aboutsummaryrefslogtreecommitdiffstats
path: root/lua_preprocess.pl
blob: d1e8f468903eee6d4b7b0f9c35b627184440696d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
#!/usr/bin/env perl

use warnings FATAL => 'all';
use strict;
use Digest::MD5;

my ( $in_dir, $out_dir ) = @ARGV;
my @files = <$in_dir/*.lua>;

sub quote_file {
	my ( $in, $out ) = @_;

	while (<$in>) {
		if (/^--.USE\s*"(\S+)"$/) {
			open( my $inc, '<', "$in_dir/$1.lua.in" )
			  or die "missing include $1";
			quote_file( $inc, $out );
		}
		else {
			s/^\s*//;    # remove unnecessary spaces at the beginning
			next if /^--/;      # skip comments
			next if /^\s*$/;    # skip empty lines
			s/(.)/'$1',/g;          # split as 'c',
			s/\'\\\'/\'\\\\'/g;     # escape backslashes
			s/\'\'\'/\'\\\'\'/g;    # escape single quotes
			print $out "$_'\\n',";
		}
	}
}

sub digest_for_file {
	my ($file) = @_;

	open( my $in, '<', $file ) or die "file missing";
	my $digest = Digest::MD5->new->addfile($in)->hexdigest;

	return $digest;
}

sub changed {
	my ( $file, $outfile ) = @_;

	open( my $out, '<', $outfile ) or return 1;

	my $in_checksum = digest_for_file($file);
	my $ln          = <$out>;

	if ( $ln =~ /^.*id:(\S+)\s.*$/ ) {
		if ( $in_checksum ne $1 ) {
			return 1;
		}
		else {
			return 0;
		}
	}

	return 1;
}

foreach my $file (@files) {
	if ( $file =~ /([^\/.]+)(.lua)$/ ) {
		my $fname      = "$1$2";
		my $varname    = "rspamadm_script_$1";
		my $definename = uc $varname;
		my $outfile    = "$out_dir/$fname.h";

		if ( changed( $file, $outfile ) ) {
			open( my $in,  '<', $file )    or die "input missing";
			open( my $out, '>', $outfile ) or die "output missing";
			my $checksum = digest_for_file($file);
			print $out <<EOD;
/* id:$checksum */
#ifndef ${definename}_GUARD_H
#define ${definename}_GUARD_H

static const char ${varname}\[\] = {
EOD
			quote_file( $in, $out );

			print $out <<EOD;
'\\0'};
#endif
EOD
		}
	}
}
#n733'>733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722
/*
Copyright (c) 2005 Health Market Science, Inc.

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
USA

You can contact Health Market Science at info@healthmarketscience.com
or at the following address:

Health Market Science
2700 Horizon Drive
Suite 200
King of Prussia, PA 19406
*/

package com.healthmarketscience.jackcess;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectOutputStream;
import java.io.ObjectStreamException;
import java.io.Reader;
import java.io.Serializable;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.nio.CharBuffer;
import java.sql.Blob;
import java.sql.Clob;
import java.sql.SQLException;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
import java.util.UUID;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import com.healthmarketscience.jackcess.scsu.Compress;
import com.healthmarketscience.jackcess.scsu.EndOfInputException;
import com.healthmarketscience.jackcess.scsu.Expand;
import com.healthmarketscience.jackcess.scsu.IllegalInputException;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Access database column definition
 * @author Tim McCune
 */
public class Column implements Comparable<Column> {
  
  private static final Log LOG = LogFactory.getLog(Column.class);

  /**
   * Meaningless placeholder object for inserting values in an autonumber
   * column.  it is not required that this value be used (any passed in value
   * is ignored), but using this placeholder may make code more obvious.
   */
  public static final Object AUTO_NUMBER = "<AUTO_NUMBER>";
  
  /**
   * Meaningless placeholder object for updating rows which indicates that a
   * given column should keep its existing value.
   */
  public static final Object KEEP_VALUE = "<KEEP_VALUE>";
  
  /**
   * Access stores numeric dates in days.  Java stores them in milliseconds.
   */
  private static final double MILLISECONDS_PER_DAY =
    (24L * 60L * 60L * 1000L);

  /**
   * Access starts counting dates at Jan 1, 1900.  Java starts counting
   * at Jan 1, 1970.  This is the # of millis between them for conversion.
   */
  private static final long MILLIS_BETWEEN_EPOCH_AND_1900 =
    25569L * (long)MILLISECONDS_PER_DAY;
  
  /**
   * Long value (LVAL) type that indicates that the value is stored on the same page
   */
  private static final byte LONG_VALUE_TYPE_THIS_PAGE = (byte) 0x80;
  /**
   * Long value (LVAL) type that indicates that the value is stored on another page
   */
  private static final byte LONG_VALUE_TYPE_OTHER_PAGE = (byte) 0x40;
  /**
   * Long value (LVAL) type that indicates that the value is stored on multiple other pages
   */
  private static final byte LONG_VALUE_TYPE_OTHER_PAGES = (byte) 0x00;

  /** mask for the fixed len bit */
  public static final byte FIXED_LEN_FLAG_MASK = (byte)0x01;
  
  /** mask for the auto number bit */
  public static final byte AUTO_NUMBER_FLAG_MASK = (byte)0x04;
  
  /** mask for the auto number guid bit */
  public static final byte AUTO_NUMBER_GUID_FLAG_MASK = (byte)0x40;
  
  /** mask for the unknown bit */
  public static final byte UNKNOWN_FLAG_MASK = (byte)0x02;

  /** pattern matching textual guid strings (allows for optional surrounding
      '{' and '}') */
  private static final Pattern GUID_PATTERN = Pattern.compile("\\s*[{]?([\\p{XDigit}]{8})-([\\p{XDigit}]{4})-([\\p{XDigit}]{4})-([\\p{XDigit}]{4})-([\\p{XDigit}]{12})[}]?\\s*");

  /** header used to indicate unicode text compression */
  private static final byte[] TEXT_COMPRESSION_HEADER = 
  { (byte)0xFF, (byte)0XFE };

  /** owning table */
  private final Table _table;
  /** For text columns, whether or not they are compressed */ 
  private boolean _compressedUnicode = false;
  /** Whether or not the column is of variable length */
  private boolean _variableLength;
  /** Whether or not the column is an autonumber column */
  private boolean _autoNumber;
  /** Numeric precision */
  private byte _precision;
  /** Numeric scale */
  private byte _scale;
  /** Data type */
  private DataType _type;
  /** Maximum column length */
  private short _columnLength;
  /** 0-based column number */
  private short _columnNumber;
  /** index of the data for this column within a list of row data */
  private int _columnIndex;
  /** Column name */
  private String _name;
  /** the offset of the fixed data in the row */
  private int _fixedDataOffset;
  /** the index of the variable length data in the var len offset table */
  private int _varLenTableIndex;
  /** the auto number generator for this column (if autonumber column) */
  private AutoNumberGenerator _autoNumberGenerator;
  
  public Column() {
    this(JetFormat.VERSION_4);
  }
  
  public Column(JetFormat format) {
    _table = null;
  }

  /**
   * Only used by unit tests
   */
  Column(boolean testing, Table table) {
    if(!testing) {
      throw new IllegalArgumentException();
    }
    _table = table;
  }
    
