/**
* 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.tajo.engine.function.string;
import org.apache.tajo.catalog.Column;
import org.apache.tajo.common.TajoDataTypes;
import org.apache.tajo.datum.Datum;
import org.apache.tajo.datum.DatumFactory;
import org.apache.tajo.datum.NullDatum;
import org.apache.tajo.datum.TextDatum;
import org.apache.tajo.engine.function.GeneralFunction;
import org.apache.tajo.engine.function.annotation.Description;
import org.apache.tajo.engine.function.annotation.ParamTypes;
import org.apache.tajo.storage.Tuple;
/**
* Function definition
*
* text right(string text, int size)
*/
@Description(
functionName = "right",
description = "Last n characters in the string",
example = "> SELECT right('ABC', 2);\n"
+ "BC",
returnType = TajoDataTypes.Type.TEXT,
paramTypes = {@ParamTypes(paramTypes = {TajoDataTypes.Type.TEXT,
TajoDataTypes.Type.INT4})}
)
public class Right extends GeneralFunction {
public Right() {
super(new Column[] {
new Column("string", TajoDataTypes.Type.TEXT),
new Column("size", TajoDataTypes.Type.INT4)
});
}
public int getSize(int length, int size) {
if (size < 0) {
size = length + size;
if (size < 0) {
size = 0;
}
}
return (size < length) ? size : length;
}
@Override
public Datum eval(Tuple params) {
Datum datum = params.get(0);
if(datum instanceof NullDatum) return NullDatum.get();
Datum sizeDatum = params.get(1);
if(sizeDatum instanceof NullDatum) return NullDatum.get();
String data = datum.asChars();
int length = data.length();
int size = sizeDatum.asInt4();
size = getSize(length, size);
if (size == 0) {
return TextDatum.EMPTY_TEXT;
}
int startIdx = length - size;
return DatumFactory.createText(data.substring(startIdx, length));
}
}