package liquibase.precondition.core;

 import liquibase.changelog.DatabaseChangeLog;

 import liquibase.changelog.ChangeSet;

 import liquibase.database.Database;

 import liquibase.exception.PreconditionErrorException;

 import liquibase.exception.PreconditionFailedException;

 import liquibase.exception.ValidationErrors;

 import liquibase.exception.Warnings;

 import liquibase.precondition.Precondition;

 import liquibase.precondition.PreconditionLogic;

 /**

  * Class for controling "not" logic in preconditions.

  */

 public class NotPrecondition extends PreconditionLogic {

     public Warnings warn(Database database) {

         return new Warnings();

     }

     public ValidationErrors validate(Database database) {

         return new ValidationErrors();

     }

     public void check(Database database, DatabaseChangeLog changeLog, ChangeSet changeSet)

             throws PreconditionFailedException, PreconditionErrorException {

         for (Precondition precondition : getNestedPreconditions()) {

             boolean threwException = false;

             try {

                 precondition.check(database, changeLog, changeSet);

             } catch (PreconditionFailedException e) {

                 ; // that's what we want with a Not precondition

                 threwException = true;

             }

             if (!threwException) {

                 throw new PreconditionFailedException("Not precondition failed", changeLog, this);

             }

         }

     }

     public String getName() {

         return "not";

     }

 }