  /**
   * Read a column definition in from a buffer
   * @param table owning table
   * @param buffer Buffer containing column definition
   * @param offset Offset in the buffer at which the column definition starts
   */
  public Column(Table table, ByteBuffer buffer, int offset)
    throws IOException
  {
    _table = table;
    if (LOG.isDebugEnabled()) {
      LOG.debug("Column def block:\n" + ByteUtil.toHexString(buffer, offset, 25));
    }
    setType(DataType.fromByte(buffer.get(offset + getFormat().OFFSET_COLUMN_TYPE)));
    _columnNumber = buffer.getShort(offset + getFormat().OFFSET_COLUMN_NUMBER);
    _columnLength = buffer.getShort(offset + getFormat().OFFSET_COLUMN_LENGTH);
    if (_type.getHasScalePrecision()) {
      _precision = buffer.get(offset + getFormat().OFFSET_COLUMN_PRECISION);
      _scale = buffer.get(offset + getFormat().OFFSET_COLUMN_SCALE);
    }
    byte flags = buffer.get(offset + getFormat().OFFSET_COLUMN_FLAGS);
    _variableLength = ((flags & FIXED_LEN_FLAG_MASK) == 0);
    _autoNumber = ((flags & (AUTO_NUMBER_FLAG_MASK | AUTO_NUMBER_GUID_FLAG_MASK)) != 0);
    setAutoNumberGenerator();
        
    _compressedUnicode = ((buffer.get(offset +
        getFormat().OFFSET_COLUMN_COMPRESSED_UNICODE) & 1) == 1);

    if(_variableLength) {
      _varLenTableIndex = buffer.getShort(offset + getFormat().OFFSET_COLUMN_VARIABLE_TABLE_INDEX);
    } else {
      _fixedDataOffset = buffer.getShort(offset + getFormat().OFFSET_COLUMN_FIXED_DATA_OFFSET);
    }
  }

  public Table getTable() {
    return _table;
  }
  
  public JetFormat getFormat() {
    return getTable().getFormat();
  }

  public PageChannel getPageChannel() {
    return getTable().getPageChannel();
  }
  
  public String getName() {
    return _name;
  }
  public void setName(String name) {
    _name = name;
  }
  
  public boolean isVariableLength() {
    return _variableLength;
  }

  public void setVariableLength(boolean variableLength) {
    _variableLength = variableLength;
  }
  
  public boolean isAutoNumber() {
    return _autoNumber;
  }

  public void setAutoNumber(boolean autoNumber) {
    _autoNumber = autoNumber;
    setAutoNumberGenerator();
  }

  public short getColumnNumber() {
    return _columnNumber;
  }

  public void setColumnNumber(short newColumnNumber) {
    _columnNumber = newColumnNumber;
  }

  public int getColumnIndex() {
    return _columnIndex;
  }

  public void setColumnIndex(int newColumnIndex) {
    _columnIndex = newColumnIndex;
  }
  
  /**
   * Also sets the length and the variable length flag, inferred from the
   * type.  For types with scale/precision, sets the scale and precision to
   * default values.
   */
  public void setType(DataType type) {
    _type = type;
    if(!type.isVariableLength()) {
      setLength((short)type.getFixedSize());
    } else if(!type.isLongValue()) {
      setLength((short)type.getDefaultSize());
    }
    setVariableLength(type.isVariableLength());
    if(type.getHasScalePrecision()) {
      setScale((byte)type.getDefaultScale());
      setPrecision((byte)type.getDefaultPrecision());
    }
  }
  public DataType getType() {
    return _type;
  }
  
  public int getSQLType() throws SQLException {
    return _type.getSQLType();
  }
  
  public void setSQLType(int type) throws SQLException {
    setSQLType(type, 0);
  }
  
  public void setSQLType(int type, int lengthInUnits) throws SQLException {
    setType(DataType.fromSQLType(type, lengthInUnits));
  }
  
  public boolean isCompressedUnicode() {
    return _compressedUnicode;
  }

  public void setCompressedUnicode(boolean newCompessedUnicode) {
    _compressedUnicode = newCompessedUnicode;
  }

  public byte getPrecision() {
    return _precision;
  }
  
  public void setPrecision(byte newPrecision) {
    _precision = newPrecision;
  }
  
  public byte getScale() {
    return _scale;
  }

  public void setScale(byte newScale) {
    _scale = newScale;
  }
  
  public void setLength(short length) {
    _columnLength = length;
  }
  public short getLength() {
    return _columnLength;
  }

  public void setLengthInUnits(short unitLength) {
    setLength((short)getType().fromUnitSize(unitLength));
  }
  public short getLengthInUnits() {
    return (short)getType().toUnitSize(getLength());
  }

  public void setVarLenTableIndex(int idx) {
    _varLenTableIndex = idx;
  }
  
  public int getVarLenTableIndex() {
    return _varLenTableIndex;
  }

  public void setFixedDataOffset(int newOffset) {
    _fixedDataOffset = newOffset;
  }
  
  public int getFixedDataOffset() {
    return _fixedDataOffset;
  }

  private void setAutoNumberGenerator()
  {
    if(!_autoNumber || (_type == null)) {
      _autoNumberGenerator = null;
      return;
    }

    if((_autoNumberGenerator != null) && 
       (_autoNumberGenerator.getType() == _type)) {
      // keep existing
      return;
    }

    switch(_type) {
    case LONG:
      _autoNumberGenerator = new LongAutoNumberGenerator();
      break;
    case GUID:
      _autoNumberGenerator = new GuidAutoNumberGenerator();
      break;
    default:
      throw new RuntimeException("Unexpected autoNumber column type " + _type);
    }
  }

  /**
   * Returns the AutoNumberGenerator for this column if this is an autonumber
   * column, {@code null} otherwise.
   */
  public AutoNumberGenerator getAutoNumberGenerator() {
    return _autoNumberGenerator;
  }

