bindings: Manually adding some python bindings

The following features are supported:
- Run basic scenarios using python.
- Iterate over FIB/PIT/CS(nfd) entries

There is a chance that there are memory leaks in the implementation, due
to extensive hacking.

Refs: #2341
diff --git a/bindings/ns3_ptr.py b/bindings/ns3_ptr.py
new file mode 100644
index 0000000..b23cbaa
--- /dev/null
+++ b/bindings/ns3_ptr.py
@@ -0,0 +1,304 @@
+
+from pybindgen.typehandlers.base import Parameter, ReturnValue, \
+    join_ctype_and_name, CodeGenerationError, \
+    param_type_matcher, return_type_matcher, CodegenErrorBase, \
+    DeclarationsScope, CodeBlock, NotSupportedError, ForwardWrapperBase, ReverseWrapperBase, \
+    TypeConfigurationError
+
+from pybindgen.cppclass import ReferenceCountingMethodsPolicy, CppClass, CppClassParameterBase, CppClassReturnValueBase, common_shared_object_return
+
+class Ns3PtrMemoryPolicy(ReferenceCountingMethodsPolicy):
+    def __init__(self, class_name):
+        """
+        Create a memory policy for using ns3::Ptr<> to manage instances of this object.
+
+        :param class_name: the full name of the class, e.g. foo::Bar
+        """
+        super(Ns3PtrMemoryPolicy, self).__init__('Ref', 'Unref', 'GetReferenceCount')
+
+        self.class_name = class_name
+        self.pointer_template = 'ns3::Ptr< %s >'
+
+    def get_pointer_name(self, class_name):
+        return self.pointer_template % (class_name,)
+
+    def get_delete_code(self, cpp_class):
+        return "self->obj.~Ptr< %s >();" % (cpp_class.full_name,)
+
+    def get_pointer_type(self, class_full_name):
+        return self.get_pointer_name(class_full_name) + ' '
+
+    def get_pointer_to_void_name(self, object_name):
+        return "::ns3::PeekPointer(%s)" % object_name
+
+    def get_instance_creation_function(self):
+        return ns3_ptr_instance_creation_function
+
+    def get_pystruct_init_code(self, cpp_class, obj):
+        return "new(&%s->obj) %s;" % (obj, self.get_pointer_name(cpp_class.full_name),)
+
+    def register_ptr_parameter_and_return(self, cls, name):
+        class ThisClassNs3PtrParameter(CppClassNs3PtrParameter):
+            """Register this C++ class as pass-by-pointer parameter"""
+            CTYPES = []
+            cpp_class = cls
+        cls.ThisClassNs3PtrParameter = ThisClassNs3PtrParameter
+        try:
+            param_type_matcher.register(self.get_pointer_name(cls.full_name), cls.ThisClassNs3PtrParameter)
+        except ValueError:
+            pass
+
+        class ThisClassNs3PtrReturn(CppClassNs3PtrReturnValue):
+            """Register this C++ class as pointer return"""
+            CTYPES = []
+            cpp_class = cls
+        cls.ThisClassNs3PtrReturn = ThisClassNs3PtrReturn
+        try:
+            return_type_matcher.register(self.get_pointer_name(cls.full_name), cls.ThisClassNs3PtrReturn)
+        except ValueError:
+            pass
+
+    def register_ptr_alias_parameter_and_return(self, cls, alias):
+        alias_ptr = '::ns3::Ptr< %s >' % alias
+        cls.ThisClassNs3PtrParameter.CTYPES.append(alias_ptr)
+        try:
+            param_type_matcher.register(alias_ptr, cls.ThisClassNs3PtrParameter)
+        except ValueError: pass
+
+        cls.ThisClassNs3PtrReturn.CTYPES.append(alias_ptr)
+        try:
+            return_type_matcher.register(alias_ptr, cls.ThisClassNs3PtrReturn)
+        except ValueError: pass
+
+def ns3_ptr_instance_creation_function(cpp_class, code_block, lvalue,
+                                       parameters, construct_type_name):
+    """
+    ns3::Ptr "instance creation function"; it is called whenever a new
+    C++ class instance needs to be created
+
+    :param cpp_class: the CppClass object whose instance is to be created
+    :param code_block: CodeBlock object on which the instance creation code should be generated
+    :param lvalue: lvalue expression that should hold the result in the end
+    :param parameters: stringified list of parameters
+    :param construct_type_name: actual name of type to be constructed (it is
+                          not always the class name, sometimes it's
+                          the python helper class)
+    """
+    assert lvalue
+    assert not lvalue.startswith('None')
+    if cpp_class.incomplete_type:
+        raise CodeGenerationError("%s cannot be constructed (incomplete type)"
+                                  % cpp_class.full_name)
+    code_block.write_code(
+        "%s = ::ns3::Create<%s>(%s);" % (lvalue, construct_type_name, parameters))
+
+class CppClassNs3PtrParameter(CppClassParameterBase):
+    "Class* handlers"
+    CTYPES = []
+    cpp_class = None #cppclass.CppClass('dummy') # CppClass instance
+    DIRECTIONS = [Parameter.DIRECTION_IN,
+                  Parameter.DIRECTION_OUT,
+                  Parameter.DIRECTION_INOUT]
+    SUPPORTS_TRANSFORMATIONS = False
+
