/**
* Copyright 2012 Twitter, Inc.
*
* Licensed 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 parquet.column.impl;
import parquet.column.ColumnDescriptor;
import parquet.column.ColumnReadStore;
import parquet.column.ColumnReader;
import parquet.column.page.PageReadStore;
import parquet.column.page.PageReader;
import parquet.io.api.Converter;
import parquet.io.api.GroupConverter;
import parquet.io.api.PrimitiveConverter;
import parquet.schema.GroupType;
import parquet.schema.MessageType;
import parquet.schema.Type;
/**
* Implementation of the ColumnReadStore
*
* Initializes individual columns based on schema and converter
*
* @author Julien Le Dem
*
*/
public class ColumnReadStoreImpl implements ColumnReadStore {
private final PageReadStore pageReadStore;
private final GroupConverter recordConverter;
private final MessageType schema;
/**
* @param pageReadStore uderlying page storage
* @param recordConverter the user provided converter to materialize records
* @param schema the schema we are reading
*/
public ColumnReadStoreImpl(PageReadStore pageReadStore, GroupConverter recordConverter, MessageType schema) {
super();
this.pageReadStore = pageReadStore;
this.recordConverter = recordConverter;
this.schema = schema;
}
@Override
public ColumnReader getColumnReader(ColumnDescriptor path) {
return newMemColumnReader(path, pageReadStore.getPageReader(path));
}
private ColumnReaderImpl newMemColumnReader(ColumnDescriptor path, PageReader pageReader) {
PrimitiveConverter converter = getPrimitiveConverter(path);
return new ColumnReaderImpl(path, pageReader, converter);
}
private PrimitiveConverter getPrimitiveConverter(ColumnDescriptor path) {
Type currentType = schema;
Converter currentConverter = recordConverter;
for (String fieldName : path.getPath()) {
final GroupType groupType = currentType.asGroupType();
int fieldIndex = groupType.getFieldIndex(fieldName);
currentType = groupType.getType(fieldName);
currentConverter = currentConverter.asGroupConverter().getConverter(fieldIndex);
}
PrimitiveConverter converter = currentConverter.asPrimitiveConverter();
return converter;
}
}