/*
* 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.vector.accessor;
import java.math.BigDecimal;
import org.joda.time.Period;
/**
* Defines a reader to obtain values from value vectors using
* a simple, uniform interface. Vector values are mapped to
* their "natural" representations: the representation closest
* to the actual vector value. For date and time values, this
* generally means a numeric value. Applications can then map
* this value to Java objects as desired. Decimal types all
* map to BigDecimal as that is the only way in Java to
* represent large decimal values.
* <p>
* In general, a column maps to just one value. However, derived
* classes may choose to provide type conversions if convenient.
* An exception is thrown if a call is made to a method that
* is not supported by the column type.
* <p>
* Values of scalars are provided directly, using the get method
* for the target type. Maps and arrays are structured types and
* require another level of reader abstraction to access each value
* in the structure.
*/
public interface ColumnReader extends ColumnAccessor {
/**
* Report if the column is null. Non-nullable columns always
* return <tt>false</tt>.
* @return true if the column value is null, false if the
* value is set
*/
boolean isNull();
int getInt();
long getLong();
double getDouble();
String getString();
byte[] getBytes();
BigDecimal getDecimal();
Period getPeriod();
TupleReader map();
ArrayReader array();
}