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[perl-Glib-Object-Introspection] Be more selective when installing object vfunc wrappers

commit ce8edf2718cfad1b615bcde07ee8d3c2c661e541
Author: Torsten SchÃnfeld <kaffeetisch gmx de>
Date:   Fri Oct 14 19:10:57 2011 +0200

    Be more selective when installing object vfunc wrappers
    
    * Only install fallback Perl vfuncs when there is an implementation somewhere
      in the ancestry.
    
    * Only set vfunc class struct fields when we can see a Perl implementation at
      INIT time.

 GObjectIntrospection.xs          |  121 +++++++++++++++++++++++++++++---------
 gperl-i11n-vfunc-object.c        |   18 +++++-
 lib/Glib/Object/Introspection.pm |   48 +++++++++++----
 t/vfunc-implementation.t         |   12 +++-
 4 files changed, 156 insertions(+), 43 deletions(-)
---
diff --git a/GObjectIntrospection.xs b/GObjectIntrospection.xs
index 03b83ea..5eac4ad 100644
--- a/GObjectIntrospection.xs
+++ b/GObjectIntrospection.xs
@@ -217,7 +217,7 @@ static void generic_interface_init (gpointer iface, gpointer data);
 static void generic_interface_finalize (gpointer iface, gpointer data);
 
 /* object vfuncs */
-static void generic_class_init (GIObjectInfo *info, gpointer class);
+static void generic_class_init (GIObjectInfo *info, const gchar *target_package, gpointer class);
 
 /* misc. */
 #define ccroak(...) call_carp_croak (form (__VA_ARGS__));
@@ -535,10 +535,11 @@ _install_overrides (class, basename, object_name, target_package)
     PREINIT:
 	GIRepository *repository;
 	GIObjectInfo *info;
-	GType gtype, object_gtype;
+	GType gtype;
 	gpointer klass;
-    PPCODE:
-	dwarn ("_install_overrides: %s.%s for %s\n", basename, object_name, target_package);
+    CODE:
+	dwarn ("_install_overrides: %s.%s for %s\n",
+	       basename, object_name, target_package);
 	repository = g_irepository_get_default ();
 	info = g_irepository_find_by_name (repository, basename, object_name);
 	if (!GI_IS_OBJECT_INFO (info))
@@ -551,13 +552,31 @@ _install_overrides (class, basename, object_name, target_package)
 	if (!klass)
 		ccroak ("internal problem: can't peek at type class for %s (%d)",
 		        g_type_name (gtype), gtype);
-	generic_class_init (info, klass);
-	/* find all non-Perl parents up to and including the object type */
+	generic_class_init (info, target_package, klass);
+	g_base_info_unref (info);
+
+void
+_find_non_perl_parents (class, basename, object_name, target_package)
+	const gchar *basename
+	const gchar *object_name
+	const gchar *target_package
+    PREINIT:
+	GIRepository *repository;
+	GIObjectInfo *info;
+	GType gtype, object_gtype;
+	GQuark reg_quark = g_quark_from_static_string ("__gperl_type_reg");
+    PPCODE:
+	repository = g_irepository_get_default ();
+	info = g_irepository_find_by_name (repository, basename, object_name);
+	g_assert (info && GI_IS_OBJECT_INFO (info));
+	gtype = gperl_object_type_from_package (target_package);
 	object_gtype = g_registered_type_info_get_g_type (info);
+	/* find all non-Perl parents up to and including the object type */
 	while ((gtype = g_type_parent (gtype))) {
 		/* FIXME: we should export gperl_type_reg_quark from Glib */
-		if (!g_type_get_qdata (gtype, g_quark_from_static_string ("__gperl_type_reg"))) {
-			XPUSHs (sv_2mortal (newSVpv (gperl_object_package_from_type (gtype), PL_na)));
+		if (!g_type_get_qdata (gtype, reg_quark)) {
+			const gchar *package = gperl_object_package_from_type (gtype);
+			XPUSHs (sv_2mortal (newSVpv (package, PL_na)));
 		}
 		if (gtype == object_gtype) {
 			break;
@@ -566,9 +585,59 @@ _install_overrides (class, basename, object_name, target_package)
 	g_base_info_unref (info);
 
