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.sql.SqlCall;
  import org.apache.calcite.sql.SqlIdentifier;
  import org.apache.calcite.sql.SqlNode;
  import org.apache.calcite.sql.SqlUnnestOperator;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * Namespace for UNNEST.
   */
  class UnnestNamespace extends AbstractNamespace {
    //~ Instance fields --------------------------------------------------------
  
    private final SqlCall unnest;
    private final SqlValidatorScope scope;
  
    //~ Constructors -----------------------------------------------------------
  
    UnnestNamespace(
        SqlValidatorImpl validator,
        SqlCall unnest,
        SqlValidatorScope scope,
        SqlNode enclosingNode) {
      super(validator, enclosingNode);
      this.unnest = unnest;
      this.scope = requireNonNull(scope, "scope");
      assert unnest.getOperator() instanceof SqlUnnestOperator;
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public @Nullable SqlValidatorTable getTable() {
      final SqlNode toUnnest = unnest.operand(0);
      if (toUnnest instanceof SqlIdentifier) {
        // When operand of SqlIdentifier type does not have struct, fake a table
        // for UnnestNamespace
        final SqlIdentifier id = (SqlIdentifier) toUnnest;
        final SqlQualified qualified = this.scope.fullyQualify(id);
        if (qualified.namespace == null) {
          return null;
        }
        return qualified.namespace.getTable();
      }
      return null;
    }
  
    /**
     * Given a field name from SelectScope, find the column in this
     * UnnestNamespace it originates from.
     *
     * @param queryFieldName Name of column
     * @return A SqlQualified if subfield comes from this unnest, null if not found
     */
    @Nullable SqlQualified getColumnUnnestedFrom(String queryFieldName) {
      for (SqlNode operand : unnest.getOperandList()) {
        // Ignore operands that are inline ARRAY[] literals
        if (operand instanceof SqlIdentifier) {
          final SqlIdentifier id = (SqlIdentifier) operand;
          final SqlQualified qualified = this.scope.fullyQualify(id);
          RelDataType dataType = this.scope.resolveColumn(qualified.suffix().get(0), id);
          if (dataType != null) {
            RelDataType repeatedEntryType = dataType.getComponentType();
            if (repeatedEntryType != null
                && repeatedEntryType.isStruct()
                && repeatedEntryType.getFieldNames().contains(queryFieldName)) {
              return qualified;
            }
          }
        }
      }
      return null;
    }
  
    @Override protected RelDataType validateImpl(RelDataType targetRowType) {
      // Validate the call and its arguments, and infer the return type.
      validator.validateCall(unnest, scope);
      RelDataType type =
          unnest.getOperator().validateOperands(validator, scope, unnest);
  
      return toStruct(type, unnest);
    }
  
    @Override public @Nullable SqlNode getNode() {
      return unnest;
    }
  }
  