Fixed #25662 -- Allowed creation of empty GEOS geometries.

11 files changed, 140 insertions, 49 deletions

diff --git a/django/contrib/gis/geos/collections.py b/django/contrib/gis/geos/collections.py
index 0f27d2bcf9..becc6b0ce3 100644
--- a/django/contrib/gis/geos/collections.py
+++ b/django/contrib/gis/geos/collections.py
@@ -25,9 +25,6 @@ class GeometryCollection(GEOSGeometry):
         "Initializes a Geometry Collection from a sequence of Geometry objects."
 
         # Checking the arguments
-        if not args:
-            raise TypeError('Must provide at least one Geometry to initialize %s.' % self.__class__.__name__)
-
         if len(args) == 1:
             # If only one geometry provided or a list of geometries is provided
             #  in the first argument.
diff --git a/django/contrib/gis/geos/linestring.py b/django/contrib/gis/geos/linestring.py
index d0edd631ce..cf74aad7fa 100644
--- a/django/contrib/gis/geos/linestring.py
+++ b/django/contrib/gis/geos/linestring.py
@@ -35,7 +35,14 @@ class LineString(ProjectInterpolateMixin, GEOSGeometry):
         if not (isinstance(coords, (tuple, list)) or numpy and isinstance(coords, numpy.ndarray)):
             raise TypeError('Invalid initialization input for LineStrings.')
 
+        # If SRID was passed in with the keyword arguments
+        srid = kwargs.get('srid')
+
         ncoords = len(coords)
+        if not ncoords:
+            super(LineString, self).__init__(self._init_func(None), srid=srid)
+            return
+
         if ncoords < self._minlength:
             raise ValueError(
                 '%s requires at least %d points, got %s.' % (
@@ -80,9 +87,6 @@ class LineString(ProjectInterpolateMixin, GEOSGeometry):
             else:
                 cs[i] = coords[i]
 
-        # If SRID was passed in with the keyword arguments
-        srid = kwargs.get('srid')
-
         # Calling the base geometry initialization with the returned pointer
         #  from the function.
         super(LineString, self).__init__(self._init_func(cs.ptr), srid=srid)
diff --git a/django/contrib/gis/geos/mutable_list.py b/django/contrib/gis/geos/mutable_list.py
index 3fe9a4fbb6..8a613600c0 100644
--- a/django/contrib/gis/geos/mutable_list.py
+++ b/django/contrib/gis/geos/mutable_list.py
@@ -229,7 +229,7 @@ class ListMixin(object):
 
     # ### Private routines ###
     def _rebuild(self, newLen, newItems):
-        if newLen < self._minlength:
+        if newLen and newLen < self._minlength:
             raise ValueError('Must have at least %d items' % self._minlength)
         if self._maxlength is not None and newLen > self._maxlength:
             raise ValueError('Cannot have more than %d items' % self._maxlength)
diff --git a/django/contrib/gis/geos/point.py b/django/contrib/gis/geos/point.py
index 34a955e924..46972629d8 100644
--- a/django/contrib/gis/geos/point.py
+++ b/django/contrib/gis/geos/point.py
@@ -14,7 +14,7 @@ class Point(GEOSGeometry):
     _maxlength = 3
     has_cs = True
 
-    def __init__(self, x, y=None, z=None, srid=None):
+    def __init__(self, x=None, y=None, z=None, srid=None):
         """
         The Point object may be initialized with either a tuple, or individual
         parameters.
@@ -23,22 +23,21 @@ class Point(GEOSGeometry):
         >>> p = Point((5, 23)) # 2D point, passed in as a tuple
         >>> p = Point(5, 23, 8) # 3D point, passed in with individual parameters
         """
-        if isinstance(x, (tuple, list)):
+        if x is None:
+            coords = []
+        elif isinstance(x, (tuple, list)):
             # Here a tuple or list was passed in under the `x` parameter.
-            ndim = len(x)
             coords = x
         elif isinstance(x, six.integer_types + (float,)) and isinstance(y, six.integer_types + (float,)):
             # Here X, Y, and (optionally) Z were passed in individually, as parameters.
             if isinstance(z, six.integer_types + (float,)):
-                ndim = 3
                 coords = [x, y, z]
             else:
-                ndim = 2
                 coords = [x, y]
         else:
             raise TypeError('Invalid parameters given for Point initialization.')
 
