Eclipse Community Forums: TMF (Xtext) » Use object as type instead of String

Home

Home » Modeling » TMF (Xtext) » Use object as type instead of String

Use object as type instead of String [message #1779350]

Fri, 05 January 2018 11:43

Eclipse User

Hello,

my grammar looks like:

Eq:
	'eq' value=STRING | NUMBER |NULL;

NUMBER:
	'-'? INT ('.' INT)?;

terminal NULL:
	'null';

Currently the interface Eq constains a method `String getValue`, how can i change this to`Object getValue`?

[Updated on: Fri, 05 January 2018 12:32] by Moderator

Re: Use object as type instead of String [message #1779359 is a reply to message #1779350]

Fri, 05 January 2018 12:25

Eclipse User

can you please give some more context. if (at all) the type would be EObject? or do you mean java.lang.Object? if yes what do you want to fill it with?

Re: Use object as type instead of String [message #1779361 is a reply to message #1779359]

Fri, 05 January 2018 12:38

Eclipse User

The EObject is ok as well.
Currently the value is always a String (at the modell class), but it can be null or 112 or 11.2. or "A".
The issue is I do not know the original value anymore.

Small example with null:

	@Test
	public void parseNull() {
		final String value = null;
		String expression = "eq"+ value;
                //parsing...
		Eq eq;
		assertThat(eq.getValue()).isEqualTo(value);
	}

JUnit result said: Expected null Actual: "null"

Thanks for your help

[Updated on: Fri, 05 January 2018 12:39] by Moderator

Re: Use object as type instead of String [message #1779367 is a reply to message #1779361]

Fri, 05 January 2018 12:51

Eclipse User

that sounds like a parse error?!?

the question is your semantic?

wouldnt it be better to have a StringLiteral, a NumberLiteral, and Null as separate types?

Re: Use object as type instead of String [message #1779371 is a reply to message #1779367]

Fri, 05 January 2018 13:06

Eclipse User

Christian Dietrich wrote on Fri, 05 January 2018 17:51

that sounds like a parse error?!?

Why should this be a parse error?

Christian Dietrich wrote on Fri, 05 January 2018 17:51

the question is your semantic?

The semantic is like:

eq(attribute, "a") or eq(attribute, 1) or eq(attribute, null)

Christian Dietrich wrote on Fri, 05 January 2018 17:51

wouldnt it be better to have a StringLiteral, a NumberLiteral, and Null as separate types?

Do you mean something like this:

Instead of

Eq:
	'eq' '(' attribute=FIELD_VALUE ',' value=STRING | INT | NULL')';

this:

Eq:
	EqString | EqInt ...
EqString:
	'eq' '(' attribute=FIELD_VALUE ',' value=STRING')';
EqInt:
       'eq' '(' attribute=FIELD_VALUE ',' value=INT')';

Re: Use object as type instead of String [message #1779372 is a reply to message #1779367]

Fri, 05 January 2018 13:07

Eclipse User

Christian Dietrich wrote on Fri, 05 January 2018 17:51

that sounds like a parse error?!?

Why should this be a parse error?

Christian Dietrich wrote on Fri, 05 January 2018 17:51

the question is your semantic?

The semantic is like:

eq(attribute, "a") or eq(attribute, 1) or eq(attribute, null)

Christian Dietrich wrote on Fri, 05 January 2018 17:51

wouldnt it be better to have a StringLiteral, a NumberLiteral, and Null as separate types?

Do you mean something like this:

Instead of

Eq:
	'eq' '(' attribute=FIELD_VALUE ',' value=STRING | INT | NULL')';

this:

Eq:
	EqString | EqInt ...
EqString:
	'eq' '(' attribute=FIELD_VALUE ',' value=STRING')';
EqInt:
       'eq' '(' attribute=FIELD_VALUE ',' value=INT')';

Re: Use object as type instead of String [message #1779373 is a reply to message #1779367]

Fri, 05 January 2018 13:07

Eclipse User

Christian Dietrich wrote on Fri, 05 January 2018 17:51

that sounds like a parse error?!?

Why should this be a parse error?

Christian Dietrich wrote on Fri, 05 January 2018 17:51

the question is your semantic?

The semantic is like:

eq(attribute, "a") or eq(attribute, 1) or eq(attribute, null)

Christian Dietrich wrote on Fri, 05 January 2018 17:51

wouldnt it be better to have a StringLiteral, a NumberLiteral, and Null as separate types?