  /**
   * Checks that this column definition is valid.
   *
   * @throws IllegalArgumentException if this column definition is invalid.
   */
  public void validate(JetFormat format) {
    if(getType() == null) {
      throw new IllegalArgumentException("must have type");
    }
    Database.validateIdentifierName(getName(), format.MAX_COLUMN_NAME_LENGTH,
                                    "column");
    
    if(isVariableLength() != getType().isVariableLength()) {
      throw new IllegalArgumentException("invalid variable length setting");
    }

    if(!isVariableLength()) {
      if(getLength() != getType().getFixedSize()) {
        if(getLength() < getType().getFixedSize()) {
          throw new IllegalArgumentException("invalid fixed length size");
        }
        LOG.warn("Column length " + getLength() + 
                 " longer than expected fixed size " + 
                 getType().getFixedSize());
      }
    } else if(!getType().isLongValue()) {
      if(!getType().isValidSize(getLength())) {
        throw new IllegalArgumentException("var length out of range");
      }
    }

    if(getType().getHasScalePrecision()) {
      if(!getType().isValidScale(getScale())) {
        throw new IllegalArgumentException(
            "Scale must be from " + getType().getMinScale() + " to " +
            getType().getMaxScale() + " inclusive");
      }
      if(!getType().isValidPrecision(getPrecision())) {
        throw new IllegalArgumentException(
            "Precision must be from " + getType().getMinPrecision() + " to " +
            getType().getMaxPrecision() + " inclusive");
      }
    }

    if(isAutoNumber()) {
      if((getType() != DataType.LONG) && (getType() != DataType.GUID)) {
        throw new IllegalArgumentException(
            "Auto number column must be long integer or guid");
      }
    }

    if(isCompressedUnicode()) {
      if((getType() != DataType.TEXT) &&
         (getType() != DataType.MEMO)) {
        throw new IllegalArgumentException(
            "Only textual columns allow unicode compression (text/memo)");
      }
    }
  }
  
  /**
   * Deserialize a raw byte value for this column into an Object
   * @param data The raw byte value
   * @return The deserialized Object
   */
  public Object read(byte[] data) throws IOException {
    return read(data, ByteOrder.LITTLE_ENDIAN);
  }
  
  /**
   * Deserialize a raw byte value for this column into an Object
   * @param data The raw byte value
   * @param order Byte order in which the raw value is stored
   * @return The deserialized Object
   */  
  public Object read(byte[] data, ByteOrder order) throws IOException {
    ByteBuffer buffer = ByteBuffer.wrap(data);
    buffer.order(order);
    if (_type == DataType.BOOLEAN) {
      throw new IOException("Tried to read a boolean from data instead of null mask.");
    } else if (_type == DataType.BYTE) {
      return Byte.valueOf(buffer.get());
    } else if (_type == DataType.INT) {
      return Short.valueOf(buffer.getShort());
    } else if (_type == DataType.LONG) {
      return Integer.valueOf(buffer.getInt());
    } else if (_type == DataType.DOUBLE) {
      return Double.valueOf(buffer.getDouble());
    } else if (_type == DataType.FLOAT) {
      return Float.valueOf(buffer.getFloat());
    } else if (_type == DataType.SHORT_DATE_TIME) {
      return readDateValue(buffer);
    } else if (_type == DataType.BINARY) {
      return data;
    } else if (_type == DataType.TEXT) {
      return decodeTextValue(data);
    } else if (_type == DataType.MONEY) {
      return readCurrencyValue(buffer);
    } else if (_type == DataType.OLE) {
      if (data.length > 0) {
        return readLongValue(data);
      }
      return null;
    } else if (_type == DataType.MEMO) {
      if (data.length > 0) {
        return readLongStringValue(data);
      }
      return null;
    } else if (_type == DataType.NUMERIC) {
      return readNumericValue(buffer);
    } else if (_type == DataType.GUID) {
      return readGUIDValue(buffer, order);
    } else if ((_type == DataType.UNKNOWN_0D) || 
               (_type == DataType.UNKNOWN_11)) {
      // treat like "binary" data
      return data;
    } else {
      throw new IOException("Unrecognized data type: " + _type);
    }
  }

  /**
   * @param lvalDefinition Column value that points to an LVAL record
   * @return The LVAL data
   */
  private byte[] readLongValue(byte[] lvalDefinition)
    throws IOException
  {
    ByteBuffer def = ByteBuffer.wrap(lvalDefinition);
    def.order(ByteOrder.LITTLE_ENDIAN);
    int length = ByteUtil.get3ByteInt(def);
    // bail out gracefully here as we don't understand the format
    if (length < 0)
    {
       return null;
    }
    byte[] rtn = new byte[length];
    byte type = def.get();

    if(type == LONG_VALUE_TYPE_THIS_PAGE) {

      // inline long value
      def.getInt();  //Skip over lval_dp
      def.getInt();  //Skip over unknown
      def.get(rtn);

    } else {

      // long value on other page(s)
      if (lvalDefinition.length != getFormat().SIZE_LONG_VALUE_DEF) {
        throw new IOException("Expected " + getFormat().SIZE_LONG_VALUE_DEF +
                              " bytes in long value definition, but found " +
                              lvalDefinition.length);
      }

      int rowNum = ByteUtil.getUnsignedByte(def);
      int pageNum = ByteUtil.get3ByteInt(def, def.position());
      ByteBuffer lvalPage = getPageChannel().createPageBuffer();
      
      switch (type) {
      case LONG_VALUE_TYPE_OTHER_PAGE:
        {
          getPageChannel().readPage(lvalPage, pageNum);

          short rowStart = Table.findRowStart(lvalPage, rowNum, getFormat());
          short rowEnd = Table.findRowEnd(lvalPage, rowNum, getFormat());

          if((rowEnd - rowStart) != length) {
            throw new IOException("Unexpected lval row length");
          }
        
          lvalPage.position(rowStart);
          lvalPage.get(rtn);
        }
        break;
        
      case LONG_VALUE_TYPE_OTHER_PAGES:

        ByteBuffer rtnBuf = ByteBuffer.wrap(rtn);
        int remainingLen = length;
        while(remainingLen > 0) {
          lvalPage.clear();
          getPageChannel().readPage(lvalPage, pageNum);

          short rowStart = Table.findRowStart(lvalPage, rowNum, getFormat());
          short rowEnd = Table.findRowEnd(lvalPage, rowNum, getFormat());
          
          // read next page information
          lvalPage.position(rowStart);
          rowNum = ByteUtil.getUnsignedByte(lvalPage);
          pageNum = ByteUtil.get3ByteInt(lvalPage);

          // update rowEnd and remainingLen based on chunkLength
          int chunkLength = (rowEnd - rowStart) - 4;
          if(chunkLength > remainingLen) {
            rowEnd = (short)(rowEnd - (chunkLength - remainingLen));
            chunkLength = remainingLen;
          }
          remainingLen -= chunkLength;
          
          lvalPage.limit(rowEnd);
          rtnBuf.put(lvalPage);
        }
        
        break;
        
      default:
        throw new IOException("Unrecognized long value type: " + type);
      }
    }
    
    return rtn;
  }
  
  /**
   * @param lvalDefinition Column value that points to an LVAL record
   * @return The LVAL data
   */
  private String readLongStringValue(byte[] lvalDefinition)
    throws IOException
  {
    byte[] binData = readLongValue(lvalDefinition);
    if(binData == null) {
      return null;
    }
    return decodeTextValue(binData);
  }