 void
-_invoke_fallback_vfunc (class, basename, object_name, vfunc_name, target_package, ...)
+_find_vfuncs_with_implementation (class, object_package, target_package)
+	const gchar *object_package
+	const gchar *target_package
+    PREINIT:
+	GIRepository *repository;
+	GType object_gtype, target_gtype;
+	gpointer object_klass, target_klass;
+	GIObjectInfo *object_info;
+	GIStructInfo *struct_info;
+	gint n_vfuncs, i;
+    PPCODE:
+	repository = g_irepository_get_default ();
+	target_gtype = gperl_object_type_from_package (target_package);
+	object_gtype = gperl_object_type_from_package (object_package);
+	g_assert (target_gtype && object_gtype);
+	target_klass = g_type_class_peek (target_gtype);
+	object_klass = g_type_class_peek (object_gtype);
+	g_assert (target_klass && object_klass);
+	object_info = g_irepository_find_by_gtype (repository, object_gtype);
+	g_assert (object_info && GI_IS_OBJECT_INFO (object_info));
+	struct_info = g_object_info_get_class_struct (object_info);
+	g_assert (struct_info);
+	n_vfuncs = g_object_info_get_n_vfuncs (object_info);
+	for (i = 0; i < n_vfuncs; i++) {
+		GIVFuncInfo *vfunc_info;
+		const gchar *vfunc_name;
+		GIFieldInfo *field_info;
+		gint field_offset;
+		gchar *perl_method_name;
+		vfunc_info = g_object_info_get_vfunc (object_info, i);
+		vfunc_name = g_base_info_get_name (vfunc_info);
+		/* FIXME: g_vfunc_info_get_offset does not seem to work here. */
+		field_info = get_field_info (struct_info, vfunc_name);
+		g_assert (field_info);
+		field_offset = g_field_info_get_offset (field_info);
+		perl_method_name = g_ascii_strup (vfunc_name, -1);
+		if (G_STRUCT_MEMBER (gpointer, target_klass, field_offset)) {
+			AV *av = newAV ();
+			av_push (av, newSVpv (vfunc_name, PL_na));
+			av_push (av, newSVpv (perl_method_name, PL_na));
+			XPUSHs (sv_2mortal (newRV_noinc ((SV *) av)));
+		}
+		g_free (perl_method_name);
+		g_base_info_unref (field_info);
+		g_base_info_unref (vfunc_info);
+	}
+	g_base_info_unref (struct_info);
+	g_base_info_unref (object_info);
+
+void
+_invoke_fallback_vfunc (class, basename, vfunc_package, vfunc_name, target_package, ...)
 	const gchar *basename
-	const gchar *object_name
+	const gchar *vfunc_package
 	const gchar *vfunc_name
 	const gchar *target_package
     PREINIT:
@@ -583,16 +652,15 @@ _invoke_fallback_vfunc (class, basename, object_name, vfunc_name, target_package
 	gint field_offset;
 	gpointer func_pointer;
     PPCODE:
-	dwarn ("_invoke_parent_vfunc: %s\n", vfunc_name);
-	repository = g_irepository_get_default ();
-	info = g_irepository_find_by_name (repository, basename, object_name);
-	g_assert (info);
+	dwarn ("_invoke_parent_vfunc: %s.%s, target = %s\n",
+	       vfunc_package, vfunc_name, target_package);
 	gtype = gperl_object_type_from_package (target_package);
-	dwarn ("  target: %s\n", target_package);
 	klass = g_type_class_peek (gtype);
-	if (!klass)
-		ccroak ("internal problem: can't peek at type class for %s (%d)",
-		        g_type_name (gtype), gtype);
+	g_assert (klass);
+	repository = g_irepository_get_default ();
+	info = g_irepository_find_by_gtype (
+		repository, gperl_object_type_from_package (vfunc_package));
+	g_assert (info && GI_IS_OBJECT_INFO (info));
 	struct_info = g_object_info_get_class_struct (info);
 	g_assert (struct_info);
 	vfunc_info = g_object_info_find_vfunc (info, vfunc_name);
@@ -602,15 +670,14 @@ _invoke_fallback_vfunc (class, basename, object_name, vfunc_name, target_package
 	g_assert (field_info);
 	field_offset = g_field_info_get_offset (field_info);
 	func_pointer = G_STRUCT_MEMBER (gpointer, klass, field_offset);
-	if (func_pointer) {
-		invoke_callable (vfunc_info, func_pointer,
-		                 sp, ax, mark, items,
-		                 internal_stack_offset);
-		/* SPAGAIN since invoke_callable probably modified the stack
-		 * pointer.  so we need to make sure that our local variable
-		 * 'sp' is correct before the implicit PUTBACK happens. */
-		SPAGAIN;
-	}
+	g_assert (func_pointer);
+	invoke_callable (vfunc_info, func_pointer,
+	                 sp, ax, mark, items,
+	                 internal_stack_offset);
+	/* SPAGAIN since invoke_callable probably modified the stack
+	 * pointer.  so we need to make sure that our local variable
+	 * 'sp' is correct before the implicit PUTBACK happens. */
+	SPAGAIN;
 	g_base_info_unref (field_info);
 	g_base_info_unref (vfunc_info);
 	g_base_info_unref (info);
diff --git a/gperl-i11n-vfunc-object.c b/gperl-i11n-vfunc-object.c
index 46ad0ef..f7355ad 100644
--- a/gperl-i11n-vfunc-object.c
+++ b/gperl-i11n-vfunc-object.c
@@ -1,7 +1,7 @@
 /* -*- mode: c; indent-tabs-mode: t; c-basic-offset: 8; -*- */
 