Do you mean something like this:

Instead of

Eq:
	'eq' '(' attribute=FIELD_VALUE ',' value=STRING | INT | NULL')';

this:

Eq:
	EqString | EqInt ...
EqString:
	'eq' '(' attribute=FIELD_VALUE ',' value=STRING')';
EqInt:
       'eq' '(' attribute=FIELD_VALUE ',' value=INT')';

Re: Use object as type instead of String [message #1779374 is a reply to message #1779373]

Fri, 05 January 2018 13:08

Eclipse User

so eq is (field, value) ?

Re: Use object as type instead of String [message #1779375 is a reply to message #1779367]

Fri, 05 January 2018 13:08

Eclipse User

Christian Dietrich wrote on Fri, 05 January 2018 17:51

that sounds like a parse error?!?

Why should this be a parse error?

Christian Dietrich wrote on Fri, 05 January 2018 17:51

the question is your semantic?

The semantic is like:

eq(attribute, "a") or eq(attribute, 1) or eq(attribute, null)

Christian Dietrich wrote on Fri, 05 January 2018 17:51

wouldnt it be better to have a StringLiteral, a NumberLiteral, and Null as separate types?

Do you mean something like this:

Instead of

Eq:
	'eq' '(' attribute=FIELD_VALUE ',' value=STRING | INT | NULL')';

this:

Eq:
	EqString | EqInt ...
EqString:
	'eq' '(' attribute=FIELD_VALUE ',' value=STRING')';
EqInt:
       'eq' '(' attribute=FIELD_VALUE ',' value=INT')';

Re: Use object as type instead of String [message #1779376 is a reply to message #1779375]

Fri, 05 January 2018 13:11

Eclipse User

i mean something like

value=ValueExpression

ValueExpression: StringLiteral | IntLiteral | NullLiteral;

StringLiteral: value=STRING
IntLiteral: value=INT
NullLiteral: {NullLiteral} "NULL";

Re: Use object as type instead of String [message #1779377 is a reply to message #1779376]

Fri, 05 January 2018 13:23

Eclipse User

Christian Dietrich wrote on Fri, 05 January 2018 18:11

i mean something like

I have already done that, I have abbreviated this only for the example.
Sorry for the confusion:

This are my type rules

Eq:
	'eq' '(' attribute=FIELD_VALUE ',' value=Literal ')';

Literal:
	(StringOrNumberLiteral | BOOLEAN | NULL);

StringOrNumberLiteral:
	STRING | NUMBER;

NUMBER:
	'-'? INT ('.' INT)?;

terminal BOOLEAN returns ecore::EBoolean:
	'true' | 'false';

terminal NULL:
	'null';

terminal FIELD_VALUE:
	('A'..'Z' | 'a'..'z') ('A'..'Z' | 'a'..'z' | '0'..'9' | '.' | '_' | '-')*;

Re: Use object as type instead of String [message #1779378 is a reply to message #1779377]

Fri, 05 January 2018 13:37

Eclipse User

And Whats your actual question

Re: Use object as type instead of String [message #1779390 is a reply to message #1779378]

Fri, 05 January 2018 17:08

Eclipse User

Christian Dietrich wrote on Fri, 05 January 2018 18:37

And Whats your actual question

The question is why looks the Eq like this

class Eq
String getValue()

insteadOf

class Eq
EObject getValue()

I have the same issue for the In operator

class In
List<Strings> getValues()

How should i validate the datatype, if all values are strings?
How can I check if it was a 1 or "1"

Re: Use object as type instead of String [message #1779393 is a reply to message #1779390]

Fri, 05 January 2018 17:46

Eclipse User

As I said. Make the literals eobjects
By using assignments
Then you can instanceof

Re: Use object as type instead of String [message #1779399 is a reply to message #1779393]

Sat, 06 January 2018 05:23

Eclipse User

Christian Dietrich wrote on Fri, 05 January 2018 22:46

As I said. Make the literals eobjects
By using assignments
Then you can instanceof

Ahh sorry didn't see the assignments. I will try that.
Thanks

Edit: Works :)

[Updated on: Mon, 08 January 2018 01:57] by Moderator

Re: Use object as type instead of String [message #1779458 is a reply to message #1779359]

Mon, 08 January 2018 05:18

Eclipse User

Christian Dietrich wrote on Fri, 05 January 2018 17:25

if (at all) the type would be EObject? or do you mean java.lang.Object? if yes what do you want to fill it with?

1 more question, sorry. Now the value of Literal(s) are EObjects. Is it possible to replace it with java.lang.Object?

