Merge branch 'range_sort'

NEWS

@@ -13,6 +13,8 @@ Bug fixes:
 What's new in psycopg 2.5.3
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+- Added arbitrary but stable order to `Range` objects, thanks to
+  Chris Withers (:ticket:`#193`).
 - Fixed debug build on Windows, thanks to James Emerton.
 
 

doc/src/extras.rst

@@ -437,8 +437,16 @@ user-defined |range| types can be adapted using `register_range()`.
 
     `!Range` objects are immutable, hashable, and support the ``in`` operator
     (checking if an element is within the range). They can be tested for
-    equivalence but not for ordering. Empty ranges evaluate to `!False` in
-    boolean context, nonempty evaluate to `!True`.
+    equivalence. Empty ranges evaluate to `!False` in boolean context,
+    nonempty evaluate to `!True`.
+
+    .. versionchanged:: 2.5.3
+
+        `!Range` objects can be sorted although, as on the server-side, this
+        ordering is not particularly meangingful. It is only meant to be used
+        by programs assuming objects using `!Range` as primary key can be
+        sorted on them. In previous versions comparing `!Range`\s raises
+        `!TypeError`.
 
     Although it is possible to instantiate `!Range` objects, the class doesn't
     have an adapter registered, so you cannot normally pass these instances as

lib/_range.py

@@ -133,12 +133,43 @@ class Range(object):
     def __hash__(self):
         return hash((self._lower, self._upper, self._bounds))
 
-    def __lt__(self, other):
-        raise TypeError(
-            'Range objects cannot be ordered; please refer to the PostgreSQL'
-            ' documentation to perform this operation in the database')
+    # as the postgres docs describe for the server-side stuff,
+    # ordering is rather arbitrary, but will remain stable
+    # and consistent.
 
-    __le__ = __gt__ = __ge__ = __lt__
+    def __lt__(self, other):
+        if not isinstance(other, Range):
+            return NotImplemented
+        for attr in ('_lower', '_upper', '_bounds'):
+            self_value = getattr(self, attr)
+            other_value = getattr(other, attr)
+            if self_value == other_value:
+                pass
+            elif self_value is None:
+                return True
+            elif other_value is None:
+                return False
+            else:
+                return self_value < other_value
+        return False
+
+    def __le__(self, other):
+        if self == other:
+            return True
+        else:
+            return self.__lt__(other)
+
+    def __gt__(self, other):
+        if isinstance(other, Range):
+            return other.__lt__(self)
+        else:
+            return NotImplemented
+
+    def __ge__(self, other):
+        if self == other:
+            return True
+        else:
+            return self.__gt__(other)
 
 
 def register_range(pgrange, pyrange, conn_or_curs, globally=False):

tests/test_types_extras.py

@@ -13,6 +13,7 @@
 # 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.
+from __future__ import with_statement
 
 import re
 import sys
@@ -22,6 +23,7 @@ from functools import wraps
 
 from testutils import unittest, skip_if_no_uuid, skip_before_postgres
 from testutils import ConnectingTestCase, decorate_all_tests
+from testutils import py3_raises_typeerror
 
 import psycopg2
 import psycopg2.extras
@@ -1236,12 +1238,73 @@ class RangeTestCase(unittest.TestCase):
         self.assertEqual(Range(10, 20), IntRange(10, 20))
         self.assertEqual(PositiveIntRange(10, 20), IntRange(10, 20))
 
-    def test_not_ordered(self):
+    # as the postgres docs describe for the server-side stuff,
+    # ordering is rather arbitrary, but will remain stable
+    # and consistent.
+
+    def test_lt_ordering(self):
         from psycopg2.extras import Range
-        self.assertRaises(TypeError, lambda: Range(empty=True) < Range(0,4))
-        self.assertRaises(TypeError, lambda: Range(1,2) > Range(0,4))
-        self.assertRaises(TypeError, lambda: Range(1,2) <= Range())
-        self.assertRaises(TypeError, lambda: Range(1,2) >= Range())
+        self.assert_(Range(empty=True) < Range(0, 4))
+        self.assert_(not Range(1, 2) < Range(0, 4))
+        self.assert_(Range(0, 4) < Range(1, 2))
+        self.assert_(not Range(1, 2) < Range())
+        self.assert_(Range() < Range(1, 2))
+        self.assert_(not Range(1) < Range(upper=1))
+        self.assert_(not Range() < Range())
+        self.assert_(not Range(empty=True) < Range(empty=True))
+        self.assert_(not Range(1, 2) < Range(1, 2))
+        with py3_raises_typeerror():
+            self.assert_(1 < Range(1, 2))
+        with py3_raises_typeerror():
+            self.assert_(not Range(1, 2) < 1)
+
+    def test_gt_ordering(self):
+        from psycopg2.extras import Range
+        self.assert_(not Range(empty=True) > Range(0, 4))
+        self.assert_(Range(1, 2) > Range(0, 4))
+        self.assert_(not Range(0, 4) > Range(1, 2))
+        self.assert_(Range(1, 2) > Range())
+        self.assert_(not Range() > Range(1, 2))
+        self.assert_(Range(1) > Range(upper=1))
+        self.assert_(not Range() > Range())
+        self.assert_(not Range(empty=True) > Range(empty=True))
+        self.assert_(not Range(1, 2) > Range(1, 2))
+        with py3_raises_typeerror():
+            self.assert_(not 1 > Range(1, 2))
+        with py3_raises_typeerror():
+            self.assert_(Range(1, 2) > 1)
+
+    def test_le_ordering(self):
+        from psycopg2.extras import Range
+        self.assert_(Range(empty=True) <= Range(0, 4))
+        self.assert_(not Range(1, 2) <= Range(0, 4))
+        self.assert_(Range(0, 4) <= Range(1, 2))
+        self.assert_(not Range(1, 2) <= Range())
+        self.assert_(Range() <= Range(1, 2))
+        self.assert_(not Range(1) <= Range(upper=1))
+        self.assert_(Range() <= Range())
+        self.assert_(Range(empty=True) <= Range(empty=True))
+        self.assert_(Range(1, 2) <= Range(1, 2))
+        with py3_raises_typeerror():
+            self.assert_(1 <= Range(1, 2))
+        with py3_raises_typeerror():
+            self.assert_(not Range(1, 2) <= 1)
+
+    def test_ge_ordering(self):
+        from psycopg2.extras import Range
+        self.assert_(not Range(empty=True) >= Range(0, 4))
+        self.assert_(Range(1, 2) >= Range(0, 4))
+        self.assert_(not Range(0, 4) >= Range(1, 2))
+        self.assert_(Range(1, 2) >= Range())
+        self.assert_(not Range() >= Range(1, 2))
+        self.assert_(Range(1) >= Range(upper=1))
+        self.assert_(Range() >= Range())
+        self.assert_(Range(empty=True) >= Range(empty=True))
+        self.assert_(Range(1, 2) >= Range(1, 2))
+        with py3_raises_typeerror():
+            self.assert_(not 1 >= Range(1, 2))
+        with py3_raises_typeerror():
+            self.assert_(Range(1, 2) >= 1)
 
 
 def skip_if_no_range(f):

tests/testutils.py

@@ -329,3 +329,13 @@ def script_to_py3(script):
         f2.close()
         os.remove(filename)
 
+class py3_raises_typeerror(object):
+
+    def __enter__(self):
+        pass
+
+    def __exit__(self, type, exc, tb):
+        if sys.version_info[0] >= 3:
+            assert type is TypeError
+            return True
+