phoenix-core/src/main/java/org/apache/phoenix/compile/SequenceValueExpression.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.compile;

import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.phoenix.expression.BaseTerminalExpression;
import org.apache.phoenix.expression.Determinism;
import org.apache.phoenix.expression.visitor.ExpressionVisitor;
import org.apache.phoenix.parse.SequenceValueParseNode.Op;
import org.apache.phoenix.schema.SequenceKey;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.schema.types.PDataType;
import org.apache.phoenix.schema.types.PLong;
import org.apache.phoenix.util.SchemaUtil;

public class SequenceValueExpression extends BaseTerminalExpression {
    private final SequenceKey key;
    final Op op;
    private final int index;
    private final long numToAllocate;

    public SequenceValueExpression(SequenceKey key, Op op, int index, long numToAllocate) {
        this.key = key;
        this.op = op;
        this.index = index;
        this.numToAllocate = numToAllocate;
    }

    public long getNumToAllocate() {
        return numToAllocate;
    }
    
    public SequenceKey getKey() {
        return key;
    }
    
    public int getIndex() {
        return index;
    }
    
    @Override
    public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
    		byte[] valueBuffer = new byte[PLong.INSTANCE.getByteSize()];
        PLong.INSTANCE.getCodec().encodeLong(tuple.getSequenceValue(index), valueBuffer, 0);
        ptr.set(valueBuffer);
        return true;
    }

    @Override
    public PDataType getDataType() {
        return PLong.INSTANCE;
    }
    
    @Override
    public boolean isNullable() {
        return false;
    }
    
    @Override
    public Determinism getDeterminism() {
        return Determinism.PER_ROW;
    }
    
    @Override
    public boolean isStateless() {
        return true;
    }

    @Override
    public String toString() {
        return op.getName() + (numToAllocate == 1 ? " VALUE " : (" " + numToAllocate + " VALUES " )) + "FOR " + SchemaUtil.getTableName(key.getSchemaName(),key.getSequenceName());
    }

    @Override
    public <T> T accept(ExpressionVisitor<T> visitor) {
        return visitor.visit(this);
    }
}