[gnome-builder/wip/gtk4-port] libie/io: add cached list model

[Christian Hergert <chergert src gnome org>]

commit 4a389c46128ff995e09c0da0adc0495f6d2d629a
Author: Christian Hergert <chergert redhat com>
Date:   Sat Jul 9 16:43:02 2022 -0700

    libie/io: add cached list model
    
    The goal is to use this in places where we want to be sure dynamic objects
    are held when things like GtkMapListModel will not keep the objects alive.

 src/libide/io/ide-cached-list-model.c | 302 ++++++++++++++++++++++++++++++++++
 src/libide/io/ide-cached-list-model.h |  40 +++++
 src/libide/io/libide-io.h             |   1 +
 src/libide/io/meson.build             |   2 +
 4 files changed, 345 insertions(+)
---
diff --git a/src/libide/io/ide-cached-list-model.c b/src/libide/io/ide-cached-list-model.c
new file mode 100644
index 000000000..fe17d3cd2
--- /dev/null
+++ b/src/libide/io/ide-cached-list-model.c
@@ -0,0 +1,302 @@
+/* ide-cached-list-model.c
+ *
+ * Copyright 2022 Christian Hergert <chergert redhat com>
+ *
+ * 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/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#define G_LOG_DOMAIN "ide-cached-list-model"
+
+#include "config.h"
+
+#include "ide-cached-list-model.h"
+
+struct _IdeCachedListModel
+{
+  GObject     parent_instance;
+  GSequence  *items;
+  GListModel *model;
+  gulong      items_changed_handler;
+};
+
+enum {
+  PROP_0,
+  PROP_MODEL,
+  N_PROPS
+};
+
+static GType
+ide_cached_list_model_get_item_type (GListModel *model)
+{
+  IdeCachedListModel *self = IDE_CACHED_LIST_MODEL (model);
+
+  if (self->model == NULL)
+    return G_TYPE_OBJECT;
+
+  return g_list_model_get_item_type (self->model);
+}
+
+static guint
+ide_cached_list_model_get_n_items (GListModel *model)
+{
+  IdeCachedListModel *self = IDE_CACHED_LIST_MODEL (model);
+
+  if (self->model == NULL)
+    return 0;
+
+  return g_list_model_get_n_items (self->model);
+}
+
+static gpointer
+ide_cached_list_model_get_item (GListModel *model,
+                                guint       position)
+{
+  IdeCachedListModel *self = IDE_CACHED_LIST_MODEL (model);
+  GSequenceIter *iter;
+  gpointer item;
+
+  if (self->model == NULL)
+    return NULL;
+
+  iter = g_sequence_get_iter_at_pos (self->items, position);
+  if (g_sequence_iter_is_end (iter))
+    return NULL;
+
+  if (!(item = g_sequence_get (iter)))
+    {
+      item = g_list_model_get_item (self->model, position);
+      g_sequence_set (iter, item);
+    }
+
+  return g_object_ref (item);
+}
+
+static void
+list_model_iface_init (GListModelInterface *iface)
+{
+  iface->get_item_type = ide_cached_list_model_get_item_type;
+  iface->get_n_items = ide_cached_list_model_get_n_items;
+  iface->get_item = ide_cached_list_model_get_item;
+}
+
+G_DEFINE_FINAL_TYPE_WITH_CODE (IdeCachedListModel, ide_cached_list_model, G_TYPE_OBJECT,
+                               G_IMPLEMENT_INTERFACE (G_TYPE_LIST_MODEL, list_model_iface_init))
+
+static GParamSpec *properties [N_PROPS];
+
+static void
+_g_object_xunref (gpointer data)
+{
+  if (data)
+    g_object_unref (data);
+}
+
+static void
+ide_cached_list_model_dispose (GObject *object)
+{
+  IdeCachedListModel *self = (IdeCachedListModel *)object;
+
+  ide_cached_list_model_set_model (self, NULL);
+
+  g_assert (self->model == NULL);
+  g_assert (self->items == NULL);
+  g_assert (self->items_changed_handler == 0);
+
+  G_OBJECT_CLASS (ide_cached_list_model_parent_class)->dispose (object);
+}
+
+static void
+ide_cached_list_model_get_property (GObject    *object,
+                                    guint       prop_id,
