path: root/lib/ephy-node.c

/* 
 *  Copyright (C) 2002 Jorn Baayen <jorn@nl.linux.org>
 *  Copyright (C) 2003 Marco Pesenti Gritti
 *  Copyright (C) 2003 Christian Persch
 *
 *  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 2 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, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 *  $Id$
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <glib.h>
#include <glib/gi18n.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <gdk/gdk.h>
#include <time.h>

#include "ephy-node.h"
#include "ephy-string.h"

typedef struct
{
    EphyNode *node;
    int id;
    EphyNodeCallback callback;
    EphyNodeSignalType type;
    gpointer data;
} EphyNodeSignalData;

typedef struct
{
    EphyNode *node;
    guint index;
} EphyNodeParent;

typedef struct
{
    EphyNode *node;
    guint property_id;
} EphyNodeChange;

struct EphyNode
{
    int ref_count;

    guint id;

    GPtrArray *properties;

    GHashTable *parents;
    GPtrArray *children;

    GHashTable *signals;
    int signal_id;

    EphyNodeDb *db;
};

typedef struct
{
    EphyNodeSignalType type;
    va_list valist;
} ENESCData;

static gboolean
int_equal (gconstpointer a,
       gconstpointer b)
{
    return GPOINTER_TO_INT (a) == GPOINTER_TO_INT (b);
}

static guint
int_hash (gconstpointer a)
{
    return GPOINTER_TO_INT (a);
}

static void
callback (long id, EphyNodeSignalData *data, gpointer *dummy)
{
    ENESCData *user_data;
    va_list valist;

    user_data = (ENESCData *) dummy;

    G_VA_COPY(valist, user_data->valist);

    if (data->type != user_data->type) return;

    switch (data->type)
    {
        case EPHY_NODE_DESTROY:
        case EPHY_NODE_RESTORED:
            data->callback (data->node, data->data);
        break;

        case EPHY_NODE_CHILD_ADDED:
        {
            EphyNode *node;

            node = va_arg (valist, EphyNode *);
        
            data->callback (data->node, node, data->data);
        }
        break;

        case EPHY_NODE_CHILD_CHANGED:
        {
            EphyNode *node;
            guint property_id;

            node = va_arg (valist, EphyNode *);
            property_id = va_arg (valist, guint);
        
            data->callback (data->node, node, property_id, data->data);
        }
        break;

        case EPHY_NODE_CHILD_REMOVED:
        {
            EphyNode *node;
            guint last_index;

            node = va_arg (valist, EphyNode *);
            last_index = va_arg (valist, guint);

            data->callback (data->node, node, last_index, data->data);
        }
        break;

        case EPHY_NODE_CHILDREN_REORDERED:
            data->callback (data->node, va_arg (valist, int *), data->data);
        break;
    }

        va_end(valist);
}

static void
ephy_node_emit_signal (EphyNode *node, EphyNodeSignalType type, ...)
{
    ENESCData data;

    va_start (data.valist, type);

    data.type = type;

    g_hash_table_foreach (node->signals,
                  (GHFunc) callback,
                  &data);

    va_end (data.valist);
}

static void
ephy_node_finalize (EphyNode *node)
{
    guint i;

    g_hash_table_destroy (node->signals);
    node->signals = NULL;

    for (i = 0; i < node->properties->len; i++) {
        GValue *val;

        val = g_ptr_array_index (node->properties, i);

        if (val != NULL) {
            g_value_unset (val);
            g_free (val);
        }
    }
    g_ptr_array_free (node->properties, TRUE);

    g_hash_table_destroy (node->parents);

    g_ptr_array_free (node->children, TRUE);

    g_free (node);
}

static inline void
real_remove_child (EphyNode *node,
           EphyNode *child,
           gboolean remove_from_parent,
           gboolean remove_from_child)
{
    EphyNodeParent *node_info;

    node_info = g_hash_table_lookup (child->parents,
                             GINT_TO_POINTER (node->id));

    if (remove_from_parent) {
        guint i;
        guint old_index;

        old_index = node_info->index;

        g_ptr_array_remove_index (node->children,
                      node_info->index);

