UnnestNamespace.java

/*
 * 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;
  }
}