path: root/e-util/e-tree-model-generator.c

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: t; c-basic-offset: 8 -*- */

/* e-tree-model-generator.c - Model wrapper that permutes underlying rows.
 *
 * Copyright (C) 1999-2008 Novell, Inc. (www.novell.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of version 2 of the GNU Lesser General Public
 * License as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Authors: Hans Petter Jansson <hpj@novell.com>
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <string.h>
#include <glib/gi18n-lib.h>
#include "e-tree-model-generator.h"

#define ETMG_DEBUG(x)

#define ITER_IS_VALID(tree_model_generator, iter) \
    ((iter)->stamp == (tree_model_generator)->priv->stamp)
#define ITER_GET(iter, group, index) \
    G_STMT_START { \
    *(group) = (iter)->user_data; \
    *(index) = GPOINTER_TO_INT ((iter)->user_data2); \
    } G_STMT_END

#define ITER_SET(tree_model_generator, iter, group, index) \
    G_STMT_START { \
    (iter)->stamp = (tree_model_generator)->priv->stamp; \
    (iter)->user_data = group; \
    (iter)->user_data2 = GINT_TO_POINTER (index); \
    } G_STMT_END

#define E_TREE_MODEL_GENERATOR_GET_PRIVATE(obj) \
    (G_TYPE_INSTANCE_GET_PRIVATE \
    ((obj), E_TYPE_TREE_MODEL_GENERATOR, ETreeModelGeneratorPrivate))

struct _ETreeModelGeneratorPrivate {
    GtkTreeModel *child_model;
    GArray *root_nodes;
    gint stamp;

    ETreeModelGeneratorGenerateFunc generate_func;
    gpointer generate_func_data;

    ETreeModelGeneratorModifyFunc modify_func;
    gpointer modify_func_data;
};

static void e_tree_model_generator_tree_model_init (GtkTreeModelIface *iface);

G_DEFINE_TYPE_WITH_CODE (
    ETreeModelGenerator, e_tree_model_generator, G_TYPE_OBJECT,
    G_IMPLEMENT_INTERFACE (GTK_TYPE_TREE_MODEL, e_tree_model_generator_tree_model_init))

static GtkTreeModelFlags e_tree_model_generator_get_flags       (GtkTreeModel       *tree_model);
static gint         e_tree_model_generator_get_n_columns   (GtkTreeModel       *tree_model);
static GType        e_tree_model_generator_get_column_type (GtkTreeModel       *tree_model,
                                gint                index);
static gboolean     e_tree_model_generator_get_iter        (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter,
                                GtkTreePath        *path);
static GtkTreePath *e_tree_model_generator_get_path        (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter);
static void         e_tree_model_generator_get_value       (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter,
                                gint                column,
                                GValue             *value);
static gboolean     e_tree_model_generator_iter_next       (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter);
static gboolean     e_tree_model_generator_iter_children   (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter,
                                GtkTreeIter        *parent);
static gboolean     e_tree_model_generator_iter_has_child  (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter);
static gint         e_tree_model_generator_iter_n_children (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter);
static gboolean     e_tree_model_generator_iter_nth_child  (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter,
                                GtkTreeIter        *parent,
                                gint                n);
static gboolean     e_tree_model_generator_iter_parent     (GtkTreeModel       *tree_model,
                                GtkTreeIter        *iter,
                                GtkTreeIter        *child);

static GArray *build_node_map     (ETreeModelGenerator *tree_model_generator, GtkTreeIter *parent_iter,
                   GArray *parent_group, gint parent_index);
static void    release_node_map   (GArray *group);

static void    child_row_changed  (ETreeModelGenerator *tree_model_generator, GtkTreePath *path, GtkTreeIter *iter);
static void    child_row_inserted (ETreeModelGenerator *tree_model_generator, GtkTreePath *path, GtkTreeIter *iter);
static void    child_row_deleted  (ETreeModelGenerator *tree_model_generator, GtkTreePath *path);

typedef struct {
    GArray *parent_group;
    gint    parent_index;

    gint    n_generated;
    GArray *child_nodes;
}
Node;

enum {
    PROP_0,
    PROP_CHILD_MODEL
};

