/*
    *    Copyright 2016-2025 the original author or authors.
    *
    *    Licensed under the Apache License, Version 2.0 (the "License");
    *    you may not use this file except in compliance with the License.
    *    You may obtain a copy of the License at
    *
    *       https://www.apache.org/licenses/LICENSE-2.0
    *
   *    Unless required by applicable law or agreed to in writing, software
   *    distributed under the License is distributed on an "AS IS" BASIS,
   *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *    See the License for the specific language governing permissions and
   *    limitations under the License.
   */
  package org.mybatis.dynamic.sql.where.condition;
  
  import java.util.function.BooleanSupplier;
  
  import org.mybatis.dynamic.sql.AbstractNoValueCondition;
  
  public class IsNull<T> extends AbstractNoValueCondition<T> implements AbstractNoValueCondition.Filterable {
      private static final IsNull<?> EMPTY = new IsNull<>() {
          @Override
          public boolean isEmpty() {
              return true;
          }
      };
  
      public static <T> IsNull<T> empty() {
          @SuppressWarnings("unchecked")
          IsNull<T> t = (IsNull<T>) EMPTY;
          return t;
      }
  
      public IsNull() {
          super();
      }
  
      @Override
      public String operator() {
          return "is null"; //$NON-NLS-1$
      }
  
      @Override
      public <S> IsNull<S> filter(BooleanSupplier booleanSupplier) {
          @SuppressWarnings("unchecked")
          IsNull<S> self = (IsNull<S>) this;
          return filterSupport(booleanSupplier, IsNull::empty, self);
      }
  }