 static void
-generic_class_init (GIObjectInfo *info, gpointer class)
+generic_class_init (GIObjectInfo *info, const gchar *target_package, gpointer class)
 {
 	GIStructInfo *struct_info;
 	gint n, i;
@@ -19,13 +19,27 @@ generic_class_init (GIObjectInfo *info, gpointer class)
 		vfunc_info = g_object_info_get_vfunc (info, i);
 		vfunc_name = g_base_info_get_name (vfunc_info);
 
+		perl_method_name = g_ascii_strup (vfunc_name, -1);
+		{
+			/* If there is no implementation of this vfunc at INIT
+			 * time, we assume that the intention is to provide no
+			 * implementation and we thus skip setting up the class
+			 * struct member. */
+			HV * stash = gv_stashpv (target_package, 0);
+			GV * slot = gv_fetchmethod (stash, perl_method_name);
+			if (!slot) {
+				g_base_info_unref (vfunc_info);
+				g_free (perl_method_name);
+				continue;
+			}
+		}
+
 		/* FIXME: g_vfunc_info_get_offset does not seem to work here. */
 		field_info = get_field_info (struct_info, vfunc_name);
 		g_assert (field_info);
 		field_offset = g_field_info_get_offset (field_info);
 		field_type_info = g_field_info_get_type (field_info);
 
-		perl_method_name = g_ascii_strup (vfunc_name, -1);
 		callback_info = create_perl_callback_closure_for_named_sub (
 		                  field_type_info, perl_method_name);
 		dwarn ("installing vfunc %s as %s at offset %d (vs. %d) inside %p\n",
diff --git a/lib/Glib/Object/Introspection.pm b/lib/Glib/Object/Introspection.pm
index d74b395..208a06e 100644
--- a/lib/Glib/Object/Introspection.pm
+++ b/lib/Glib/Object/Introspection.pm
@@ -28,6 +28,10 @@ $Carp::Internal{(__PACKAGE__)}++;
 require XSLoader;
 XSLoader::load(__PACKAGE__, $VERSION);
 
+my %FORBIDDEN_SUB_NAMES = map { $_ => 1 } qw/AUTOLOAD CLONE DESTROY BEGIN
+                                             UNITCHECK CHECK INIT END/;
+my @_OBJECT_PACKAGES_WITH_VFUNCS = ();
+
 sub _create_invoker_sub {
   my ($basename, $namespace, $name,
       $shift_package_name, $flatten_array_ref_return,
@@ -143,39 +147,59 @@ sub setup {
     };
   }
 