  /**
   * Decodes "Currency" values.
   * 
   * @param buffer Column value that points to currency data
   * @return BigDecimal representing the monetary value
   * @throws IOException if the value cannot be parsed 
   */
  private BigDecimal readCurrencyValue(ByteBuffer buffer)
    throws IOException
  {
    if(buffer.remaining() != 8) {
      throw new IOException("Invalid money value.");
    }
    
    return new BigDecimal(BigInteger.valueOf(buffer.getLong(0)), 4);
  }

  /**
   * Writes "Currency" values.
   */
  private void writeCurrencyValue(ByteBuffer buffer, Object value)
    throws IOException
  {
    try {
      BigDecimal decVal = toBigDecimal(value);

      // adjust scale (will cause the an ArithmeticException if number has too
      // many decimal places)
      decVal = decVal.setScale(4);
    
      // now, remove scale and convert to long (this will throw if the value is
      // too big)
      buffer.putLong(decVal.movePointRight(4).longValueExact());
    } catch(ArithmeticException e) {
      throw (IOException)
        new IOException("Currency value out of range").initCause(e);
    }
  }

  /**
   * Decodes a NUMERIC field.
   */
  private BigDecimal readNumericValue(ByteBuffer buffer)
  {
    boolean negate = (buffer.get() != 0);

    byte[] tmpArr = new byte[16];
    buffer.get(tmpArr);

    if(buffer.order() != ByteOrder.BIG_ENDIAN) {
      fixNumericByteOrder(tmpArr);
    }

    BigInteger intVal = new BigInteger(tmpArr);
    if(negate) {
      intVal = intVal.negate();
    }
    return new BigDecimal(intVal, getScale());
  }

  /**
   * Writes a numeric value.
   */
  private void writeNumericValue(ByteBuffer buffer, Object value)
    throws IOException
  {
    try {
      BigDecimal decVal = toBigDecimal(value);

      boolean negative = (decVal.compareTo(BigDecimal.ZERO) < 0);
      if(negative) {
        decVal = decVal.negate();
      }

      // write sign byte
      buffer.put(negative ? (byte)0x80 : (byte)0);

      // adjust scale according to this column type (will cause the an
      // ArithmeticException if number has too many decimal places)
      decVal = decVal.setScale(getScale());

      // check precision
      if(decVal.precision() > getPrecision()) {
        throw new IOException(
            "Numeric value is too big for specified precision "
            + getPrecision() + ": " + decVal);
      }
    
      // convert to unscaled BigInteger, big-endian bytes
      byte[] intValBytes = decVal.unscaledValue().toByteArray();
      int maxByteLen = getType().getFixedSize() - 1;
      if(intValBytes.length > maxByteLen) {
        throw new IOException("Too many bytes for valid BigInteger?");
      }
      if(intValBytes.length < maxByteLen) {
        byte[] tmpBytes = new byte[maxByteLen];
        System.arraycopy(intValBytes, 0, tmpBytes,
                         (maxByteLen - intValBytes.length),
                         intValBytes.length);
        intValBytes = tmpBytes;
      }
      if(buffer.order() != ByteOrder.BIG_ENDIAN) {
        fixNumericByteOrder(intValBytes);
      }
      buffer.put(intValBytes);
    } catch(ArithmeticException e) {
      throw (IOException)
        new IOException("Numeric value out of range").initCause(e);
    }
  }

  /**
   * Decodes a date value.
   */
  private Date readDateValue(ByteBuffer buffer)
  {
    // seems access stores dates in the local timezone.  guess you just hope
    // you read it in the same timezone in which it was written!
    long dateBits = buffer.getLong();
    long time = fromDateDouble(Double.longBitsToDouble(dateBits));
    return new DateExt(time, dateBits);
  }
  
  /**
   * Returns a java long time value converted from an access date double.
   */
  private static long fromDateDouble(double value)
  {
    long time = Math.round(value * MILLISECONDS_PER_DAY);
    time -= MILLIS_BETWEEN_EPOCH_AND_1900;
    time -= getTimeZoneOffset(time);
    return time;
  }

  /**
   * Writes a date value.
   */
  private void writeDateValue(ByteBuffer buffer, Object value)
  {
    if(value == null) {
      buffer.putDouble(0d);
    } else if(value instanceof DateExt) {
      
      // this is a Date value previously read from readDateValue().  use the
      // original bits to store the value so we don't lose any precision
      buffer.putLong(((DateExt)value).getDateBits());
      
    } else {
      
      buffer.putDouble(toDateDouble(value));
    }
  }

  /**
   * Returns an access date double converted from a java Date/Calendar/Number
   * time value.
   */
  private static double toDateDouble(Object value)
  {
      // seems access stores dates in the local timezone.  guess you just
      // hope you read it in the same timezone in which it was written!
      long time = ((value instanceof Date) ?
                   ((Date)value).getTime() :
                   ((value instanceof Calendar) ?
                    ((Calendar)value).getTimeInMillis() :
                    ((Number)value).longValue()));
      time += getTimeZoneOffset(time);
      time += MILLIS_BETWEEN_EPOCH_AND_1900;
      return time / MILLISECONDS_PER_DAY;
  }

  /**
   * Gets the timezone offset from UTC for the given time (including DST).
   */
  private static long getTimeZoneOffset(long time)
  {
    Calendar c = Calendar.getInstance();
    c.setTimeInMillis(time);
    return ((long)c.get(Calendar.ZONE_OFFSET) + c.get(Calendar.DST_OFFSET));
  }  
  
  /**
   * Decodes a GUID value.
   */
  private String readGUIDValue(ByteBuffer buffer, ByteOrder order)
  {
    if(order != ByteOrder.BIG_ENDIAN) {
      byte[] tmpArr = new byte[16];
      buffer.get(tmpArr);

        // the first 3 guid components are integer components which need to
        // respect endianness, so swap 4-byte int, 2-byte int, 2-byte int
      ByteUtil.swap4Bytes(tmpArr, 0);
      ByteUtil.swap2Bytes(tmpArr, 4);
      ByteUtil.swap2Bytes(tmpArr, 6);
      buffer = ByteBuffer.wrap(tmpArr);
    }

