content: /*
   * 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.
   */
  package org.apache.calcite.sql.validate;
  
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeField;
  import org.apache.calcite.sql.SqlNode;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Implementation of {@link SqlValidatorNamespace} for a field of a record.
   *
   * <p>A field is not a very interesting namespace - except if the field has a
   * record or multiset type - but this class exists to make fields behave
   * similarly to other records for purposes of name resolution.
   */
  class FieldNamespace extends AbstractNamespace {
    //~ Constructors -----------------------------------------------------------
  
    /**
     * Creates a FieldNamespace.
     *
     * @param validator Validator
     * @param dataType  Data type of field
     */
    FieldNamespace(
        SqlValidatorImpl validator,
        RelDataType dataType) {
      super(validator, null);
      this.rowType = requireNonNull(dataType, "dataType");
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public void setType(RelDataType type) {
      throw new UnsupportedOperationException();
    }
  
    @Override protected RelDataType validateImpl(RelDataType targetRowType) {
      return requireNonNull(rowType, "rowType");
    }
  
    @Override public @Nullable SqlNode getNode() {
      return null;
    }
  
    @Override public @Nullable SqlValidatorNamespace lookupChild(String name) {
      if (requireNonNull(rowType, "rowType").isStruct()) {
        return validator.lookupFieldNamespace(
            rowType,
            name);
      }
      return null;
    }
  
    @Override public @Nullable RelDataTypeField field(String name) {
      return null;
    }
  }
  