Using Hampi to generate constraints od the type >

[Bikash Chandra]

Hi,

I am trying to generate some string lexicographically greater than or
equal to a given string. Let the given string be "C" for the moment.
The hampi code that I have written is

var v : 10;

cfg Digit := ['0'-'9'];
cfg Letter := ['a'-'z'] | ['A'-'Z'];
cfg Ascii := Letter | Digit | " " | "'";
reg Asciistar := star(Ascii);
reg Greater:= concat("C", Asciistar,"");

assert v in Greater;

Running hampi on this file throws an exception:

java.lang.NullPointerException
at
hampi.parser.HConstraintPreparer.prepareRegForVar(HConstraintPreparer.java:
171)
at
hampi.parser.HConstraintPreparer.prepareRegexp(HConstraintPreparer.java:
204)
at
hampi.parser.HConstraintPreparer.prepareRegexp(HConstraintPreparer.java:
188)
at
hampi.parser.HConstraintPreparer.prepareRegForVar(HConstraintPreparer.java:
172)
at
hampi.parser.HConstraintPreparer.prepareRegexp(HConstraintPreparer.java:
204)
at
hampi.parser.HConstraintPreparer.prepareRegexps(HConstraintPreparer.java:
214)
at
hampi.parser.HConstraintPreparer.prepareRegexp(HConstraintPreparer.java:
196)
at
hampi.parser.HConstraintPreparer.prepareRegForVar(HConstraintPreparer.java:
172)
at
hampi.parser.HConstraintPreparer.prepareIn(HConstraintPreparer.java:
144)
at hampi.parser.HConstraintPreparer.prepare(HConstraintPreparer.java:
47)
at hampi.parser.HConstraintPreparer.prepare(HConstraintPreparer.java:
34)
at hampi.Hampi.run(Hampi.java:294)
at hampi.Hampi.run(Hampi.java:270)
at hampi.Hampi.main(Hampi.java:249)


Could you please tell me what is wrong with my hampi code. I am using
the hampi code uploaded on May28,2010 which is the latest version on
svn.

[Devdatta Akhawe]

try

> var v : 10;
>
> cfg Digit := ['0'-'9'];
> cfg Letter := ['a'-'z'] | ['A'-'Z'];
> cfg Ascii := Letter | Digit | " " | "'";

> cfg Asciistar := Ascii Asciistar | ;
> cfg Greater:= "C" Asciistart;
>
> assert v in Greater;

On 13 September 2011 01:51, Bikash Chandra

[Bikash Chandra]

Thanks.
The length of v is constant which is equal to 10. If I want to let the range of v vary from 2 to 10. I should define
var v: 2..10

But this gives a parse error

ERROR Parse errors
line 1:1 no viable alternative at input 'var'

--
Bikash Chandra.

[Adam Kiezun]

Bikash,

are you using the latest from SVN?

also, there's a quirk/bug in the parser, try playing with spaces, eg "2 .. 10" etc

./adam

[Bikash Chandra]

Thanks Adam for the clarification.
BTW I just figured out that using Kaluza would be a better option for the type of problems I am interested to solve. Should i direct my queries regarding Kaluza directly to you or there is some group for that

[Prateek Saxena]

Hi Bikash,

Please direct your queries to me (Prateek) @ prat...@cs.berkeley.edu directly if you are interested in using Kaluza (http://webblaze.cs.berkeley.edu/2010/kaluza/)

Cheers,

Prateek.