    StringBuilder sb = new StringBuilder(22);
    sb.append("{");
    sb.append(ByteUtil.toHexString(buffer, 0, 4,
                                   false));
    sb.append("-");
    sb.append(ByteUtil.toHexString(buffer, 4, 2,
                                   false));
    sb.append("-");
    sb.append(ByteUtil.toHexString(buffer, 6, 2,
                                   false));
    sb.append("-");
    sb.append(ByteUtil.toHexString(buffer, 8, 2,
                                   false));
    sb.append("-");
    sb.append(ByteUtil.toHexString(buffer, 10, 6,
                                   false));
    sb.append("}");
    return (sb.toString());
  }

  /**
   * Writes a GUID value.
   */
  private void writeGUIDValue(ByteBuffer buffer, Object value, 
                              ByteOrder order)
    throws IOException
  {
    Matcher m = GUID_PATTERN.matcher(toCharSequence(value));
    if(m.matches()) {
      ByteBuffer origBuffer = null;
      byte[] tmpBuf = null;
      if(order != ByteOrder.BIG_ENDIAN) {
        // write to a temp buf so we can do some swapping below
        origBuffer = buffer;
        tmpBuf = new byte[16];
        buffer = ByteBuffer.wrap(tmpBuf);
      }

      ByteUtil.writeHexString(buffer, m.group(1));
      ByteUtil.writeHexString(buffer, m.group(2));
      ByteUtil.writeHexString(buffer, m.group(3));
      ByteUtil.writeHexString(buffer, m.group(4));
      ByteUtil.writeHexString(buffer, m.group(5));
      
      if(tmpBuf != null) {
        // the first 3 guid components are integer components which need to
        // respect endianness, so swap 4-byte int, 2-byte int, 2-byte int
        ByteUtil.swap4Bytes(tmpBuf, 0);
        ByteUtil.swap2Bytes(tmpBuf, 4);
        ByteUtil.swap2Bytes(tmpBuf, 6);
        origBuffer.put(tmpBuf);
      }

    } else {
      throw new IOException("Invalid GUID: " + value);
    }
  }
  
  /**
   * Write an LVAL column into a ByteBuffer inline if it fits, otherwise in
   * other data page(s).
   * @param value Value of the LVAL column
   * @return A buffer containing the LVAL definition and (possibly) the column
   *         value (unless written to other pages)
   */
  public ByteBuffer writeLongValue(byte[] value,
                                   int remainingRowLength) throws IOException
  {
    if(value.length > getType().getMaxSize()) {
      throw new IOException("value too big for column, max " +
                            getType().getMaxSize() + ", got " +
                            value.length);
    }

    // determine which type to write
    byte type = 0;
    int lvalDefLen = getFormat().SIZE_LONG_VALUE_DEF;
    if(((getFormat().SIZE_LONG_VALUE_DEF + value.length) <= remainingRowLength)
       && (value.length <= getFormat().MAX_INLINE_LONG_VALUE_SIZE)) {
      type = LONG_VALUE_TYPE_THIS_PAGE;
      lvalDefLen += value.length;
    } else if(value.length <= getFormat().MAX_LONG_VALUE_ROW_SIZE) {
      type = LONG_VALUE_TYPE_OTHER_PAGE;
    } else {
      type = LONG_VALUE_TYPE_OTHER_PAGES;
    }

    ByteBuffer def = getPageChannel().createBuffer(lvalDefLen);
    ByteUtil.put3ByteInt(def, value.length);
    def.put(type);

    if(type == LONG_VALUE_TYPE_THIS_PAGE) {
      // write long value inline
      def.putInt(0);
      def.putInt(0);  //Unknown
      def.put(value);
    } else {
      
      TempPageHolder lvalBufferH = getTable().getLongValueBuffer();
      ByteBuffer lvalPage = null;
      int firstLvalPageNum = PageChannel.INVALID_PAGE_NUMBER;
      byte firstLvalRow = 0;

      // write other page(s)
      switch(type) {
      case LONG_VALUE_TYPE_OTHER_PAGE:
        lvalPage = getLongValuePage(value.length, lvalBufferH);
        firstLvalPageNum = lvalBufferH.getPageNumber();
        firstLvalRow = (byte)Table.addDataPageRow(lvalPage, value.length,
                                                  getFormat(), 0);
        lvalPage.put(value);
        getPageChannel().writePage(lvalPage, firstLvalPageNum);
        break;

      case LONG_VALUE_TYPE_OTHER_PAGES:

        ByteBuffer buffer = ByteBuffer.wrap(value);
        int remainingLen = buffer.remaining();
        buffer.limit(0);
        lvalPage = getLongValuePage(getFormat().MAX_LONG_VALUE_ROW_SIZE,
                                    lvalBufferH);
        firstLvalPageNum = lvalBufferH.getPageNumber();
        int lvalPageNum = firstLvalPageNum;
        ByteBuffer nextLvalPage = null;
        int nextLvalPageNum = 0;
        while(remainingLen > 0) {
          lvalPage.clear();

          // figure out how much we will put in this page (we need 4 bytes for
          // the next page pointer)
          int chunkLength = Math.min(getFormat().MAX_LONG_VALUE_ROW_SIZE - 4,
                                     remainingLen);

          // figure out if we will need another page, and if so, allocate it
          if(chunkLength < remainingLen) {
            // force a new page to be allocated
            lvalBufferH.clear();
            nextLvalPage = getLongValuePage(
                getFormat().MAX_LONG_VALUE_ROW_SIZE, lvalBufferH);
            nextLvalPageNum = lvalBufferH.getPageNumber();
          } else {
            nextLvalPage = null;
            nextLvalPageNum = 0;
          }

          // add row to this page
          byte lvalRow = (byte)Table.addDataPageRow(lvalPage, chunkLength + 4,
                                                    getFormat(), 0);
          
          // write next page info (we'll always be writing into row 0 for
          // newly created pages)
          lvalPage.put((byte)0); // row number
          ByteUtil.put3ByteInt(lvalPage, nextLvalPageNum); // page number

          // write this page's chunk of data
          buffer.limit(buffer.limit() + chunkLength);
          lvalPage.put(buffer);
          remainingLen -= chunkLength;

          // write new page to database
          getPageChannel().writePage(lvalPage, lvalPageNum);

          if(lvalPageNum == firstLvalPageNum) {
            // save initial row info
            firstLvalRow = lvalRow;
          } else {
            // check assertion that we wrote to row 0 for all subsequent pages
            if(lvalRow != (byte)0) {
              throw new IllegalStateException("Expected row 0, but was " +
                                              lvalRow);
            }
          }
          
          // move to next page
          lvalPage = nextLvalPage;
          lvalPageNum = nextLvalPageNum;
        }
        break;

      default:
        throw new IOException("Unrecognized long value type: " + type);
      }

      // update def
      def.put(firstLvalRow);
      ByteUtil.put3ByteInt(def, firstLvalPageNum);
      def.putInt(0);  //Unknown
      