+    def __init__(self, ctype, name, direction=Parameter.DIRECTION_IN, is_const=False,
+                 null_ok=False, default_value=None):
+        super(CppClassNs3PtrParameter, self).__init__(
+            ctype, name, direction, is_const, default_value)
+        self.null_ok = null_ok
+
+
+    def convert_python_to_c(self, wrapper):
+        "parses python args to get C++ value"
+        assert isinstance(wrapper, ForwardWrapperBase)
+        assert isinstance(self.cpp_class, CppClass)
+
+        self.py_name = wrapper.declarations.declare_variable(
+            self.cpp_class.pystruct+'*', self.name,
+            initializer=(self.default_value and 'NULL' or None))
+
+        value_ptr = wrapper.declarations.declare_variable(
+            self.cpp_class.memory_policy.get_pointer_name(self.cpp_class.full_name), "%s_ptr" % self.name)
+
+        if self.null_ok:
+            num = wrapper.parse_params.add_parameter('O', ['&'+self.py_name], self.name, optional=bool(self.default_value))
+
+            wrapper.before_call.write_error_check(
+
+                "%s && ((PyObject *) %s != Py_None) && !PyObject_IsInstance((PyObject *) %s, (PyObject *) &%s)"
+                % (self.py_name, self.py_name, self.py_name, self.cpp_class.pytypestruct),
+
+                'PyErr_SetString(PyExc_TypeError, "Parameter %i must be of type %s");' % (num, self.cpp_class.name))
+
+            wrapper.before_call.write_code("if (%(PYNAME)s) {\n"
+                                           "    if ((PyObject *) %(PYNAME)s == Py_None)\n"
+                                           "        %(VALUE)s = NULL;\n"
+                                           "    else\n"
+                                           "        %(VALUE)s = %(PYNAME)s->obj;\n"
+                                           "} else {\n"
+                                           "    %(VALUE)s = NULL;\n"
+                                           "}" % dict(PYNAME=self.py_name, VALUE=value_ptr))
+
+        else:
+
+            wrapper.parse_params.add_parameter(
+                'O!', ['&'+self.cpp_class.pytypestruct, '&'+self.py_name], self.name, optional=bool(self.default_value))
+            wrapper.before_call.write_code("if (%s) { %s = %s->obj; }" % (self.py_name, value_ptr, self.py_name))
+
+        wrapper.call_params.append(value_ptr)
+
+
+
+    def convert_c_to_python(self, wrapper):
+        """foo"""
+
+        ## Value transformations
+        value = self.transformation.untransform(
+            self, wrapper.declarations, wrapper.after_call, self.value)
+
+        ## declare wrapper variable
+        py_name = wrapper.declarations.declare_variable(
+            self.cpp_class.pystruct+'*', 'py_'+self.cpp_class.name)
+        self.py_name = py_name
+
+        def write_create_new_wrapper():
+            """Code path that creates a new wrapper for the parameter"""
+
+            ## Find out what Python wrapper to use, in case
+            ## automatic_type_narrowing is active and we are not forced to
+            ## make a copy of the object
+            if self.cpp_class.automatic_type_narrowing:
+
+                typeid_map_name = self.cpp_class.get_type_narrowing_root().typeid_map_name
+                wrapper_type = wrapper.declarations.declare_variable(
+                    'PyTypeObject*', 'wrapper_type', '0')
+                wrapper.before_call.write_code(
+                    '%s = %s.lookup_wrapper(typeid(*%s), &%s);'
+                    % (wrapper_type, typeid_map_name, value, self.cpp_class.memory_policy.get_pointer_to_void_name(self.cpp_class.pytypestruct)))
+            else:
+                wrapper_type = '&'+self.cpp_class.pytypestruct
+
+            ## Create the Python wrapper object
+            self.cpp_class.write_allocate_pystruct(wrapper.before_call, py_name, wrapper_type)
+            self.py_name = py_name
+
+            wrapper.before_call.write_code("%s->flags = PYBINDGEN_WRAPPER_FLAG_NONE;" % py_name)
+
+            ## Assign the C++ value to the Python wrapper
+            wrapper.before_call.write_code("%s->obj = %s;" % (py_name, value))
+
+        if self.cpp_class.helper_class is None:
+            try:
+                self.cpp_class.wrapper_registry.write_lookup_wrapper(
+                    wrapper.before_call, self.cpp_class.pystruct, py_name, value)
+            except NotSupportedError:
+                write_create_new_wrapper()
+                self.cpp_class.wrapper_registry.write_register_new_wrapper(wrapper.before_call, py_name,
+                                                                           "%s->obj" % py_name)
+            else:
+                wrapper.before_call.write_code("if (%s == NULL)\n{" % py_name)
+                wrapper.before_call.indent()
+                write_create_new_wrapper()
+                self.cpp_class.wrapper_registry.write_register_new_wrapper(wrapper.before_call, py_name,