+                                    GValue     *value,
+                                    GParamSpec *pspec)
+{
+  IdeCachedListModel *self = IDE_CACHED_LIST_MODEL (object);
+
+  switch (prop_id)
+    {
+    case PROP_MODEL:
+      g_value_set_object (value, ide_cached_list_model_get_model (self));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+ide_cached_list_model_set_property (GObject      *object,
+                                    guint         prop_id,
+                                    const GValue *value,
+                                    GParamSpec   *pspec)
+{
+  IdeCachedListModel *self = IDE_CACHED_LIST_MODEL (object);
+
+  switch (prop_id)
+    {
+    case PROP_MODEL:
+      ide_cached_list_model_set_model (self, g_value_get_object (value));
+      break;
+
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
+    }
+}
+
+static void
+ide_cached_list_model_class_init (IdeCachedListModelClass *klass)
+{
+  GObjectClass *object_class = G_OBJECT_CLASS (klass);
+
+  object_class->dispose = ide_cached_list_model_dispose;
+  object_class->get_property = ide_cached_list_model_get_property;
+  object_class->set_property = ide_cached_list_model_set_property;
+
+  properties [PROP_MODEL] =
+    g_param_spec_object ("model", NULL, NULL,
+                         G_TYPE_LIST_MODEL,
+                         (G_PARAM_READWRITE | G_PARAM_EXPLICIT_NOTIFY | G_PARAM_STATIC_STRINGS));
+
+  g_object_class_install_properties (object_class, N_PROPS, properties);
+}
+
+static void
+ide_cached_list_model_init (IdeCachedListModel *self)
+{
+}
+
+/**
+ * ide_cached_list_model_get_model:
+ * @self: a #IdeCachedListModel
+ *
+ * Gets the underlying model.
+ *
+ * Returns: (transfer none) (nullable): a #GListModel or %NULL
+ */
+GListModel *
+ide_cached_list_model_get_model (IdeCachedListModel *self)
+{
+  g_return_val_if_fail (IDE_IS_CACHED_LIST_MODEL (self), NULL);
+
+  return self->model;
+}
+
+static void
+ide_cached_list_model_items_changed_cb (IdeCachedListModel *self,
+                                        guint               position,
+                                        guint               removed,
+                                        guint               added,
+                                        GListModel         *model)
+{
+  GSequenceIter *iter;
+
+  g_assert (IDE_IS_CACHED_LIST_MODEL (self));
+  g_assert (G_IS_LIST_MODEL (model));
+  g_assert (self->items != NULL);
+
+  iter = g_sequence_get_iter_at_pos (self->items, position);
+
+  if (removed > 0)
+    {
+      GSequenceIter *end;
+
+      if (removed == 1)
+        end = iter;
+      else
+        end = g_sequence_iter_prev (g_sequence_get_iter_at_pos (self->items, position+removed));
+
+      g_sequence_remove_range (iter, end);
+
+      iter = g_sequence_get_iter_at_pos (self->items, position);
+    }
+
+  for (guint i = 0; i < added; i++)
+    g_sequence_insert_before (iter, NULL);
+
+  g_list_model_items_changed (G_LIST_MODEL (self), position, removed, added);
+}
+
+void
+ide_cached_list_model_set_model (IdeCachedListModel *self,
+                                 GListModel         *model)
+{
+  g_autoptr(GSequence) old_items = NULL;
+  guint removed = 0;
+  guint added = 0;
+
+  g_return_if_fail (IDE_IS_CACHED_LIST_MODEL (self));
+  g_return_if_fail (!model || G_IS_LIST_MODEL (model));
+
+  if (self->model == model)
+    return;
+
+  if (self->model != NULL)
+    {
+      removed = g_list_model_get_n_items (self->model);
+      g_clear_signal_handler (&self->items_changed_handler, self->model);
+      old_items = g_steal_pointer (&self->items);
