Add very basic support for HBase database

src/qir/driver/hbase/HBaseDriver.java

+package qir.driver.hbase;
+
+import java.io.IOException;
+import java.util.ArrayDeque;
+import java.util.Deque;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.Cell;
+import org.apache.hadoop.hbase.CellUtil;
+import org.apache.hadoop.hbase.HBaseConfiguration;
+import org.apache.hadoop.hbase.TableName;
+import org.apache.hadoop.hbase.client.Connection;
+import org.apache.hadoop.hbase.client.ConnectionFactory;
+import org.apache.hadoop.hbase.client.Result;
+import org.apache.hadoop.hbase.client.ResultScanner;
+import org.apache.hadoop.hbase.client.Table;
+import org.apache.hadoop.hbase.util.Bytes;
+
+import qir.ast.QIRNode;
+import qir.ast.data.QIRLcons;
+import qir.ast.data.QIRList;
+import qir.ast.data.QIRLnil;
+import qir.ast.data.QIRTcons;
+import qir.ast.data.QIRTnil;
+import qir.ast.data.QIRTuple;
+import qir.ast.value.QIRNumber;
+import qir.ast.value.QIRString;
+import qir.driver.ConnectionData;
+import qir.driver.DBDriver;
+import qir.util.QIRException;
+
+/**
+ * Abstract driver for HBase databases. Drivers for HBase databases should extend this class.
+ *
+ * @param DBRepr The type of representation of a query for the database.
+ */
+public final class HBaseDriver extends DBDriver<HBaseQuery> {
+    protected Connection conn;
+
+    public HBaseDriver(final ConnectionData connData) {
+        super(connData);
+    }
+
+    @Override
+    public void openConnection(final ConnectionData data) throws QIRException {
+        if (conn != null)
+            closeConnection();
+        final Configuration conf = HBaseConfiguration.create();
+        conf.set("hbase.rootdir", "/home/julien/hbase/root");
+        conf.set("hbase.zookeeper.property.dataDir", "/home/julien/hbase/root/zookeeper");
+        try {
+            conn = ConnectionFactory.createConnection(conf);
+        } catch (final IOException e) {
+            e.printStackTrace();
+            throw new QIRException("Could not open connection to HBase database: " + data.serverName);
+        }
+        connData = data;
+    }
+
+    @Override
+    public final void closeConnection() throws QIRException {
+        if (conn == null)
+            return;
+        try {
+            conn.close();
+        } catch (final IOException e) {
+            e.printStackTrace();
+            throw new QIRException("Could not close connection to SQL database: " + connData.serverName);
+        }
+        conn = null;
+    }
+
+    @Override
+    public final boolean isConnOpen() {
+        return conn != null;
+    }
+
+    @Override
+    public HBaseQuery translate(final QIRNode root) {
+        return root.accept(new QIRHBaseQueryVisitor());
+    }
+
+    @Override
+    public QIRList run(final HBaseQuery query) throws QIRException {
+        final ResultScanner rs;
+        final Deque<QIRTuple> tmp = new ArrayDeque<>();
+        QIRList result = QIRLnil.getInstance();
+        QIRNode data;
+
+        try (final Table table = conn.getTable(TableName.valueOf(query.tableName))) {
+            rs = table.getScanner(query.scan);
+            for (Result r = rs.next(); r != null; r = rs.next()) {
+                QIRTuple newTuple = QIRTnil.getInstance();
+                for (final Cell cell : r.listCells()) {
+                    final String value = Bytes.toString(CellUtil.cloneValue(cell));
+                    try {
+                        data = new QIRNumber(null, Long.parseLong(value));
+                    } catch (NumberFormatException e) {
+                        data = new QIRString(null, value);
+                    }
+                    newTuple = new QIRTcons(null, Bytes.toString(CellUtil.cloneQualifier(cell)), data, newTuple);
+                }
+                tmp.push(newTuple);
+            }
+        } catch (IOException e) {
+            e.printStackTrace();
+            throw new QIRException("Could not execute query " + query.scan);
+        }
+        rs.close();
+        while (!tmp.isEmpty())
+            result = new QIRLcons(null, tmp.pop(), result);
+        return result;
+    }
+}
\ No newline at end of file

src/qir/driver/hbase/HBaseQuery.java

+package qir.driver.hbase;
+
+import org.apache.hadoop.hbase.client.Scan;
+
+/**
+ * Represents a query for a HBase database.
+ */
+public class HBaseQuery {
+    public final Scan scan;
+    public final String tableName;
+
+    public HBaseQuery(Scan scan, String tableName) {
+        this.scan = scan;
+        this.tableName = tableName;
+    }
+}

src/qir/driver/hbase/QIRHBaseQueryVisitor.java

+package qir.driver.hbase;
+
+import org.apache.hadoop.hbase.client.Scan;
+
+import qir.ast.*;
+import qir.ast.data.*;
+import qir.ast.expression.arithmetic.*;
+import qir.ast.expression.logic.*;
+import qir.ast.expression.relational.*;
+import qir.ast.operator.*;
+import qir.ast.value.*;
+import qir.driver.IQIRVisitor;
+
+/**
+ * Translation from QIR to HBase query.
+ */
+final class QIRHBaseQueryVisitor implements IQIRVisitor<HBaseQuery> {
+    @Override
+    public HBaseQuery visit(QIRProject qirProject) {
+        final HBaseQuery child = qirProject.child.accept(this);
+        child.scan.addColumn("default".getBytes(), "ename".getBytes());
+        return child;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRScan qirScan) {
+        return new HBaseQuery(new Scan(), (String) ((QIRBaseValue<?>) ((QIRTable<?>) qirScan.table).tableName).value);
+    }
+
+    @Override
+    public HBaseQuery visit(QIRFilter qirFilter) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRGroupBy qirGroup) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRSortBy qirOrder) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRJoin qirJoin) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRLeftJoin qirJoin) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRRightJoin qirJoin) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRLimit qirLimit) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public <DBRepr> HBaseQuery visit(QIRDBNode<DBRepr> qirDBNode) {
+        return (HBaseQuery) qirDBNode.translation;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRBuiltin qirBuiltin) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRVariable qirVariable) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRLambda qirLambda) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRApply qirApply) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRIf qirIf) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRPlus qirPlus) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRMinus qirMinus) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRStar qirStar) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRDiv qirDiv) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRMod qirMod) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRAnd qirAnd) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIROr qirOr) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIREqual qirEqual) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRLowerOrEqual qirLowerOrEqual) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRLowerThan qirLowerThan) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRNot qirNot) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public <DBRepr> HBaseQuery visit(QIRTable<DBRepr> qirTable) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRLnil qirLnil) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRLcons qirLcons) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRLdestr qirLdestr) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRTnil qirTnil) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRTcons qirTcons) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRTdestr qirTdestr) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRString qirString) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRNumber qirNumber) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRBigNumber qirBigNumber) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRDouble qirDouble) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRBoolean qirBoolean) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRNull qirNull) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+    @Override
+    public HBaseQuery visit(QIRTruffleNode qirTruffleNode) {
+        // TODO Auto-generated method stub
+        return null;
+    }
+
+}
\ No newline at end of file