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.adapter.file;
  
  import org.apache.calcite.adapter.java.JavaTypeFactory;
  import org.apache.calcite.rel.type.RelDataType;
  import org.apache.calcite.rel.type.RelDataTypeFactory;
  import org.apache.calcite.rel.type.RelProtoDataType;
  import org.apache.calcite.schema.impl.AbstractTable;
  import org.apache.calcite.util.Source;
  
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.util.ArrayList;
  import java.util.List;
  
  /**
   * Base class for table that reads CSV files.
   *
   * <p>Copied from {@code CsvFilterableTable} in demo CSV adapter,
   * with more advanced features.
   */
  public abstract class CsvTable extends AbstractTable {
    protected final Source source;
    protected final @Nullable RelProtoDataType protoRowType;
    private @Nullable RelDataType rowType;
    private @Nullable List<RelDataType> fieldTypes;
  
    /** Creates a CsvTable. */
    CsvTable(Source source, @Nullable RelProtoDataType protoRowType) {
      this.source = source;
      this.protoRowType = protoRowType;
    }
  
    @Override public RelDataType getRowType(RelDataTypeFactory typeFactory) {
      if (protoRowType != null) {
        return protoRowType.apply(typeFactory);
      }
      if (rowType == null) {
        rowType =
            CsvEnumerator.deduceRowType((JavaTypeFactory) typeFactory, source,
                null, isStream());
      }
      return rowType;
    }
  
    /** Returns the field types of this CSV table. */
    public List<RelDataType> getFieldTypes(RelDataTypeFactory typeFactory) {
      if (fieldTypes == null) {
        fieldTypes = new ArrayList<>();
        CsvEnumerator.deduceRowType((JavaTypeFactory) typeFactory, source,
            fieldTypes, isStream());
      }
      return fieldTypes;
    }
  
    /** Returns whether the table represents a stream. */
    protected boolean isStream() {
      return false;
    }
  
    /** Various degrees of table "intelligence". */
    public enum Flavor {
      SCANNABLE, FILTERABLE, TRANSLATABLE
    }
  }
  