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Could not resolve reference to Type (Type: DataType | Class) [message #759299]

Mon, 28 November 2011 10:03

lin.lin

Messages: 17
Registered: September 2011

Junior Member

The intention is to let the class varialbe can be an datatype or a class
, but grammar simply not working.

grammar
--
Type:
{Type}
datatype=DataType | class=Class
;

DataType:
'datatype' name = ID

Class:
'class' name = ID
('extends' superType = [Class | QualifiedName ])?

Variable:
(modifiers += Modifier)*
type = [Type | ID] // [DataType | ID] is OK, this one problem.
name = ID

...

model
--
datatype Integer

class CCCINCAPABILITIES
{
Integer usClass // Error: Couldn't resolve reference to Type 'Integer'.
Boolean bVandalCheck
}

Could you please give a hint about the correct form of the grammar?

~peter lin

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Re: Could not resolve reference to Type (Type: DataType | Class) [message #759320 is a reply to message #759299]

Mon, 28 November 2011 11:20

Meinte Boersma

Messages: 434
Registered: July 2009
Location: Leiden, Netherlands

Senior Member

This should work (untested!):

grammar
--
Type:
DataType | Class
;

DataType:
'datatype' name = ID 

Class:
'class' name = ID
('extends' superType = [Class | QualifiedName ])?


Variable:
(modifiers += Modifier)*
type = [Type | ID]
name = ID

The problem with your grammar is that your original type 'Type' doesn't expose a name of its own because it composes either a DataType or a Class. Because 'Type' doesn't expose a name, it can't be resolved as the target of a cross-reference. By making 'Type' the super type of both DataType and Class, both of which expose a name (=ID), linking works as intended.

Xtext blogs: executable models...again? | workshop material | custom scoping with Xtend

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Re: Could not resolve reference to Type (Type: DataType | Class) [message #759532 is a reply to message #759299]

Tue, 29 November 2011 02:26

lin.lin

Messages: 17
Registered: September 2011

Junior Member

It does the trick. Whether it is called "Feature Normalization"?

Here below is a taken from the documentation:

"6.3.4. Feature Normalization
In the next step the generator examines all generated EClass and lifts up similar features
to super types if there is more than one subtype and the feature is defined in every
subtypes. This does even work for multiple super types."

If yes, could you share why this "lifts up" will not work with "assignment".

thanks a lot.

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Re: Could not resolve reference to Type (Type: DataType | Class) [message #759564 is a reply to message #759532]

Tue, 29 November 2011 08:34

Meinte Boersma

Messages: 434
Registered: July 2009
Location: Leiden, Netherlands

Senior Member

Feature Normalization only "lifts up" common features (i.e., assignments with the same name, type and cardinality) from sub types to (the most generic) super type. In your original grammar, the type 'Type' didn't have any sub or super types since it composed DataType and Class.

Xtext blogs: executable models...again? | workshop material | custom scoping with Xtend

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Re: Could not resolve reference to Type (Type: DataType | Class) [message #784273 is a reply to message #759299]

Fri, 27 January 2012 09:24

Alex G

Messages: 96
Registered: January 2012

Member

Hi!

I have a similar problem like lin.lin. Here is his grammar again:

------------------
Type:
{Type}
datatype=DataType | class=Class
;

DataType:
'datatype' name = ID

Class:
'class' name = ID
('extends' superType = [Class | QualifiedName ])?

Variable:
(modifiers += Modifier)*
type = [Type | ID] // [DataType | ID] is OK, this one problem.
name = ID

--------------------

I do want to leave the feature "datatype" in the type "Type" (in order to do local scoping). Is it still possible to reference somehow by [Type | ID]? If yes, what do I have to do?

Thank you,
Alex.

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