phoenix-core/src/main/java/org/apache/phoenix/expression/function/SignFunction.java

/*
 * 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.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PDecimal;
import org.apache.phoenix.schema.types.PInteger;
import org.apache.phoenix.schema.types.PNumericType;

/**
 * Base class for built-in SIGN function.
 * @since 4.3.0
 */
@BuiltInFunction(name = SignFunction.NAME, args = { @Argument(allowedTypes = { PDecimal.class }) })
public class SignFunction extends ScalarFunction {

    public static final String NAME = "SIGN";

    private static final byte[][] RESULT = { PInteger.INSTANCE.toBytes(Integer.valueOf(-1)),
            PInteger.INSTANCE.toBytes(Integer.valueOf(0)),
            PInteger.INSTANCE.toBytes(Integer.valueOf(1)), };

    public SignFunction() {
    }

    public SignFunction(List<Expression> children) throws SQLException {
        super(children);
    }

    @Override
    public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
        Expression childExpr = children.get(0);
        PDataType dataType = childExpr.getDataType();
        if (childExpr.evaluate(tuple, ptr)) {
            if (ptr.getLength()==0) {
                return true;
            }
            int ret = ((PNumericType) dataType).signum(ptr, childExpr.getSortOrder());
            ptr.set(RESULT[ret + 1]);
            return true;
        }
        return false;
    }

    @Override
    public PDataType getDataType() {
        return PInteger.INSTANCE;
    }

    @Override
    public String getName() {
        return NAME;
    }

    @Override
    public OrderPreserving preservesOrder() {
        return OrderPreserving.YES;
    }
}