- basic framework for generic functions, [ticket:615]

- changed the various "literal" generation functions to use an anonymous
bind parameter.  not much changes here except their labels now look
like ":param_1", ":param_2" instead of ":literal"
- from_obj keyword argument to select() can be a scalar or a list.

1 files changed, 78 insertions, 0 deletions

diff --git a/lib/sqlalchemy/sql/functions.py b/lib/sqlalchemy/sql/functions.py
new file mode 100644
index 000000000..d39032b91
--- /dev/null
+++ b/lib/sqlalchemy/sql/functions.py
@@ -0,0 +1,78 @@
+from sqlalchemy import types as sqltypes
+from sqlalchemy.sql.expression import _Function, _literal_as_binds, ClauseList, _FigureVisitName
+from sqlalchemy.sql import operators
+
+class _GenericMeta(_FigureVisitName):
+    def __init__(cls, clsname, bases, dict):
+        cls.__visit_name__ = 'function'
+        type.__init__(cls, clsname, bases, dict)
+       
+    def __call__(self, *args, **kwargs):
+        args = [_literal_as_binds(c) for c in args]
+        return type.__call__(self, *args, **kwargs)
+        
+class GenericFunction(_Function):
+    __metaclass__ = _GenericMeta
+
+    def __init__(self, type_=None, group=True, args=(), **kwargs):
+        self.packagenames = []
+        self.oid_column = None
+        self.name = self.__class__.__name__
+        self._bind = kwargs.get('bind', None)
+        if group:
+            self.clause_expr = ClauseList(operator=operators.comma_op, group_contents=True, *args).self_group()
+        else:
+            self.clause_expr = ClauseList(operator=operators.comma_op, group_contents=True, *args)
+        self.type = sqltypes.to_instance(type_ or getattr(self, '__return_type__', None))
+        
+class AnsiFunction(GenericFunction):
+    def __init__(self, **kwargs):
+        GenericFunction.__init__(self, **kwargs)
+
+        
+class coalesce(GenericFunction):
+    def __init__(self, *args, **kwargs):
+        kwargs.setdefault('type_', _type_from_args(args))
+        GenericFunction.__init__(self, args=args, **kwargs)
+
+class concat(GenericFunction):
+    __return_type__ = sqltypes.String
+    def __init__(self, *args, **kwargs):
+        GenericFunction.__init__(self, args=args, **kwargs)
+
+class char_length(GenericFunction):
+    __return_type__ = sqltypes.Integer
+
+    def __init__(self, arg, **kwargs):
+        GenericFunction.__init__(self, args=[arg], **kwargs)
+        
+class current_date(AnsiFunction):
+    __return_type__ = sqltypes.Date
+        
+class current_time(AnsiFunction):
+    __return_type__ = sqltypes.Time
+
+class current_timestamp(AnsiFunction):
+    __return_type__ = sqltypes.DateTime
+
+class current_user(AnsiFunction):
+    __return_type__ = sqltypes.String
+
+class localtime(AnsiFunction):
+    __return_type__ = sqltypes.DateTime
+
+class localtimestamp(AnsiFunction):
+    __return_type__ = sqltypes.DateTime
+
+class session_user(AnsiFunction):
+    __return_type__ = sqltypes.String
+
+class user(AnsiFunction):
+    __return_type__ = sqltypes.String
+
+def _type_from_args(args):
+    for a in args:
+        if not isinstance(a.type, sqltypes.NullType):
+            return a.type
+    else:
+        return sqltypes.NullType
\ No newline at end of file