django/contrib/gis/gdal/geomtype.py

from django.contrib.gis.gdal.error import GDALException
from django.utils import six


class OGRGeomType(object):
    "Encapsulates OGR Geometry Types."

    wkb25bit = -2147483648

    # Dictionary of acceptable OGRwkbGeometryType s and their string names.
    _types = {0: 'Unknown',
              1: 'Point',
              2: 'LineString',
              3: 'Polygon',
              4: 'MultiPoint',
              5: 'MultiLineString',
              6: 'MultiPolygon',
              7: 'GeometryCollection',
              100: 'None',
              101: 'LinearRing',
              102: 'PointZ',
              1 + wkb25bit: 'Point25D',
              2 + wkb25bit: 'LineString25D',
              3 + wkb25bit: 'Polygon25D',
              4 + wkb25bit: 'MultiPoint25D',
              5 + wkb25bit: 'MultiLineString25D',
              6 + wkb25bit: 'MultiPolygon25D',
              7 + wkb25bit: 'GeometryCollection25D',
              }
    # Reverse type dictionary, keyed by lower-case of the name.
    _str_types = {v.lower(): k for k, v in _types.items()}

    def __init__(self, type_input):
        "Figures out the correct OGR Type based upon the input."
        if isinstance(type_input, OGRGeomType):
            num = type_input.num
        elif isinstance(type_input, six.string_types):
            type_input = type_input.lower()
            if type_input == 'geometry':
                type_input = 'unknown'
            num = self._str_types.get(type_input)
            if num is None:
                raise GDALException('Invalid OGR String Type "%s"' % type_input)
        elif isinstance(type_input, int):
            if type_input not in self._types:
                raise GDALException('Invalid OGR Integer Type: %d' % type_input)
            num = type_input
        else:
            raise TypeError('Invalid OGR input type given.')

        # Setting the OGR geometry type number.
        self.num = num

    def __str__(self):
        "Returns the value of the name property."
        return self.name

    def __eq__(self, other):
        """
        Does an equivalence test on the OGR type with the given
        other OGRGeomType, the short-hand string, or the integer.
        """
        if isinstance(other, OGRGeomType):
            return self.num == other.num
        elif isinstance(other, six.string_types):
            return self.name.lower() == other.lower()
        elif isinstance(other, int):
            return self.num == other
        else:
            return False

    def __ne__(self, other):
        return not (self == other)

    @property
    def name(self):
        "Returns a short-hand string form of the OGR Geometry type."
        return self._types[self.num]

    @property
    def django(self):
        "Returns the Django GeometryField for this OGR Type."
        s = self.name.replace('25D', '')
        if s in ('LinearRing', 'None'):
            return None
        elif s == 'Unknown':
            s = 'Geometry'
        elif s == 'PointZ':
            s = 'Point'
        return s + 'Field'

    def to_multi(self):
        """
        Transform Point, LineString, Polygon, and their 25D equivalents
        to their Multi... counterpart.
        """
        if self.name.startswith(('Point', 'LineString', 'Polygon')):
            self.num += 3