    }
      
    def.flip();
    return def;
  }

  /**
   * Writes the header info for a long value page.
   */
  private void writeLongValueHeader(ByteBuffer lvalPage)
  {
    lvalPage.put(PageTypes.DATA); //Page type
    lvalPage.put((byte) 1); //Unknown
    lvalPage.putShort((short)getFormat().PAGE_INITIAL_FREE_SPACE); //Free space
    lvalPage.put((byte) 'L');
    lvalPage.put((byte) 'V');
    lvalPage.put((byte) 'A');
    lvalPage.put((byte) 'L');
    lvalPage.putInt(0); //unknown
    lvalPage.putShort((short)0); // num rows in page
  }

  /**
   * Returns a long value data page with space for data of the given length.
   */
  private ByteBuffer getLongValuePage(int dataLength,
                                      TempPageHolder lvalBufferH)
    throws IOException
  {
    ByteBuffer lvalPage = null;
    if(lvalBufferH.getPageNumber() != PageChannel.INVALID_PAGE_NUMBER) {
      lvalPage = lvalBufferH.getPage(getPageChannel());
      if(Table.rowFitsOnDataPage(dataLength, lvalPage, getFormat())) {
        // the current page has space
        return lvalPage;
      }
    }

    // need new page
    lvalPage = lvalBufferH.setNewPage(getPageChannel());
    writeLongValueHeader(lvalPage);
    return lvalPage;
  }
  
  /**
   * Serialize an Object into a raw byte value for this column in little endian order
   * @param obj Object to serialize
   * @return A buffer containing the bytes
   */
  public ByteBuffer write(Object obj, int remainingRowLength)
    throws IOException
  {
    return write(obj, remainingRowLength, ByteOrder.LITTLE_ENDIAN);
  }
  
  /**
   * Serialize an Object into a raw byte value for this column
   * @param obj Object to serialize
   * @param order Order in which to serialize
   * @return A buffer containing the bytes
   */
  public ByteBuffer write(Object obj, int remainingRowLength, ByteOrder order)
    throws IOException
  {
    if(isRawData(obj)) {
      // just slap it right in (not for the faint of heart!)
      return ByteBuffer.wrap(((RawData)obj).getBytes());
    }

    if(!isVariableLength()) {
      return writeFixedLengthField(obj, order);
    }
      
    // var length column
    if(!getType().isLongValue()) {

      // this is an "inline" var length field
      switch(getType()) {
      case NUMERIC:
        // don't ask me why numerics are "var length" columns...
        ByteBuffer buffer = getPageChannel().createBuffer(
            getType().getFixedSize(), order);
        writeNumericValue(buffer, obj);
        buffer.flip();
        return buffer;

      case TEXT:
        byte[] encodedData = encodeTextValue(
            obj, 0, getLengthInUnits(), false).array();
        obj = encodedData;
        break;
        
      case BINARY:
      case UNKNOWN_0D:
        // should already be "encoded"
        break;
      default:
        throw new RuntimeException("unexpected inline var length type: " +
                                   getType());
      }

      ByteBuffer buffer = ByteBuffer.wrap(toByteArray(obj));
      buffer.order(order);
      return buffer;
    }

    // var length, long value column
    switch(getType()) {
    case OLE:
      // should already be "encoded"
      break;
    case MEMO:
      int maxMemoChars = DataType.MEMO.toUnitSize(DataType.MEMO.getMaxSize());
      obj = encodeTextValue(obj, 0, maxMemoChars, false).array();
      break;
    default:
      throw new RuntimeException("unexpected var length, long value type: " +
                                 getType());
    }    

    // create long value buffer
    return writeLongValue(toByteArray(obj), remainingRowLength);
  }

  /**
   * Serialize an Object into a raw byte value for this column
   * @param obj Object to serialize
   * @param order Order in which to serialize
   * @return A buffer containing the bytes
   */
  public ByteBuffer writeFixedLengthField(Object obj, ByteOrder order)
    throws IOException
  {
    int size = getType().getFixedSize(_columnLength);

    // create buffer for data
    ByteBuffer buffer = getPageChannel().createBuffer(size, order);

    // since booleans are not written by this method, it's safe to convert any
    // incoming boolean into an integer.
    obj = booleanToInteger(obj);

    switch(getType()) {
    case BOOLEAN:
      //Do nothing
      break;
    case  BYTE:
      buffer.put(toNumber(obj).byteValue());
      break;
    case INT:
      buffer.putShort(toNumber(obj).shortValue());
      break;
    case LONG:
      buffer.putInt(toNumber(obj).intValue());
      break;
    case MONEY:
      writeCurrencyValue(buffer, obj);
      break;
    case FLOAT:
      buffer.putFloat(toNumber(obj).floatValue());
      break;
    case DOUBLE:
      buffer.putDouble(toNumber(obj).doubleValue());
      break;
    case SHORT_DATE_TIME:
      writeDateValue(buffer, obj);
      break;
    case TEXT:
      // apparently text numeric values are also occasionally written as fixed
      // length...
      int numChars = getLengthInUnits();
      // force uncompressed encoding for fixed length text
      buffer.put(encodeTextValue(obj, numChars, numChars, true));
      break;
    case GUID:
      writeGUIDValue(buffer, obj, order);
      break;
    case NUMERIC:
      // yes, that's right, occasionally numeric values are written as fixed
      // length...
      writeNumericValue(buffer, obj);
      break;
    case BINARY:
    case UNKNOWN_0D:
    case UNKNOWN_11:
      byte[] bytes = toByteArray(obj);
      if(bytes.length != getLength()) {
        throw new IOException("Invalid fixed size binary data, size "
                              + getLength() + ", got " + bytes.length);
      }
      buffer.put(bytes);
      break;
    default:
      throw new IOException("Unsupported data type: " + getType());
    }
    buffer.flip();
    return buffer;
  }
  
  /**
   * Decodes a compressed or uncompressed text value.
   */
  private String decodeTextValue(byte[] data)
    throws IOException
  {
    try {

      // see if data is compressed.  the 0xFF, 0xFE sequence indicates that
      // compression is used (sort of, see algorithm below)
      boolean isCompressed = ((data.length > 1) &&
                              (data[0] == TEXT_COMPRESSION_HEADER[0]) &&
                              (data[1] == TEXT_COMPRESSION_HEADER[1]));

      if(isCompressed) {

        Expand expander = new Expand();
        
        // this is a whacky compression combo that switches back and forth
        // between compressed/uncompressed using a 0x00 byte (starting in
        // compressed mode)
        StringBuilder textBuf = new StringBuilder(data.length);
        // start after two bytes indicating compression use
        int dataStart = TEXT_COMPRESSION_HEADER.length;
        int dataEnd = dataStart;
        boolean inCompressedMode = true;
        while(dataEnd < data.length) {
          if(data[dataEnd] == (byte)0x00) {

