code: /*
   * Copyright (c) 2019 the Eclipse Milo Authors
   *
   * This program and the accompanying materials are made
   * available under the terms of the Eclipse Public License 2.0
   * which is available at https://www.eclipse.org/legal/epl-2.0/
   *
   * SPDX-License-Identifier: EPL-2.0
   */
  
  package org.eclipse.milo.opcua.sdk.server.events.operators;
  
  import com.google.common.collect.ImmutableSet;
  import org.eclipse.milo.opcua.sdk.server.events.FilterContext;
  import org.eclipse.milo.opcua.sdk.server.events.OperatorContext;
  import org.eclipse.milo.opcua.sdk.server.events.ValidationException;
  import org.eclipse.milo.opcua.sdk.server.model.nodes.objects.BaseEventTypeNode;
  import org.eclipse.milo.opcua.stack.core.StatusCodes;
  import org.eclipse.milo.opcua.stack.core.UaException;
  import org.eclipse.milo.opcua.stack.core.types.enumerated.FilterOperator;
  import org.eclipse.milo.opcua.stack.core.types.structured.FilterOperand;
  import org.jetbrains.annotations.Nullable;
  
  public class Operators {
  
      public static final Equals EQUALS = new Equals();
      public static final IsNull IS_NULL = new IsNull();
      public static final GreaterThan GREATER_THAN = new GreaterThan();
      public static final LessThan LESS_THAN = new LessThan();
      public static final GreaterThanOrEqual GREATER_THAN_OR_EQUAL = new GreaterThanOrEqual();
      public static final LessThanOrEqual LESS_THAN_OR_EQUAL = new LessThanOrEqual();
      public static final Not NOT = new Not();
      public static final Cast CAST = new Cast();
      public static final OfType OF_TYPE = new OfType();
  
      public static final Operator<Object> UNSUPPORTED = new Operator<Object>() {
          @Nullable
          @Override
          public Object apply(
              OperatorContext context,
              BaseEventTypeNode eventNode,
              FilterOperand[] operands) throws UaException {
  
              throw new UaException(StatusCodes.Bad_FilterOperatorUnsupported);
          }
  
          @Override
          public void validate(FilterContext context, FilterOperand[] operands) throws ValidationException {
              throw new ValidationException(StatusCodes.Bad_FilterOperatorUnsupported);
          }
      };
  
      public static final ImmutableSet<FilterOperator> SUPPORTED_OPERATORS = ImmutableSet.<FilterOperator>builder()
          .add(FilterOperator.Equals)
          .add(FilterOperator.IsNull)
          .add(FilterOperator.GreaterThan)
          .add(FilterOperator.LessThan)
          .add(FilterOperator.GreaterThanOrEqual)
          .add(FilterOperator.LessThanOrEqual)
          .add(FilterOperator.Not)
          .add(FilterOperator.Cast)
          .add(FilterOperator.OfType)
          .build();
  
  }
  