[gnome-builder/wip/chergert/multi-process: 3/7] pygobject: add Builder.py overrides

[Christian Hergert <chergert src gnome org>]

commit e150bc23eadc8d0fad7856c512f20542d4b7f0fd
Author: Christian Hergert <chergert redhat com>
Date:   Mon Oct 19 21:12:22 2015 -0700

    pygobject: add Builder.py overrides
    
    This allows us to create a GDBus-based service without all of the pain
    of multiple dbus implementations in process (python-dbus and GDBus). It
    only supports methods currently, and is based on a proposal from Martin
    Pitt which can be found on
    
      https://bugzilla.gnome.org/show_bug.cgi?id=656330
    
    This can be used by worker processes to communicate with the parent
    Builder process over a soon to be added private bus.

 build/Makefile.am |    1 +
 configure.ac      |    5 ++
 src/Builder.py    |  154 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/Makefile.am   |    5 ++
 4 files changed, 165 insertions(+), 0 deletions(-)
---
diff --git a/build/Makefile.am b/build/Makefile.am
index c44cfa2..5b499e8 100644
--- a/build/Makefile.am
+++ b/build/Makefile.am
@@ -8,6 +8,7 @@ GITIGNOREFILES = \
        install-sh \
        ltmain.sh \
        missing \
+       py-compile \
        test-driver \
        $(NULL)
 
diff --git a/configure.ac b/configure.ac
index b72c2aa..011ec58 100644
--- a/configure.ac
+++ b/configure.ac
@@ -258,7 +258,9 @@ dnl Check for Required Python
 dnl ***********************************************************************
 enable_python_scripting=no
 AS_IF([test "x$have_pygobject" = "xyes"],[
+       AM_PATH_PYTHON([3.2.3])
        AC_PATH_TOOL(PYTHON3_CONFIG, "python3-config")
+
        AS_IF([test -z "${PYTHON3_CONFIG}"],[
                AC_MSG_RESULT([Failed to locate python3-config.])
        ],[
@@ -267,6 +269,9 @@ AS_IF([test "x$have_pygobject" = "xyes"],[
                LIBIDE_LDFLAGS="${LIBIDE_LDFLAGS} `${PYTHON3_CONFIG} --ldflags`"
                enable_python_scripting=yes
        ])
+
+       pyoverridesdir="\$(pyexecdir)/gi/overrides"
+       AC_SUBST(pyoverridesdir)
 ])
 