            // handle current segment
            decodeTextSegment(data, dataStart, dataEnd, inCompressedMode,
                              expander, textBuf);
            inCompressedMode = !inCompressedMode;
            ++dataEnd;
            dataStart = dataEnd;
            
          } else {
            ++dataEnd;
          }
        }
        // handle last segment
        decodeTextSegment(data, dataStart, dataEnd, inCompressedMode,
                          expander, textBuf);

        return textBuf.toString();
        
      }
      
      return decodeUncompressedText(data, getFormat());
      
    } catch (IllegalInputException e) {
      throw (IOException)
        new IOException("Can't expand text column").initCause(e);
    } catch (EndOfInputException e) {
      throw (IOException)
        new IOException("Can't expand text column").initCause(e);
    }
  }

  /**
   * Decodes a segnment of a text value into the given buffer according to the
   * given status of the segment (compressed/uncompressed).
   */
  private void decodeTextSegment(byte[] data, int dataStart, int dataEnd,
                                 boolean inCompressedMode, Expand expander,
                                 StringBuilder textBuf)
    throws IllegalInputException, EndOfInputException
  {
    if(dataEnd <= dataStart) {
      // no data
      return;
    }
    int dataLength = dataEnd - dataStart;
    if(inCompressedMode) {
      // handle compressed data
      byte[] tmpData = new byte[dataLength];
      System.arraycopy(data, dataStart, tmpData, 0, dataLength);
      expander.reset();
      textBuf.append(expander.expand(tmpData));
    } else {
      // handle uncompressed data
      textBuf.append(decodeUncompressedText(data, dataStart, dataLength,
                                            getFormat()));
    }
  }

  /**
   * @param textBytes bytes of text to decode
   * @return the decoded string
   */
  private static CharBuffer decodeUncompressedText(
      byte[] textBytes, int startPos, int length, JetFormat format)
  {
    return format.CHARSET.decode(ByteBuffer.wrap(textBytes, startPos, length));
  }  

  /**
   * Encodes a text value, possibly compressing.
   */
  private ByteBuffer encodeTextValue(Object obj, int minChars, int maxChars,
                                     boolean forceUncompressed)
    throws IOException
  {
    CharSequence text = toCharSequence(obj);
    if((text.length() > maxChars) || (text.length() < minChars)) {
      throw new IOException("Text is wrong length for " + getType() +
                            " column, max " + maxChars
                            + ", min " + minChars + ", got " + text.length());
    }
    
    // may only compress if column type allows it
    if(!forceUncompressed && isCompressedUnicode()) {

      // for now, only do very simple compression (only compress text which is
      // all ascii text)
      if(isAsciiCompressible(text)) {

        byte[] encodedChars = new byte[TEXT_COMPRESSION_HEADER.length + 
                                       text.length()];
        encodedChars[0] = TEXT_COMPRESSION_HEADER[0];
        encodedChars[1] = TEXT_COMPRESSION_HEADER[1];
        for(int i = 0; i < text.length(); ++i) {
          encodedChars[i + TEXT_COMPRESSION_HEADER.length] = 
            (byte)text.charAt(i);
        }
        return ByteBuffer.wrap(encodedChars);
      }
    }

    return encodeUncompressedText(text, getFormat());
  }

  /**
   * Returns {@code true} if the given text can be compressed using simple
   * ASCII encoding, {@code false} otherwise.
   */
  private static boolean isAsciiCompressible(CharSequence text) {
    // only attempt to compress > 2 chars (compressing less than 3 chars would
    // not result in a space savings due to the 2 byte compression header)
    if(text.length() <= TEXT_COMPRESSION_HEADER.length) {
      return false;
    }
    // now, see if it is all printable ASCII
    for(int i = 0; i < text.length(); ++i) {
      char c = text.charAt(i);
      if(!Compress.isAsciiCrLfOrTab(c)) {
        return false;
      }
    }
    return true;
  }

  @Override
  public String toString() {
    StringBuilder rtn = new StringBuilder();
    rtn.append("\tName: (" + _table.getName() + ") " + _name);
    rtn.append("\n\tType: 0x" + Integer.toHexString(_type.getValue()) +
               " (" + _type + ")");
    rtn.append("\n\tNumber: " + _columnNumber);
    rtn.append("\n\tLength: " + _columnLength);
    rtn.append("\n\tVariable length: " + _variableLength);
    if(_variableLength) {
      rtn.append("\n\tCompressed Unicode: " + _compressedUnicode);
    }
    if(_autoNumber) {
      rtn.append("\n\tLast AutoNumber: " + _autoNumberGenerator.getLast());
    }
    rtn.append("\n\n");
    return rtn.toString();
  }
  
  /**
   * @param textBytes bytes of text to decode
   * @param format relevant db format
   * @return the decoded string
   */
  public static String decodeUncompressedText(byte[] textBytes,
                                              JetFormat format)
  {
    return decodeUncompressedText(textBytes, 0, textBytes.length, format)
      .toString();
  }

  /**
   * @param text Text to encode
   * @param format relevant db format
   * @return A buffer with the text encoded
   */
  public static ByteBuffer encodeUncompressedText(CharSequence text,
                                                  JetFormat format)
  {
    return format.CHARSET.encode(CharBuffer.wrap(text));
  }

  
  public int compareTo(Column other) {
    if (_columnNumber > other.getColumnNumber()) {
      return 1;
    } else if (_columnNumber < other.getColumnNumber()) {
      return -1;
    } else {
      return 0;
    }
  }
  
  /**
   * @param columns A list of columns in a table definition
   * @return The number of variable length columns found in the list
   */
  public static short countVariableLength(List<Column> columns) {
    short rtn = 0;
    for (Column col : columns) {
      if (col.isVariableLength()) {
        rtn++;
      }
    }
    return rtn;
  }

  /**
   * @param columns A list of columns in a table definition
   * @return The number of variable length columns which are not long values
   *         found in the list
   */
  public static short countNonLongVariableLength(List<Column> columns) {
    short rtn = 0;
    for (Column col : columns) {
      if (col.isVariableLength() && !col.getType().isLongValue()) {
        rtn++;
      }
    }
    return rtn;
  }
  
  /**
   * @return an appropriate BigDecimal representation of the given object.
   *         <code>null</code> is returned as 0 and Numbers are converted
   *         using their double representation.
   */
  private static BigDecimal toBigDecimal(Object value)
  {
    if(value == null) {
      return BigDecimal.ZERO;
    } else if(value instanceof BigDecimal) {
      return (BigDecimal)value;
    } else if(value instanceof BigInteger) {
      return new BigDecimal((BigInteger)value);
    } else if(value instanceof Number) {
      return new BigDecimal(((Number)value).doubleValue());
    }
    return new BigDecimal(value.toString());
  }

