Add downcasting

newbinding/binding.py

@@ -28,10 +28,10 @@ class Namespace(object):
     def __str__(self):
         return self.name
 
-class Type(object):
+class _Type(object):
     pass
 
-class BuiltinTypes(Type):
+class BuiltinTypes(_Type):
     def __init__(self, name):
         self.name = name
 
@@ -47,7 +47,7 @@ Unsigned = BuiltinTypes('unsigned')
 Bool = BuiltinTypes('bool')
 ConstStdString = BuiltinTypes('const std::string')
 
-class Class(Type):
+class Class(_Type):
     format = 'O'
 
     def __init__(self, ns, *bases):
@@ -57,9 +57,11 @@ class Class(Type):
         self.methods = []
         self.enums = []
         self.includes = set()
+        self.downcastables = set()
 
     def __call__(self, defn):
         assert not self._is_defined
+        # process the definition in "defn"
         self.name = defn.__name__
         for k, v in defn.__dict__.items():
             if isinstance(v, Method):
@@ -79,6 +81,12 @@ class Class(Type):
                 else:
                     for i in v:
                         self.includes.add(i)
+            elif k == '_downcast_':
+                if isinstance(v, Class):
+                    self.downcastables.add(v)
+                else:
+                    for i in v:
+                        self.downcastables.add(i)
         return self
 
     def compile_cpp(self, writer):
@@ -106,12 +114,11 @@ class Class(Type):
             bases = ', '.join(x.name for x in self.bases)
         writer.println('@capsule.register_class')
         with writer.block('class %(clsname)s(%(bases)s):' % locals()):
+            writer.println('_llvm_type_ = "%s"' % self.fullname)
             for enum in self.enums:
                 enum.compile_py(writer)
             for meth in self.methods:
                 meth.compile_py(writer)
-            if not self.enums and not self.methods:
-                writer.println('pass')
         writer.println()
 
     @property
@@ -178,6 +185,7 @@ class Enum(object):
 
     def compile_py(self, writer):
         with writer.block('class %s:' % self.name):
+            writer.println('_llvm_type_ = "%s"' % self.fullname)
             for v in self.value_names:
                 writer.println('%(v)s = "%(v)s"' % locals())
         writer.println()
@@ -340,7 +348,7 @@ class Constructor(StaticMethod):
         ret = writer.declare(retty.fullname, stmt)
         return ret
 
-class ref(Type):
+class ref(_Type):
     def __init__(self, element):
         assert isinstance(element, Class), type(element)
         self.element = element
@@ -369,7 +377,7 @@ class ref(Type):
         return writer.declare(self.fullname, '*%s' % p)
 
 
-class ptr(Type):
+class ptr(_Type):
     def __init__(self, element):
         assert isinstance(element, Class)
         self.element = element
@@ -393,7 +401,7 @@ class ptr(Type):
         return writer.pycapsule_new(val, self.element.capsule_name,
                                     self.element.fullname)
 
-class cast(Type):
+class cast(_Type):
     format = 'O'
 
     def __init__(self, original, target):
@@ -406,14 +414,14 @@ class cast(Type):
 
     @property
     def python_type(self):
-        if not isinstance(self.target, Type):
+        if not isinstance(self.target, _Type):
             return self.target
         else:
             return self.original
 
     @property
     def binding_type(self):
-        if isinstance(self.target, Type):
+        if isinstance(self.target, _Type):
             return self.target
         else:
             return self.original

newbinding/capsule.py

@@ -19,7 +19,7 @@ def set_debug(enabled):
 
 
 class WeakRef(ref):
-    __slots__ = 'capsule', 'dtor'
+    __slots__ = 'capsule', 'dtor', 'owning'
 
 _pyclasses = {}
 _addr2obj = WeakValueDictionary()
@@ -33,12 +33,20 @@ def classof(cap):
     return _pyclasses[cls]
 
 def _capsule_destructor(weak):
-    cap = weak.capsule
-    addr = _capsule.getPointer(cap)
-    cls = _capsule.getClassName(cap)
-    logger.debug("destroy pointer 0x%08X to %s", addr, cls)
-    weak.dtor(cap)
-    del _owners[addr]
+    if weak.owning:
+        cap = weak.capsule
+        addr = _capsule.getPointer(cap)
+        cls = _capsule.getClassName(cap)
+        logger.debug("destroy pointer 0x%08X to %s", addr, cls)
+        weak.dtor(cap)
+        del _owners[addr]
+
+def release_ownership(old):
+    addr = _capsule.getPointer(old)
+    if hasattr(old, '_delete_'):
+        oldweak = _owners[addr]
+        oldweak.owning = False # dis-own
+        del _owners[addr]
 
 def wrap(cap):
     '''Wrap a PyCapsule with the corresponding Wrapper class.
@@ -60,13 +68,26 @@ def wrap(cap):
             weak = WeakRef(obj, _capsule_destructor)
             _owners[addr] = weak
             weak.capsule = cap
+            weak.owning = True
             weak.dtor = cls._delete_
     else:
-        assert classof(obj._ptr) is classof(cap)
-        # Unset destructor for capsules that are repeated
-        _capsule.setDestructor(cap, None)
+        oldcls = classof(obj._ptr)
+        newcls = classof(cap)
+        if issubclass(oldcls, newcls):
+            # do auto downcast
+            pass
+        else:
+            assert oldcls is newcls
     return obj
 