+    }
+
+  if (model != NULL)
+    {
+      GSequenceIter *end;
+
+      added = g_list_model_get_n_items (model);
+      self->items_changed_handler =
+        g_signal_connect_object (model,
+                                 "items-changed",
+                                 G_CALLBACK (ide_cached_list_model_items_changed_cb),
+                                 self,
+                                 G_CONNECT_SWAPPED);
+
+      self->items = g_sequence_new (_g_object_xunref);
+      end = g_sequence_get_end_iter (self->items);
+      for (guint i = 0; i < added; i++)
+        g_sequence_insert_before (end, NULL);
+    }
+
+  g_set_object (&self->model, model);
+
+  if (removed || added)
+    g_list_model_items_changed (G_LIST_MODEL (self), 0, removed, added);
+
+  g_object_notify_by_pspec (G_OBJECT (self), properties[PROP_MODEL]);
+}
+
+/**
+ * ide_cached_list_model_new:
+ * @model: (nullable) (transfer full): a #GListModel or %NULL
+ *
+ * Creates a new list model that caches the items.
+ *
+ * This might be useful if have a GtkMapListModel which would otherwise discard your
+ * mapped items.
+ *
+ * Returns: (transfer full): an #IdeCachedListModel
+ */
+IdeCachedListModel *
+ide_cached_list_model_new (GListModel *model)
+{
+  IdeCachedListModel *ret;
+
+  g_return_val_if_fail (!model || G_IS_LIST_MODEL (model), NULL);
+
+  ret = g_object_new (IDE_TYPE_CACHED_LIST_MODEL,
+                      "model", model,
+                      NULL);
+  g_clear_object (&model);
+  return ret;
+}
diff --git a/src/libide/io/ide-cached-list-model.h b/src/libide/io/ide-cached-list-model.h
new file mode 100644
index 000000000..1d7ee6b68
--- /dev/null
+++ b/src/libide/io/ide-cached-list-model.h
@@ -0,0 +1,40 @@
+/* ide-cached-list-model.h
+ *
+ * Copyright 2022 Christian Hergert <chergert redhat com>
+ *
+ * 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/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <libide-core.h>
+
+G_BEGIN_DECLS
+
+#define IDE_TYPE_CACHED_LIST_MODEL (ide_cached_list_model_get_type())
+
+IDE_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (IdeCachedListModel, ide_cached_list_model, IDE, CACHED_LIST_MODEL, GObject)
+
+IDE_AVAILABLE_IN_ALL
+IdeCachedListModel *ide_cached_list_model_new       (GListModel         *model);
+IDE_AVAILABLE_IN_ALL
+GListModel         *ide_cached_list_model_get_model (IdeCachedListModel *self);
+IDE_AVAILABLE_IN_ALL
+void                ide_cached_list_model_set_model (IdeCachedListModel *self,
+                                                     GListModel         *model);
+
+G_END_DECLS
diff --git a/src/libide/io/libide-io.h b/src/libide/io/libide-io.h
index 4ce1a4ca0..13e7a67c1 100644
--- a/src/libide/io/libide-io.h
+++ b/src/libide/io/libide-io.h
@@ -26,6 +26,7 @@
 G_BEGIN_DECLS
 
 #define IDE_IO_INSIDE
+# include "ide-cached-list-model.h"
 # include "ide-content-type.h"
 # include "ide-directory-reaper.h"
 # include "ide-file-transfer.h"
diff --git a/src/libide/io/meson.build b/src/libide/io/meson.build
index 26ce93820..1f726cd1e 100644
--- a/src/libide/io/meson.build
+++ b/src/libide/io/meson.build
@@ -7,6 +7,7 @@ libide_include_directories += include_directories('.')
 #
 
 libide_io_public_headers = [
+  'ide-cached-list-model.h',
   'ide-content-type.h',
   'ide-directory-reaper.h',
   'ide-file-transfer.h',
@@ -37,6 +38,7 @@ install_headers(libide_io_public_headers, subdir: libide_io_header_subdir)
 #
 
 libide_io_public_sources = [
+  'ide-cached-list-model.c',
   'ide-content-type.c',
   'ide-directory-reaper.c',
   'ide-file-transfer.c',