-        point = self._create_point(ndim, coords)
+        point = self._create_point(len(coords), coords)
 
         # Initializing using the address returned from the GEOS
         #  createPoint factory.
@@ -48,6 +47,9 @@ class Point(GEOSGeometry):
         """
         Create a coordinate sequence, set X, Y, [Z], and create point
         """
+        if not ndim:
+            return capi.create_point(None)
+
         if ndim < 2 or ndim > 3:
             raise TypeError('Invalid point dimension: %s' % str(ndim))
 
diff --git a/django/contrib/gis/geos/polygon.py b/django/contrib/gis/geos/polygon.py
index fdf7515bed..067730063f 100644
--- a/django/contrib/gis/geos/polygon.py
+++ b/django/contrib/gis/geos/polygon.py
@@ -29,7 +29,8 @@ class Polygon(GEOSGeometry):
         ...                ((4, 4), (4, 6), (6, 6), (6, 4), (4, 4)))
         """
         if not args:
-            raise TypeError('Must provide at least one LinearRing, or a tuple, to initialize a Polygon.')
+            super(Polygon, self).__init__(self._create_polygon(0, None), **kwargs)
+            return
 
         # Getting the ext_ring and init_holes parameters from the argument list
         ext_ring = args[0]
@@ -73,6 +74,9 @@ class Polygon(GEOSGeometry):
         # _construct_ring will throw a TypeError if a parameter isn't a valid ring
         # If we cloned the pointers here, we wouldn't be able to clean up
         # in case of error.
+        if not length:
+            return capi.create_empty_polygon()
+
         rings = []
         for r in items:
             if isinstance(r, GEOM_PTR):
diff --git a/django/contrib/gis/geos/prototypes/__init__.py b/django/contrib/gis/geos/prototypes/__init__.py
index 595555897d..32073749d8 100644
--- a/django/contrib/gis/geos/prototypes/__init__.py
+++ b/django/contrib/gis/geos/prototypes/__init__.py
@@ -9,11 +9,12 @@ from django.contrib.gis.geos.prototypes.coordseq import (  # NOQA
     cs_gety, cs_getz, cs_setordinate, cs_setx, cs_sety, cs_setz, get_cs,
 )
 from django.contrib.gis.geos.prototypes.geom import (  # NOQA
-    create_collection, create_linearring, create_linestring, create_point,
-    create_polygon, destroy_geom, from_hex, from_wkb, from_wkt, geom_clone,
-    geos_get_srid, geos_normalize, geos_set_srid, geos_type, geos_typeid,
-    get_dims, get_extring, get_geomn, get_intring, get_nrings, get_num_coords,
-    get_num_geoms, to_hex, to_wkb, to_wkt,
+    create_collection, create_empty_polygon, create_linearring,
+    create_linestring, create_point, create_polygon, destroy_geom, from_hex,
+    from_wkb, from_wkt, geom_clone, geos_get_srid, geos_normalize,
+    geos_set_srid, geos_type, geos_typeid, get_dims, get_extring, get_geomn,
+    get_intring, get_nrings, get_num_coords, get_num_geoms, to_hex, to_wkb,
+    to_wkt,
 )
 from django.contrib.gis.geos.prototypes.misc import *  # NOQA
 from django.contrib.gis.geos.prototypes.predicates import (  # NOQA
diff --git a/django/contrib/gis/geos/prototypes/geom.py b/django/contrib/gis/geos/prototypes/geom.py
index e4bd0b0a51..9e14f214dc 100644
--- a/django/contrib/gis/geos/prototypes/geom.py
+++ b/django/contrib/gis/geos/prototypes/geom.py
@@ -94,6 +94,7 @@ create_linearring = GeomOutput('GEOSGeom_createLinearRing', [CS_PTR])
 # Polygon and collection creation routines are special and will not
 # have their argument types defined.
 create_polygon = GeomOutput('GEOSGeom_createPolygon', None)
+create_empty_polygon = GeomOutput('GEOSGeom_createEmptyPolygon', None)
 create_collection = GeomOutput('GEOSGeom_createCollection', None)
 