 
diff --git a/src/Builder.py b/src/Builder.py
new file mode 100644
index 0000000..a6784ef
--- /dev/null
+++ b/src/Builder.py
@@ -0,0 +1,154 @@
+#!/usr/bin/env python3
+
+#
+# Builder.py
+#
+# Copyright (C) 2015 Christian Hergert <christian hergert me>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+
+from gi.repository import GLib
+from gi.repository import GObject
+from gi.repository import Gio
+import inspect
+
+from ..importer import modules
+
+Builder = modules['Builder']._introspection_module
+__all__ = []
+
+#
+# The following GDBus wrapper is based upon code by Martin Pitt from
+# https://bugzilla.gnome.org/show_bug.cgi?id=656330
+# demo D-Bus server using GDBus
+# (C) 2010 Martin Pitt <martin piware de>
+#
+
+class _Gio_DBusMethodInfo:
+    interface = None
+    in_args = None
+    out_signature = None
+
+def DBusMethod(dbus_interface, in_signature=None, out_signature=None):
+    def decorator(func):
+        func._dbus_method = _Gio_DBusMethodInfo()
+        func._dbus_method.interface = dbus_interface
+        #func._dbus_method.out_signature = '(' + (out_signature or '') + ')'
+        func._dbus_method.out_signature = out_signature or ''
+
+        func._dbus_method.in_args = []
+        in_signature_list = GLib.Variant.split_signature(in_signature)
+        arg_names = inspect.getargspec(func).args
+        arg_names.pop(0) # eat "self" argument
+        if len(in_signature) != len(arg_names):
+            raise TypeError('specified signature %s for method %s does not match length of arguments' % 
(str(in_signature_list), func.func_name))
+        for pair in zip(in_signature_list, arg_names):
+            func._dbus_method.in_args.append(pair)
+        return func
+    return decorator
+
+class DBusService:
+    class _DBusInfo:
+        object_path = None
+        connection = None
+        reg_id = None
+        methods = None # interface -> method_name -> info_map
+                       # info_map keys: method_name, in_signature, out_signature
+
+    def __init__(self, object_path=None):
+        self.__dbus_info = self.__class__._DBusInfo()
+        self.__dbus_info.object_path = object_path
+    
+        # set up the vtable maps, for more efficient lookups at runtime
+        self.__dbus_info.methods = {}
+        for id in dir(self):
+            attr = getattr(self, id)
+            if hasattr(attr, '_dbus_method'):
+                self.__dbus_info.methods.setdefault(attr._dbus_method.interface, {})[id] = {
+                    'in_args': attr._dbus_method.in_args,
+                    'out_signature': attr._dbus_method.out_signature,
+                }
+
+    def export(self, connection, object_path=None):
+        """
+        @connection: A Gio.DBusConnection
+        @object_path: an optional path to register at
+
+        Exports the service onto the Gio.DBusConnection provided.
+ 
+        If @object_path is None, then the object path registered during object
+        creation will be used.
+        """
+        self.__dbus_info.connection = connection
+        node_info = Gio.DBusNodeInfo.new_for_xml(self.__dbus_introspection_xml())
+        for interface in self.__dbus_info.methods:
+            self.__dbus_info.reg_id = connection.register_object(
+                    object_path or self.__dbus_info.object_path,
+                    node_info.lookup_interface(interface),
+                    self.__dbus_method_call,
+                    self.__dbus_get_property,
+                    self.__dbus_set_property)
+
+    def unexport(self):
+        """
+        Unregisters a previous registration to a connection using
+        export_object().
+        """
+        self.connection.unregister_object(self.__dbus_info.reg_id)
+        self.__dbus_info.reg_id = None
+        self.__dbus_info.connection = None
+
+    def __dbus_introspection_xml(self):
+        '''Generate introspection XML'''
+        parts = ['<node>']
+        for interface in self.__dbus_info.methods:
+            parts.append('  <interface name="%s">' % interface)
+            for method, data in self.__dbus_info.methods[interface].items():
+                parts.append('    <method name="%s">' % method)
+                for (sig, name) in data['in_args']:
+                    parts.append('      <arg type="%s" name="%s" direction="in"/>' % (sig, name))
+                parts.append('      <arg type="%s" name="return" direction="out"/>' % data['out_signature'])
+                parts.append('    </method>')
+            parts.append('  </interface>')
+        parts.append('</node>')
+        return '\n'.join(parts)
+
+    def __dbus_method_call(self, conn, sender, object_path, iface_name, method_name, parameters, invocation):
+        try:
+            info = self.__dbus_info.methods[iface_name][method_name]
+        except KeyError:
+            invocation.return_error_literal(Gio.dbus_error_quark(), 
+                                            Gio.DBusError.UNKNOWN_METHOD,
+                                            'No such interface or method: %s.%s' % (iface_name, method_name))
+            return
+
+        try:
+            ret = getattr(self, method_name)(*parameters.unpack())
+            invocation.return_value(GLib.Variant('(' + info['out_signature'] + ')', (ret,)))
+        except Exception as e:
+            invocation.return_error_literal(Gio.dbus_error_quark(), 
+                                            Gio.DBusError.IO_ERROR,
+                                            'Method %s.%s failed with: %s' % (iface_name, method_name, 
str(e)))
+
+    def __dbus_get_property(self, conn, sender, object_path, iface_name, prop_name, error):
+        error = GLib.Error.new_literal(GLib.io_channel_error_quark(), 1, 'Not implemented yet')
+        return None
+
+    def __dbus_set_property(self, conn, sender, object_path, iface_name, prop_name, value, error):
+        error = GLib.Error.new_literal(GLib.io_channel_error_quark(), 1, 'Not implemented yet')
+        return False
+
+Builder.DBusService = DBusService
+Builder.DBusMethod = DBusMethod
diff --git a/src/Makefile.am b/src/Makefile.am
index c3bb3d5..4e90e31 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -8,6 +8,11 @@ bin_PROGRAMS = gnome-builder
 pkglibdir = $(libdir)/gnome-builder
 pkglib_LTLIBRARIES = libgnome-builder.la
 
+if ENABLE_PYTHON_SCRIPTING
+overridesdir = $(pyoverridesdir)
+overrides_PYTHON = Builder.py
+endif
+
 # XXX: Keep in sync with gnome-builder.h
 libgnome_builder_public_sources = \
        gnome-builder.h \