1 files changed, 467 insertions, 0 deletions
diff --git a/tablib/packages/dbfpy3/fields.py b/tablib/packages/dbfpy3/fields.py
new file mode 100644
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+++ b/tablib/packages/dbfpy3/fields.py
@@ -0,0 +1,467 @@
+"""DBF fields definitions.
+
+TODO:
+  - make memos work
+"""
+"""History (most recent first):
+26-may-2009 [als]   DbfNumericFieldDef.decodeValue: strip zero bytes
+05-feb-2009 [als]   DbfDateFieldDef.encodeValue: empty arg produces empty date
+16-sep-2008 [als]   DbfNumericFieldDef decoding looks for decimal point
+                    in the value to select float or integer return type
+13-mar-2008 [als]   check field name length in constructor
+11-feb-2007 [als]   handle value conversion errors
+10-feb-2007 [als]   DbfFieldDef: added .rawFromRecord()
+01-dec-2006 [als]   Timestamp columns use None for empty values
+31-oct-2006 [als]   support field types 'F' (float), 'I' (integer)
+                    and 'Y' (currency);
+                    automate export and registration of field classes
+04-jul-2006 [als]   added export declaration
+10-mar-2006 [als]   decode empty values for Date and Logical fields;
+                    show field name in errors
+10-mar-2006 [als]   fix Numeric value decoding: according to spec,
+                    value always is string representation of the number;
+                    ensure that encoded Numeric value fits into the field
+20-dec-2005 [yc]    use field names in upper case
+15-dec-2005 [yc]    field definitions moved from `dbf`.
+"""
+
+__version__ = "$Revision: 1.14 $"[11:-2]
+__date__ = "$Date: 2009/05/26 05:16:51 $"[7:-2]
+
+__all__ = ["lookupFor",] # field classes added at the end of the module
+
+import datetime
+import struct
+import sys
+
+from . import utils
+
+## abstract definitions
+
+class DbfFieldDef(object):
+    """Abstract field definition.
+
+    Child classes must override ``type`` class attribute to provide datatype
+    infromation of the field definition. For more info about types visit
+    `http://www.clicketyclick.dk/databases/xbase/format/data_types.html`
+
+    Also child classes must override ``defaultValue`` field to provide
+    default value for the field value.
+
+    If child class has fixed length ``length`` class attribute must be
+    overriden and set to the valid value. None value means, that field
+    isn't of fixed length.
+
+    Note: ``name`` field must not be changed after instantiation.
+
+    """
+
+
+    __slots__ = ("name", "decimalCount",
+        "start", "end", "ignoreErrors")
+
+    # length of the field, None in case of variable-length field,
+    # or a number if this field is a fixed-length field
+    length = None
+
+    # field type. for more information about fields types visit
+    # `http://www.clicketyclick.dk/databases/xbase/format/data_types.html`
+    # must be overriden in child classes
+    typeCode = None
+
+    # default value for the field. this field must be
+    # overriden in child classes
+    defaultValue = None
+
+    def __init__(self, name, length=None, decimalCount=None,
+        start=None, stop=None, ignoreErrors=False,
+    ):
+        """Initialize instance."""
+        assert self.typeCode is not None, "Type code must be overriden"
+        assert self.defaultValue is not None, "Default value must be overriden"
+        ## fix arguments
+        if len(name) >10:
+            raise ValueError("Field name \"%s\" is too long" % name)
+        name = str(name).upper()
+        if self.__class__.length is None:
+            if length is None:
+                raise ValueError("[%s] Length isn't specified" % name)
+            length = int(length)
+            if length <= 0:
+                raise ValueError("[%s] Length must be a positive integer"
+                    % name)
+        else:
+            length = self.length
+        if decimalCount is None:
+            decimalCount = 0
+        ## set fields
+        self.name = name
+        # FIXME: validate length according to the specification at
+        # http://www.clicketyclick.dk/databases/xbase/format/data_types.html
+        self.length = length
+        self.decimalCount = decimalCount
+        self.ignoreErrors = ignoreErrors
+        self.start = start
+        self.end = stop
+
+    def __cmp__(self, other):
+        return cmp(self.name, str(other).upper())
+
+    def __hash__(self):
+        return hash(self.name)
+
+    def fromString(cls, string, start, ignoreErrors=False):
+        """Decode dbf field definition from the string data.
+
+        Arguments:
+            string:
+                a string, dbf definition is decoded from. length of
+                the string must be 32 bytes.
+            start:
+                position in the database file.
+            ignoreErrors:
+                initial error processing mode for the new field (boolean)
+
+        """
+        assert len(string) == 32
+        _length = string[16]
+        return cls(utils.unzfill(string)[:11].decode('utf-8'), _length,
+            string[17], start, start + _length, ignoreErrors=ignoreErrors)
+    fromString = classmethod(fromString)
+
+    def toString(self):
+        """Return encoded field definition.