Model code:

 EObject getValue();

Re: Use object as type instead of String [message #1779461 is a reply to message #1779458]

Mon, 08 January 2018 05:23

Eclipse User

why do you want to?

Re: Use object as type instead of String [message #1779462 is a reply to message #1779461]

Mon, 08 January 2018 05:24

Eclipse User

and how does the grammar look like. maybe you did something wrong

Re: Use object as type instead of String [message #1779466 is a reply to message #1779461]

Mon, 08 January 2018 05:39

Eclipse User

Christian Dietrich wrote on Mon, 08 January 2018 10:23

why do you want to?

Because a EObject is a interface and a Object is easier to use:
This will not compile if the list contains EObjects

assertThat(inFilter.getValues()).contains("a", "b");

I found this solution, but this no good idea, becuase the conversion is not working anymore

Literal returns ecore::EJavaObject:
	StringOrNumberLiteral | BOOLEAN | NULL;

StringOrNumberLiteral returns ecore::EJavaObject:
	(STRING | NUMBER);

[Updated on: Mon, 08 January 2018 06:58] by Moderator

Re: Use object as type instead of String [message #1779472 is a reply to message #1779462]

Mon, 08 January 2018 07:17

Eclipse User

Christian Dietrich wrote on Mon, 08 January 2018 10:24

and how does the grammar look like. maybe you did something wrong

Currently looks like, but iam not happy with it.

That's way too many classes. That's why an object would be my favorite. Is that not possible?

Literal returns ecore::EObject:
	(StringOrNumberLiteral | BooleanValue | NullValue);
	
StringOrNumberLiteral returns ecore::EObject:
	(StringLiteral | NumberValue);
	
StringLiteral returns ecore::EObject:
	StringValue;
	
StringValue:
	value = STRING;

NumberValue:
	value = DOUBLE;
	
BooleanValue:
	value = BOOLEAN;
	
NullValue:
	value = NULL;

[Updated on: Mon, 08 January 2018 07:35] by Moderator

Re: Use object as type instead of String [message #1779475 is a reply to message #1779472]

Mon, 08 January 2018 07:48

Eclipse User

no i meant

Literal:
(StringOrNumberLiteral | BooleanValue | NullValue);

StringOrNumberLiteral:
(StringLiteral | NumberValue);

StringLiteral:
value = STRING;

NumberValue:
value = DOUBLE;

BooleanValue:
value = BOOLEAN;

NullValue:
value = NULL;

Re: Use object as type instead of String [message #1779477 is a reply to message #1779475]

Mon, 08 January 2018 07:54

Eclipse User

Yes but then i have a Literal Class and a lot of sub classes.
Is that unavoidable?

i would prefer something like

value=(STRING | INT)

Object getValue()

[Updated on: Mon, 08 January 2018 08:00] by Moderator

Re: Use object as type instead of String [message #1779480 is a reply to message #1779477]

Mon, 08 January 2018 08:10

Eclipse User

import "http://www.eclipse.org/emf/2002/Ecore" as ecore

Model:
greetings+=Greeting*;

Greeting:
'Hello' name=WhyTypesIfYouCanHaveObject '!';

// TODO implement value converter
WhyTypesIfYouCanHaveObject returns ecore::EJavaObject:
INT | STRING
;

Re: Use object as type instead of String [message #1779481 is a reply to message #1779480]

Mon, 08 January 2018 08:19

Eclipse User

Okay understand will try to solve it better with types.

Re: Use object as type instead of String [message #1779482 is a reply to message #1779475]

Mon, 08 January 2018 09:00

Eclipse User

Christian Dietrich wrote on Mon, 08 January 2018 12:48

no i meant

Literal:
(StringOrNumberLiteral | BooleanValue | NullValue);

StringOrNumberLiteral:
(StringLiteral | NumberValue);

StringLiteral:
value = STRING;

NumberValue:
value = DOUBLE;

BooleanValue:
value = BOOLEAN;

NullValue:
value = NULL;

Mhm ok this works, but with this solution i have a lots of cast, because the Literal class has no getValue(). Just the subclasses has a getValue

		StringLiteral literal = (StringLiteral) eq.getLiteral();
		assertThat(literal.getValue()).isEqualTo("4711");

Previous Topic:	Unit Test with @Traced
Next Topic:	Deploying xtext features

Goto Forum:

-=] Back to Top [=-

Current Time: Wed Jul 23 17:24:30 EDT 2025

.:: Contact :: Home ::.

Breadcrumbs

Sign up to our Newsletter