Method parseQueryLogicalPlan

src/java/simpledb/Parser.java:140–276

(TransactionId tid, ZQuery q)

    }

    public LogicalPlan parseQueryLogicalPlan(TransactionId tid, ZQuery q)
            throws IOException, Zql.ParseException, simpledb.ParsingException {
        @SuppressWarnings("unchecked")
        List<ZFromItem> from = q.getFrom();
        LogicalPlan lp = new LogicalPlan();
        lp.setQuery(q.toString());
        // walk through tables in the FROM clause
        for (int i = 0; i < from.size(); i++) {
            ZFromItem fromIt = from.get(i);
            try {

                int id = Database.getCatalog().getTableId(fromIt.getTable()); // will
                                                                              // fall
                                                                              // through
                                                                              // if
                                                                              // table
                                                                              // doesn't
                                                                              // exist
                String name;

                if (fromIt.getAlias() != null)
                    name = fromIt.getAlias();
                else
                    name = fromIt.getTable();

                lp.addScan(id, name);

                // XXX handle subquery?
            } catch (NoSuchElementException e) {
                e.printStackTrace();
                throw new simpledb.ParsingException("Table "
                        + fromIt.getTable() + " is not in catalog");
            }
        }

        // now parse the where clause, creating Filter and Join nodes as needed
        ZExp w = q.getWhere();
        if (w != null) {

            if (!(w instanceof ZExpression)) {
                throw new simpledb.ParsingException(
                        "Nested queries are currently unsupported.");
            }
            ZExpression wx = (ZExpression) w;
            processExpression(tid, wx, lp);

        }

        // now look for group by fields
        ZGroupBy gby = q.getGroupBy();
        String groupByField = null;
        if (gby != null) {
            @SuppressWarnings("unchecked")
            List<ZExp> gbs = gby.getGroupBy();
            if (gbs.size() > 1) {
                throw new simpledb.ParsingException(
                        "At most one grouping field expression supported.");
            }