+                                                                           "%s->obj" % py_name)
+                wrapper.before_call.unindent()
+                wrapper.before_call.write_code('}')
+            wrapper.build_params.add_parameter("N", [py_name])
+        else:
+            wrapper.before_call.write_code("if (typeid(*(%s)).name() == typeid(%s).name())\n{"
+                                          % (value, self.cpp_class.helper_class.name))
+            wrapper.before_call.indent()
+
+            if self.type_traits.target_is_const:
+                wrapper.before_call.write_code(
+                    "%s = (%s*) (((%s*) ((%s*) %s))->m_pyself);"
+                    % (py_name, self.cpp_class.pystruct,
+                       self.cpp_class.helper_class.name, self.cpp_class.full_name, value))
+                wrapper.before_call.write_code("%s->obj =  (%s*) (%s);" %
+                                               (py_name, self.cpp_class.full_name, value))
+            else:
+                wrapper.before_call.write_code(
+                    "%s = (%s*) (((%s*) %s)->m_pyself);"
+                    % (py_name, self.cpp_class.pystruct,
+                       self.cpp_class.helper_class.name, value))
+                wrapper.before_call.write_code("%s->obj = %s;" % (py_name, value))
+            wrapper.before_call.write_code("Py_INCREF(%s);" % py_name)
+            wrapper.before_call.unindent()
+            wrapper.before_call.write_code("} else {")
+            wrapper.before_call.indent()
+
+            try:
+                self.cpp_class.wrapper_registry.write_lookup_wrapper(
+                    wrapper.before_call, self.cpp_class.pystruct, py_name, value)
+            except NotSupportedError:
+                write_create_new_wrapper()
+                self.cpp_class.wrapper_registry.write_register_new_wrapper(
+                    wrapper.before_call, py_name, "%s->obj" % py_name)
+            else:
+                wrapper.before_call.write_code("if (%s == NULL)\n{" % py_name)
+                wrapper.before_call.indent()
+                write_create_new_wrapper()
+                self.cpp_class.wrapper_registry.write_register_new_wrapper(wrapper.before_call, py_name,
+                                                                           "%s->obj" % py_name)
+                wrapper.before_call.unindent()
+                wrapper.before_call.write_code('}') # closes if (%s == NULL)
+
+            wrapper.before_call.unindent()
+            wrapper.before_call.write_code("}") # closes if (typeid(*(%s)) == typeid(%s))\n{
+            wrapper.build_params.add_parameter("N", [py_name])
+
+
+
+
+class CppClassNs3PtrReturnValue(CppClassReturnValueBase):
+    "Class* return handler"
+    CTYPES = []
+    SUPPORTS_TRANSFORMATIONS = True
+    cpp_class = None #cppclass.CppClass('dummy') # CppClass instance
+
+    def __init__(self, ctype, is_const=False):
+        super(CppClassNs3PtrReturnValue, self).__init__(ctype, is_const=is_const)
+
+    def get_c_error_return(self): # only used in reverse wrappers
+        """See ReturnValue.get_c_error_return"""
+        return "return NULL;"
+
+    def convert_c_to_python(self, wrapper):
+        """See ReturnValue.convert_c_to_python"""
+
+        ## Value transformations
+        value = self.transformation.untransform(
+            self, wrapper.declarations, wrapper.after_call, self.value)
+
+        # if value is NULL, return None
+        wrapper.after_call.write_code("if (!(%s)) {\n"
+                                      "    Py_INCREF(Py_None);\n"
+                                      "    return Py_None;\n"
+                                      "}" % value)
+
+        ## declare wrapper variable
+        py_name = wrapper.declarations.declare_variable(
+            self.cpp_class.pystruct+'*', 'py_'+self.cpp_class.name)
+        self.py_name = py_name
+
+        common_shared_object_return(value, py_name, self.cpp_class, wrapper.after_call,
+                                    self.type_traits, caller_owns_return=True,
+                                    reference_existing_object=False,
+                                    type_is_pointer=True)
+
+        # return the value
+        wrapper.build_params.add_parameter("N", [py_name], prepend=True)
+
+
+    def convert_python_to_c(self, wrapper):
+        """See ReturnValue.convert_python_to_c"""
+        name = wrapper.declarations.declare_variable(
+            self.cpp_class.pystruct+'*', "tmp_%s" % self.cpp_class.name)
+        wrapper.parse_params.add_parameter(
+            'O!', ['&'+self.cpp_class.pytypestruct, '&'+name])
+
+        value = self.transformation.transform(
+            self, wrapper.declarations, wrapper.after_call, "%s->obj" % name)
+
+        # caller gets a shared pointer
+        wrapper.after_call.write_code("%s = %s;" % (self.value, value))