 # Ring routines
diff --git a/docs/ref/contrib/gis/geos.txt b/docs/ref/contrib/gis/geos.txt
index e53acbc99c..74fb2e5e54 100644
--- a/docs/ref/contrib/gis/geos.txt
+++ b/docs/ref/contrib/gis/geos.txt
@@ -647,7 +647,7 @@ is returned instead.
 ``Point``
 ---------
 
-.. class:: Point(x, y, z=None, srid=None)
+.. class:: Point(x=None, y=None, z=None, srid=None)
 
    ``Point`` objects are instantiated using arguments that represent
    the component coordinates of the point or with a single sequence
@@ -656,6 +656,16 @@ is returned instead.
        >>> pnt = Point(5, 23)
        >>> pnt = Point([5, 23])
 
+   Empty ``Point`` objects may be instantiated by passing no arguments or an
+   empty sequence. The following are equivalent::
+
+       >>> pnt = Point()
+       >>> pnt = Point([])
+
+   .. versionchanged:: 1.10
+
+       In previous versions, an empty ``Point`` couldn't be instantiated.
+
 ``LineString``
 --------------
 
@@ -674,6 +684,16 @@ is returned instead.
        >>> ls = LineString( ((0, 0), (1, 1)) )
        >>> ls = LineString( [Point(0, 0), Point(1, 1)] )
 
+   Empty ``LineString`` objects may be instantiated by passing no arguments
+   or an empty sequence. The following are equivalent::
+
+       >>> ls = LineString()
+       >>> ls = LineString([])
+
+   .. versionchanged:: 1.10
+
+       In previous versions, an empty ``LineString`` couldn't be instantiated.
+
 ``LinearRing``
 --------------
 
@@ -694,16 +714,20 @@ is returned instead.
 
 .. class:: Polygon(*args, **kwargs)
 
-   ``Polygon`` objects may be instantiated by passing in one or
-   more parameters that represent the rings of the polygon.  The
-   parameters must either be :class:`LinearRing` instances, or
-   a sequence that may be used to construct a :class:`LinearRing`::
+   ``Polygon`` objects may be instantiated by passing in parameters that
+   represent the rings of the polygon.  The parameters must either be
+   :class:`LinearRing` instances, or a sequence that may be used to construct a
+   :class:`LinearRing`::
 
        >>> ext_coords = ((0, 0), (0, 1), (1, 1), (1, 0), (0, 0))
        >>> int_coords = ((0.4, 0.4), (0.4, 0.6), (0.6, 0.6), (0.6, 0.4), (0.4, 0.4))
        >>> poly = Polygon(ext_coords, int_coords)
        >>> poly = Polygon(LinearRing(ext_coords), LinearRing(int_coords))
 
+   .. versionchanged:: 1.10
+
+       In previous versions, an empty ``Polygon`` couldn't be instantiated.
+
    .. classmethod:: from_bbox(bbox)
 
    Returns a polygon object from the given bounding-box, a 4-tuple
@@ -732,27 +756,35 @@ Geometry Collections
 
 .. class:: MultiPoint(*args, **kwargs)
 
-   ``MultiPoint`` objects may be instantiated by passing in one
-   or more :class:`Point` objects as arguments, or a single
-   sequence of :class:`Point` objects::
+   ``MultiPoint`` objects may be instantiated by passing in :class:`Point`
+   objects as arguments, or a single sequence of :class:`Point` objects::
 
        >>> mp = MultiPoint(Point(0, 0), Point(1, 1))
        >>> mp = MultiPoint( (Point(0, 0), Point(1, 1)) )
 
+   .. versionchanged:: 1.10
+
+       In previous versions, an empty ``MultiPoint`` couldn't be instantiated.
+
 ``MultiLineString``
 -------------------
 
 .. class:: MultiLineString(*args, **kwargs)
 
-   ``MultiLineString`` objects may be instantiated by passing in one
-   or more :class:`LineString` objects as arguments, or a single
-   sequence of :class:`LineString` objects::
+   ``MultiLineString`` objects may be instantiated by passing in
+   :class:`LineString` objects as arguments, or a single sequence of
+   :class:`LineString` objects::
 