/* ------------------ *
 * Class/object setup *
 * ------------------ */

static void
tree_model_generator_set_property (GObject *object,
                                   guint prop_id,
                                   const GValue *value,
                                   GParamSpec *pspec)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (object);

    switch (prop_id)
    {
        case PROP_CHILD_MODEL:
            tree_model_generator->priv->child_model = g_value_get_object (value);
            g_object_ref (tree_model_generator->priv->child_model);

            if (tree_model_generator->priv->root_nodes)
                release_node_map (tree_model_generator->priv->root_nodes);
            tree_model_generator->priv->root_nodes =
                build_node_map (tree_model_generator, NULL, NULL, -1);

            g_signal_connect_swapped (
                tree_model_generator->priv->child_model, "row-changed",
                G_CALLBACK (child_row_changed), tree_model_generator);
            g_signal_connect_swapped (
                tree_model_generator->priv->child_model, "row-deleted",
                G_CALLBACK (child_row_deleted), tree_model_generator);
            g_signal_connect_swapped (
                tree_model_generator->priv->child_model, "row-inserted",
                G_CALLBACK (child_row_inserted), tree_model_generator);
            break;

        default:
            G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
            break;
    }
}

static void
tree_model_generator_get_property (GObject *object,
                                   guint prop_id,
                                   GValue *value,
                                   GParamSpec *pspec)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (object);

    switch (prop_id)
    {
        case PROP_CHILD_MODEL:
            g_value_set_object (value, tree_model_generator->priv->child_model);
            break;

        default:
            G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
            break;
    }
}

static void
tree_model_generator_finalize (GObject *object)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (object);

    if (tree_model_generator->priv->child_model) {
        g_signal_handlers_disconnect_matched (
            tree_model_generator->priv->child_model,
            G_SIGNAL_MATCH_DATA, 0, 0, NULL, NULL,
            tree_model_generator);
        g_object_unref (tree_model_generator->priv->child_model);
    }

    if (tree_model_generator->priv->root_nodes)
        release_node_map (tree_model_generator->priv->root_nodes);

    /* Chain up to parent's finalize() method. */
    G_OBJECT_CLASS (e_tree_model_generator_parent_class)->finalize (object);
}

static void
e_tree_model_generator_class_init (ETreeModelGeneratorClass *class)
{
    GObjectClass *object_class;

    g_type_class_add_private (class, sizeof (ETreeModelGeneratorPrivate));

    object_class = G_OBJECT_CLASS (class);
    object_class->get_property = tree_model_generator_get_property;
    object_class->set_property = tree_model_generator_set_property;
    object_class->finalize = tree_model_generator_finalize;

    g_object_class_install_property (
        object_class,
        PROP_CHILD_MODEL,
        g_param_spec_object (
            "child-model",
            "Child Model",
            "The child model to extend",
            G_TYPE_OBJECT,
            G_PARAM_READWRITE |
            G_PARAM_CONSTRUCT_ONLY));
}

static void
e_tree_model_generator_tree_model_init (GtkTreeModelIface *iface)
{
    iface->get_flags       = e_tree_model_generator_get_flags;
    iface->get_n_columns   = e_tree_model_generator_get_n_columns;
    iface->get_column_type = e_tree_model_generator_get_column_type;
    iface->get_iter        = e_tree_model_generator_get_iter;
    iface->get_path        = e_tree_model_generator_get_path;
    iface->get_value       = e_tree_model_generator_get_value;
    iface->iter_next       = e_tree_model_generator_iter_next;
    iface->iter_children   = e_tree_model_generator_iter_children;
    iface->iter_has_child  = e_tree_model_generator_iter_has_child;
    iface->iter_n_children = e_tree_model_generator_iter_n_children;
    iface->iter_nth_child  = e_tree_model_generator_iter_nth_child;
    iface->iter_parent     = e_tree_model_generator_iter_parent;
}

static void
e_tree_model_generator_init (ETreeModelGenerator *tree_model_generator)
{
    tree_model_generator->priv =
        E_TREE_MODEL_GENERATOR_GET_PRIVATE (tree_model_generator);

    tree_model_generator->priv->stamp      = g_random_int ();
    tree_model_generator->priv->root_nodes = g_array_new (FALSE, FALSE, sizeof (Node));
}

/* ------------------ *
 * Row update helpers *
 * ------------------ */

static void
row_deleted (ETreeModelGenerator *tree_model_generator,
             GtkTreePath *path)
{
    g_assert (path);

    ETMG_DEBUG (g_print ("row_deleted emitting\n"));
    gtk_tree_model_row_deleted (GTK_TREE_MODEL (tree_model_generator), path);
}

static void
row_inserted (ETreeModelGenerator *tree_model_generator,
              GtkTreePath *path)
{
    GtkTreeIter iter;

    g_assert (path);

    if (gtk_tree_model_get_iter (GTK_TREE_MODEL (tree_model_generator), &iter, path)) {
        ETMG_DEBUG (g_print ("row_inserted emitting\n"));
        gtk_tree_model_row_inserted (GTK_TREE_MODEL (tree_model_generator), path, &iter);
    } else {
        ETMG_DEBUG (g_print ("row_inserted could not get iter!\n"));
    }
}

static void
row_changed (ETreeModelGenerator *tree_model_generator,
             GtkTreePath *path)
{
    GtkTreeIter iter;

    g_assert (path);

    if (gtk_tree_model_get_iter (GTK_TREE_MODEL (tree_model_generator), &iter, path)) {
        ETMG_DEBUG (g_print ("row_changed emitting\n"));
        gtk_tree_model_row_changed (GTK_TREE_MODEL (tree_model_generator), path, &iter);
    } else {
        ETMG_DEBUG (g_print ("row_changed could not get iter!\n"));
    }
}

