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package edu.caltech.nanodb.commands;
import java.util.Collections;
import java.util.List;
import edu.caltech.nanodb.expressions.Expression;
import edu.caltech.nanodb.expressions.ExpressionException;
import edu.caltech.nanodb.expressions.TupleLiteral;
import edu.caltech.nanodb.queryast.SelectClause;
import edu.caltech.nanodb.queryeval.Planner;
import edu.caltech.nanodb.queryeval.TupleProcessor;
import edu.caltech.nanodb.relations.Schema;
import edu.caltech.nanodb.relations.TableInfo;
import edu.caltech.nanodb.relations.Tuple;
import edu.caltech.nanodb.relations.TupleUtils;
import edu.caltech.nanodb.server.EventDispatcher;
import edu.caltech.nanodb.server.NanoDBServer;
import edu.caltech.nanodb.storage.TableManager;
import edu.caltech.nanodb.storage.TupleFile;
import edu.caltech.nanodb.storage.StorageManager;
/**
* This command object represents a top-level <tt>INSERT</tt> command issued
* against the database. <tt>INSERT</tt> commands have two forms. The first
* form is <tt>INSERT ... VALUES</tt>, in which case a literal tuple-value is
* specified and stored. The second form is <tt>INSERT</tt> ... <tt>SELECT</tt>,
* in which case a select-clause object is evaluated, and its results are stored
* into the specified table.
*
* @see edu.caltech.nanodb.expressions.TupleLiteral
* @see SelectClause
*/
public class InsertCommand extends QueryCommand {
/**
* An implementation of the tuple processor interface used by the
* {@link InsertCommand} to insert tuples into a table, when the command is
* of the form <tt>INSERT</tt> ... <tt>SELECT</tt>.
*/
private static class TupleInserter implements TupleProcessor {
/** The table into which the new tuples will be inserted. */
private TableInfo tableInfo;
private TupleFile tupleFile;
/**
* The event-dispatcher for reporting insert events to other
* components.
*/
EventDispatcher eventDispatcher;
/**
* Initialize the tuple-inserter object with the details it needs to
* insert tuples into the specified table.
*
* @param tableInfo details of the table that will be modified
*/
TupleInserter(EventDispatcher eventDispatcher, TableInfo tableInfo) {
this.tableInfo = tableInfo;
this.tupleFile = tableInfo.getTupleFile();
this.eventDispatcher = eventDispatcher;
}
/**
* This implementation ignores the schema of the results, since we
* just don't care.
*/
public void setSchema(Schema schema) {
// Ignore.
}
/** This implementation simply inserts each tuple it is handed. */
public void process(Tuple tuple) {
Tuple coerced =
TupleUtils.coerceToSchema(tuple, tableInfo.getSchema());
eventDispatcher.fireBeforeRowInserted(tableInfo, coerced);
Tuple newTuple = tupleFile.addTuple(coerced);
eventDispatcher.fireAfterRowInserted(tableInfo, newTuple);
newTuple.unpin();
}
public void finish() {
// Not used
}
}
/** The name of the table that the data will be inserted into. */
private String tableName;
/**
* An optional list of column-names that can be specified in the INSERT
* command. If the INSERT command didn't specify a list of column-names
* then this will be <code>null</code>.
*/
private List<String> colNames;
/**
* When the insert command is of the form <code>INSERT ... VALUES</code>,
* the literal values are stored in this variable. Otherwise this will be
* set to <code>null</code>.
*/
private List<Expression> values;
/**
* When the insert command is of the form <code>INSERT ... SELECT</code>,
* the details of the select-clause are stored in this variable.
* Otherwise this will be set to <code>null</code>.
*/
private SelectClause selClause;
/**
* The table that the data will be inserted into, once it has been opened.
*/
private TableInfo tableInfo;
/**
* Constructs a new insert command for <tt>INSERT</tt> ... <tt>VALUES</tt>
* statements.
