xText Variable/Attribute Assignment - variable-assignment

Question

I built a grammar in xText to recognize formal expressions of a specific format
and to use the generated object tree in Java.
This is what it looks like:
grammar eu.gemtec.device.espa.texpr.Texpr with org.eclipse.xtext.common.Terminals
generate texpr "http://www.gemtec.eu/device/espa/texpr/Texpr"
Model:
(expressions+=AbstractExpression)*
;
AbstractExpression:
MatcherExpression | Assignment;
MatcherExpression:
TerminalMatcher ({Operation.left=current} operator='or' right= MatcherExpression)?
;
TerminalMatcher returns MatcherExpression:
'(' MatcherExpression ')' | {MatcherLiteral} value=Literal
;
Literal:
CharMatcher | ExactMatcher
;
CharMatcher:
type=('text'|'number'|'symbol'|'whitespace') ('(' cardinality=Cardinality ')')?
;
/* Kardinalitäten für CharMatcher*/
Cardinality:
CardinalityMin | CardinalityMinMax | CardinalityMax| CardinalityExact
;
CardinalityMin: min=INT '->';
CardinalityMinMax: min=INT '->' max=INT;
CardinalityMax: '->' max=INT;
CardinalityExact: exact=INT;
ExactMatcher:
(ignoreCase='ignoreCase''(' expected=STRING ')') | expected=STRING
;
/* Variablenzuweisung
*
* z.B. $myVar=number
* */
Assignment:
'$' name=ID '=' expression=MatcherExpression
;
Everything works fine except for the 'cardinality' assignment.
The Expressions look like this:
text number(3) - (an arbitrary amount of letters followed by exactly 3 numbers)
symbol number(2->) - (an arbitrary amount of special characters followed by at least 2 numbers)
whitespace number(->4) - (an arbitrary amount of whitespaces followed by a maximum of 4 numbers)
number(3->6) - (at least 3 numbers but not more than 6)
When I run Eclipse with this grammar (so that my language is recognized and has code completion and so on), everything I type is shown in the "Outline"-tab as a tree-structure as it should, except for the cardinality values.
When I add a cardinality statement to a CharMatcher, the little plus appears before it, but when I click on it it just disappears.
Can anyone tell me why this does not work?

Answer 1

I found the solution myself, I think the problem was that the compiler could not decide which class to create at this point:
Cardinality:
CardinalityMin | CardinalityMinMax | CardinalityMax| CardinalityExact
;
CardinalityMin: min=INT '->';
CardinalityMinMax: min=INT '->' max=INT;
CardinalityMax: '->' max=INT;
CardinalityExact: exact=INT;
So I simplified the whole thing a little, it now looks like this:
Cardinality:
CardinalityMinMax | CardinalityExact
;
CardinalityMinMax: (min=INT '..' max=INT) | (min=INT '..') | ('..' max=INT);
CardinalityExact: exact=INT;
It is still not shown in the "Outline"-Tab, but I suppose that is a problem of the visualisation.
The generated classes now work as intended.