        /* correct indices on kids */
        for (i = node_info->index; i < node->children->len; i++) {
            EphyNode *borked_node;
            EphyNodeParent *borked_node_info;

            borked_node = g_ptr_array_index (node->children, i);


            borked_node_info = g_hash_table_lookup (borked_node->parents,
                                        GINT_TO_POINTER (node->id));
            borked_node_info->index--;
        }

        ephy_node_emit_signal (node, EPHY_NODE_CHILD_REMOVED, child, old_index);
    }

    if (remove_from_child) {
        g_hash_table_remove (child->parents,
                     GINT_TO_POINTER (node->id));
    }
}

static void
remove_child (long id,
          EphyNodeParent *node_info,
          EphyNode *node)
{
    real_remove_child (node_info->node, node, TRUE, FALSE);
}

static void
signal_object_weak_notify (EphyNodeSignalData *signal_data,
                           GObject *where_the_object_was)
{
    ephy_node_signal_disconnect (signal_data->node, signal_data->id);
}

static void
unref_signal_objects (long id,
                  EphyNodeSignalData *signal_data,
                  EphyNode *node)
{
    if (signal_data->data)
    {
        g_object_weak_unref (G_OBJECT (signal_data->data),
                     (GWeakNotify)signal_object_weak_notify,
                     signal_data);
    }
}

static void
ephy_node_dispose (EphyNode *node)
{
    guint i;

    ephy_node_emit_signal (node, EPHY_NODE_DESTROY);

    /* remove from DAG */
    g_hash_table_foreach (node->parents,
                  (GHFunc) remove_child,
                  node);

    for (i = 0; i < node->children->len; i++) {
        EphyNode *child;

        child = g_ptr_array_index (node->children, i);

        real_remove_child (node, child, FALSE, TRUE);
    }

    g_hash_table_foreach (node->signals,
                  (GHFunc) unref_signal_objects,
                  node);

    _ephy_node_db_remove_id (node->db, node->id);
}

EphyNode *
ephy_node_new (EphyNodeDb *db)
{
    long id;

    g_return_val_if_fail (EPHY_IS_NODE_DB (db), NULL);

    if (ephy_node_db_is_immutable (db)) return NULL;

    id = _ephy_node_db_new_id (db);

    return ephy_node_new_with_id (db, id);
}

EphyNode *
ephy_node_new_with_id (EphyNodeDb *db, guint reserved_id)
{
    EphyNode *node;

    g_return_val_if_fail (EPHY_IS_NODE_DB (db), NULL);

    if (ephy_node_db_is_immutable (db)) return NULL;

    node = g_new0 (EphyNode, 1);

    node->ref_count = 1;

    node->id = reserved_id;

    node->db = db;

    node->properties = g_ptr_array_new ();

    node->children = g_ptr_array_new ();

    node->parents = g_hash_table_new_full (int_hash,
                           int_equal,
                           NULL,
                           g_free);

    node->signals = g_hash_table_new_full (int_hash,
                           int_equal,
                           NULL,
                           g_free);
    node->signal_id = 0;

    _ephy_node_db_add_id (db, reserved_id, node);

    return node;
}

EphyNodeDb *
ephy_node_get_db (EphyNode *node)
{
    g_return_val_if_fail (EPHY_IS_NODE (node), NULL);
    
    return node->db;
}

guint
ephy_node_get_id (EphyNode *node)
{
    long ret;

    g_return_val_if_fail (EPHY_IS_NODE (node), G_MAXUINT);

    ret = node->id;

    return ret;
}

void
ephy_node_ref (EphyNode *node)
{
    g_return_if_fail (EPHY_IS_NODE (node));

    node->ref_count++;
}

void
ephy_node_unref (EphyNode *node)
{
    g_return_if_fail (EPHY_IS_NODE (node));

    node->ref_count--;