+def downcast(old, new):
+    assert old is not new
+    oldcls = classof(old)
+    newcls = classof(new)
+    assert issubclass(newcls, oldcls)
+    release_ownership(old)
+    del _addr2obj[_capsule.getPointer(old)] # clear cache
+    return wrap(new)
 
 def unwrap(obj):
     '''Unwrap a Wrapper instance into the underlying PyCapsule.
@@ -96,8 +117,3 @@ class Wrapper(object):
     def _ptr(self):
         return self.__ptr
 
-    def _release_ownership(self):
-        _capsule.setDestructor(self._ptr, None)
-
-
-

newbinding/extra.py

@@ -3,8 +3,13 @@ Wrapped the extra functions in _api.so
 '''
 
 import capsule
+import _api
+#
+# Re-export the native API from the _api.extra and wrap the functions
+#
 
 def _wrapper(func):
+    "Wrap the re-exported functions"
     def _core(*args):
         unwrapped = map(capsule.unwrap, args)
         ret = func(*unwrapped)
@@ -12,9 +17,27 @@ def _wrapper(func):
     return _core
 
 def _init(glob):
-    from _api import extra
-    for k, v in extra.__dict__.items():
+    for k, v in _api.extra.__dict__.items():
         glob[k] = _wrapper(v)
 
 _init(globals())
 
+#
+# Downcasts
+#
+
+def downcast(obj, cls):
+    if type(obj) is cls:
+        return obj
+    fromty = obj._llvm_type_
+    toty = cls._llvm_type_
+    fname = 'downcast_%s_to_%s' % (fromty, toty)
+    fname = fname.replace('::', '_')
+    try:
+        caster = getattr(_api, fname)
+    except AttributeError:
+        fmt = "Downcast from %s to %s is not supported"
+        raise TypeError(fmt % (fromty, toty))
+    old = capsule.unwrap(obj)
+    new = caster(old)
+    return capsule.downcast(old, new)

newbinding/gen.py

@@ -72,6 +72,20 @@ def main():
             print cls
             units.append(cls)
 
+    # add extra stuffs
+    downcastlist = []
+    ## add downcast
+    for cls in units:
+        if isinstance(cls, Class):
+            for bcls in cls.downcastables:
+                from_to = bcls.fullname, cls.fullname
+                name = 'downcast_%s_to_%s' % tuple(map(codegen.mangle, from_to))
+                fn = Function(namespaces[''], name, ptr(cls), ptr(bcls))
+                downcastlist.append((from_to, fn))
+                units.append(fn)
+
+
+    # generate cpp source
     with open('%s.cpp' % outputfilename, 'w') as cppfile:
         println = wrap_println_from_file(cppfile)
 
@@ -87,6 +101,18 @@ def main():
             println('#include "%s"' % inc)
         println()
 
+        # generate downcast
+        for ((fromty, toty), fn) in downcastlist:
+            name = fn.name
+            fmt = '''
+static
+%(toty)s* %(name)s(%(fromty)s* arg)
+{
+    return typecast<%(toty)s>::from(arg);
+}
+'''
+            println(fmt % locals())
+
         # write methods and method tables
         for u in units:
             writer = codegen.CppCodeWriter(println)

newbinding/include/llvm_binding/extra.h

@@ -37,9 +37,9 @@ PyObject* make_small_vector_from_types(PyObject* self, PyObject* args) {
 }
 
 static PyMethodDef extra_methodtable[] = {
-#define method(func) { #func, (PyCFunction)func, METH_VARARGS, NULL }
-method( make_raw_ostream_for_printing ),
-method( make_small_vector_from_types ),
-{ NULL }
-#undef method
+    #define method(func) { #func, (PyCFunction)func, METH_VARARGS, NULL }
+    method( make_raw_ostream_for_printing ),
+    method( make_small_vector_from_types ),
+    #undef method
+    { NULL }
 };

newbinding/src/namespace.py

@@ -1,3 +1,4 @@
 from binding import *
 
 llvm = Namespace('llvm')
+default = Namespace('')