phoenix-core/src/main/java/org/apache/phoenix/expression/KeyValueColumnExpression.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;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.util.Arrays;

import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.phoenix.expression.visitor.ExpressionVisitor;
import org.apache.phoenix.schema.PColumn;
import org.apache.phoenix.schema.PDatum;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.util.SchemaUtil;


/**
 * 
 * Class to access a column value stored in a KeyValue
 *
 * 
 * @since 0.1
 */
public class KeyValueColumnExpression extends ColumnExpression {
    private byte[] cf;
    private byte[] cq;
    private String displayName; // client-side only.

    public KeyValueColumnExpression() {
    }
    
    public KeyValueColumnExpression(PColumn column) {
        super(column);
        this.cf = column.getFamilyName().getBytes();
        // for backward compatibility since older tables won't have columnQualifierBytes in their metadata
        this.cq = column.getColumnQualifierBytes() != null ? column.getColumnQualifierBytes() : column.getName().getBytes();
        this.displayName = column.getName().getString();
    }
    
    public KeyValueColumnExpression(PColumn column, String displayName) {
        super(column);
        this.cf = column.getFamilyName().getBytes();
        // for backward compatibility since older tables won't have columnQualifierBytes in their metadata
        this.cq = column.getColumnQualifierBytes() != null ? column.getColumnQualifierBytes() : column.getName().getBytes();
        this.displayName = displayName;
    }

    public KeyValueColumnExpression(PDatum column, byte[] cf, byte[] cq) {
        super(column);
        this.cf = cf;
        this.cq = cq;
    }

    public byte[] getColumnFamily() {
        return cf;
    }
    
    public byte[] getColumnQualifier() {
        return cq;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + Arrays.hashCode(cf);
        result = prime * result + Arrays.hashCode(cq);
        return result;
    }

    // TODO: assumes single table
    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        KeyValueColumnExpression other = (KeyValueColumnExpression)obj;
        if (!Arrays.equals(cf, other.cf)) return false;
        if (!Arrays.equals(cq, other.cq)) return false;
        return true;
    }

    @Override
    public String toString() {
        if (displayName == null) {
            displayName = SchemaUtil.getColumnDisplayName(cf, cq);
        }
        return displayName;
    }

    @Override
    public boolean evaluate(Tuple tuple, ImmutableBytesWritable ptr) {
        return tuple.getValue(cf, cq, ptr);
    }

    @Override
    public void readFields(DataInput input) throws IOException {
        super.readFields(input);
        cf = Bytes.readByteArray(input);
        cq = Bytes.readByteArray(input);
    }

    @Override
    public void write(DataOutput output) throws IOException {
        super.write(output);
        Bytes.writeByteArray(output, cf);
        Bytes.writeByteArray(output, cq);
    }

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

}