/**
* Execute SELECT statement.
*
* @param node the root node of the statement.
* @return null.
*/
public Object execute(ICodeNode node) {
// Is there already an entry for this SELECT node in the
// jump table cache? If not, create a jump table entry.
HashMap<Object, ICodeNode> jumpTable = jumpCache.get(node);
if (jumpTable == null) {
jumpTable = createJumpTable(node);
jumpCache.put(node, jumpTable);
}
// Get the SELECT node's children.
ArrayList<ICodeNode> selectChildren = node.getChildren();
ICodeNode exprNode = selectChildren.get(0);
// Evaluate the SELECT expression.
ExpressionExecutor expressionExecutor = new ExpressionExecutor(this);
Object selectValue = expressionExecutor.execute(exprNode);
// If there is a selection, execute the SELECT_BRANCH's statement.
ICodeNode statementNode = jumpTable.get(selectValue);
if (statementNode != null) {
StatementExecutor statementExecutor = new StatementExecutor(this);
statementExecutor.execute(statementNode);
}
++executionCount; // count the SELECT statement itself
return null;
}
@Override
public String toString() {
final StringBuilder builder = new StringBuilder();
builder.append(executor.toString());
builder.append(" [");
String separator = "";
for (final int n : inputs) {
builder.append(separator);
builder.append(String.format("%d", n));
separator = ", ";
}
builder.append(']');
return builder.toString();
}