/**
* 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.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 reverse(string text)
*/
@Description(
functionName = "repeat",
description = "Repeat string the specified number of times.",
example = "> SELECT repeat('Pg', 4);\n"
+ "PgPgPgPg",
returnType = TajoDataTypes.Type.TEXT,
paramTypes = {@ParamTypes(paramTypes = {TajoDataTypes.Type.TEXT,
TajoDataTypes.Type.INT4})}
)
public class Repeat extends GeneralFunction {
public Repeat() {
super(new Column[] {
new Column("string", TajoDataTypes.Type.TEXT),
new Column("count", TajoDataTypes.Type.INT4)
});
}
private String repeat(String word, int count) {
StringBuilder builder = new StringBuilder();
for (int i = 0; i < count; i++) {
builder.append(word);
}
return builder.toString();
}
@Override
public Datum eval(Tuple params) {
Datum datum = params.get(0);
if(datum instanceof NullDatum) return NullDatum.get();
Datum countDatum = params.get(1);
if(countDatum instanceof NullDatum) return NullDatum.get();
return DatumFactory.createText(repeat(datum.asChars(), countDatum.asInt4()));
}
}