+
+        Return:
+            Return value is a string object containing encoded
+            definition of this field.
+
+        """
+        if sys.version_info < (2, 4):
+            # earlier versions did not support padding character
+            _name = self.name[:11] + "\0" * (11 - len(self.name))
+        else:
+            _name = self.name.ljust(11, '\0')
+        return (
+            _name +
+            self.typeCode +
+            #data address
+            chr(0) * 4 +
+            chr(self.length) +
+            chr(self.decimalCount) +
+            chr(0) * 14
+        )
+
+    def __repr__(self):
+        return "%-10s %1s %3d %3d" % self.fieldInfo()
+
+    def fieldInfo(self):
+        """Return field information.
+
+        Return:
+            Return value is a (name, type, length, decimals) tuple.
+
+        """
+        return (self.name, self.typeCode, self.length, self.decimalCount)
+
+    def rawFromRecord(self, record):
+        """Return a "raw" field value from the record string."""
+        return record[self.start:self.end]
+
+    def decodeFromRecord(self, record):
+        """Return decoded field value from the record string."""
+        try:
+            return self.decodeValue(self.rawFromRecord(record))
+        except:
+            if self.ignoreErrors:
+                return utils.INVALID_VALUE
+            else:
+                raise
+
+    def decodeValue(self, value):
+        """Return decoded value from string value.
+
+        This method shouldn't be used publicly. It's called from the
+        `decodeFromRecord` method.
+
+        This is an abstract method and it must be overridden in child classes.
+        """
+        raise NotImplementedError
+
+    def encodeValue(self, value):
+        """Return str object containing encoded field value.
+
+        This is an abstract method and it must be overriden in child classes.
+        """
+        raise NotImplementedError
+
+## real classes
+
+class DbfCharacterFieldDef(DbfFieldDef):
+    """Definition of the character field."""
+
+    typeCode = "C"
+    defaultValue = b''
+
+    def decodeValue(self, value):
+        """Return string object.
+
+        Return value is a ``value`` argument with stripped right spaces.
+
+        """
+        return value.rstrip(b' ').decode('utf-8')
+
+    def encodeValue(self, value):
+        """Return raw data string encoded from a ``value``."""
+        return str(value)[:self.length].ljust(self.length)
+
+
+class DbfNumericFieldDef(DbfFieldDef):
+    """Definition of the numeric field."""
+
+    typeCode = "N"
+    # XXX: now I'm not sure it was a good idea to make a class field
+    # `defaultValue` instead of a generic method as it was implemented
+    # previously -- it's ok with all types except number, cuz
+    # if self.decimalCount is 0, we should return 0 and 0.0 otherwise.
+    defaultValue = 0
+
+    def decodeValue(self, value):
+        """Return a number decoded from ``value``.
+
+        If decimals is zero, value will be decoded as an integer;
+        or as a float otherwise.
+
+        Return:
+            Return value is a int (long) or float instance.
+
+        """
+        value = value.strip(b' \0')
+        if b'.' in value:
+            # a float (has decimal separator)
+            return float(value)
+        elif value:
+            # must be an integer
+            return int(value)
+        else:
+            return 0
+
+    def encodeValue(self, value):
+        """Return string containing encoded ``value``."""
+        _rv = ("%*.*f" % (self.length, self.decimalCount, value))
+        if len(_rv) > self.length:
+            _ppos = _rv.find(".")
+            if 0 <= _ppos <= self.length:
+                _rv = _rv[:self.length]
+            else:
+                raise ValueError("[%s] Numeric overflow: %s (field width: %i)"
+                    % (self.name, _rv, self.length))
+        return _rv
+
+class DbfFloatFieldDef(DbfNumericFieldDef):
+    """Definition of the float field - same as numeric."""
+
+    typeCode = "F"
+
+class DbfIntegerFieldDef(DbfFieldDef):
+    """Definition of the integer field."""
+
+    typeCode = "I"
+    length = 4
+    defaultValue = 0
+
+    def decodeValue(self, value):
+        """Return an integer number decoded from ``value``."""
+        return struct.unpack("<i", value)[0]
+
+    def encodeValue(self, value):
+        """Return string containing encoded ``value``."""
+        return struct.pack("<i", int(value))
+
+class DbfCurrencyFieldDef(DbfFieldDef):
+    """Definition of the currency field."""
+
+    typeCode = "Y"
+    length = 8
+    defaultValue = 0.0
+
+    def decodeValue(self, value):
+        """Return float number decoded from ``value``."""
+        return struct.unpack("<q", value)[0] / 10000.
+
+    def encodeValue(self, value):
+        """Return string containing encoded ``value``."""
+        return struct.pack("<q", round(value * 10000))
+
+class DbfLogicalFieldDef(DbfFieldDef):
+    """Definition of the logical field."""
+
+    typeCode = "L"
+    defaultValue = -1
+    length = 1
+
+    def decodeValue(self, value):
+        """Return True, False or -1 decoded from ``value``."""