    if (node->ref_count <= 0) {
        ephy_node_dispose (node);
        ephy_node_finalize (node);
    }
}

static void
child_changed (guint id,
           EphyNodeParent *node_info,
           EphyNodeChange *change)
{
    ephy_node_emit_signal (node_info->node, EPHY_NODE_CHILD_CHANGED,
                   change->node, change->property_id);
}

static inline void
real_set_property (EphyNode *node,
           guint property_id,
           GValue *value)
{
    GValue *old;

    if (property_id >= node->properties->len) {
        g_ptr_array_set_size (node->properties, property_id + 1);
    }

    old = g_ptr_array_index (node->properties, property_id);
    if (old != NULL) {
        g_value_unset (old);
        g_free (old);
    }

    g_ptr_array_index (node->properties, property_id) = value;
}

void
ephy_node_set_property (EphyNode *node,
                guint property_id,
                const GValue *value)
{
    GValue *new;
    EphyNodeChange change;

    g_return_if_fail (EPHY_IS_NODE (node));
    g_return_if_fail (property_id >= 0);
    g_return_if_fail (value != NULL);

    if (ephy_node_db_is_immutable (node->db)) return;

    new = g_new0 (GValue, 1);
    g_value_init (new, G_VALUE_TYPE (value));
    g_value_copy (value, new);

    real_set_property (node, property_id, new);

    change.node = node;
    change.property_id = property_id;
    g_hash_table_foreach (node->parents,
                  (GHFunc) child_changed,
                  &change);
}

gboolean
ephy_node_get_property (EphyNode *node,
                guint property_id,
                GValue *value)
{
    GValue *ret;

    g_return_val_if_fail (EPHY_IS_NODE (node), FALSE);
    g_return_val_if_fail (property_id >= 0, FALSE);
    g_return_val_if_fail (value != NULL, FALSE);

    if (property_id >= node->properties->len) {
        return FALSE;
    }

    ret = g_ptr_array_index (node->properties, property_id);
    if (ret == NULL) {
        return FALSE;
    }

    g_value_init (value, G_VALUE_TYPE (ret));
    g_value_copy (ret, value);

    return TRUE;
}

const char *
ephy_node_get_property_string (EphyNode *node,
                   guint property_id)
{
    GValue *ret;
    const char *retval;

    g_return_val_if_fail (EPHY_IS_NODE (node), NULL);
    g_return_val_if_fail (property_id >= 0, NULL);

    if (property_id >= node->properties->len) {
        return NULL;
    }

    ret = g_ptr_array_index (node->properties, property_id);
    if (ret == NULL) {
        return NULL;
    }

    retval = g_value_get_string (ret);

    return retval;
}

gboolean
ephy_node_get_property_boolean (EphyNode *node,
                    guint property_id)
{
    GValue *ret;
    gboolean retval;

    g_return_val_if_fail (EPHY_IS_NODE (node), FALSE);
    g_return_val_if_fail (property_id >= 0, FALSE);

    if (property_id >= node->properties->len) {
        return FALSE;
    }

    ret = g_ptr_array_index (node->properties, property_id);
    if (ret == NULL) {
        return FALSE;
    }

    retval = g_value_get_boolean (ret);

    return retval;
}

long
ephy_node_get_property_long (EphyNode *node,
                 guint property_id)
{
    GValue *ret;
    long retval;

    g_return_val_if_fail (EPHY_IS_NODE (node), -1);
    g_return_val_if_fail (property_id >= 0, -1);

    if (property_id >= node->properties->len) {
        return -1;
    }

    ret = g_ptr_array_index (node->properties, property_id);
    if (ret == NULL) {
        return -1;
    }

    retval = g_value_get_long (ret);

    return retval;
}

int
ephy_node_get_property_int (EphyNode *node,
                guint property_id)
{
    GValue *ret;
    int retval;

    g_return_val_if_fail (EPHY_IS_NODE (node), -1);
    g_return_val_if_fail (property_id >= 0, -1);

