :
> Hi Sebastian, thanx for the clarification, indeed, my grammar was
> erroneous in respect to associativity. But sadly, the problem is
> elsewhere. I've investigated and narrowed the issue.
>
> The following grammar serializes correctly:
>
> Expression : Addition;
>
> Addition returns Expression :
> Multiplication ({Operation.left=current} op=OPERATOR_ADD
> right=Multiplication) *
> ;
>
> Multiplication returns Expression :
> Literal ({Operation.left=current} op=OPERATOR_MUL right=Literal) *
> ;
>
> Literal returns Expression:
> '(' Expression ')'
> | {IntLiteral} value=INT
> ;
>
> terminal OPERATOR_MUL : '*'|'/';
> terminal OPERATOR_ADD : '+'|'-';
>
> When using rules instead of terminals, serialization fails to include
> parentheses:
>
> Expression : Addition;
>
> Addition returns Expression :
> Multiplication ({Operation.left=current} op=OPERATOR_ADD
> right=Multiplication) *
> ;
>
> Multiplication returns Expression :
> Literal ({Operation.left=current} op=OPERATOR_MUL right=Literal) *
> ;
>
> Literal returns Expression:
> '(' Expression ')'
> | {IntLiteral} value=INT
> ;
>
> OPERATOR_MUL : '*'|'/'; // <-- using rules instead of terminals
> OPERATOR_ADD : '+'|'-';
>
> --> parentheses are not serialized
>
> When operators are specific meta classes which are referenced, it also
> fails. The following DSL illustrates that. It adds the possibility to
> define operators and reference them.
>
> Evaluation:
> (ops+=Operator ';') *
> 'exp' exp=Expression
> ;
>
> Expression : Addition;
>
> Addition returns Expression :
> Multiplication ({Operation.left=current} op=[Operator|OPERATOR_ADD]
> right=Multiplication) *
> ;
>
> Multiplication returns Expression :
> Literal ({Operation.left=current} op=[Operator|OPERATOR_MUL]
> right=Literal) *
> ;
>
> Literal returns Expression:
> '(' Expression ')'
> | {IntLiteral} value=INT
> ;
>
> terminal OPERATOR_MUL : '*'|'/';
> terminal OPERATOR_ADD : '+'|'-';
>
> Operator :
> 'op' name=(OPERATOR_ADD|OPERATOR_MUL)
> ;
>
> --> fails with "org.eclipse.xtext.conversion.ValueConverterException:
> The value '*' is an invalid OPERATOR_ADD"
>
> Regards,
>
> Cédric
>
> Le 29/11/2010 16:36, Sebastian Zarnekow a écrit :
>> That was to fast. The expression should read:
>>
>> Addition returns Expression :
>> Multiplication ({Operation.left=current} op=('+'|'-')
>> right=Multiplication/* <- !!*/) * /* <- !! */
>> ;
>>
>> Regards,
>> Sebastian
>
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| Re: [Xtext] Serializing an expression DSL with parentheses and different operator priorities [message #642084 is a reply to message #642081] |
Mon, 29 November 2010 18:23 |
Sebastian Zarnekow
Messages: 3118
Registered: July 2009 |
Senior Member |
|
|
Hi Cedric,
would you please be so kind and file your reproducable sample as a
bugzilla? Thanks.
Regards,
Sebastian
--
Need professional support for Eclipse Modeling?
Go visit: http://xtext.itemis.com
Am 29.11.10 19:08, schrieb Cédric Vidal:
> Hi Sebastian, thanx for the clarification, indeed, my grammar was
> erroneous in respect to associativity. But sadly, the problem is
> elsewhere. I've investigated and narrowed the issue.
>
> The following grammar serializes correctly:
>
> Expression : Addition;
>
> Addition returns Expression :
> Multiplication ({Operation.left=current} op=OPERATOR_ADD
> right=Multiplication) *
> ;
>
> Multiplication returns Expression :
> Literal ({Operation.left=current} op=OPERATOR_MUL right=Literal) *
> ;
>
> Literal returns Expression:
> '(' Expression ')'
> | {IntLiteral} value=INT
> ;
>
> terminal OPERATOR_MUL : '*'|'/';
> terminal OPERATOR_ADD : '+'|'-';
>
> When using rules instead of terminals, serialization fails to include
> parentheses:
>
> Expression : Addition;
>
> Addition returns Expression :
> Multiplication ({Operation.left=current} op=OPERATOR_ADD
> right=Multiplication) *
> ;
>
> Multiplication returns Expression :
> Literal ({Operation.left=current} op=OPERATOR_MUL right=Literal) *
> ;
>
> Literal returns Expression:
> '(' Expression ')'
> | {IntLiteral} value=INT
> ;
>
> OPERATOR_MUL : '*'|'/'; // <-- using rules instead of terminals
> OPERATOR_ADD : '+'|'-';
>
> --> parentheses are not serialized
>
> When operators are specific meta classes which are referenced, it also
> fails. The following DSL illustrates that. It adds the possibility to
> define operators and reference them.
>
> Evaluation:
> (ops+=Operator ';') *
> 'exp' exp=Expression
> ;
>
> Expression : Addition;
>
> Addition returns Expression :
> Multiplication ({Operation.left=current} op=[Operator|OPERATOR_ADD]
> right=Multiplication) *
> ;
>
> Multiplication returns Expression :
> Literal ({Operation.left=current} op=[Operator|OPERATOR_MUL]
> right=Literal) *
> ;
>
> Literal returns Expression:
> '(' Expression ')'
> | {IntLiteral} value=INT
> ;
>
> terminal OPERATOR_MUL : '*'|'/';
> terminal OPERATOR_ADD : '+'|'-';
>
> Operator :
> 'op' name=(OPERATOR_ADD|OPERATOR_MUL)
> ;
>
> --> fails with "org.eclipse.xtext.conversion.ValueConverterException:
> The value '*' is an invalid OPERATOR_ADD"
>
> Regards,
>
> Cédric
>
> Le 29/11/2010 16:36, Sebastian Zarnekow a écrit :
>> That was to fast. The expression should read:
>>
>> Addition returns Expression :
>> Multiplication ({Operation.left=current} op=('+'|'-')
>> right=Multiplication/* <- !!*/) * /* <- !! */
>> ;
>>
>> Regards,
>> Sebastian
>
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After all, the grammar isn't very big.)