/**
* 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;