        >>> ls1 = LineString((0, 0), (1, 1))
        >>> ls2 = LineString((2, 2), (3, 3))
        >>> mls = MultiLineString(ls1, ls2)
        >>> mls = MultiLineString([ls1, ls2])
 
+   .. versionchanged:: 1.10
+
+       In previous versions, an empty ``MultiLineString`` couldn't be
+       instantiated.
+
    .. attribute:: merged
 
    Returns a :class:`LineString` representing the line merge of
@@ -764,15 +796,19 @@ Geometry Collections
 
 .. class:: MultiPolygon(*args, **kwargs)
 
-   ``MultiPolygon`` objects may be instantiated by passing one or
-   more :class:`Polygon` objects as arguments, or a single sequence
-   of :class:`Polygon` objects::
+   ``MultiPolygon`` objects may be instantiated by passing :class:`Polygon`
+   objects as arguments, or a single sequence of :class:`Polygon` objects::
 
        >>> p1 = Polygon( ((0, 0), (0, 1), (1, 1), (0, 0)) )
        >>> p2 = Polygon( ((1, 1), (1, 2), (2, 2), (1, 1)) )
        >>> mp = MultiPolygon(p1, p2)
        >>> mp = MultiPolygon([p1, p2])
 
+   .. versionchanged:: 1.10
+
+       In previous versions, an empty ``MultiPolygon`` couldn't be
+       instantiated.
+
    .. attribute:: cascaded_union
 
    .. deprecated:: 1.10
@@ -789,14 +825,19 @@ Geometry Collections
 
 .. class:: GeometryCollection(*args, **kwargs)
 
-   ``GeometryCollection`` objects may be instantiated by passing in
-   one or more other :class:`GEOSGeometry` as arguments, or a single
-   sequence of :class:`GEOSGeometry` objects::
+   ``GeometryCollection`` objects may be instantiated by passing in other
+   :class:`GEOSGeometry` as arguments, or a single sequence of
+   :class:`GEOSGeometry` objects::
 
        >>> poly = Polygon( ((0, 0), (0, 1), (1, 1), (0, 0)) )
        >>> gc = GeometryCollection(Point(0, 0), MultiPoint(Point(0, 0), Point(1, 1)), poly)
        >>> gc = GeometryCollection((Point(0, 0), MultiPoint(Point(0, 0), Point(1, 1)), poly))
 
+   .. versionchanged:: 1.10
+
+       In previous versions, an empty ``GeometryCollection`` couldn't be
+       instantiated.
+
 .. _prepared-geometries:
 
 Prepared Geometries
diff --git a/docs/releases/1.10.txt b/docs/releases/1.10.txt
index d932887a51..853955f936 100644
--- a/docs/releases/1.10.txt
+++ b/docs/releases/1.10.txt
@@ -92,6 +92,8 @@ Minor features
   :class:`~django.contrib.gis.db.models.functions.SymDifference`
   functions on MySQL.
 
+* Added support for instantiating empty GEOS geometries.
+
 :mod:`django.contrib.messages`
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
diff --git a/tests/gis_tests/geos_tests/test_geos.py b/tests/gis_tests/geos_tests/test_geos.py
index da9db06c33..fd08e3037a 100644
--- a/tests/gis_tests/geos_tests/test_geos.py
+++ b/tests/gis_tests/geos_tests/test_geos.py
@@ -793,6 +793,9 @@ class GEOSTest(SimpleTestCase, TestDataMixin):
         p[:] = (1, 2, 3)
         self.assertEqual(p, Point(1, 2, 3))
 
+        p[:] = ()
+        self.assertEqual(p.wkt, Point())
+
         p[:] = (1, 2)
         self.assertEqual(p.wkt, Point(1, 2))
 
@@ -804,6 +807,9 @@ class GEOSTest(SimpleTestCase, TestDataMixin):
     def test_linestring_list_assignment(self):
         ls = LineString((0, 0), (1, 1))
 
+        ls[:] = ()
+        self.assertEqual(ls, LineString())
+
         ls[:] = ((0, 0), (1, 1), (2, 2))
         self.assertEqual(ls, LineString((0, 0), (1, 1), (2, 2)))
 