/* -------------------- *
 * Node map translation *
 * -------------------- */

static gint
generated_offset_to_child_offset (GArray *group,
                                  gint offset,
                                  gint *internal_offset)
{
    gboolean success      = FALSE;
    gint     accum_offset = 0;
    gint     i;

    for (i = 0; i < group->len; i++) {
        Node *node = &g_array_index (group, Node, i);

        accum_offset += node->n_generated;
        if (accum_offset > offset) {
            accum_offset -= node->n_generated;
            success = TRUE;
            break;
        }
    }

    if (!success)
        return -1;

    if (internal_offset)
        *internal_offset = offset - accum_offset;

    return i;
}

static gint
child_offset_to_generated_offset (GArray *group,
                                  gint offset)
{
    gint accum_offset = 0;
    gint i;

    g_return_val_if_fail (group != NULL, -1);

    for (i = 0; i < group->len && i < offset; i++) {
        Node *node = &g_array_index (group, Node, i);

        accum_offset += node->n_generated;
    }

    return accum_offset;
}

static gint
count_generated_nodes (GArray *group)
{
    gint accum_offset = 0;
    gint i;

    for (i = 0; i < group->len; i++) {
        Node *node = &g_array_index (group, Node, i);

        accum_offset += node->n_generated;
    }

    return accum_offset;
}

/* ------------------- *
 * Node map management *
 * ------------------- */

static void
release_node_map (GArray *group)
{
    gint i;

    for (i = 0; i < group->len; i++) {
        Node *node = &g_array_index (group, Node, i);

        if (node->child_nodes)
            release_node_map (node->child_nodes);
    }

    g_array_free (group, TRUE);
}

static gint
append_node (GArray *group)
{
    g_array_set_size (group, group->len + 1);
    return group->len - 1;
}

static GArray *
build_node_map (ETreeModelGenerator *tree_model_generator,
                GtkTreeIter *parent_iter,
                GArray *parent_group,
                gint parent_index)
{
    GArray      *group;
    GtkTreeIter  iter;
    gboolean     result;

    if (parent_iter)
        result = gtk_tree_model_iter_children (tree_model_generator->priv->child_model, &iter, parent_iter);
    else
        result = gtk_tree_model_get_iter_first (tree_model_generator->priv->child_model, &iter);

    if (!result)
        return NULL;

    group = g_array_new (FALSE, FALSE, sizeof (Node));

    do {
        Node *node;
        gint  i;

        i = append_node (group);
        node = &g_array_index (group, Node, i);

        node->parent_group = parent_group;
        node->parent_index = parent_index;

        if (tree_model_generator->priv->generate_func)
            node->n_generated =
                tree_model_generator->priv->generate_func (tree_model_generator->priv->child_model,
                                     &iter, tree_model_generator->priv->generate_func_data);
        else
            node->n_generated = 1;

        node->child_nodes = build_node_map (tree_model_generator, &iter, group, i);
    } while (gtk_tree_model_iter_next (tree_model_generator->priv->child_model, &iter));

    return group;
}

static gint
get_first_visible_index_from (GArray *group,
                              gint index)
{
    gint i;

    for (i = index; i < group->len; i++) {
        Node *node = &g_array_index (group, Node, i);

        if (node->n_generated)
            break;
    }

    if (i >= group->len)
        i = -1;

    return i;
}

static Node *
get_node_by_child_path (ETreeModelGenerator *tree_model_generator,
                        GtkTreePath *path,
                        GArray **node_group)
{
    Node   *node = NULL;
    GArray *group;
    gint    depth;

    group = tree_model_generator->priv->root_nodes;

    for (depth = 0; depth < gtk_tree_path_get_depth (path); depth++) {
        gint  index;

        if (!group) {
            g_warning ("ETreeModelGenerator got unknown child element!");
            break;
        }

        index = gtk_tree_path_get_indices (path)[depth];
        node = &g_array_index (group, Node, index);

        if (depth + 1 < gtk_tree_path_get_depth (path))
            group = node->child_nodes;
    }

    if (!node)
        group = NULL;

    if (node_group)
        *node_group = group;

    return node;
}

static Node *
create_node_at_child_path (ETreeModelGenerator *tree_model_generator,
                           GtkTreePath *path)
{
    GtkTreePath *parent_path;
    gint         parent_index;
    GArray      *parent_group;
    GArray      *group;
    gint         index;
    Node        *node;

    parent_path = gtk_tree_path_copy (path);
    gtk_tree_path_up (parent_path);
    node = get_node_by_child_path (tree_model_generator, parent_path, &parent_group);

