Bug 368180

Description Thomas Williams 2012-01-09 11:43:42 EST

Steps to Reproduce
------------------

1. Using this grammar:
----------------------

grammar psenterprise.xtext.MyLanguage with org.eclipse.xtext.common.Terminals 

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

generate myLanguage "http://www.mycompany.com/MyLanguage"

GeneralProcessModellingSystem:
    variableTypeEntity=VariableTypeEntity ;

VariableTypeEntity:
    name = ID
    '=' default=RealNumber
    ':' lowerBound=RealNumber 
    ':' upperBound=RealNumber 
    ("UNIT" '=' unit=STRING)? ;

RealNumber returns ecore::EDouble:
    ('-')? INT ( '.' INT )? ;

2. Parse and serialize a String like this:
------------------------------------------

private static String LANGUAGE_TEXT = "GasConcentration = 1.0 : 0.0 : 10.0 UNIT = \"mol/m3\"";

public static void main(String[] args) throws IOException {

    new org.eclipse.emf.mwe.utils.StandaloneSetup().setPlatformUri("../");
    Injector injector = new MyLanguageStandaloneSetup().createInjectorAndDoEMFRegistration();
    XtextResourceSet resourceSet = injector.getInstance(XtextResourceSet.class);
    resourceSet.addLoadOption(XtextResource.OPTION_RESOLVE_ALL, Boolean.TRUE);
    Resource resource = resourceSet.createResource(URI.createURI("dummy:/example.myLanguage"));

    InputStream in = new ByteArrayInputStream(LANGUAGE_TEXT.getBytes());

    resource.load(in, resourceSet.getLoadOptions());
    if (!resource.getErrors().isEmpty()) {
        System.out.println(resource.getErrors());
        return;
    }

    GeneralProcessModellingSystem gpms = (GeneralProcessModellingSystem) resource.getContents().get(0);		
    VariableTypeEntity variableTypeEntity = gpms.getVariableTypeEntity();
    System.out.println(org.eclipse.xtext.util.EmfFormatter.objToStr(gpms));
    Serializer serializer = injector.getInstance(Serializer.class);  
    String s = serializer.serialize(gpms);
    System.out.println(s);
}

Actual Results
--------------

The following output is produced by EmfFormatter#objToStr(gpms):

GeneralProcessModellingSystem {
    cref VariableTypeEntity variableTypeEntity VariableTypeEntity {
        attr EString name 'GasConcentration'
        attr EDouble default '1.0'
        attr EDouble upperBound '10.0'
        attr EString unit 'mol/m3'
    }
}

N.B. Missing 'lowerBound' feature.

The Serializer#serialize() call fails with:

Exception in thread "main" java.lang.RuntimeException: Could not serialize EObject via backtracking.
Constraint: null name=ID default=RealNumber lowerBound=RealNumber upperBound=RealNumber unit=STRING? null
Values: name(1), default(1), upperBound(1), unit(1)
Semantic Object: GeneralProcessModellingSystem.variableTypeEntity->VariableTypeEntity'GasConcentration'
Context: VariableTypeEntity
	at org.eclipse.xtext.serializer.diagnostic.ISerializationDiagnostic$ExceptionThrowingAcceptor.accept(ISerializationDiagnostic.java:70)
	at org.eclipse.xtext.serializer.sequencer.BacktrackingSemanticSequencer.createSequence(BacktrackingSemanticSequencer.java:425)
	at psenterprise.xtext.serializer.AbstractMyLanguageSemanticSequencer.sequence_VariableTypeEntity(AbstractMyLanguageSemanticSequencer.java:112)
	at psenterprise.xtext.serializer.AbstractMyLanguageSemanticSequencer.createSequence(AbstractMyLanguageSemanticSequencer.java:67)
	at org.eclipse.xtext.serializer.acceptor.SequenceFeeder.acceptEObjectRuleCall(SequenceFeeder.java:299)
	at org.eclipse.xtext.serializer.acceptor.SequenceFeeder.acceptRuleCall(SequenceFeeder.java:325)
	at org.eclipse.xtext.serializer.acceptor.SequenceFeeder.accept(SequenceFeeder.java:215)
	at psenterprise.xtext.serializer.AbstractMyLanguageSemanticSequencer.sequence_GeneralProcessModellingSystem(AbstractMyLanguageSemanticSequencer.java:102)
	at psenterprise.xtext.serializer.AbstractMyLanguageSemanticSequencer.createSequence(AbstractMyLanguageSemanticSequencer.java:60)
	at org.eclipse.xtext.serializer.impl.Serializer.serialize(Serializer.java:84)
	at org.eclipse.xtext.serializer.impl.Serializer.serialize(Serializer.java:103)
	at org.eclipse.xtext.serializer.impl.Serializer.serialize(Serializer.java:117)
	at org.eclipse.xtext.serializer.impl.Serializer.serialize(Serializer.java:50)
	at psenterprise.gparser.Main.serializeGPMS(Main.java:108)
	at psenterprise.gparser.Main.main(Main.java:53)

Expected Results
----------------

The following output should be produced by EmfFormatter#objToStr(gpms):

GeneralProcessModellingSystem {
    cref VariableTypeEntity variableTypeEntity VariableTypeEntity {
        attr EString name 'GasConcentration'
        attr EDouble default '1.0'
        attr EDouble lowerBound '0.0'
        attr EDouble upperBound '10.0'
        attr EString unit 'mol/m3'
    }
}

The Serializer#serialize() call should return the String:

    GasConcentration = 1.0 : 0.0 : 10.0 UNIT = "mol/m3"

Speculation as to cause
-----------------------

The 'lowerBound' feature is being considered transient because 0.0 is the
default value for EDouble.

Workarounds
-----------

1. Use EDoubleObject instead of EDouble in the grammar file.
2. Define a custom org.eclipse.xtext.serializer.sequencer.ITransientValueService
   that returns ValueTransient.NO.
3. Use the old Serializer (not tested)