Turn oracle BINARY_DOUBLE, BINARY_FLOAT, DOUBLE_PRECISION into floats

The Oracle BINARY_FLOAT and BINARY_DOUBLE datatypes now participate within
cx_Oracle.setinputsizes(), passing along NATIVE_FLOAT, so as to support the
NaN value.  Additionally, :class:`.oracle.BINARY_FLOAT`,
:class:`.oracle.BINARY_DOUBLE` and :class:`.oracle.DOUBLE_PRECISION` now
subclass :class:`.Float`, since these are floating point datatypes, not
decimal.  These datatypes were already defaulting the
:paramref:`.Float.asdecimal` flag to False in line with what
:class:`.Float` already does.

Added reflection capabilities for the :class:`.oracle.BINARY_FLOAT`,
:class:`.oracle.BINARY_DOUBLE` datatypes.

Change-Id: Id99b912e83052654a17d07dc92b4dcb958cb7600
Fixes: #4264

1 files changed, 29 insertions, 1 deletions

diff --git a/lib/sqlalchemy/sql/type_api.py b/lib/sqlalchemy/sql/type_api.py
index 1d1d6e089..6a323683b 100644
--- a/lib/sqlalchemy/sql/type_api.py
+++ b/lib/sqlalchemy/sql/type_api.py
@@ -445,6 +445,20 @@ class TypeEngine(Visitable):
         except KeyError:
             return self._dialect_info(dialect)['impl']
 
+    def _unwrapped_dialect_impl(self, dialect):
+        """Return the 'unwrapped' dialect impl for this type.
+
+        For a type that applies wrapping logic (e.g. TypeDecorator), give
+        us the real, actual dialect-level type that is used.
+
+        This is used by TypeDecorator itself as well at least one case where
+        dialects need to check that a particular specific dialect-level
+        type is in use, within the :meth:`.DefaultDialect.set_input_sizes`
+        method.
+
+        """
+        return self.dialect_impl(dialect)
+
     def _cached_literal_processor(self, dialect):
         """Return a dialect-specific literal processor for this type."""
         try:
@@ -922,7 +936,7 @@ class TypeDecorator(SchemaEventTarget, TypeEngine):
         # otherwise adapt the impl type, link
         # to a copy of this TypeDecorator and return
         # that.
-        typedesc = self.load_dialect_impl(dialect).dialect_impl(dialect)
+        typedesc = self._unwrapped_dialect_impl(dialect)
         tt = self.copy()
         if not isinstance(tt, self.__class__):
             raise AssertionError('Type object %s does not properly '
@@ -989,6 +1003,20 @@ class TypeDecorator(SchemaEventTarget, TypeEngine):
         """
         return self.impl
 
+    def _unwrapped_dialect_impl(self, dialect):
+        """Return the 'unwrapped' dialect impl for this type.
+
+        For a type that applies wrapping logic (e.g. TypeDecorator), give
+        us the real, actual dialect-level type that is used.
+
+        This is used by TypeDecorator itself as well at least one case where
+        dialects need to check that a particular specific dialect-level
+        type is in use, within the :meth:`.DefaultDialect.set_input_sizes`
+        method.
+
+        """
+        return self.load_dialect_impl(dialect).dialect_impl(dialect)
+
     def __getattr__(self, key):
         """Proxy all other undefined accessors to the underlying
         implementation."""