    if (node) {
        if (!node->child_nodes)
            node->child_nodes = g_array_new (FALSE, FALSE, sizeof (Node));

        group = node->child_nodes;
        parent_index = gtk_tree_path_get_indices (parent_path)[gtk_tree_path_get_depth (parent_path) - 1];
    } else {
        if (!tree_model_generator->priv->root_nodes)
            tree_model_generator->priv->root_nodes = g_array_new (FALSE, FALSE, sizeof (Node));

        group = tree_model_generator->priv->root_nodes;
        parent_index = -1;
    }

    gtk_tree_path_free (parent_path);

    index = gtk_tree_path_get_indices (path)[gtk_tree_path_get_depth (path) - 1];
    ETMG_DEBUG (g_print ("Inserting index %d into group of length %d\n", index, group->len));
    index = MIN (index, group->len);

    append_node (group);

    if (group->len - 1 - index > 0) {
        gint i;

        memmove (
            (Node *) group->data + index + 1,
            (Node *) group->data + index,
            (group->len - 1 - index) * sizeof (Node));

        /* Update parent pointers */
        for (i = index + 1; i < group->len; i++) {
            Node   *pnode = &g_array_index (group, Node, i);
            GArray *child_group;
            gint    j;

            child_group = pnode->child_nodes;
            if (!child_group)
                continue;

            for (j = 0; j < child_group->len; j++) {
                Node *child_node = &g_array_index (child_group, Node, j);
                child_node->parent_index = i;
            }
        }
    }

    node = &g_array_index (group, Node, index);
    node->parent_group = parent_group;
    node->parent_index = parent_index;
    node->n_generated  = 0;
    node->child_nodes  = NULL;

    ETMG_DEBUG (
        g_print ("Created node at offset %d, parent_group = %p, parent_index = %d\n",
        index, node->parent_group, node->parent_index));

    return node;
}

ETMG_DEBUG (

static void
dump_group (GArray *group)
{
    gint i;

    g_print ("\nGroup %p:\n", group);

    for (i = 0; i < group->len; i++) {
        Node *node = &g_array_index (group, Node, i);
        g_print (
            "  %04d: pgroup=%p, pindex=%d, n_generated=%d, child_nodes=%p\n",
            i, node->parent_group, node->parent_index, node->n_generated, node->child_nodes);
    }
}

)

static void
delete_node_at_child_path (ETreeModelGenerator *tree_model_generator,
                           GtkTreePath *path)
{
    GtkTreePath *parent_path;
    GArray      *parent_group;
    GArray      *group;
    gint         index;
    Node        *node;
    gint         i;

    parent_path = gtk_tree_path_copy (path);
    gtk_tree_path_up (parent_path);
    node = get_node_by_child_path (tree_model_generator, parent_path, &parent_group);

    if (node) {
        group = node->child_nodes;
    } else {
        group = tree_model_generator->priv->root_nodes;
    }

    gtk_tree_path_free (parent_path);

    if (!group)
        return;

    index = gtk_tree_path_get_indices (path)[gtk_tree_path_get_depth (path) - 1];
    if (index >= group->len)
        return;

    node = &g_array_index (group, Node, index);
    if (node->child_nodes)
        release_node_map (node->child_nodes);
    g_array_remove_index (group, index);

    /* Update parent pointers */
    for (i = index; i < group->len; i++) {
        Node   *pnode = &g_array_index (group, Node, i);
        GArray *child_group;
        gint    j;

        child_group = pnode->child_nodes;
        if (!child_group)
            continue;

        for (j = 0; j < child_group->len; j++) {
            Node *child_node = &g_array_index (child_group, Node, j);
            child_node->parent_index = i;
        }
    }
}

static void
child_row_changed (ETreeModelGenerator *tree_model_generator,
                   GtkTreePath *path,
                   GtkTreeIter *iter)
{
    GtkTreePath *generated_path;
    Node        *node;
    gint         n_generated;
    gint         i;

    if (tree_model_generator->priv->generate_func)
        n_generated =
            tree_model_generator->priv->generate_func (tree_model_generator->priv->child_model,
                                 iter, tree_model_generator->priv->generate_func_data);
    else
        n_generated = 1;

    node = get_node_by_child_path (tree_model_generator, path, NULL);
    if (!node)
        return;

    generated_path = e_tree_model_generator_convert_child_path_to_path (tree_model_generator, path);

