exec/java-exec/src/main/java/org/apache/drill/exec/store/easy/json/values/ScalarListener.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.drill.exec.store.easy.json.values;

import org.apache.commons.lang3.StringUtils;
import org.apache.drill.common.exceptions.UserException;
import org.apache.drill.exec.record.metadata.ColumnMetadata;
import org.apache.drill.exec.store.easy.json.loader.JsonLoaderImpl;
import org.apache.drill.exec.store.easy.json.parser.TokenIterator;
import org.apache.drill.exec.store.easy.json.parser.ValueListener;
import org.apache.drill.exec.vector.accessor.ScalarWriter;
import org.apache.drill.exec.vector.accessor.UnsupportedConversionError;

import com.fasterxml.jackson.core.JsonToken;

import java.util.Map;

/**
 * Base class for scalar field listeners
 */
public abstract class ScalarListener implements ValueListener {

  protected final JsonLoaderImpl loader;
  protected final ScalarWriter writer;
  protected final boolean isArray;

  public ScalarListener(JsonLoaderImpl loader, ScalarWriter writer) {
    this.loader = loader;
    this.writer = writer;
    isArray = writer.schema().isArray();
  }

  public ColumnMetadata schema() { return writer.schema(); }

  @Override
  public void onValue(JsonToken token, TokenIterator tokenizer) {
    throw typeConversionError(token.name());
  }

  @Override
  public void onText(String value) {
    throw typeConversionError("text");
  }

  protected void setNull() {
    try {
      if (isArray) {
        setArrayNull();
      } else {
        writer.setNull();
      }
    } catch (UnsupportedConversionError e) {
      throw loader.buildError(schema(),
          UserException.dataReadError()
            .message("Null value encountered in JSON input where Drill does not allow nulls."));
    }
  }

  protected void setArrayNull() {
    // Default is no "natural" null value
    throw loader.nullDisallowedError(schema());
  }

  protected UserException typeConversionError(String jsonType) {
    return loader.typeConversionError(schema(), jsonType);
  }

  /**
   * Adds a field's most recent value to the column listener map.
   * This data is only stored if the listener column map is defined, and has keys.
   * @param key The key of the listener field
   * @param value The value of to be retained
   */
  protected void addValueToListenerMap(String key, String value) {
    Map<String,Object> listenerColumnMap = loader.listenerColumnMap();

    if (listenerColumnMap == null || listenerColumnMap.isEmpty()) {
      return;
    } else if (listenerColumnMap.containsKey(key) && StringUtils.isNotEmpty(value)) {
      listenerColumnMap.put(key, value);
    }
  }

  protected void addValueToListenerMap(String key, Object value) {
    Map<String, Object> listenerColumnMap = loader.listenerColumnMap();

    if (listenerColumnMap == null || listenerColumnMap.isEmpty()) {
      return;
    } else if (listenerColumnMap.containsKey(key) && value != null) {
      listenerColumnMap.put(key, value);
    }
  }
}