| /* |
| * 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. |
| */ |
| /** |
| * Drill expression materialization and evaluation facilities. |
| * |
| * Drill exposes an interface for defining custom scalar and aggregate functions. |
| * These functions are found by scanning the classpath at runtime and allow users |
| * to add their own functions without rebuilding Drill or changing cluster |
| * configuration. |
| * |
| * The classes that define these functions are actually decomposed at the source |
| * level, copied into generated code blocks to evaluate an entire expression |
| * tree. This generated source is built at run-time as schema is discovered. |
| * |
| * This package contains the {@link DrillSimpleFunc} and {@link DrillAggFunc} |
| * interfaces that can be implemented by users to define their own aggregate |
| * and scalar functions. |
| */ |
| package org.apache.drill.exec.expr; |