    /* FIXME: Converting the path to an iter every time is inefficient */

    for (i = 0; i < n_generated && i < node->n_generated; i++) {
        row_changed (tree_model_generator, generated_path);
        gtk_tree_path_next (generated_path);
    }

    for (; i < node->n_generated; ) {
        node->n_generated--;
        row_deleted (tree_model_generator, generated_path);
    }

    for (; i < n_generated; i++) {
        node->n_generated++;
        row_inserted (tree_model_generator, generated_path);
        gtk_tree_path_next (generated_path);
    }

    gtk_tree_path_free (generated_path);
}

static void
child_row_inserted (ETreeModelGenerator *tree_model_generator,
                    GtkTreePath *path,
                    GtkTreeIter *iter)
{
    GtkTreePath *generated_path;
    Node        *node;
    gint         n_generated;

    if (tree_model_generator->priv->generate_func)
        n_generated =
            tree_model_generator->priv->generate_func (tree_model_generator->priv->child_model,
                                 iter, tree_model_generator->priv->generate_func_data);
    else
        n_generated = 1;

    node = create_node_at_child_path (tree_model_generator, path);
    if (!node)
        return;

    generated_path = e_tree_model_generator_convert_child_path_to_path (tree_model_generator, path);

    /* FIXME: Converting the path to an iter every time is inefficient */

    for (node->n_generated = 0; node->n_generated < n_generated; ) {
        node->n_generated++;
        row_inserted (tree_model_generator, generated_path);
        gtk_tree_path_next (generated_path);
    }

    gtk_tree_path_free (generated_path);
}

static void
child_row_deleted (ETreeModelGenerator *tree_model_generator,
                   GtkTreePath *path)
{
    GtkTreePath *generated_path;
    Node        *node;

    node = get_node_by_child_path (tree_model_generator, path, NULL);
    if (!node)
        return;

    generated_path = e_tree_model_generator_convert_child_path_to_path (tree_model_generator, path);

    /* FIXME: Converting the path to an iter every time is inefficient */

    for (; node->n_generated; ) {
        node->n_generated--;
        row_deleted (tree_model_generator, generated_path);
    }

    delete_node_at_child_path (tree_model_generator, path);
    gtk_tree_path_free (generated_path);
}

/* ----------------------- *
 * ETreeModelGenerator API *
 * ----------------------- */

/**
 * e_tree_model_generator_new:
 * @child_model: a #GtkTreeModel
 *
 * Creates a new #ETreeModelGenerator wrapping @child_model.
 *
 * Returns: A new #ETreeModelGenerator.
 **/
ETreeModelGenerator *
e_tree_model_generator_new (GtkTreeModel *child_model)
{
    g_return_val_if_fail (GTK_IS_TREE_MODEL (child_model), NULL);

    return E_TREE_MODEL_GENERATOR (
        g_object_new (E_TYPE_TREE_MODEL_GENERATOR,
        "child-model", child_model, NULL));
}

/**
 * e_tree_model_generator_get_model:
 * @tree_model_generator: an #ETreeModelGenerator
 *
 * Gets the child model being wrapped by @tree_model_generator.
 *
 * Returns: A #GtkTreeModel being wrapped.
 **/
GtkTreeModel *
e_tree_model_generator_get_model (ETreeModelGenerator *tree_model_generator)
{
    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model_generator), NULL);

    return tree_model_generator->priv->child_model;
}

/**
 * e_tree_model_generator_set_generate_func:
 * @tree_model_generator: an #ETreeModelGenerator
 * @func: an #ETreeModelGeneratorGenerateFunc, or %NULL
 * @data: user data to pass to @func
 * @destroy:
 *
 * Sets the callback function used to filter or generate additional rows
 * based on the child model's data. This function is called for each child
 * row, and returns a value indicating the number of rows that will be
 * used to represent the child row - 0 or more.
 *
 * If @func is %NULL, a filtering/generating function will not be applied.
 **/
void
e_tree_model_generator_set_generate_func (ETreeModelGenerator *tree_model_generator,
                                          ETreeModelGeneratorGenerateFunc func,
                                          gpointer data,
                                          GDestroyNotify destroy)
{
    g_return_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model_generator));

    tree_model_generator->priv->generate_func      = func;
    tree_model_generator->priv->generate_func_data = data;
}

/**
 * e_tree_model_generator_set_modify_func:
 * @tree_model_generator: an #ETreeModelGenerator
 * @func: an @ETreeModelGeneratorModifyFunc, or %NULL
 * @data: user data to pass to @func
 * @destroy:
 *
 * Sets the callback function used to override values for the child row's
 * columns and specify values for generated rows' columns.
 *
 * If @func is %NULL, the child model's values will always be used.
 **/
void
e_tree_model_generator_set_modify_func (ETreeModelGenerator *tree_model_generator,
                                        ETreeModelGeneratorModifyFunc func,
                                        gpointer data,
                                        GDestroyNotify destroy)
{
    g_return_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model_generator));

    tree_model_generator->priv->modify_func      = func;
    tree_model_generator->priv->modify_func_data = data;
}