    if (property_id >= node->properties->len) {
        return -1;
    }

    ret = g_ptr_array_index (node->properties, property_id);
    if (ret == NULL) {
        return -1;
    }

    retval = g_value_get_int (ret);

    return retval;
}

double
ephy_node_get_property_double (EphyNode *node,
                   guint property_id)
{
    GValue *ret;
    double retval;

    g_return_val_if_fail (EPHY_IS_NODE (node), -1);
    g_return_val_if_fail (property_id >= 0, -1);

    if (property_id >= node->properties->len) {
        return -1;
    }

    ret = g_ptr_array_index (node->properties, property_id);
    if (ret == NULL) {
        return -1;
    }

    retval = g_value_get_double (ret);

    return retval;
}

float
ephy_node_get_property_float (EphyNode *node,
                  guint property_id)
{
    GValue *ret;
    float retval;

    g_return_val_if_fail (EPHY_IS_NODE (node), -1);
    g_return_val_if_fail (property_id >= 0, -1);

    if (property_id >= node->properties->len) {
        return -1;
    }

    ret = g_ptr_array_index (node->properties, property_id);
    if (ret == NULL) {
        return -1;
    }

    retval = g_value_get_float (ret);

    return retval;
}

EphyNode *
ephy_node_get_property_node (EphyNode *node,
                 guint property_id)
{
    GValue *ret;
    EphyNode *retval;

    g_return_val_if_fail (EPHY_IS_NODE (node), NULL);
    g_return_val_if_fail (property_id >= 0, NULL);

    if (property_id >= node->properties->len) {
        return NULL;
    }

    ret = g_ptr_array_index (node->properties, property_id);
    if (ret == NULL) {
        return NULL;
    }

    retval = g_value_get_pointer (ret);

    return retval;
}

typedef struct
{
    xmlTextWriterPtr writer;
    int ret;
} ForEachData;

static void
write_parent (guint id,
          EphyNodeParent *node_info,
          ForEachData* data)
{
    xmlTextWriterPtr writer = data->writer;

    /* there already was an error, do nothing. this works around
     * the fact that g_hash_table_foreach cannot be cancelled.
     */
    if (data->ret < 0) return;

    data->ret = xmlTextWriterStartElement (writer, "parent");
    if (data->ret < 0) return;

    data->ret = xmlTextWriterWriteFormatAttribute
            (writer, "id", "%ld", node_info->node->id);
    if (data->ret < 0) return;

    data->ret = xmlTextWriterEndElement (writer); /* parent */
    if (data->ret < 0) return;
}

int
ephy_node_write_to_xml(EphyNode *node,
               xmlTextWriterPtr writer)
{
    xmlChar xml_buf[G_ASCII_DTOSTR_BUF_SIZE];
    guint i;
    int ret;
    ForEachData data;

    g_return_val_if_fail (EPHY_IS_NODE (node), -1);
    g_return_val_if_fail (writer != NULL, -1);

    /* start writing the node */
    ret = xmlTextWriterStartElement (writer, "node");
    if (ret < 0) goto out;

    /* write node id */
    ret = xmlTextWriterWriteFormatAttribute (writer, "id", "%ld", node->id);
    if (ret < 0) goto out;

    /* write node properties */
    for (i = 0; i < node->properties->len; i++)
    {
        GValue *value;

        value = g_ptr_array_index (node->properties, i);

        if (value == NULL) continue;

        ret = xmlTextWriterStartElement (writer, "property");
        if (ret < 0) break;

        ret = xmlTextWriterWriteFormatAttribute (writer, "id", "%d", i);
        if (ret < 0) break;

        ret = xmlTextWriterWriteAttribute
            (writer, "value_type", g_type_name (G_VALUE_TYPE (value)));
        if (ret < 0) break;

