[RFC PATCH 1/2] libxl: add Function class to IDL

[Nick Rosbrook <rosbrookn@xxxxxxxxx>]

Add a Function and CtxFunction classes to idl.py to allow generator
scripts to generate wrappers which are repetitive and straight forward
when doing so by hand. Examples of such functions are the
device_add/remove functions.

To start, a Function has attributes for namespace, name, parameters,
return type, and an indication if the return value should be interpreted as
a status code. The CtxFunction class extends this by indicating that a
libxl_ctx is a required parmeter, and can optionally be an async
function.

Also, add logic to idl.parse to return the list of functions found in an
IDL file. For now, have users of idl.py -- i.e. libxl/gentypes.py and
golang/xenlight/gengotypes.py -- ignore the list of functions returned.

Signed-off-by: Nick Rosbrook <rosbrookn@xxxxxxxxxxxx>
---
 tools/golang/xenlight/gengotypes.py |  2 +-
 tools/libxl/gentypes.py             |  2 +-
 tools/libxl/idl.py                  | 46 ++++++++++++++++++++++++++++-
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/tools/golang/xenlight/gengotypes.py 
b/tools/golang/xenlight/gengotypes.py
index 557fecd07b..bd3663c9ea 100644
--- a/tools/golang/xenlight/gengotypes.py
+++ b/tools/golang/xenlight/gengotypes.py
@@ -718,7 +718,7 @@ def xenlight_golang_fmt_name(name, exported = True):
 if __name__ == '__main__':
     idlname = sys.argv[1]
 
-    (builtins, types) = idl.parse(idlname)
+    (builtins, types, _) = idl.parse(idlname)
 
     for b in builtins:
         name = b.typename
diff --git a/tools/libxl/gentypes.py b/tools/libxl/gentypes.py
index 9a45e45acc..ac7306f3f7 100644
--- a/tools/libxl/gentypes.py
+++ b/tools/libxl/gentypes.py
@@ -592,7 +592,7 @@ if __name__ == '__main__':
 
     (_, idlname, header, header_private, header_json, impl) = sys.argv
 
-    (builtins,types) = idl.parse(idlname)
+    (builtins,types,_) = idl.parse(idlname)
 
     print("outputting libxl type definitions to %s" % header)
 
diff --git a/tools/libxl/idl.py b/tools/libxl/idl.py
index d7367503b4..1839871f86 100644
--- a/tools/libxl/idl.py
+++ b/tools/libxl/idl.py
@@ -347,6 +347,45 @@ class OrderedDict(dict):
     def ordered_items(self):
         return [(x,self[x]) for x in self.__ordered]
 
+class Function(object):
+    """
+    A general description of a function signature.
+
+    Attributes:
+      name (str): name of the function, excluding namespace.
+      params (list of (str,Type)): list of function parameters.
+      return_type (Type): the Type (if any), returned by the function.
+      return_is_status (bool): Indicates that the return value should be
+                               interpreted as an error/status code.
+    """
+    def __init__(self, name=None, params=None, return_type=None,
+                 return_is_status=False, namespace=None):
+
+        if namespace is None:
+            self.namespace = _get_default_namespace()
+        else:
+            self.namespace = namespace
+
+        self.name = self.namespace + name
+        self.params = params
+        self.return_type = return_type
+        self.return_is_status = return_is_status
+
+class CtxFunction(Function):
+    """
+    A function that requires a libxl_ctx.
+
+    Attributes:
+      is_asyncop (bool): indicates that the function accepts a
+                         libxl_asyncop_how parameter.
+    """
+    def __init__(self, name=None, params=None, return_type=None,
+                 return_is_status=False, is_asyncop=False):
+
+        self.is_asyncop = is_asyncop
+
+        Function.__init__(self, name, params, return_type, return_is_status)
+
 def parse(f):
     print("Parsing %s" % f, file=sys.stderr)
 
@@ -358,6 +397,10 @@ def parse(f):
             globs[n] = t
         elif isinstance(t,type(object)) and issubclass(t, Type):
             globs[n] = t
+        elif isinstance(t, Function):
+            globs[n] = t
+        elif isinstance(t,type(object)) and issubclass(t, Function):
+            globs[n] = t
         elif n in ['PASS_BY_REFERENCE', 'PASS_BY_VALUE',
                    'DIR_NONE', 'DIR_IN', 'DIR_OUT', 'DIR_BOTH',
                    'namespace', 'hidden']:
@@ -370,8 +413,9 @@ def parse(f):
                           % (e.lineno, f, e.text))
 
     types = [t for t in locs.ordered_values() if isinstance(t,Type)]
+    funcs = [f for f in locs.ordered_values() if isinstance(f,Function)]
 
     builtins = [t for t in types if isinstance(t,Builtin)]
     types = [t for t in types if not isinstance(t,Builtin)]
 
-    return (builtins,types)
+    return (builtins,types,funcs)
-- 
2.17.1