/**
 * e_tree_model_generator_convert_child_path_to_path:
 * @tree_model_generator: an #ETreeModelGenerator
 * @child_path: a #GtkTreePath
 *
 * Convert a path to a child row to a path to a @tree_model_generator row.
 *
 * Returns: A new GtkTreePath, owned by the caller.
 **/
GtkTreePath *
e_tree_model_generator_convert_child_path_to_path (ETreeModelGenerator *tree_model_generator,
                                                   GtkTreePath *child_path)
{
    GtkTreePath *path;
    GArray      *group;
    gint         depth;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model_generator), NULL);
    g_return_val_if_fail (child_path != NULL, NULL);

    path = gtk_tree_path_new ();

    group = tree_model_generator->priv->root_nodes;

    for (depth = 0; depth < gtk_tree_path_get_depth (child_path); depth++) {
        Node *node;
        gint  index;
        gint  generated_index;

        if (!group) {
            g_warning ("ETreeModelGenerator was asked for path to unknown child element!");
            break;
        }

        index = gtk_tree_path_get_indices (child_path)[depth];
        generated_index = child_offset_to_generated_offset (group, index);
        node = &g_array_index (group, Node, index);
        group = node->child_nodes;

        gtk_tree_path_append_index (path, generated_index);
    }

    return path;
}

/**
 * e_tree_model_generator_convert_child_iter_to_iter:
 * @tree_model_generator: an #ETreeModelGenerator
 * @generator_iter: a #GtkTreeIter to set
 * @child_iter: a #GtkTreeIter to convert
 *
 * Convert @child_iter to a corresponding #GtkTreeIter for @tree_model_generator,
 * storing the result in @generator_iter.
 **/
void
e_tree_model_generator_convert_child_iter_to_iter (ETreeModelGenerator *tree_model_generator,
                                                   GtkTreeIter *generator_iter,
                                                   GtkTreeIter *child_iter)
{
    GtkTreePath *path;
    GArray      *group;
    gint         depth;
    gint         index = 0;

    g_return_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model_generator));

    path = gtk_tree_model_get_path (tree_model_generator->priv->child_model, child_iter);
    if (!path)
        return;

    group = tree_model_generator->priv->root_nodes;

    for (depth = 0; depth < gtk_tree_path_get_depth (path); depth++) {
        Node *node;

        index = gtk_tree_path_get_indices (path)[depth];
        node = &g_array_index (group, Node, index);

        if (depth + 1 < gtk_tree_path_get_depth (path))
            group = node->child_nodes;

        if (!group) {
            g_warning ("ETreeModelGenerator was asked for iter to unknown child element!");
            break;
        }
    }

    g_return_if_fail (group != NULL);

    index = child_offset_to_generated_offset (group, index);
    ITER_SET (tree_model_generator, generator_iter, group, index);
    gtk_tree_path_free (path);
}

/**
 * e_tree_model_generator_convert_path_to_child_path:
 * @tree_model_generator: an #ETreeModelGenerator
 * @generator_path: a #GtkTreePath to a @tree_model_generator row
 *
 * Converts @generator_path to a corresponding #GtkTreePath in the child model.
 *
 * Returns: A new #GtkTreePath, owned by the caller.
 **/
GtkTreePath *
e_tree_model_generator_convert_path_to_child_path (ETreeModelGenerator *tree_model_generator,
                                                   GtkTreePath *generator_path)
{
    GtkTreePath *path;
    GArray      *group;
    gint         depth;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model_generator), NULL);
    g_return_val_if_fail (generator_path != NULL, NULL);

    path = gtk_tree_path_new ();

    group = tree_model_generator->priv->root_nodes;

    for (depth = 0; depth < gtk_tree_path_get_depth (generator_path); depth++) {
        Node *node;
        gint  index;
        gint  child_index;

        if (!group) {
            g_warning ("ETreeModelGenerator was asked for path to unknown child element!");
            break;
        }

        index = gtk_tree_path_get_indices (generator_path)[depth];
        child_index = generated_offset_to_child_offset (group, index, NULL);
        node = &g_array_index (group, Node, child_index);
        group = node->child_nodes;

        gtk_tree_path_append_index (path, child_index);
    }

    return path;
}

/**
 * e_tree_model_generator_convert_iter_to_child_iter:
 * @tree_model_generator: an #ETreeModelGenerator
 * @child_iter: a #GtkTreeIter to set
 * @permutation_n: a permutation index to set
 * @generator_iter: a #GtkTreeIter indicating the row to convert
 *
 * Converts a @tree_model_generator row into a child row and permutation index.
 * The permutation index is the index of the generated row based on this
 * child row, with the first generated row based on this child row being 0.
 **/
void
e_tree_model_generator_convert_iter_to_child_iter (ETreeModelGenerator *tree_model_generator,
                                                   GtkTreeIter *child_iter,
                                                   gint *permutation_n,
                                                   GtkTreeIter *generator_iter)
{
    GtkTreePath *path;
    GArray      *group;
    gint         index;
    gint         internal_offset = 0;

