[Grammatica-users] Bug: ParseException.Details will crash when error does not provide a Details list

[William Lahti]

If you receive a ParseException and try to inspect it's Details property, it may crash if the exception has a null 'details' field, as get_Details tries to make a copy of the 'details' field without checking if it's null.

Here's the exception I received:

System.ArgumentNullException: Collection cannot be null.

Parameter name: c

   at System.Collections.ArrayList..ctor(ICollection c)

   at PerCederberg.Grammatica.Runtime.ParseException.get_Details()

   ...

Here's the offending property:

       public ArrayList Details {

            get {

                return new ArrayList(details);

            }

        }

It's found at line 208 in src/csharp/PerCederberg.Grammatica.Runtime/ParseException.cs

The fix is easy:

       public ArrayList Details {

            get {

                if (details == null)

                       return new ArrayList (); // or just null, but an empty list makes more sense imho

                return new ArrayList(details);

            }

        }

Sorry I couldn't provide a patch, but I don't have a proper diff tool on this Windows box and it's a really minor change (though hard to get around without recompiling Grammatica).

--
rezonant

long name: William Lahti
handle :: rezonant
freenode :: xfury
blog :: http://xfurious.blogspot.com/
site :: http://komodocorp.com/~wilahti