        switch (G_VALUE_TYPE (value))
        {
        case G_TYPE_STRING:
            ret = xmlTextWriterWriteString
                (writer, g_value_get_string (value));
            break;
        case G_TYPE_BOOLEAN:
            ret = xmlTextWriterWriteFormatString
                (writer, "%d", g_value_get_boolean (value));
            break;
        case G_TYPE_INT:
            ret = xmlTextWriterWriteFormatString
                (writer, "%d", g_value_get_int (value));
            break;
        case G_TYPE_LONG:
            ret = xmlTextWriterWriteFormatString
                (writer, "%ld", g_value_get_long (value));
            break;
        case G_TYPE_FLOAT:
            g_ascii_dtostr (xml_buf, sizeof (xml_buf), 
                    g_value_get_float (value));
            ret = xmlTextWriterWriteString (writer, xml_buf);
            break;
        case G_TYPE_DOUBLE:
            g_ascii_dtostr (xml_buf, sizeof (xml_buf),
                    g_value_get_double (value));
            ret = xmlTextWriterWriteString (writer, xml_buf);
            break;
        default:
            g_assert_not_reached ();
            break;
        }
        if (ret < 0) break;
    
        ret = xmlTextWriterEndElement (writer); /* property */
        if (ret < 0) break;
    }
    if (ret < 0) goto out;

    /* now write parent node ids */
    data.writer = writer;
    data.ret = 0;

    g_hash_table_foreach (node->parents,
                  (GHFunc) write_parent,
                  &data);
    ret = data.ret;
    if (ret < 0) goto out;

    ret = xmlTextWriterEndElement (writer); /* node */
    if (ret < 0) goto out;

out:
    return ret >= 0 ? 0 : -1;
}

static inline void
real_add_child (EphyNode *node,
        EphyNode *child)
{
    EphyNodeParent *node_info;

    if (g_hash_table_lookup (child->parents,
                 GINT_TO_POINTER (node->id)) != NULL) {
        return;
    }

    g_ptr_array_add (node->children, child);

    node_info = g_new0 (EphyNodeParent, 1);
    node_info->node  = node;
    node_info->index = node->children->len - 1;

    g_hash_table_insert (child->parents,
                 GINT_TO_POINTER (node->id),
                 node_info);
}

EphyNode *
ephy_node_new_from_xml (EphyNodeDb *db, xmlNodePtr xml_node)
{
    EphyNode *node;
    xmlNodePtr xml_child;
    char *xml;
    long id;

    g_return_val_if_fail (EPHY_IS_NODE_DB (db), NULL);
    g_return_val_if_fail (xml_node != NULL, NULL);

    if (ephy_node_db_is_immutable (db)) return NULL; 

    xml = xmlGetProp (xml_node, "id");
    if (xml == NULL)
        return NULL;
    id = atol (xml);
    xmlFree (xml);

    node = ephy_node_new_with_id (db, id);

    for (xml_child = xml_node->children; xml_child != NULL; xml_child = xml_child->next) {
        if (strcmp (xml_child->name, "parent") == 0) {
            EphyNode *parent;
            long parent_id;

            xml = xmlGetProp (xml_child, "id");
            g_assert (xml != NULL);
            parent_id = atol (xml);
            xmlFree (xml);

            parent = ephy_node_db_get_node_from_id (db, parent_id);

            if (parent != NULL)
            {
                real_add_child (parent, node);

                ephy_node_emit_signal (parent, EPHY_NODE_CHILD_ADDED, node);
            }
        } else if (strcmp (xml_child->name, "property") == 0) {
            GType value_type;
            GValue *value;
            int property_id;

            xml = xmlGetProp (xml_child, "id");
            property_id = atoi (xml);
            xmlFree (xml);

            xml = xmlGetProp (xml_child, "value_type");
            value_type = g_type_from_name (xml);
            xmlFree (xml);

            xml = xmlNodeGetContent (xml_child);
            value = g_new0 (GValue, 1);
            g_value_init (value, value_type);

