| Why the cross-reference does not work? [message #854738] |
Tue, 24 April 2012 03:46  |
Eclipse User |
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Hi, all,
In my simple grammar (see the code below), I want to reference attributes of some entities, e.g., the age of a people. But when I use the grammar, an error occurs as below:
Couldn't resolve reference to Attribute 'age'.
My grammar is below:
Model:
entity += Entity+
expr += Expr*
;
Entity: 'entity' name=ID '{' attrs+=Attribute* '}';
Attribute: Type name=ID;
Expr: ref=[Attribute];
Type: 'int' | 'string';
and the instance is below:
entity People {
int age
}
age
What is the problem?
Thanks.
Robin
[Updated on: Tue, 24 April 2012 03:47] by Moderator |
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| Re: Why the cross-reference does not work? [message #854761 is a reply to message #854738] |
Tue, 24 April 2012 04:07  |
| Eclipse User |
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From outside the Entity, the age attribute has to be referred to with
the fully qualified name, i.e. 'People.age'. Unfortunately, you specify
the cross-reference as being
[Attribute]
which is equivalent to
[Attribute|ID]
and the ID rule does not allow to the separator char '.'
Am 24.04.12 09:46, schrieb Robin Zhou:
> Hi, all,
>
> In my simple grammar (see the code below), I want to reference
> attributes of some entities, e.g., the age of a people. But when I use
> the grammar, an error occurs as below:
>
> Couldn't resolve reference to Attribute 'age'.
>
> My grammar is below:
>
>
> Model:
> entity += Entity+
> expr += Expr*
> ;
>
> Entity: 'entity' name=ID '{' attrs+=Attribute* '}';
>
> Attribute: Type name=ID;
>
> Expr: ref=[Attribute];
>
> Type: 'int' | 'string';
>
>
> and the instance is below:
>
> entity People {
> int age
> }
> age
>
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| Re: Why the cross-reference does not work? [message #854835 is a reply to message #854800] |
Tue, 24 April 2012 05:18 |
| Eclipse User |
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I sovled the problem using a format of
Expr: attr=[Attribute|QualifiedAttributeName];
QualifiedAttributeName: ID ('.' ID)*;
The question here is how to replace the '.' by '@' if the last ID is an attribute, so that I can gain the following elments like:
People.Child
People.Child@name
Of couse, I changed the grammar to allow entity nesting.
Thanks.
Robin
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