org.apache.tajo.engine.function.string.Locate.java Source code

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Here is the source code for org.apache.tajo.engine.function.string.Locate.java

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/**
 * 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.commons.lang.StringUtils;
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.plan.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.
 * 
 * INT4 locate(string TEXT, substr TEXT, [, pos INT4])
 */
@Description(functionName = "locate", description = "Location of specified substring", example = "> SELECT locate('high', 'ig')\n"
        + "2", returnType = TajoDataTypes.Type.INT4, paramTypes = {
                @ParamTypes(paramTypes = { TajoDataTypes.Type.TEXT, TajoDataTypes.Type.TEXT }),
                @ParamTypes(paramTypes = { TajoDataTypes.Type.TEXT, TajoDataTypes.Type.TEXT,
                        TajoDataTypes.Type.INT4 }) })
public class Locate extends GeneralFunction {
    public Locate() {
        super(new Column[] { new Column("string", TajoDataTypes.Type.TEXT),
                new Column("substr", TajoDataTypes.Type.TEXT), new Column("pos", TajoDataTypes.Type.INT4) });
    }

    /**
     * Returns the position of the first occurance of substr in string after position pos (using one-based index).
     * 
     * if substr is empty string, it always matches except 
     * pos is greater than string length + 1.(mysql locate() function spec.)
     * At any not matched case, it returns 0.
     */
    private int locate(String str, String substr, int pos) {
        if (substr.length() == 0) {
            if (pos <= (str.length() + 1)) {
                return pos;
            } else {
                return 0;
            }
        }
        int idx = StringUtils.indexOf(str, substr, pos - 1);
        if (idx == -1) {
            return 0;
        }
        return idx + 1;
    }

    @Override
    public Datum eval(Tuple params) {
        if (params.isBlankOrNull(0) || params.isBlankOrNull(1)) {
            return NullDatum.get();
        }

        int pos = 1; // one-based index
        if (params.size() > 2) {
            pos = params.getInt4(2);
            if (pos < 0) {
                return DatumFactory.createInt4(0); // negative value is not acceptable.
            }
            if (pos == 0) {
                pos = 1; // one-based index
            }
        }

        String str = params.getText(0);
        String substr = params.getText(1);

        return DatumFactory.createInt4(locate(str, substr, pos));
    }
}