/*
* 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.phoenix.expression.function;
import java.sql.SQLException;
import java.util.List;
import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.parse.FunctionParseNode.Argument;
import org.apache.phoenix.parse.FunctionParseNode.BuiltInFunction;
import org.apache.phoenix.schema.ColumnModifier;
import org.apache.phoenix.schema.PDataType;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.util.StringUtil;
@BuiltInFunction(name=ReverseFunction.NAME, args={
@Argument(allowedTypes={PDataType.VARCHAR})} )
public class ReverseFunction extends ScalarFunction {
public static final String NAME = "REVERSE";
public ReverseFunction() {
}
public ReverseFunction(List<Expression> children) throws SQLException {
super(children);
}
@Override
public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
Expression arg = getChildren().get(0);
if (!arg.evaluate(tuple, ptr)) {
return false;
}
int targetOffset = ptr.getLength();
if (targetOffset == 0) {
return true;
}
byte[] source = ptr.get();
byte[] target = new byte[targetOffset];
int sourceOffset = ptr.getOffset();
int endOffset = sourceOffset + ptr.getLength();
ColumnModifier modifier = arg.getColumnModifier();
while (sourceOffset < endOffset) {
int nBytes = StringUtil.getBytesInChar(source[sourceOffset], modifier);
targetOffset -= nBytes;
System.arraycopy(source, sourceOffset, target, targetOffset, nBytes);
sourceOffset += nBytes;
}
ptr.set(target);
return true;
}
@Override
public ColumnModifier getColumnModifier() {
return getChildren().get(0).getColumnModifier();
}
@Override
public PDataType getDataType() {
return PDataType.VARCHAR;
}
@Override
public String getName() {
return NAME;
}
}