--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/lib/django/contrib/gis/db/models/sql/aggregates.py	Wed Jun 02 18:57:35 2010 +0200
@@ -0,0 +1,61 @@
+from django.db.models.sql.aggregates import *
+from django.contrib.gis.db.models.fields import GeometryField
+from django.contrib.gis.db.models.sql.conversion import GeomField
+
+class GeoAggregate(Aggregate):
+    # Default SQL template for spatial aggregates.
+    sql_template = '%(function)s(%(field)s)'
+
+    # Conversion class, if necessary.
+    conversion_class = None
+
+    # Flags for indicating the type of the aggregate.
+    is_extent = False
+
+    def __init__(self, col, source=None, is_summary=False, tolerance=0.05, **extra):
+        super(GeoAggregate, self).__init__(col, source, is_summary, **extra)
+
+        # Required by some Oracle aggregates.
+        self.tolerance = tolerance
+
+        # Can't use geographic aggregates on non-geometry fields.
+        if not isinstance(self.source, GeometryField):
+            raise ValueError('Geospatial aggregates only allowed on geometry fields.')
+
+    def as_sql(self, qn, connection):
+        "Return the aggregate, rendered as SQL."
+
+        if connection.ops.oracle:
+            self.extra['tolerance'] = self.tolerance
+
+        if hasattr(self.col, 'as_sql'):
+            field_name = self.col.as_sql(qn, connection)
+        elif isinstance(self.col, (list, tuple)):
+            field_name = '.'.join([qn(c) for c in self.col])
+        else:
+            field_name = self.col
+
+        sql_template, sql_function = connection.ops.spatial_aggregate_sql(self)
+
+        params = {
+            'function': sql_function,
+            'field': field_name
+        }
+        params.update(self.extra)
+
+        return sql_template % params
+
+class Collect(GeoAggregate):
+    pass
+
+class Extent(GeoAggregate):
+    is_extent = '2D'
+
+class Extent3D(GeoAggregate):
+    is_extent = '3D'
+
+class MakeLine(GeoAggregate):
+    pass
+
+class Union(GeoAggregate):
+    pass