Add support for py3k's keyword only arguments

PEP 3102

4 files changed, 31 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index d53599d5..fee4fe2b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,8 @@ Change log for the astroid package (used to be astng)
     * Added the test_utils module for building ASTs and
       extracting deeply nested nodes for easier testing.
 
+    * Add support for py3k's keyword only arguments (PEP 3102)
+
     * rename the project as astroid
 
 2013-04-16  --  0.24.3
diff --git a/node_classes.py b/node_classes.py
index 8c6ad8aa..97bd9079 100644
--- a/node_classes.py
+++ b/node_classes.py
@@ -253,9 +253,11 @@ class Name(LookupMixIn, NodeNG):
 
 class Arguments(NodeNG, AssignTypeMixin):
     """class representing an Arguments node"""
-    _astroid_fields = ('args', 'defaults')
+    _astroid_fields = ('args', 'defaults', 'kwonlyargs', 'kw_defaults')
     args = None
     defaults = None
+    kwonlyargs = None
+    kw_defaults = None
 
     def __init__(self, vararg=None, kwarg=None):
         self.vararg = vararg
@@ -275,6 +277,10 @@ class Arguments(NodeNG, AssignTypeMixin):
             result.append('*%s' % self.vararg)
         if self.kwarg:
             result.append('**%s' % self.kwarg)
+        if self.kwonlyargs:
+            if not self.vararg:
+                result.append('*')
+            result.append(_format_args(self.kwonlyargs, self.kw_defaults))
         return ', '.join(result)
 
     def default_value(self, argname):
@@ -287,6 +293,9 @@ class Arguments(NodeNG, AssignTypeMixin):
             idx = i - (len(self.args) - len(self.defaults))
             if idx >= 0:
                 return self.defaults[idx]
+        i = _find_arg(argname, self.kwonlyargs)[0]
+        if i is not None and self.kw_defaults[i] is not None:
+            return self.kw_defaults[i]
         raise NoDefault()
 
     def is_argument(self, name):
@@ -303,6 +312,12 @@ class Arguments(NodeNG, AssignTypeMixin):
             return _find_arg(argname, self.args, rec)
         return None, None
 
+    def get_children(self):
+        """override get_children to skip over None elements in kw_defaults"""
+        for child in super(Arguments, self).get_children():
+            if child is not None:
+                yield child
+
 
 def _find_arg(argname, args, rec=False):
     for i, arg in enumerate(args):
@@ -328,7 +343,8 @@ def _format_args(args, defaults=None):
         else:
             values.append(arg.name)
             if defaults is not None and i >= default_offset:
-                values[-1] += '=' + defaults[i-default_offset].as_string()
+                if defaults[i-default_offset] is not None:
+                    values[-1] += '=' + defaults[i-default_offset].as_string()
     return ', '.join(values)
 
 
diff --git a/rebuilder.py b/rebuilder.py
index e06adeaf..cf92da09 100644
--- a/rebuilder.py
+++ b/rebuilder.py
@@ -185,6 +185,8 @@ class TreeRebuilder(object):
         newnode.args = [self.visit(child, newnode) for child in node.args]
         self.asscontext = None
         newnode.defaults = [self.visit(child, newnode) for child in node.defaults]
+        newnode.kwonlyargs = []
+        newnode.kw_defaults = []
         newnode.vararg = node.vararg
         newnode.kwarg = node.kwarg
         # save argument names in locals:
@@ -836,6 +838,14 @@ class TreeRebuilder3k(TreeRebuilder):
         # XXX or we should instead introduce a Arg node in astroid ?
         return self.visit_assname(node, parent, node.arg)
 
+    def visit_arguments(self, node, parent):
+        newnode = super(TreeRebuilder3k, self).visit_arguments(node, parent)
+        self.asscontext = "Ass"
+        newnode.kwonlyargs = [self.visit(child, newnode) for child in node.kwonlyargs]
+        self.asscontext = None
+        newnode.kw_defaults = [self.visit(child, newnode) if child else None for child in node.kw_defaults]
+        return newnode
+
     def visit_excepthandler(self, node, parent):
         """visit an ExceptHandler node by returning a fresh instance of it"""
         newnode = new.ExceptHandler()
diff --git a/scoped_nodes.py b/scoped_nodes.py
index dabaf0c7..3886b7e1 100644
--- a/scoped_nodes.py
+++ b/scoped_nodes.py
@@ -506,7 +506,7 @@ class Lambda(LocalsDictNodeNG, FilterStmtsMixin):
         return self.body.infer(context)
 
     def scope_lookup(self, node, name, offset=0):
-        if node in self.args.defaults:
+        if node in self.args.defaults or node in self.args.kw_defaults:
             frame = self.parent.frame()
             # line offset to avoid that def func(f=func) resolve the default
             # value to the defined function