- Added math negation operator support, -x.

3 files changed, 9 insertions, 1 deletions

diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index e635e20e1..4486c24db 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -73,6 +73,7 @@ OPERATORS =  {
     # end Py2K
     operators.mod : ' % ',
     operators.truediv : ' / ',
+    operators.neg : '-',
     operators.lt : ' < ',
     operators.le : ' <= ',
     operators.ne : ' != ',
diff --git a/lib/sqlalchemy/sql/expression.py b/lib/sqlalchemy/sql/expression.py
index 5c61777fe..89137d2ce 100644
--- a/lib/sqlalchemy/sql/expression.py
+++ b/lib/sqlalchemy/sql/expression.py
@@ -1363,6 +1363,9 @@ class ColumnOperators(Operators):
     def __ge__(self, other):
         return self.operate(operators.ge, other)
 
+    def __neg__(self):
+        return self.operate(operators.neg)
+
     def concat(self, other):
         return self.operate(operators.concat_op, other)
 
@@ -1537,6 +1540,9 @@ class _CompareMixin(ColumnOperators):
 
         return self.__compare(op, ClauseList(*args).self_group(against=op), negate=negate_op)
 
+    def __neg__(self):
+        return _UnaryExpression(self, operator=operators.neg)
+        
     def startswith(self, other, escape=None):
         """Produce the clause ``LIKE '<other>%'``"""
 
diff --git a/lib/sqlalchemy/sql/operators.py b/lib/sqlalchemy/sql/operators.py
index 879f0f3e5..6f70b1778 100644
--- a/lib/sqlalchemy/sql/operators.py
+++ b/lib/sqlalchemy/sql/operators.py
@@ -4,7 +4,7 @@
 """Defines operators used in SQL expressions."""
 
 from operator import (
-    and_, or_, inv, add, mul, sub, mod, truediv, lt, le, ne, gt, ge, eq
+    and_, or_, inv, add, mul, sub, mod, truediv, lt, le, ne, gt, ge, eq, neg
     )
     
 # Py2K
@@ -98,6 +98,7 @@ _PRECEDENCE = {
     div: 7,
     # end Py2K
     mod: 7,
+    neg: 7,
     add: 6,
     sub: 6,
     concat_op: 6,