            switch (value_type)
            {
            case G_TYPE_STRING:
                g_value_set_string (value, xml);
                break;
            case G_TYPE_INT:
                g_value_set_int (value, atoi (xml));
                break;
            case G_TYPE_BOOLEAN:
                g_value_set_boolean (value, atoi (xml));
                break;
            case G_TYPE_LONG:
                g_value_set_long (value, atol (xml));
                break;
            case G_TYPE_FLOAT:
                g_value_set_float (value, g_ascii_strtod (xml, NULL));
                break;
            case G_TYPE_DOUBLE:
                g_value_set_double (value, g_ascii_strtod (xml, NULL));
                break;
            case G_TYPE_POINTER:
            {
                EphyNode *property_node;

                property_node = ephy_node_db_get_node_from_id (db, atol (xml));

                g_value_set_pointer (value, property_node);
                break;
            }
            default:
                g_assert_not_reached ();
                break;
            }

            real_set_property (node, property_id, value);

            xmlFree (xml);
        }
    }

    ephy_node_emit_signal (node, EPHY_NODE_RESTORED);

    return node;
}

void
ephy_node_add_child (EphyNode *node,
             EphyNode *child)
{
    g_return_if_fail (EPHY_IS_NODE (node));

    if (ephy_node_db_is_immutable (node->db)) return;
    
    real_add_child (node, child);

    ephy_node_emit_signal (node, EPHY_NODE_CHILD_ADDED, child);
}

void
ephy_node_remove_child (EphyNode *node,
                EphyNode *child)
{
    g_return_if_fail (EPHY_IS_NODE (node));

    if (ephy_node_db_is_immutable (node->db)) return;

    real_remove_child (node, child, TRUE, TRUE);
}

gboolean
ephy_node_has_child (EphyNode *node,
             EphyNode *child)
{
    gboolean ret;

    g_return_val_if_fail (EPHY_IS_NODE (node), FALSE);
    
    ret = (g_hash_table_lookup (child->parents,
                    GINT_TO_POINTER (node->id)) != NULL);

    return ret;
}

static int
ephy_node_real_get_child_index (EphyNode *node,
               EphyNode *child)
{
    EphyNodeParent *node_info;
    int ret;

    node_info = g_hash_table_lookup (child->parents,
                     GINT_TO_POINTER (node->id));

    if (node_info == NULL)
        return -1;

    ret = node_info->index;

    return ret;
}

void
ephy_node_sort_children (EphyNode *node,
             GCompareFunc compare_func)
{
    GPtrArray *newkids;
    int i, *new_order;

    if (ephy_node_db_is_immutable (node->db)) return;

    g_return_if_fail (EPHY_IS_NODE (node));
    g_return_if_fail (compare_func != NULL);

    newkids = g_ptr_array_new ();
    g_ptr_array_set_size (newkids, node->children->len);

    /* dup the array */
    for (i = 0; i < node->children->len; i++)
    {
        g_ptr_array_index (newkids, i) = g_ptr_array_index (node->children, i);
    }

    g_ptr_array_sort (newkids, compare_func);

    new_order = g_new (int, newkids->len);
    memset (new_order, -1, sizeof (int) * newkids->len);

    for (i = 0; i < newkids->len; i++)
    {
        EphyNodeParent *node_info;
        EphyNode *child;

        child = g_ptr_array_index (newkids, i);
        new_order[ephy_node_real_get_child_index (node, child)] = i;
        node_info = g_hash_table_lookup (child->parents,
                             GINT_TO_POINTER (node->id));
        node_info->index = i;
    }

    g_ptr_array_free (node->children, FALSE);
    node->children = newkids;

    ephy_node_emit_signal (node, EPHY_NODE_CHILDREN_REORDERED, new_order);

    g_free (new_order);
}

void
ephy_node_reorder_children (EphyNode *node,
                int *new_order)
{
    GPtrArray *newkids;
    int i;

    g_return_if_fail (EPHY_IS_NODE (node));
    g_return_if_fail (new_order != NULL);

    if (ephy_node_db_is_immutable (node->db)) return;

    newkids = g_ptr_array_new ();
    g_ptr_array_set_size (newkids, node->children->len);

    for (i = 0; i < node->children->len; i++) {
        EphyNode *child;
        EphyNodeParent *node_info;

        child = g_ptr_array_index (node->children, i);

