/**
* 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 substr(string text, from int4 [, length int4])
*/
@Description(
functionName = "substr",
description = "Extract substring.",
example = "> SELECT substr('alphabet', 3, 2);\n"
+ "ph",
returnType = TajoDataTypes.Type.TEXT,
paramTypes = {
@ParamTypes(paramTypes = {TajoDataTypes.Type.TEXT,TajoDataTypes.Type.INT4}),
@ParamTypes(paramTypes = {TajoDataTypes.Type.TEXT,TajoDataTypes.Type.INT4,
TajoDataTypes.Type.INT4})
}
)
public class Substr extends GeneralFunction {
public Substr() {
super(new Column[] {
new Column("text", TajoDataTypes.Type.TEXT),
new Column("from", TajoDataTypes.Type.INT4),
new Column("length", TajoDataTypes.Type.INT4) //optional
});
}
@Override
public Datum eval(Tuple params) {
Datum valueDatum = params.get(0);
Datum fromDatum = params.get(1);
Datum countDatum = params.size() > 2 ? params.get(2) : null;
if(valueDatum instanceof NullDatum || fromDatum instanceof NullDatum || countDatum instanceof NullDatum) {
return NullDatum.get();
}
String value = valueDatum.asChars();
int from = fromDatum.asInt4();
int strLength = value.length();
int count;
if (countDatum == null) {
count = strLength;
} else {
count = (countDatum.asInt4() + from) - 1;
}
if (count > strLength) {
count = strLength;
}
if (from < 1) {
from = 0;
} else {
from --;
}
if (from >= count) {
return DatumFactory.createText("");
}
return DatumFactory.createText(value.substring(from, count));
}
}