Quadcap Embeddable Database

com/quadcap/sql/ItemsCursor.java

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package com.quadcap.sql;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Vector;

import java.sql.SQLException;

import com.quadcap.sql.types.Type;
import com.quadcap.sql.types.TypeAny;
import com.quadcap.sql.types.Value;

import com.quadcap.util.Debug;

/**
 * This cursor performs the name-mapping function associated with the
 * <code>SELECT</code> clause.
 *
 * @author Stan Bailes
 */
public class ItemsCursor extends CursorImpl {
    Cursor                              cursor;
    ItemsRow                            currentRow      = null;
    int[]                               map             = null;
    Vector                              items;

    public ItemsCursor(Session session, Cursor cursor, Vector gitems)
        throws SQLException
    {
        super(session, cursor.getName());
        this.session = session;
        this.cursor = cursor;
        this.items = expandWildCard(session, cursor, gitems);
        this.map = new int[items.size()];
        for (int i = 0; i < items.size(); i++) {
            SelectItem item = (SelectItem)items.elementAt(i);
            Expression e = item.getExpression();
            if (e instanceof NameExpression) {
                String name = ((NameExpression)e).getName();
                String asName = item.getAsName();
                if (asName == null) asName = name;
                Column col = cursor.getColumn(name);
                if (col == null) {
                    //#ifdef DEBUG
                    Debug.println(0, cursor.toString());
                    //#endif
                    throw new SQLException("Bad column name: " + name,
                                           "42000");
                }
                addColumn(new Column(asName, col));
                map[i] = col.getColumn();
            } else {
                String asName = item.getAsName();
                if (asName == null) {
                    asName = "Column" + (i+1);
                }
                addColumn(new Column(asName, e.getType(session, cursor)));
                map[i] = -1;
            }
        }
    }

    final Vector expandWildCard(Session session, Cursor cursor, Vector items)
        throws SQLException
    {
        Vector nitems = new Vector();
        for (int i = 0; i < items.size(); i++) {
            SelectItem item = (SelectItem)items.elementAt(i);
            Expression e = item.getExpression();
            String name = "Column" + (i + 1);
            if (e instanceof NameExpression) {
                name = ((NameExpression)e).getName();
                if (name.endsWith(".*")) {
                    String rname = name.substring(0, name.length() - 2);
                    String qname =
                        session.getConnection().resolveName(rname) + ".";
                    rname = rname + ".";
                    boolean found = false;
                    for (int j = 1; j <= cursor.getColumnCount(); j++) {
                        Column col = cursor.getColumn(j);
                        if (col.isJoinColumn()) continue;
                        String sname = col.getShortName();
                        String cname = col.getName();
                        if (sname.startsWith(rname) || sname.startsWith(qname)) {
                            found = true;
                            nitems.addElement(
                                new SelectItem(new NameExpression(sname)));
                        } else if (cname.startsWith(qname) || cname.startsWith(rname)) {
                            found = true;
                            nitems.addElement(
                                new SelectItem(new NameExpression(cname)));
                        }
                    }
                    if (!found) {
                        throw new SQLException("Bad column name: " + name,
                                               "42000");
                    }
                } else {
                    nitems.addElement(item);
                }
            } else {
                nitems.addElement(item);
            }
        }
        return nitems;
    }

    public Row getEmptyAggregate() throws SQLException {
        return new ItemsRow(session, items, null, null, map);
    }

    public void updateRow(Row row) throws SQLException {
        for (int i = 1; i <= map.length; i++) {
            Value v = row.item(i);
            currentRow.set(i, v);
        }
        cursor.updateRow(currentRow.getBaseRow());
    }

    public void insertRow(Row row) throws SQLException {
        if (currentRow == null) {
            makeCurrentRow();
        }
        for (int i = 1; i <= map.length; i++) {
            Value v = row.item(i);
            currentRow.set(i, v);
        }
        cursor.insertRow(currentRow.getBaseRow());
    }

    public void deleteRow() throws SQLException {
        cursor.deleteRow();
    }

    public boolean isWritable(int column) throws SQLException { 
        return cursor.isWritable(map[column-1]);
    }

    public void beforeFirst() throws SQLException {
        cursor.beforeFirst();
    }

    public void afterLast() throws SQLException {
        cursor.afterLast();
    }

    final void makeFirstRow() throws SQLException {
        Row r = cursor.getRow();
        currentRow = new ItemsRow(session, items, cursor, r, map);
        for (int i = 0; i < map.length; i++) {
            if (map[i] == -1) {
                Column col = getColumn(i+1);
                Value v = currentRow.item(i+1);
                col.setType(v.getType());
            }
        }
    }

    final void makeCurrentRow() throws SQLException {
        currentRow = new ItemsRow(session, items, cursor, null, map);
    }
    
    public boolean next() throws SQLException {
        return cursor.next();
    }

    public Row getRow() throws SQLException {
        if (currentRow == null) {
            makeFirstRow();
        } else {
            currentRow.nextRow(cursor.getRow());
        }
        return currentRow;
    }

    public void setOuterCursor(Cursor c) {
        super.setOuterCursor(c);
        if (cursor != null) cursor.setOuterCursor(c);
    }

    public void close() throws SQLException {
        cursor.close();
    }

    public long size() throws SQLException { return cursor.size(); }
    
    public Cursor getBaseCursor() { return cursor; }

    //#ifdef DEBUG
    public String toString() {
        return super.toString() + " : (cursor = " + cursor + ")";
    }
    //#endif

}