*/
public InsertCommand(String tableName, List<String> colNames,
List<Expression> values) {
super(QueryCommand.Type.INSERT);
if (tableName == null)
throw new NullPointerException("tableName cannot be null");
if (values == null)
throw new NullPointerException("values cannot be null");
this.tableName = tableName;
this.colNames = colNames;
this.values = values;
}
/**
* Constructs a new insert command for <tt>INSERT</tt> ... <tt>SELECT</tt>
* statements.
*/
public InsertCommand(String tableName, List<String> colNames,
SelectClause selClause) {
super(QueryCommand.Type.INSERT);
if (tableName == null)
throw new NullPointerException("tableName cannot be null");
if (selClause == null)
throw new NullPointerException("selClause cannot be null");
this.tableName = tableName;
this.colNames = colNames;
this.selClause = selClause;
}
public String getTableName() {
return tableName;
}
public List<String> getColNames() {
if (colNames == null)
return null;
return Collections.unmodifiableList(colNames);
}
public List<Expression> getValues() {
if (values == null)
return null;
return Collections.unmodifiableList(values);
}
public SelectClause getSelectClause() {
return selClause;
}
@Override
public void execute(NanoDBServer server) throws ExecutionException {
if (values != null) {
// Inserting a single row.
if (!explain)
insertSingleRow(server);
else
out.println("Nothing to explain about INSERT ... VALUES");
}
else {
// Inserting the results of a SELECT query.
super.execute(server);
}
}
/** This method is used when inserting only a single row of data. */
private void insertSingleRow(NanoDBServer server)
throws ExecutionException {
// Try to open the table with the specified name.
StorageManager storageManager = server.getStorageManager();
TableManager tableManager = storageManager.getTableManager();
tableInfo = tableManager.openTable(tableName);
if (tableInfo == null)
throw new ExecutionException("No table named " + tableName);
// Build up a tuple-literal from the values we have.
TupleLiteral tuple = new TupleLiteral();
for (Expression expr : values) {
if (expr.hasSymbols()) {
throw new ExecutionException(
"INSERT values cannot contain symbols!");
}
try {
tuple.addValue(expr.evaluate());
}
catch (ExpressionException e) {
// This should be rare, but is still possible -- users
// can type anything...
throw new ExecutionException("Couldn't evaluate an INSERT value.", e);
}
}
EventDispatcher eventDispatcher = server.getEventDispatcher();
TupleFile tupleFile = tableInfo.getTupleFile();
Tuple coerced =
TupleUtils.coerceToSchema(tuple, tableInfo.getSchema());
eventDispatcher.fireBeforeRowInserted(tableInfo, coerced);
Tuple newTuple = tupleFile.addTuple(coerced);
eventDispatcher.fireAfterRowInserted(tableInfo, newTuple);
newTuple.unpin();
}
@Override
protected void prepareQueryPlan(NanoDBServer server) {
// Open the table and save the TableInfo so that the
// getTupleProcessor() method can use it.
StorageManager storageManager = server.getStorageManager();
TableManager tableManager = storageManager.getTableManager();
tableInfo = tableManager.openTable(tableName);
//Schema resultSchema = selClause.computeSchema();
// Create a plan for executing the SQL query.
Planner planner = server.getQueryPlanner();
plan = planner.makePlan(selClause, null);
}
@Override
protected TupleProcessor getTupleProcessor(EventDispatcher eventDispatcher) {
return new TupleInserter(eventDispatcher, tableInfo);
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append("InsertCommand[");
if (colNames != null) {
sb.append("cols=(");
boolean first = true;
for (String colName : colNames) {
if (first)
first = false;
else
sb.append(',');
sb.append(colName);
}
sb.append("), ");
}
if (values != null) {
sb.append("values=(");
boolean first = true;
for (Expression e : values) {
if (first)
first = false;
else
sb.append(',');
sb.append(e);
}
sb.append(')');
}
else {
sb.append("select=");
sb.append(selClause);
}
sb.append(']');
return sb.toString();
}
}