package org.apache.maven.search.request;
   
   /*
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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
   *
   *   http://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.
   */
  
  import java.util.Map;
  import java.util.Objects;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Field, that is used as key in record.
   */
  public abstract class Field
  {
      private final String fieldName;
  
      private final boolean searchable;
  
      private Field( String fieldName, boolean searchable )
      {
          this.fieldName = requireNonNull( fieldName );
          this.searchable = searchable;
      }
  
      /**
       * Returns the field name.
       */
      public String getFieldName()
      {
          return fieldName;
      }
  
      /**
       * Returns {@code true} if field may be used for {@link FieldQuery} (is searchable).
       */
      public boolean isSearchable()
      {
          return searchable;
      }
  
      /**
       * Returns the value of the field from given record instance, or {@code null} if field not present in record.
       * See subclasses for proper return types.
       */
      public abstract Object getFieldValue( Map<Field, Object> record );
  
      @Override
      public boolean equals( Object o )
      {
          if ( this == o )
          {
              return true;
          }
          if ( o == null || getClass() != o.getClass() )
          {
              return false;
          }
          Field fieldName1 = (Field) o;
          return Objects.equals( getFieldName(), fieldName1.getFieldName() );
      }
  
      @Override
      public int hashCode()
      {
          return Objects.hash( getFieldName() );
      }
  
      @Override
      public String toString()
      {
          return fieldName;
      }
  
      public static class StringField extends Field
      {
          public StringField( String fieldName, boolean searchable )
          {
              super( fieldName, searchable );
          }
  
          @Override
          public String getFieldValue( Map<Field, Object> record )
         {
             return (String) record.get( this );
         }
     }
 
     public static class NumberField extends Field
     {
         public NumberField( String fieldName, boolean searchable )
         {
             super( fieldName, searchable );
         }
 
         @Override
         public Number getFieldValue( Map<Field, Object> record )
         {
             return (Number) record.get( this );
         }
     }
 
     public static class BooleanField extends Field
     {
         public BooleanField( String fieldName, boolean searchable )
         {
             super( fieldName, searchable );
         }
 
         @Override
         public Boolean getFieldValue( Map<Field, Object> record )
         {
             return (Boolean) record.get( this );
         }
     }
 }