  /**
   * @return an appropriate Number representation of the given object.
   *         <code>null</code> is returned as 0 and Strings are parsed as
   *         Doubles.
   */
  private static Number toNumber(Object value)
  {
    if(value == null) {
      return BigDecimal.ZERO;
    } if(value instanceof Number) {
      return (Number)value;
    }
    return Double.valueOf(value.toString());
  }
  
  /**
   * @return an appropriate CharSequence representation of the given object.
   */
  public static CharSequence toCharSequence(Object value)
    throws IOException
  {
    if(value == null) {
      return null;
    } else if(value instanceof CharSequence) {
      return (CharSequence)value;
    } else if(value instanceof Clob) {
      try {
        Clob c = (Clob)value;
        // note, start pos is 1-based
        return c.getSubString(1L, (int)c.length());
      } catch(SQLException e) {
        throw (IOException)(new IOException(e.getMessage())).initCause(e);
      }
    } else if(value instanceof Reader) {
      char[] buf = new char[8 * 1024];
      StringBuilder sout = new StringBuilder();
      Reader in = (Reader)value;
      int read = 0;
      while((read = in.read(buf)) != -1) {
        sout.append(buf, 0, read);
      }
      return sout;
    }

    return value.toString();
  }

  /**
   * @return an appropriate byte[] representation of the given object.
   */
  public static byte[] toByteArray(Object value)
    throws IOException
  {
    if(value == null) {
      return null;
    } else if(value instanceof byte[]) {
      return (byte[])value;
    } else if(value instanceof Blob) {
      try {
        Blob b = (Blob)value;
        // note, start pos is 1-based
        return b.getBytes(1L, (int)b.length());
      } catch(SQLException e) {
        throw (IOException)(new IOException(e.getMessage())).initCause(e);
      }
    }

    ByteArrayOutputStream bout = new ByteArrayOutputStream();

    if(value instanceof InputStream) {
      byte[] buf = new byte[8 * 1024];
      InputStream in = (InputStream)value;
      int read = 0;
      while((read = in.read(buf)) != -1) {
        bout.write(buf, 0, read);
      }
    } else {
      // if all else fails, serialize it
      ObjectOutputStream oos = new ObjectOutputStream(bout);
      oos.writeObject(value);
      oos.close();
    }

    return bout.toByteArray();
  }

  /**
   * Interpret a boolean value (null == false)
   */
  public static boolean toBooleanValue(Object obj) {
    return ((obj != null) && ((Boolean)obj).booleanValue());
  }
  
  /**
   * Swaps the bytes of the given numeric in place.
   */
  private static void fixNumericByteOrder(byte[] bytes)
  {
    // fix endianness of each 4 byte segment
    for(int i = 0; i < 4; ++i) {
      ByteUtil.swap4Bytes(bytes, i * 4);
    }
  }

  /**
   * Treat booleans as integers (C-style).
   */
  private static Object booleanToInteger(Object obj) {
    if (obj instanceof Boolean) {
      obj = ((Boolean) obj) ? 1 : 0;
    }
    return obj;
  }

  /**
   * Returns a wrapper for raw column data that can be written without
   * understanding the data.  Useful for wrapping unparseable data for
   * re-writing.
   */
  static RawData rawDataWrapper(byte[] bytes) {
    return new RawData(bytes);
  }

  /**
   * Returs {@code true} if the given value is "raw" column data,
   * {@code false} otherwise.
   */
  static boolean isRawData(Object value) {
    return(value instanceof RawData);
  }

  /**
   * Date subclass which stashes the original date bits, in case we attempt to
   * re-write the value (will not lose precision).
   */
  private static final class DateExt extends Date
  {
    private static final long serialVersionUID = 0L;

    /** cached bits of the original date value */
    private transient final long _dateBits;

    private DateExt(long time, long dateBits) {
      super(time);
      _dateBits = dateBits;
    }

    public long getDateBits() {
      return _dateBits;
    }
    
    private Object writeReplace() throws ObjectStreamException {
      // if we are going to serialize this Date, convert it back to a normal
      // Date (in case it is restored outside of the context of jackcess)
      return new Date(super.getTime());
    }
  }

  /**
   * Wrapper for raw column data which can be re-written.
   */
  private static class RawData implements Serializable
  {
    private static final long serialVersionUID = 0L;

    private final byte[] _bytes;

    private RawData(byte[] bytes) {
      _bytes = bytes;
    }

    private byte[] getBytes() {
      return _bytes;
    }

    @Override
    public String toString() {
      return "RawData: " + ByteUtil.toHexString(getBytes());
    }

    private Object writeReplace() throws ObjectStreamException {
      // if we are going to serialize this, convert it back to a normal
      // byte[] (in case it is restored outside of the context of jackcess)
      return getBytes();
    }
  }

  /**
   * Base class for the supported autonumber types.
   */
  public abstract class AutoNumberGenerator
  {
    protected AutoNumberGenerator() {}

    /**
     * Returns the last autonumber generated by this generator.  Only valid
     * after a call to {@link Table#addRow}, otherwise undefined.
     */
    public abstract Object getLast();

    /**
     * Returns the next autonumber for this generator.
     * <p>
     * <i>Warning, calling this externally will result in this value being
     * "lost" for the table.</i>
     */
    public abstract Object getNext();

    /**
     * Returns the flags used when writing this column.
     */
    public abstract int getColumnFlags();

    /**
     * Returns the type of values generated by this generator.
     */
    public abstract DataType getType();
  }

  private final class LongAutoNumberGenerator extends AutoNumberGenerator
  {
    private LongAutoNumberGenerator() {}

    @Override
    public Object getLast() {
      // the table stores the last long autonumber used
      return getTable().getLastLongAutoNumber();
    }

    @Override
    public Object getNext() {
      // the table stores the last long autonumber used
      return getTable().getNextLongAutoNumber();
    }

    @Override
    public int getColumnFlags() {
      return AUTO_NUMBER_FLAG_MASK;
    }

    @Override
    public DataType getType() {
      return DataType.LONG;
    }
  }

  private final class GuidAutoNumberGenerator extends AutoNumberGenerator
  {
    private Object _lastAutoNumber;

    private GuidAutoNumberGenerator() {}

    @Override
    public Object getLast() {
      return _lastAutoNumber;
    }

    @Override
    public Object getNext() {
      // format guids consistently w/ Column.readGUIDValue()
      _lastAutoNumber = "{" + UUID.randomUUID() + "}";
      return _lastAutoNumber;
    }

    @Override
    public int getColumnFlags() {
      return AUTO_NUMBER_GUID_FLAG_MASK;
    }

    @Override
    public DataType getType() {
      return DataType.GUID;
    }
  }

}