+        # Note: value always is 1-char string
+        if value == "?":
+            return -1
+        if value in "NnFf ":
+            return False
+        if value in "YyTt":
+            return True
+        raise ValueError("[%s] Invalid logical value %r" % (self.name, value))
+
+    def encodeValue(self, value):
+        """Return a character from the "TF?" set.
+
+        Return:
+            Return value is "T" if ``value`` is True
+            "?" if value is -1 or False otherwise.
+
+        """
+        if value is True:
+            return "T"
+        if value == -1:
+            return "?"
+        return "F"
+
+
+class DbfMemoFieldDef(DbfFieldDef):
+    """Definition of the memo field.
+
+    Note: memos aren't currenly completely supported.
+
+    """
+
+    typeCode = "M"
+    defaultValue = " " * 10
+    length = 10
+
+    def decodeValue(self, value):
+        """Return int .dbt block number decoded from the string object."""
+        #return int(value)
+        raise NotImplementedError
+
+    def encodeValue(self, value):
+        """Return raw data string encoded from a ``value``.
+
+        Note: this is an internal method.
+
+        """
+        #return str(value)[:self.length].ljust(self.length)
+        raise NotImplementedError
+
+
+class DbfDateFieldDef(DbfFieldDef):
+    """Definition of the date field."""
+
+    typeCode = "D"
+    defaultValue = utils.classproperty(lambda cls: datetime.date.today())
+    # "yyyymmdd" gives us 8 characters
+    length = 8
+
+    def decodeValue(self, value):
+        """Return a ``datetime.date`` instance decoded from ``value``."""
+        if value.strip():
+            return utils.getDate(value)
+        else:
+            return None
+
+    def encodeValue(self, value):
+        """Return a string-encoded value.
+
+        ``value`` argument should be a value suitable for the
+        `utils.getDate` call.
+
+        Return:
+            Return value is a string in format "yyyymmdd".
+
+        """
+        if value:
+            return utils.getDate(value).strftime("%Y%m%d")
+        else:
+            return " " * self.length
+
+
+class DbfDateTimeFieldDef(DbfFieldDef):
+    """Definition of the timestamp field."""
+
+    # a difference between JDN (Julian Day Number)
+    # and GDN (Gregorian Day Number). note, that GDN < JDN
+    JDN_GDN_DIFF = 1721425
+    typeCode = "T"
+    defaultValue = utils.classproperty(lambda cls: datetime.datetime.now())
+    # two 32-bits integers representing JDN and amount of
+    # milliseconds respectively gives us 8 bytes.
+    # note, that values must be encoded in LE byteorder.
+    length = 8
+
+    def decodeValue(self, value):
+        """Return a `datetime.datetime` instance."""
+        assert len(value) == self.length
+        # LE byteorder
+        _jdn, _msecs = struct.unpack("<2I", value)
+        if _jdn >= 1:
+            _rv = datetime.datetime.fromordinal(_jdn - self.JDN_GDN_DIFF)
+            _rv += datetime.timedelta(0, _msecs / 1000.0)
+        else:
+            # empty date
+            _rv = None
+        return _rv
+
+    def encodeValue(self, value):
+        """Return a string-encoded ``value``."""
+        if value:
+            value = utils.getDateTime(value)
+            # LE byteorder
+            _rv = struct.pack("<2I", value.toordinal() + self.JDN_GDN_DIFF,
+                (value.hour * 3600 + value.minute * 60 + value.second) * 1000)
+        else:
+            _rv = "\0" * self.length
+        assert len(_rv) == self.length
+        return _rv
+
+
+_fieldsRegistry = {}
+
+def registerField(fieldCls):
+    """Register field definition class.
+
+    ``fieldCls`` should be subclass of the `DbfFieldDef`.
+
+    Use `lookupFor` to retrieve field definition class
+    by the type code.
+
+    """
+    assert fieldCls.typeCode is not None, "Type code isn't defined"
+    # XXX: use fieldCls.typeCode.upper()? in case of any decign
+    # don't forget to look to the same comment in ``lookupFor`` method
+    _fieldsRegistry[fieldCls.typeCode] = fieldCls
+
+
+def lookupFor(typeCode):
+    """Return field definition class for the given type code.
+
+    ``typeCode`` must be a single character. That type should be
+    previously registered.
+
+    Use `registerField` to register new field class.
+
+    Return:
+        Return value is a subclass of the `DbfFieldDef`.
+
+    """
+    # XXX: use typeCode.upper()? in case of any decign don't
+    # forget to look to the same comment in ``registerField``
+    return _fieldsRegistry[chr(typeCode)]
+
+## register generic types
+
+for (_name, _val) in list(globals().items()):
+    if isinstance(_val, type) and issubclass(_val, DbfFieldDef) \
+    and (_name != "DbfFieldDef"):
+        __all__.append(_name)
+        registerField(_val)
+del _name, _val
+
+# vim: et sts=4 sw=4 :