        g_ptr_array_index (newkids, new_order[i]) = child;

        node_info = g_hash_table_lookup (child->parents,
                             GINT_TO_POINTER (node->id));
        node_info->index = new_order[i];
    }

    g_ptr_array_free (node->children, FALSE);
    node->children = newkids;

    ephy_node_emit_signal (node, EPHY_NODE_CHILDREN_REORDERED, new_order);
}

GPtrArray *
ephy_node_get_children (EphyNode *node)
{
    g_return_val_if_fail (EPHY_IS_NODE (node), NULL);

    return node->children;
}

int
ephy_node_get_n_children (EphyNode *node)
{
    int ret;

    g_return_val_if_fail (EPHY_IS_NODE (node), -1);

    ret = node->children->len;

    return ret;
}

EphyNode *
ephy_node_get_nth_child (EphyNode *node,
                 guint n)
{
    EphyNode *ret;

    g_return_val_if_fail (EPHY_IS_NODE (node), NULL);
    g_return_val_if_fail (n >= 0, NULL);

    if (n < node->children->len) {
        ret = g_ptr_array_index (node->children, n);
    } else {
        ret = NULL;
    }

    return ret;
}

static inline int
get_child_index_real (EphyNode *node,
              EphyNode *child)
{
    EphyNodeParent *node_info;

    node_info = g_hash_table_lookup (child->parents,
                     GINT_TO_POINTER (node->id));

    if (node_info == NULL)
        return -1;

    return node_info->index;
}


int
ephy_node_get_child_index (EphyNode *node,
               EphyNode *child)
{
    int ret;

    g_return_val_if_fail (EPHY_IS_NODE (node), -1);
    g_return_val_if_fail (EPHY_IS_NODE (child), -1);

    ret = ephy_node_real_get_child_index (node, child);

    return ret;
}

EphyNode *
ephy_node_get_next_child (EphyNode *node,
              EphyNode *child)
{
    EphyNode *ret;
    guint idx;

    g_return_val_if_fail (EPHY_IS_NODE (node), NULL);
    g_return_val_if_fail (EPHY_IS_NODE (child), NULL);
    
    idx = get_child_index_real (node, child);

    if ((idx + 1) < node->children->len) {
        ret = g_ptr_array_index (node->children, idx + 1);
    } else {
        ret = NULL;
    }

    return ret;
}

EphyNode *
ephy_node_get_previous_child (EphyNode *node,
                  EphyNode *child)
{
    EphyNode *ret;
    int idx;

    g_return_val_if_fail (EPHY_IS_NODE (node), NULL);
    g_return_val_if_fail (EPHY_IS_NODE (child), NULL);
    
    idx = get_child_index_real (node, child);

    if ((idx - 1) >= 0) {
        ret = g_ptr_array_index (node->children, idx - 1);
    } else {
        ret = NULL;
    }

    return ret;
}

int
ephy_node_signal_connect_object (EphyNode *node,
                 EphyNodeSignalType type,
                 EphyNodeCallback callback,
                 GObject *object)
{
    EphyNodeSignalData *signal_data;
    int ret;

    g_return_val_if_fail (EPHY_IS_NODE (node), -1);

    signal_data = g_new0 (EphyNodeSignalData, 1);
    signal_data->node = node;
    signal_data->id = node->signal_id;
    signal_data->callback = callback;
    signal_data->type = type;
    signal_data->data = object;

    g_hash_table_insert (node->signals,
                 GINT_TO_POINTER (node->signal_id),
                 signal_data);
    if (object)
    {
        g_object_weak_ref (object,
                   (GWeakNotify)signal_object_weak_notify,
                   signal_data);
    }

    ret = node->signal_id;
    node->signal_id++;

    return ret;
}

void
ephy_node_signal_disconnect (EphyNode *node,
                 int signal_id)
{
    g_return_if_fail (EPHY_IS_NODE (node));

    g_hash_table_remove (node->signals,
                 GINT_TO_POINTER (signal_id));
}