OperatorDescr op = entry.getValue();
Declaration leftDecl = createDeclarationForOperator(context, pattern, op.getLeftString());
Declaration rightDecl = createDeclarationForOperator(context, pattern, op.getRightString());
Target left = leftDecl != null && leftDecl.isPatternDeclaration() ? Target.HANDLE : Target.FACT;
Target right = rightDecl != null && rightDecl.isPatternDeclaration() ? Target.HANDLE : Target.FACT;
op.setLeftIsHandle( left == Target.HANDLE );
op.setRightIsHandle( right == Target.HANDLE );
Evaluator evaluator = getConstraintBuilder( context ).getEvaluator(