/**
* 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.ArrayList;
import java.util.List;
import org.apache.drill.common.expression.ExpressionPosition;
import org.apache.drill.common.expression.FunctionHolderExpression;
import org.apache.drill.common.expression.LogicalExpression;
import org.apache.drill.common.types.TypeProtos;
import org.apache.drill.common.types.TypeProtos.MajorType;
import org.apache.drill.common.types.TypeProtos.MinorType;
import org.apache.drill.common.types.Types;
import org.apache.drill.exec.expr.ClassGenerator.HoldingContainer;
import org.apache.drill.exec.expr.DrillFunc;
import org.apache.drill.exec.expr.DrillFuncHolderExpr;
import org.apache.drill.exec.expr.HoldingContainerExpression;
import com.google.common.collect.ImmutableList;
public class FunctionGenerationHelper {
public static final String COMPARE_TO = "compare_to";
/**
* Given materialized arguments find the "compare_to" FunctionHolderExpression
* @param left
* @param right
* @param registry
* @return FunctionHolderExpression containing the function implementation
*/
public static FunctionHolderExpression getComparator(HoldingContainer left,
HoldingContainer right,
FunctionImplementationRegistry registry) {
return getFunctionExpression(COMPARE_TO, Types.required(MinorType.INT), registry, left, right);
}
public static FunctionHolderExpression getFunctionExpression(String name, MajorType returnType, FunctionImplementationRegistry registry, HoldingContainer... args){
List<MajorType> argTypes = new ArrayList<MajorType>(args.length);
List<LogicalExpression> argExpressions = new ArrayList<LogicalExpression>(args.length);
for(HoldingContainer c : args){
argTypes.add(c.getMajorType());
argExpressions.add(new HoldingContainerExpression(c));
}
DrillFuncHolder holder = registry.findExactMatchingDrillFunction(name, argTypes, returnType);
if (holder != null) {
return holder.getExpr(name, argExpressions, ExpressionPosition.UNKNOWN);
}
StringBuilder sb = new StringBuilder();
sb.append("Failure finding function that runtime code generation expected. Signature: ");
sb.append(name);
sb.append("( ");
for(int i =0; i < args.length; i++){
MajorType mt = args[i].getMajorType();
appendType(mt, sb);
if(i != 0) sb.append(", ");
}
sb.append(" ) returns ");
appendType(returnType, sb);
throw new UnsupportedOperationException(sb.toString());
}
private static final void appendType(MajorType mt, StringBuilder sb){
sb.append(mt.getMinorType().name());
sb.append(":");
sb.append(mt.getMode().name());
}
}