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.RelDataTypeFactory;
  import org.apache.calcite.sql.SqlJoin;
  import org.apache.calcite.sql.SqlNode;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /**
   * Namespace representing the row type produced by joining two relations.
   */
  class JoinNamespace extends AbstractNamespace {
    //~ Instance fields --------------------------------------------------------
  
    private final SqlJoin join;
  
    //~ Constructors -----------------------------------------------------------
  
    JoinNamespace(SqlValidatorImpl validator, SqlJoin join) {
      super(validator, null);
      this.join = join;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override protected RelDataType validateImpl(RelDataType targetRowType) {
      RelDataType leftType =
          validator.getNamespaceOrThrow(join.getLeft()).getRowType();
      RelDataType rightType =
          validator.getNamespaceOrThrow(join.getRight()).getRowType();
      final RelDataTypeFactory typeFactory = validator.getTypeFactory();
      switch (join.getJoinType()) {
      case LEFT:
      case LEFT_ASOF:
        rightType = typeFactory.createTypeWithNullability(rightType, true);
        break;
      case RIGHT:
        leftType = typeFactory.createTypeWithNullability(leftType, true);
        break;
      case FULL:
        leftType = typeFactory.createTypeWithNullability(leftType, true);
        rightType = typeFactory.createTypeWithNullability(rightType, true);
        break;
      // LEFT SEMI JOIN and LEFT ANTI JOIN can only come from Babel.
      case LEFT_SEMI_JOIN:
      case LEFT_ANTI_JOIN:
        return typeFactory.createJoinType(leftType);
      default:
        break;
      }
      return typeFactory.createJoinType(leftType, rightType);
    }
  
    @Override public @Nullable SqlNode getNode() {
      return join;
    }
  }
  