-  my %forbidden_sub_names = map { $_ => 1 } qw/AUTOLOAD CLONE DESTROY
-                                               BEGIN UNITCHECK CHECK INIT END/;
-
   foreach my $object_name (keys %{$objects_with_vfuncs}) {
     my $object_package = $package . '::' . $object_name;
     my $installer_name = $object_package . '::_INSTALL_OVERRIDES';
     *{$installer_name} = sub {
       my ($target_package) = @_;
+
+      # For each vfunc in our ancestry that has an implementation, add a
+      # wrapper sub to our immediate parent.
       my @non_perl_parent_packages =
-        __PACKAGE__->_install_overrides($basename, $object_name,
-                                        $target_package);
+        __PACKAGE__->_find_non_perl_parents($basename, $object_name,
+                                            $target_package);
+      my $first_parent = $non_perl_parent_packages[0];
       foreach my $parent_package (@non_perl_parent_packages) {
+        my @vfuncs = __PACKAGE__->_find_vfuncs_with_implementation(
+                       $parent_package, $first_parent);
         VFUNC:
-        foreach my $vfunc_names (@{$objects_with_vfuncs->{$object_name}}) {
-          my $vfunc_name = $vfunc_names->[0];
-          my $perl_vfunc_name = $vfunc_names->[1];
-          if (exists $forbidden_sub_names{$perl_vfunc_name}) {
+        foreach my $vfunc_names (@vfuncs) {
+          my ($vfunc_name, $perl_vfunc_name) = @{$vfunc_names};
+          if (exists $FORBIDDEN_SUB_NAMES{$perl_vfunc_name}) {
             $perl_vfunc_name .= '_VFUNC';
           }
-          my $full_perl_vfunc_name = $parent_package . '::' . $perl_vfunc_name;
+          my $full_perl_vfunc_name =
+            $first_parent . '::' . $perl_vfunc_name;
           if (defined &{$full_perl_vfunc_name}) {
             next VFUNC;
           }
           *{$full_perl_vfunc_name} = sub {
-            __PACKAGE__->_invoke_fallback_vfunc($basename, $object_name, $vfunc_name,
-                                                $parent_package, @_);
+            __PACKAGE__->_invoke_fallback_vfunc($basename,
+                                                $parent_package,
+                                                $vfunc_name,
+                                                $first_parent,
+                                                @_);
           }
         }
       }
+
+      # Delay hooking up the vfuncs until INIT so that we can see whether the
+      # package defines the relevant subs or not.
+      push @_OBJECT_PACKAGES_WITH_VFUNCS,
+           [$basename, $object_name, $target_package];
     };
   }
 }
 
+sub INIT {
+  no strict qw(refs);
+  foreach my $target (@_OBJECT_PACKAGES_WITH_VFUNCS) {
+    my ($basename, $object_name, $target_package) = @{$target};
+    __PACKAGE__->_install_overrides($basename, $object_name, $target_package);
+  }
+  @_OBJECT_PACKAGES_WITH_VFUNCS = ();
+}
+
 package Glib::Object::Introspection::_FuncWrapper;
 
 use overload
diff --git a/t/vfunc-implementation.t b/t/vfunc-implementation.t
index 17618e7..94de845 100644
--- a/t/vfunc-implementation.t
+++ b/t/vfunc-implementation.t
@@ -5,7 +5,7 @@ BEGIN { require './t/inc/setup.pl' };
 use strict;
 use warnings;
 
-plan tests => 35;
+plan tests => 31;
 
 {
   package GoodImplementation;
@@ -109,6 +109,8 @@ plan tests => 35;
   is ($foo->get ('int'), 23);
 }
 
+=for segfault
+
 {
   package NoImplementation;
   use Glib::Object::Subclass 'GI::Object';
@@ -121,6 +123,10 @@ plan tests => 35;
   like ($@, qr/method_int8_in/);
 }
 
+=cut
+
+=for supported?
+
 {
   package BadChaininig;
   use Glib::Object::Subclass 'GI::Object';
@@ -136,5 +142,7 @@ plan tests => 35;
   my $foo = BadChaininig->new;
   local $@;
   eval { $foo->method_int8_in (23) };
-  like ($@, qr/method_int8_in/);
+  like ($@, qr/method_int8_in/i);
 }
+
+=cut
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