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.stack.core.types.builtin;
  
  import java.util.Arrays;
  import java.util.Objects;
  import java.util.Optional;
  
  import com.google.common.base.MoreObjects;
  import com.google.common.base.MoreObjects.ToStringHelper;
  import org.eclipse.milo.opcua.stack.core.Identifiers;
  import org.eclipse.milo.opcua.stack.core.serialization.UaEnumeration;
  import org.eclipse.milo.opcua.stack.core.serialization.UaStructure;
  import org.eclipse.milo.opcua.stack.core.util.ArrayUtil;
  import org.eclipse.milo.opcua.stack.core.util.TypeUtil;
  import org.jetbrains.annotations.Nullable;
  
  import static com.google.common.base.Preconditions.checkArgument;
  
  public final class Variant {
  
      public static final Variant NULL_VALUE = new Variant(null);
  
      private final Object value;
  
      /**
       * Create a new Variant with a given value.
       *
       * @param value the value this Variant holds.
       */
      public Variant(@Nullable Object value) {
          if (value != null) {
              boolean clazzIsArray = value.getClass().isArray();
  
              Class<?> componentClazz = clazzIsArray ?
                  ArrayUtil.getType(value) : value.getClass();
  
              checkArgument(clazzIsArray || !Variant.class.equals(componentClazz), "Variant cannot contain Variant");
              checkArgument(!DiagnosticInfo.class.equals(componentClazz), "Variant cannot contain DiagnosticInfo");
          }
  
          this.value = value;
      }
  
      public Optional<ExpandedNodeId> getDataType() {
          if (value == null) return Optional.empty();
  
          if (value instanceof UaStructure) {
              return Optional.of(((UaStructure) value).getTypeId());
          } else if (value instanceof UaEnumeration) {
              return Optional.of(Identifiers.Int32.expanded());
          } else {
              Class<?> clazz = value.getClass().isArray() ?
                  ArrayUtil.getType(value) : value.getClass();
  
              int typeId = TypeUtil.getBuiltinTypeId(clazz);
  
              return typeId == -1 ?
                  Optional.empty() : Optional.of(new NodeId(0, typeId).expanded());
          }
      }
  
      public Object getValue() {
          return value;
      }
  
      public boolean isNull() {
          return value == null;
      }
  
      public boolean isNotNull() {
          return !isNull();
      }
  
      @Override
      public boolean equals(Object o) {
          if (this == o) return true;
          if (o == null || getClass() != o.getClass()) return false;
  
          Variant variant = (Variant) o;
  
          return Objects.deepEquals(value, variant.value);
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(valueHash());
      }
  
      private int valueHash() {
          if (value instanceof Object[]) {
              return Arrays.deepHashCode((Object[]) value);
          } else if (value instanceof boolean[]) {
              return Arrays.hashCode((boolean[]) value);
          } else if (value instanceof byte[]) {
              return Arrays.hashCode((byte[]) value);
          } else if (value instanceof short[]) {
              return Arrays.hashCode((short[]) value);
          } else if (value instanceof int[]) {
              return Arrays.hashCode((int[]) value);
          } else if (value instanceof long[]) {
              return Arrays.hashCode((long[]) value);
          } else if (value instanceof float[]) {
              return Arrays.hashCode((float[]) value);
          } else if (value instanceof double[]) {
              return Arrays.hashCode((double[]) value);
          } else {
              return Objects.hashCode(value);
          }
      }
  
      @Override
      public String toString() {
          ToStringHelper helper = MoreObjects.toStringHelper(this);
  
          helper.add("value", value);
  
          return helper.toString();
      }
  
  }
  