phoenix-core/src/main/java/org/apache/phoenix/schema/ColumnRef.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.schema;

import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Arrays;

import org.apache.hadoop.hbase.io.ImmutableBytesWritable;
import org.apache.http.annotation.Immutable;
import org.apache.phoenix.compile.ExpressionCompiler;
import org.apache.phoenix.compile.StatementContext;
import org.apache.phoenix.expression.Expression;
import org.apache.phoenix.expression.KeyValueColumnExpression;
import org.apache.phoenix.expression.ProjectedColumnExpression;
import org.apache.phoenix.expression.RowKeyColumnExpression;
import org.apache.phoenix.expression.SingleCellColumnExpression;
import org.apache.phoenix.expression.function.DefaultValueExpression;
import org.apache.phoenix.jdbc.PhoenixConnection;
import org.apache.phoenix.jdbc.PhoenixStatement;
import org.apache.phoenix.parse.ParseNode;
import org.apache.phoenix.parse.SQLParser;
import org.apache.phoenix.schema.PTable.ImmutableStorageScheme;
import org.apache.phoenix.util.ExpressionUtil;
import org.apache.phoenix.util.PhoenixRuntime;
import org.apache.phoenix.util.SchemaUtil;


/**
 * 
 * Class that represents a reference to a PColumn in a PTable
 *
 * 
 * @since 0.1
 */
@Immutable
public class ColumnRef {
    private final TableRef tableRef;
    private final int columnPosition;
    private final int pkSlotPosition;
    
    protected ColumnRef(ColumnRef columnRef, long timeStamp) {
        this.tableRef = new TableRef(columnRef.tableRef, timeStamp);
        this.columnPosition = columnRef.columnPosition;
        this.pkSlotPosition = columnRef.pkSlotPosition;
    }

    public ColumnRef(TableRef tableRef, String familyName, String columnName) throws MetaDataEntityNotFoundException {
        this(tableRef, tableRef.getTable().getColumnFamily(familyName).getPColumnForColumnName(columnName).getPosition());
    }

    public ColumnRef(TableRef tableRef, int columnPosition) {
        if (tableRef == null) {
            throw new NullPointerException();
        }
        if (columnPosition < 0 || columnPosition >= tableRef.getTable().getColumns().size()) {
            throw new IllegalArgumentException("Column position of " + columnPosition + " must be between 0 and " + tableRef.getTable().getColumns().size() + " for table " + tableRef.getTable().getName().getString());
        }
        this.tableRef = tableRef;
        this.columnPosition = columnPosition;
        PColumn column = getColumn();
        int i = -1;
        if (SchemaUtil.isPKColumn(column)) {
            for (PColumn pkColumn : tableRef.getTable().getPKColumns()) {
                i++;
                if (pkColumn == column) {
                    break;
                }
            }
        }
        pkSlotPosition = i;
    }

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

    @Override
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null) return false;
        if (getClass() != obj.getClass()) return false;
        ColumnRef other = (ColumnRef)obj;
        if (columnPosition != other.columnPosition) return false;
        if (!tableRef.equals(other.tableRef)) return false;
        return true;
    }

    public Expression newColumnExpression() throws SQLException {
        return newColumnExpression(false, false);
    }

    public Expression newColumnExpression(boolean schemaNameCaseSensitive, boolean colNameCaseSensitive) throws SQLException {
        PTable table = tableRef.getTable();
        PColumn column = this.getColumn();
        String displayName = tableRef.getColumnDisplayName(this, schemaNameCaseSensitive, colNameCaseSensitive);
        if (SchemaUtil.isPKColumn(column)) {
            return new RowKeyColumnExpression(
                    column, 
                    new RowKeyValueAccessor(table.getPKColumns(), pkSlotPosition),
                    displayName);
        }
        
        if (table.getType() == PTableType.PROJECTED || table.getType() == PTableType.SUBQUERY) {
        	return new ProjectedColumnExpression(column, table, displayName);
        }

        Expression expression = table.getImmutableStorageScheme() == ImmutableStorageScheme.SINGLE_CELL_ARRAY_WITH_OFFSETS ? 
        		new SingleCellColumnExpression(column, displayName, table.getEncodingScheme()) : new KeyValueColumnExpression(column, displayName);

        if (column.getExpressionStr() != null) {
            String url = PhoenixRuntime.JDBC_PROTOCOL
                    + PhoenixRuntime.JDBC_PROTOCOL_SEPARATOR
                    + PhoenixRuntime.CONNECTIONLESS;
            PhoenixConnection conn =
                    DriverManager.getConnection(url).unwrap(PhoenixConnection.class);
            StatementContext context = new StatementContext(new PhoenixStatement(conn));

            ExpressionCompiler compiler = new ExpressionCompiler(context);
            ParseNode defaultParseNode = new SQLParser(column.getExpressionStr()).parseExpression();
            Expression defaultExpression = defaultParseNode.accept(compiler);
            if (!ExpressionUtil.isNull(defaultExpression, new ImmutableBytesWritable())) {
                return new DefaultValueExpression(Arrays.asList(expression, defaultExpression));
            }
        }
        return expression;
    }

    public ColumnRef cloneAtTimestamp(long timestamp) {
        return new ColumnRef(this, timestamp);
    }

    public int getColumnPosition() {
        return columnPosition;
    }
    
    public int getPKSlotPosition() {
        return pkSlotPosition;
    }
    
    public PColumn getColumn() {
        return tableRef.getTable().getColumns().get(columnPosition);
    }

    public PTable getTable() {
        return tableRef.getTable();
    }
    
    public TableRef getTableRef() {
        return tableRef;
    }
}