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/**
* 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.expr.fn;
import java.util.Collection;
import java.util.List;
import java.util.Map.Entry;
import java.util.Set;
import org.apache.drill.common.config.DrillConfig;
import org.apache.drill.common.util.PathScanner;
import org.apache.drill.exec.ExecConstants;
import org.apache.drill.exec.expr.DrillFunc;
import org.apache.drill.exec.planner.sql.DrillOperatorTable;
import org.apache.drill.exec.planner.sql.DrillSqlAggOperator;
import org.apache.drill.exec.planner.sql.DrillSqlOperator;
import org.eigenbase.sql.SqlOperator;
import com.google.common.collect.ArrayListMultimap;
import com.google.common.collect.Sets;
public class DrillFunctionRegistry {
static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(DrillFunctionRegistry.class);
private ArrayListMultimap<String, DrillFuncHolder> methods = ArrayListMultimap.create();
public DrillFunctionRegistry(DrillConfig config){
FunctionConverter converter = new FunctionConverter();
Set<Class<? extends DrillFunc>> providerClasses = PathScanner.scanForImplementations(DrillFunc.class, config.getStringList(ExecConstants.FUNCTION_PACKAGES));
for (Class<? extends DrillFunc> clazz : providerClasses) {
DrillFuncHolder holder = converter.getHolder(clazz);
if(holder != null){
// register handle for each name the function can be referred to
String[] names = holder.getRegisteredNames();
for(String name : names) methods.put(name.toLowerCase(), holder);
}else{
logger.warn("Unable to initialize function for class {}", clazz.getName());
}
}
if (logger.isTraceEnabled()) {
StringBuilder allFunctions = new StringBuilder();
for (DrillFuncHolder method: methods.values()) {
allFunctions.append(method.toString()).append("\n");
}
logger.trace("Registered functions: [\n{}]", allFunctions);
}
}
/** Returns functions with given name. Function name is case insensitive. */
public List<DrillFuncHolder> getMethods(String name) {
return this.methods.get(name.toLowerCase());
}
public void register(DrillOperatorTable operatorTable) {
SqlOperator op;
for (Entry<String, Collection<DrillFuncHolder>> function : methods.asMap().entrySet()) {
Set<Integer> argCounts = Sets.newHashSet();
String name = function.getKey().toUpperCase();
for (DrillFuncHolder f : function.getValue()) {
if (argCounts.add(f.getParamCount())) {
if (f.isAggregating()) {
op = new DrillSqlAggOperator(name, f.getParamCount());
} else {
op = new DrillSqlOperator(name, f.getParamCount());
}
operatorTable.add(function.getKey(), op);
}
}
}
}
}
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