[RFC v2 2/7] libxl: add Function class to IDL

[Nick Rosbrook <rosbrookn@gmail.com>]

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,
and return type. The CtxFunction class extends this by indicating that a
libxl_ctx is a required parmeter.

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@ainfosec.com>
---
 tools/golang/xenlight/gengotypes.py |  2 +-
 tools/libs/light/gentypes.py        |  2 +-
 tools/libs/light/idl.py             | 36 ++++++++++++++++++++++++++++-
 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/tools/golang/xenlight/gengotypes.py b/tools/golang/xenlight/gengotypes.py
index 3e40c3d5dc..484e121746 100644
--- a/tools/golang/xenlight/gengotypes.py
+++ b/tools/golang/xenlight/gengotypes.py
@@ -725,7 +725,7 @@ 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/libs/light/gentypes.py b/tools/libs/light/gentypes.py
index 37de0f68b3..f9957b79a2 100644
--- a/tools/libs/light/gentypes.py
+++ b/tools/libs/light/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/libs/light/idl.py b/tools/libs/light/idl.py
index d7367503b4..20278c272a 100644
--- a/tools/libs/light/idl.py
+++ b/tools/libs/light/idl.py
@@ -347,6 +347,35 @@ 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.
+    """
+    def __init__(self, name=None, params=None, return_type=None, namespace=None):
+
+        if namespace is None:
+            self.namespace = _get_default_namespace()
+        else:
+            self.namespace = namespace
+
+        self.name = self.namespace + name
+        self.rawname = name
+        self.params = params
+        self.return_type = return_type
+
+class CtxFunction(Function):
+    """ A function that requires a libxl_ctx. """
+    def __init__(self, name=None, params=None, return_type=None):
+        ctx = Builtin("ctx", passby=PASS_BY_REFERENCE)
+        params.insert(0, ("ctx", ctx))
+
+        Function.__init__(self, name, params, return_type)
+
 def parse(f):
     print("Parsing %s" % f, file=sys.stderr)
 
@@ -358,6 +387,10 @@ 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 +403,9 @@ 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