| /* |
| * 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.physical.impl.scan.convert; |
| |
| import org.apache.drill.exec.record.metadata.ColumnMetadata; |
| import org.apache.drill.exec.vector.accessor.ScalarWriter; |
| import org.apache.drill.exec.vector.accessor.UnsupportedConversionError; |
| |
| /** |
| * Base class for any kind of column converter. Extend this class if |
| * your columns work with reader-specific types, such as having to |
| * call a type-specific method on some row object. In this case, |
| * all your subclasses would implement the same method, say |
| * {@code void convertValue(MyRow row)}. Subclases might know their |
| * column indexes within the row object, extract the value using |
| * type-specific methods, then pass the value onto the scalar writer. |
| */ |
| public class ColumnConverter { |
| protected final ScalarWriter baseWriter; |
| |
| public ColumnConverter(ScalarWriter colWriter) { |
| this.baseWriter = colWriter; |
| } |
| |
| public ScalarWriter writer() { return baseWriter; } |
| public ColumnMetadata schema() { return baseWriter.schema(); } |
| |
| protected UnsupportedConversionError conversionError(String javaType) { |
| return UnsupportedConversionError.writeError(schema(), javaType); |
| } |
| } |