| /* |
| * 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. |
| */ |
| /** |
| * Logical expression tree representation. |
| * |
| * Drill manages expressions provided in many different parts of SQL queries. |
| * This includes scalar expressions in select, filter and join conditions, as |
| * well as aggregate and window functions. These expressions are represented |
| * logically as ASTs during planning. The classes defined here provide the |
| * different nodes in the expression tree, as well as utilities for building |
| * and manipulating expressions during parsing and planning. |
| * |
| */ |
| package org.apache.drill.common.expression; |