@@ -813,12 +819,34 @@ class GEOSTest(SimpleTestCase, TestDataMixin):
     def test_linearring_list_assignment(self):
         ls = LinearRing((0, 0), (0, 1), (1, 1), (0, 0))
 
+        ls[:] = ()
+        self.assertEqual(ls, LinearRing())
+
         ls[:] = ((0, 0), (0, 1), (1, 1), (1, 0), (0, 0))
         self.assertEqual(ls, LinearRing((0, 0), (0, 1), (1, 1), (1, 0), (0, 0)))
 
         with self.assertRaises(ValueError):
             ls[:] = ((0, 0), (1, 1), (2, 2))
 
+    def test_polygon_list_assignment(self):
+        pol = Polygon()
+
+        pol[:] = (((0, 0), (0, 1), (1, 1), (1, 0), (0, 0)),)
+        self.assertEqual(pol, Polygon(((0, 0), (0, 1), (1, 1), (1, 0), (0, 0)),))
+
+        pol[:] = ()
+        self.assertEqual(pol, Polygon())
+
+    def test_geometry_collection_list_assignment(self):
+        p = Point()
+        gc = GeometryCollection()
+
+        gc[:] = [p]
+        self.assertEqual(gc, GeometryCollection(p))
+
+        gc[:] = ()
+        self.assertEqual(gc, GeometryCollection())
+
     def test_threed(self):
         "Testing three-dimensional geometries."
         # Testing a 3D Point
@@ -874,16 +902,27 @@ class GEOSTest(SimpleTestCase, TestDataMixin):
 
     def test_emptyCollections(self):
         "Testing empty geometries and collections."
-        gc1 = GeometryCollection([])
-        gc2 = fromstr('GEOMETRYCOLLECTION EMPTY')
-        pnt = fromstr('POINT EMPTY')
-        ls = fromstr('LINESTRING EMPTY')
-        poly = fromstr('POLYGON EMPTY')
-        mls = fromstr('MULTILINESTRING EMPTY')
-        mpoly1 = fromstr('MULTIPOLYGON EMPTY')
-        mpoly2 = MultiPolygon(())
+        geoms = [
+            GeometryCollection([]),
+            fromstr('GEOMETRYCOLLECTION EMPTY'),
+            GeometryCollection(),
+            fromstr('POINT EMPTY'),
+            Point(),
+            fromstr('LINESTRING EMPTY'),
+            LineString(),
+            fromstr('POLYGON EMPTY'),
+            Polygon(),
+            fromstr('MULTILINESTRING EMPTY'),
+            MultiLineString(),
+            fromstr('MULTIPOLYGON EMPTY'),
+            MultiPolygon(()),
+            MultiPolygon(),
+        ]
+
+        if numpy:
+            geoms.append(LineString(numpy.array([])))
 
-        for g in [gc1, gc2, pnt, ls, poly, mls, mpoly1, mpoly2]:
+        for g in geoms:
             self.assertEqual(True, g.empty)
 
             # Testing len() and num_geom.
diff --git a/tests/gis_tests/geos_tests/test_mutable_list.py b/tests/gis_tests/geos_tests/test_mutable_list.py
index 67338ee865..8f2242ea31 100644
--- a/tests/gis_tests/geos_tests/test_mutable_list.py
+++ b/tests/gis_tests/geos_tests/test_mutable_list.py
@@ -299,18 +299,18 @@ class ListMixinTest(unittest.TestCase):
 
     def test08_min_length(self):
         'Length limits'
-        pl, ul = self.lists_of_len()
-        ul._minlength = 1
+        pl, ul = self.lists_of_len(5)
+        ul._minlength = 3
 
         def delfcn(x, i):
             del x[:i]
 
         def setfcn(x, i):
             x[:i] = []
-        for i in range(self.limit - ul._minlength + 1, self.limit + 1):
+        for i in range(len(ul) - ul._minlength + 1, len(ul)):
             self.assertRaises(ValueError, delfcn, ul, i)
             self.assertRaises(ValueError, setfcn, ul, i)
-        del ul[:ul._minlength]
+        del ul[:len(ul) - ul._minlength]
 
         ul._maxlength = 4
         for i in range(0, ul._maxlength - len(ul)):