    g_return_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model_generator));
    g_return_if_fail (ITER_IS_VALID (tree_model_generator, generator_iter));

    path = gtk_tree_path_new ();
    ITER_GET (generator_iter, &group, &index);

    index = generated_offset_to_child_offset (group, index, &internal_offset);
    gtk_tree_path_prepend_index (path, index);

    while (group) {
        Node *node = &g_array_index (group, Node, index);

        group = node->parent_group;
        index = node->parent_index;

        if (group)
            gtk_tree_path_prepend_index (path, index);
    }

    if (child_iter)
        gtk_tree_model_get_iter (tree_model_generator->priv->child_model, child_iter, path);
    if (permutation_n)
        *permutation_n = internal_offset;

    gtk_tree_path_free (path);
}

/* ---------------- *
 * GtkTreeModel API *
 * ---------------- */

static GtkTreeModelFlags
e_tree_model_generator_get_flags (GtkTreeModel *tree_model)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), 0);

    return gtk_tree_model_get_flags (tree_model_generator->priv->child_model);
}

static gint
e_tree_model_generator_get_n_columns (GtkTreeModel *tree_model)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), 0);

    return gtk_tree_model_get_n_columns (tree_model_generator->priv->child_model);
}

static GType
e_tree_model_generator_get_column_type (GtkTreeModel *tree_model,
                                        gint index)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), G_TYPE_INVALID);

    return gtk_tree_model_get_column_type (tree_model_generator->priv->child_model, index);
}

static gboolean
e_tree_model_generator_get_iter (GtkTreeModel *tree_model,
                                 GtkTreeIter *iter,
                                 GtkTreePath *path)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    GArray              *group;
    gint                 depth;
    gint                 index = 0;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), FALSE);
    g_return_val_if_fail (gtk_tree_path_get_depth (path) > 0, FALSE);

    group = tree_model_generator->priv->root_nodes;
    if (!group)
        return FALSE;

    for (depth = 0; depth < gtk_tree_path_get_depth (path); depth++) {
        Node *node;
        gint  child_index;

        index = gtk_tree_path_get_indices (path)[depth];
        child_index = generated_offset_to_child_offset (group, index, NULL);
        if (child_index < 0)
            return FALSE;

        node = &g_array_index (group, Node, child_index);

        if (depth + 1 < gtk_tree_path_get_depth (path)) {
            group = node->child_nodes;
            if (!group)
                return FALSE;
        }
    }

    ITER_SET (tree_model_generator, iter, group, index);
    return TRUE;
}

static GtkTreePath *
e_tree_model_generator_get_path (GtkTreeModel *tree_model,
                                 GtkTreeIter *iter)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    GtkTreePath         *path;
    GArray              *group;
    gint                 index;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), NULL);
    g_return_val_if_fail (ITER_IS_VALID (tree_model_generator, iter), NULL);

    ITER_GET (iter, &group, &index);
    path = gtk_tree_path_new ();

    /* FIXME: Converting a path to an iter is a destructive operation, because
     * we don't store a node for each generated entry... Doesn't matter for
     * lists, not sure about trees. */

    gtk_tree_path_prepend_index (path, index);
    index = generated_offset_to_child_offset (group, index, NULL);

    while (group) {
        Node *node = &g_array_index (group, Node, index);
        gint  generated_index;

        group = node->parent_group;
        index = node->parent_index;
        if (group) {
            generated_index = child_offset_to_generated_offset (group, index);
            gtk_tree_path_prepend_index (path, generated_index);
        }
    }

    return path;
}

static gboolean
e_tree_model_generator_iter_next (GtkTreeModel *tree_model,
                                  GtkTreeIter *iter)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    Node                *node;
    GArray              *group;
    gint                 index;
    gint                 child_index;
    gint                 internal_offset = 0;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), FALSE);
    g_return_val_if_fail (ITER_IS_VALID (tree_model_generator, iter), FALSE);

    ITER_GET (iter, &group, &index);
    child_index = generated_offset_to_child_offset (group, index, &internal_offset);
    node = &g_array_index (group, Node, child_index);

    if (internal_offset + 1 < node->n_generated ||
        get_first_visible_index_from (group, child_index + 1) >= 0) {
        ITER_SET (tree_model_generator, iter, group, index + 1);
        return TRUE;
    }

    return FALSE;
}

static gboolean
e_tree_model_generator_iter_children (GtkTreeModel *tree_model,
                                      GtkTreeIter *iter,
                                      GtkTreeIter *parent)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    Node                *node;
    GArray              *group;
    gint                 index;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), FALSE);

    if (!parent) {
        if (!tree_model_generator->priv->root_nodes ||
            !count_generated_nodes (tree_model_generator->priv->root_nodes))
            return FALSE;

