giscanner: support nullable return types too

Promote the 'nullable' field to the TypeContainer base class (which is
shared by Return and Parameter types).

Add .gir support for nullability on return values, both in the writer
and in the (scanner's) parser.

https://bugzilla.gnome.org/show_bug.cgi?id=660879

3 files changed, 9 insertions, 6 deletions

diff --git a/giscanner/ast.py b/giscanner/ast.py
index 12304eb7..a9537e8d 100644
--- a/giscanner/ast.py
+++ b/giscanner/ast.py
@@ -760,9 +760,10 @@ class Alias(Node):
 class TypeContainer(Annotated):
     """A fundamental base class for Return and Parameter."""
 
-    def __init__(self, typenode, transfer):
+    def __init__(self, typenode, nullable, transfer):
         Annotated.__init__(self)
         self.type = typenode
+        self.nullable = nullable
         if transfer is not None:
             self.transfer = transfer
         elif typenode.is_const:
@@ -778,10 +779,9 @@ class Parameter(TypeContainer):
                  transfer=None, nullable=False, optional=False,
                  allow_none=False, scope=None,
                  caller_allocates=False):
-        TypeContainer.__init__(self, typenode, transfer)
+        TypeContainer.__init__(self, typenode, nullable, transfer)
         self.argname = argname
         self.direction = direction
-        self.nullable = nullable
         self.optional = optional
 
         if allow_none:
@@ -799,8 +799,8 @@ class Parameter(TypeContainer):
 class Return(TypeContainer):
     """A return value from a function."""
 
-    def __init__(self, rtype, transfer=None):
-        TypeContainer.__init__(self, rtype, transfer)
+    def __init__(self, rtype, nullable=False, transfer=None):
+        TypeContainer.__init__(self, rtype, nullable, transfer)
         self.direction = PARAM_DIRECTION_OUT
 
 
diff --git a/giscanner/girparser.py b/giscanner/girparser.py
index b1583998..40bc49e0 100644
--- a/giscanner/girparser.py
+++ b/giscanner/girparser.py
@@ -294,7 +294,8 @@ class GIRParser(object):
         if not returnnode:
             raise ValueError('node %r has no return-value' % (name, ))
         transfer = returnnode.attrib.get('transfer-ownership')
-        retval = ast.Return(self._parse_type(returnnode), transfer)
+        nullable = returnnode.attrib.get('nullable') == '1'
+        retval = ast.Return(self._parse_type(returnnode), nullable, transfer)
         self._parse_generic_attribs(returnnode, retval)
         parameters = []
 
diff --git a/giscanner/girwriter.py b/giscanner/girwriter.py
index 49545e62..3bea2a1c 100644
--- a/giscanner/girwriter.py
+++ b/giscanner/girwriter.py
@@ -215,6 +215,8 @@ class GIRWriter(XMLWriter):
             attrs.append(('transfer-ownership', return_.transfer))
         if return_.skip:
             attrs.append(('skip', '1'))
+        if return_.nullable:
+            attrs.append(('nullable', '1'))
         with self.tagcontext('return-value', attrs):
             self._write_generic(return_)
             self._write_type(return_.type, parent=parent)