        ITER_SET (tree_model_generator, iter, tree_model_generator->priv->root_nodes, 0);
        return TRUE;
    }

    ITER_GET (parent, &group, &index);
    index = generated_offset_to_child_offset (group, index, NULL);
    if (index < 0)
        return FALSE;

    node = &g_array_index (group, Node, index);

    if (!node->child_nodes)
        return FALSE;

    if (!count_generated_nodes (node->child_nodes))
        return FALSE;

    ITER_SET (tree_model_generator, iter, node->child_nodes, 0);
    return TRUE;
}

static gboolean
e_tree_model_generator_iter_has_child (GtkTreeModel *tree_model,
                                       GtkTreeIter *iter)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    Node                *node;
    GArray              *group;
    gint                 index;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), FALSE);

    if (iter == NULL) {
        if (!tree_model_generator->priv->root_nodes ||
            !count_generated_nodes (tree_model_generator->priv->root_nodes))
            return FALSE;

        return TRUE;
    }

    ITER_GET (iter, &group, &index);
    index = generated_offset_to_child_offset (group, index, NULL);
    if (index < 0)
        return FALSE;

    node = &g_array_index (group, Node, index);

    if (!node->child_nodes)
        return FALSE;

    if (!count_generated_nodes (node->child_nodes))
        return FALSE;

    return TRUE;
}

static gint
e_tree_model_generator_iter_n_children (GtkTreeModel *tree_model,
                                        GtkTreeIter *iter)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    Node                *node;
    GArray              *group;
    gint                 index;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), 0);

    if (iter == NULL)
        return tree_model_generator->priv->root_nodes ?
            count_generated_nodes (tree_model_generator->priv->root_nodes) : 0;

    ITER_GET (iter, &group, &index);
    index = generated_offset_to_child_offset (group, index, NULL);
    if (index < 0)
        return 0;

    node = &g_array_index (group, Node, index);

    if (!node->child_nodes)
        return 0;

    return count_generated_nodes (node->child_nodes);
}

static gboolean
e_tree_model_generator_iter_nth_child (GtkTreeModel *tree_model,
                                       GtkTreeIter *iter,
                                       GtkTreeIter *parent,
                                       gint n)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    Node                *node;
    GArray              *group;
    gint                 index;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), FALSE);

    if (!parent) {
        if (!tree_model_generator->priv->root_nodes)
            return FALSE;

        if (n >= count_generated_nodes (tree_model_generator->priv->root_nodes))
            return FALSE;

        ITER_SET (tree_model_generator, iter, tree_model_generator->priv->root_nodes, n);
        return TRUE;
    }

    ITER_GET (parent, &group, &index);
    index = generated_offset_to_child_offset (group, index, NULL);
    if (index < 0)
        return FALSE;

    node = &g_array_index (group, Node, index);

    if (!node->child_nodes)
        return FALSE;

    if (n >= count_generated_nodes (node->child_nodes))
        return FALSE;

    ITER_SET (tree_model_generator, iter, node->child_nodes, n);
    return TRUE;
}

static gboolean
e_tree_model_generator_iter_parent (GtkTreeModel *tree_model,
                                    GtkTreeIter *iter,
                                    GtkTreeIter *child)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    Node                *node;
    GArray              *group;
    gint                 index;

    g_return_val_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model), FALSE);
    g_return_val_if_fail (ITER_IS_VALID (tree_model_generator, iter), FALSE);

    ITER_GET (child, &group, &index);
    index = generated_offset_to_child_offset (group, index, NULL);
    if (index < 0)
        return FALSE;

    node = &g_array_index (group, Node, index);

    group = node->parent_group;
    if (!group)
        return FALSE;

    ITER_SET (tree_model_generator, iter, group, node->parent_index);
    return TRUE;
}

static void
e_tree_model_generator_get_value (GtkTreeModel *tree_model,
                                  GtkTreeIter *iter,
                                  gint column,
                                  GValue *value)
{
    ETreeModelGenerator *tree_model_generator = E_TREE_MODEL_GENERATOR (tree_model);
    GtkTreeIter          child_iter;
    gint                 permutation_n;

    g_return_if_fail (E_IS_TREE_MODEL_GENERATOR (tree_model));
    g_return_if_fail (ITER_IS_VALID (tree_model_generator, iter));

    e_tree_model_generator_convert_iter_to_child_iter (
        tree_model_generator, &child_iter,
        &permutation_n, iter);

    if (tree_model_generator->priv->modify_func) {
        tree_model_generator->priv->modify_func (tree_model_generator->priv->child_model,
                           &child_iter, permutation_n,
                           column, value,
                           tree_model_generator->priv->modify_func_data);
        return;
    }

    gtk_tree_model_get_value (tree_model_generator->priv->child_model, &child_iter, column, value);
}